+++ /dev/null
-use super::coercion::DynamicCoerceMany;
-use super::{Diverges, EnclosingBreakables, Inherited, UnsafetyState};
-use crate::astconv::AstConv;
-
-use rustc_hir as hir;
-use rustc_hir::def_id::DefId;
-use rustc_infer::infer;
-use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
-use rustc_middle::hir::map::blocks::FnLikeNode;
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::subst::GenericArgKind;
-use rustc_middle::ty::{self, Const, Ty, TyCtxt};
-use rustc_session::Session;
-use rustc_span::{self, Span};
-use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode};
-
-use std::cell::{Cell, RefCell};
-use std::ops::Deref;
-
-// The impl for this struct lives in fn_ctxt_impl.rs for file length reasons.
-pub struct FnCtxt<'a, 'tcx> {
- pub(super) body_id: hir::HirId,
-
- /// The parameter environment used for proving trait obligations
- /// in this function. This can change when we descend into
- /// closures (as they bring new things into scope), hence it is
- /// not part of `Inherited` (as of the time of this writing,
- /// closures do not yet change the environment, but they will
- /// eventually).
- pub(super) param_env: ty::ParamEnv<'tcx>,
-
- /// Number of errors that had been reported when we started
- /// checking this function. On exit, if we find that *more* errors
- /// have been reported, we will skip regionck and other work that
- /// expects the types within the function to be consistent.
- // FIXME(matthewjasper) This should not exist, and it's not correct
- // if type checking is run in parallel.
- err_count_on_creation: usize,
-
- /// If `Some`, this stores coercion information for returned
- /// expressions. If `None`, this is in a context where return is
- /// inappropriate, such as a const expression.
- ///
- /// This is a `RefCell<DynamicCoerceMany>`, which means that we
- /// can track all the return expressions and then use them to
- /// compute a useful coercion from the set, similar to a match
- /// expression or other branching context. You can use methods
- /// like `expected_ty` to access the declared return type (if
- /// any).
- pub(super) ret_coercion: Option<RefCell<DynamicCoerceMany<'tcx>>>,
-
- pub(super) ret_coercion_impl_trait: Option<Ty<'tcx>>,
-
- pub(super) ret_type_span: Option<Span>,
-
- /// Used exclusively to reduce cost of advanced evaluation used for
- /// more helpful diagnostics.
- pub(super) in_tail_expr: bool,
-
- /// First span of a return site that we find. Used in error messages.
- pub(super) ret_coercion_span: RefCell<Option<Span>>,
-
- pub(super) resume_yield_tys: Option<(Ty<'tcx>, Ty<'tcx>)>,
-
- pub(super) ps: RefCell<UnsafetyState>,
-
- /// Whether the last checked node generates a divergence (e.g.,
- /// `return` will set this to `Always`). In general, when entering
- /// an expression or other node in the tree, the initial value
- /// indicates whether prior parts of the containing expression may
- /// have diverged. It is then typically set to `Maybe` (and the
- /// old value remembered) for processing the subparts of the
- /// current expression. As each subpart is processed, they may set
- /// the flag to `Always`, etc. Finally, at the end, we take the
- /// result and "union" it with the original value, so that when we
- /// return the flag indicates if any subpart of the parent
- /// expression (up to and including this part) has diverged. So,
- /// if you read it after evaluating a subexpression `X`, the value
- /// you get indicates whether any subexpression that was
- /// evaluating up to and including `X` diverged.
- ///
- /// We currently use this flag only for diagnostic purposes:
- ///
- /// - To warn about unreachable code: if, after processing a
- /// sub-expression but before we have applied the effects of the
- /// current node, we see that the flag is set to `Always`, we
- /// can issue a warning. This corresponds to something like
- /// `foo(return)`; we warn on the `foo()` expression. (We then
- /// update the flag to `WarnedAlways` to suppress duplicate
- /// reports.) Similarly, if we traverse to a fresh statement (or
- /// tail expression) from a `Always` setting, we will issue a
- /// warning. This corresponds to something like `{return;
- /// foo();}` or `{return; 22}`, where we would warn on the
- /// `foo()` or `22`.
- ///
- /// An expression represents dead code if, after checking it,
- /// the diverges flag is set to something other than `Maybe`.
- pub(super) diverges: Cell<Diverges>,
-
- /// Whether any child nodes have any type errors.
- pub(super) has_errors: Cell<bool>,
-
- pub(super) enclosing_breakables: RefCell<EnclosingBreakables<'tcx>>,
-
- pub(super) inh: &'a Inherited<'a, 'tcx>,
-}
-
-impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
- pub fn new(
- inh: &'a Inherited<'a, 'tcx>,
- param_env: ty::ParamEnv<'tcx>,
- body_id: hir::HirId,
- ) -> FnCtxt<'a, 'tcx> {
- FnCtxt {
- body_id,
- param_env,
- err_count_on_creation: inh.tcx.sess.err_count(),
- ret_coercion: None,
- ret_coercion_impl_trait: None,
- ret_type_span: None,
- in_tail_expr: false,
- ret_coercion_span: RefCell::new(None),
- resume_yield_tys: None,
- ps: RefCell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)),
- diverges: Cell::new(Diverges::Maybe),
- has_errors: Cell::new(false),
- enclosing_breakables: RefCell::new(EnclosingBreakables {
- stack: Vec::new(),
- by_id: Default::default(),
- }),
- inh,
- }
- }
-
- pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> {
- ObligationCause::new(span, self.body_id, code)
- }
-
- pub fn misc(&self, span: Span) -> ObligationCause<'tcx> {
- self.cause(span, ObligationCauseCode::MiscObligation)
- }
-
- pub fn sess(&self) -> &Session {
- &self.tcx.sess
- }
-
- pub fn errors_reported_since_creation(&self) -> bool {
- self.tcx.sess.err_count() > self.err_count_on_creation
- }
-}
-
-impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> {
- type Target = Inherited<'a, 'tcx>;
- fn deref(&self) -> &Self::Target {
- &self.inh
- }
-}
-
-impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
- fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
- self.tcx
- }
-
- fn item_def_id(&self) -> Option<DefId> {
- None
- }
-
- fn default_constness_for_trait_bounds(&self) -> hir::Constness {
- // FIXME: refactor this into a method
- let node = self.tcx.hir().get(self.body_id);
- if let Some(fn_like) = FnLikeNode::from_node(node) {
- fn_like.constness()
- } else {
- hir::Constness::NotConst
- }
- }
-
- fn get_type_parameter_bounds(&self, _: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
- let tcx = self.tcx;
- let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
- let item_id = tcx.hir().ty_param_owner(hir_id);
- let item_def_id = tcx.hir().local_def_id(item_id);
- let generics = tcx.generics_of(item_def_id);
- let index = generics.param_def_id_to_index[&def_id];
- ty::GenericPredicates {
- parent: None,
- predicates: tcx.arena.alloc_from_iter(
- self.param_env.caller_bounds().iter().filter_map(|predicate| {
- match predicate.skip_binders() {
- ty::PredicateAtom::Trait(data, _) if data.self_ty().is_param(index) => {
- // HACK(eddyb) should get the original `Span`.
- let span = tcx.def_span(def_id);
- Some((predicate, span))
- }
- _ => None,
- }
- }),
- ),
- }
- }
-
- fn re_infer(&self, def: Option<&ty::GenericParamDef>, span: Span) -> Option<ty::Region<'tcx>> {
- let v = match def {
- Some(def) => infer::EarlyBoundRegion(span, def.name),
- None => infer::MiscVariable(span),
- };
- Some(self.next_region_var(v))
- }
-
- fn allow_ty_infer(&self) -> bool {
- true
- }
-
- fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
- if let Some(param) = param {
- if let GenericArgKind::Type(ty) = self.var_for_def(span, param).unpack() {
- return ty;
- }
- unreachable!()
- } else {
- self.next_ty_var(TypeVariableOrigin {
- kind: TypeVariableOriginKind::TypeInference,
- span,
- })
- }
- }
-
- fn ct_infer(
- &self,
- ty: Ty<'tcx>,
- param: Option<&ty::GenericParamDef>,
- span: Span,
- ) -> &'tcx Const<'tcx> {
- if let Some(param) = param {
- if let GenericArgKind::Const(ct) = self.var_for_def(span, param).unpack() {
- return ct;
- }
- unreachable!()
- } else {
- self.next_const_var(
- ty,
- ConstVariableOrigin { kind: ConstVariableOriginKind::ConstInference, span },
- )
- }
- }
-
- fn projected_ty_from_poly_trait_ref(
- &self,
- span: Span,
- item_def_id: DefId,
- item_segment: &hir::PathSegment<'_>,
- poly_trait_ref: ty::PolyTraitRef<'tcx>,
- ) -> Ty<'tcx> {
- let (trait_ref, _) = self.replace_bound_vars_with_fresh_vars(
- span,
- infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id),
- &poly_trait_ref,
- );
-
- let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
- self,
- self.tcx,
- span,
- item_def_id,
- item_segment,
- trait_ref.substs,
- );
-
- self.tcx().mk_projection(item_def_id, item_substs)
- }
-
- fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
- if ty.has_escaping_bound_vars() {
- ty // FIXME: normalization and escaping regions
- } else {
- self.normalize_associated_types_in(span, &ty)
- }
- }
-
- fn set_tainted_by_errors(&self) {
- self.infcx.set_tainted_by_errors()
- }
-
- fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, _span: Span) {
- self.write_ty(hir_id, ty)
- }
-}
--- /dev/null
+use crate::astconv::{
+ AstConv, ExplicitLateBound, GenericArgCountMismatch, GenericArgCountResult, PathSeg,
+};
+use crate::check::callee::{self, DeferredCallResolution};
+use crate::check::method::{self, MethodCallee, SelfSource};
+use crate::check::{BreakableCtxt, Diverges, Expectation, FallbackMode, FnCtxt, LocalTy};
+
+use rustc_data_structures::captures::Captures;
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::{Applicability, DiagnosticBuilder, ErrorReported};
+use rustc_hir as hir;
+use rustc_hir::def::{CtorOf, DefKind, Res};
+use rustc_hir::def_id::DefId;
+use rustc_hir::lang_items::LangItem;
+use rustc_hir::{ExprKind, GenericArg, Node, QPath};
+use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
+use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
+use rustc_infer::infer::{InferOk, InferResult};
+use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
+use rustc_middle::ty::fold::TypeFoldable;
+use rustc_middle::ty::subst::{
+ self, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSelfTy, UserSubsts,
+};
+use rustc_middle::ty::{
+ self, AdtKind, CanonicalUserType, DefIdTree, GenericParamDefKind, ToPolyTraitRef, ToPredicate,
+ Ty, UserType,
+};
+use rustc_session::lint;
+use rustc_span::hygiene::DesugaringKind;
+use rustc_span::source_map::{original_sp, DUMMY_SP};
+use rustc_span::symbol::{kw, sym, Ident};
+use rustc_span::{self, BytePos, MultiSpan, Span};
+use rustc_trait_selection::infer::InferCtxtExt as _;
+use rustc_trait_selection::opaque_types::InferCtxtExt as _;
+use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
+use rustc_trait_selection::traits::{self, ObligationCauseCode, TraitEngine, TraitEngineExt};
+
+use std::collections::hash_map::Entry;
+use std::slice;
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+ /// Produces warning on the given node, if the current point in the
+ /// function is unreachable, and there hasn't been another warning.
+ pub(in super::super) fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) {
+ // FIXME: Combine these two 'if' expressions into one once
+ // let chains are implemented
+ if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() {
+ // If span arose from a desugaring of `if` or `while`, then it is the condition itself,
+ // which diverges, that we are about to lint on. This gives suboptimal diagnostics.
+ // Instead, stop here so that the `if`- or `while`-expression's block is linted instead.
+ if !span.is_desugaring(DesugaringKind::CondTemporary)
+ && !span.is_desugaring(DesugaringKind::Async)
+ && !orig_span.is_desugaring(DesugaringKind::Await)
+ {
+ self.diverges.set(Diverges::WarnedAlways);
+
+ debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind);
+
+ self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, |lint| {
+ let msg = format!("unreachable {}", kind);
+ lint.build(&msg)
+ .span_label(span, &msg)
+ .span_label(
+ orig_span,
+ custom_note
+ .unwrap_or("any code following this expression is unreachable"),
+ )
+ .emit();
+ })
+ }
+ }
+ }
+
+ /// Resolves type and const variables in `ty` if possible. Unlike the infcx
+ /// version (resolve_vars_if_possible), this version will
+ /// also select obligations if it seems useful, in an effort
+ /// to get more type information.
+ pub(in super::super) fn resolve_vars_with_obligations(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
+ debug!("resolve_vars_with_obligations(ty={:?})", ty);
+
+ // No Infer()? Nothing needs doing.
+ if !ty.has_infer_types_or_consts() {
+ debug!("resolve_vars_with_obligations: ty={:?}", ty);
+ return ty;
+ }
+
+ // If `ty` is a type variable, see whether we already know what it is.
+ ty = self.resolve_vars_if_possible(&ty);
+ if !ty.has_infer_types_or_consts() {
+ debug!("resolve_vars_with_obligations: ty={:?}", ty);
+ return ty;
+ }
+
+ // If not, try resolving pending obligations as much as
+ // possible. This can help substantially when there are
+ // indirect dependencies that don't seem worth tracking
+ // precisely.
+ self.select_obligations_where_possible(false, |_| {});
+ ty = self.resolve_vars_if_possible(&ty);
+
+ debug!("resolve_vars_with_obligations: ty={:?}", ty);
+ ty
+ }
+
+ pub(in super::super) fn record_deferred_call_resolution(
+ &self,
+ closure_def_id: DefId,
+ r: DeferredCallResolution<'tcx>,
+ ) {
+ let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
+ deferred_call_resolutions.entry(closure_def_id).or_default().push(r);
+ }
+
+ pub(in super::super) fn remove_deferred_call_resolutions(
+ &self,
+ closure_def_id: DefId,
+ ) -> Vec<DeferredCallResolution<'tcx>> {
+ let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
+ deferred_call_resolutions.remove(&closure_def_id).unwrap_or(vec![])
+ }
+
+ pub fn tag(&self) -> String {
+ format!("{:p}", self)
+ }
+
+ pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> {
+ self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| {
+ span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid))
+ })
+ }
+
+ #[inline]
+ pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) {
+ debug!(
+ "write_ty({:?}, {:?}) in fcx {}",
+ id,
+ self.resolve_vars_if_possible(&ty),
+ self.tag()
+ );
+ self.typeck_results.borrow_mut().node_types_mut().insert(id, ty);
+
+ if ty.references_error() {
+ self.has_errors.set(true);
+ self.set_tainted_by_errors();
+ }
+ }
+
+ pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) {
+ self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index);
+ }
+
+ pub(in super::super) fn write_resolution(
+ &self,
+ hir_id: hir::HirId,
+ r: Result<(DefKind, DefId), ErrorReported>,
+ ) {
+ self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r);
+ }
+
+ pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) {
+ debug!("write_method_call(hir_id={:?}, method={:?})", hir_id, method);
+ self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id)));
+ self.write_substs(hir_id, method.substs);
+
+ // When the method is confirmed, the `method.substs` includes
+ // parameters from not just the method, but also the impl of
+ // the method -- in particular, the `Self` type will be fully
+ // resolved. However, those are not something that the "user
+ // specified" -- i.e., those types come from the inferred type
+ // of the receiver, not something the user wrote. So when we
+ // create the user-substs, we want to replace those earlier
+ // types with just the types that the user actually wrote --
+ // that is, those that appear on the *method itself*.
+ //
+ // As an example, if the user wrote something like
+ // `foo.bar::<u32>(...)` -- the `Self` type here will be the
+ // type of `foo` (possibly adjusted), but we don't want to
+ // include that. We want just the `[_, u32]` part.
+ if !method.substs.is_noop() {
+ let method_generics = self.tcx.generics_of(method.def_id);
+ if !method_generics.params.is_empty() {
+ let user_type_annotation = self.infcx.probe(|_| {
+ let user_substs = UserSubsts {
+ substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| {
+ let i = param.index as usize;
+ if i < method_generics.parent_count {
+ self.infcx.var_for_def(DUMMY_SP, param)
+ } else {
+ method.substs[i]
+ }
+ }),
+ user_self_ty: None, // not relevant here
+ };
+
+ self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf(
+ method.def_id,
+ user_substs,
+ ))
+ });
+
+ debug!("write_method_call: user_type_annotation={:?}", user_type_annotation);
+ self.write_user_type_annotation(hir_id, user_type_annotation);
+ }
+ }
+ }
+
+ pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) {
+ if !substs.is_noop() {
+ debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag());
+
+ self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs);
+ }
+ }
+
+ /// Given the substs that we just converted from the HIR, try to
+ /// canonicalize them and store them as user-given substitutions
+ /// (i.e., substitutions that must be respected by the NLL check).
+ ///
+ /// This should be invoked **before any unifications have
+ /// occurred**, so that annotations like `Vec<_>` are preserved
+ /// properly.
+ pub fn write_user_type_annotation_from_substs(
+ &self,
+ hir_id: hir::HirId,
+ def_id: DefId,
+ substs: SubstsRef<'tcx>,
+ user_self_ty: Option<UserSelfTy<'tcx>>,
+ ) {
+ debug!(
+ "write_user_type_annotation_from_substs: hir_id={:?} def_id={:?} substs={:?} \
+ user_self_ty={:?} in fcx {}",
+ hir_id,
+ def_id,
+ substs,
+ user_self_ty,
+ self.tag(),
+ );
+
+ if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) {
+ let canonicalized = self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf(
+ def_id,
+ UserSubsts { substs, user_self_ty },
+ ));
+ debug!("write_user_type_annotation_from_substs: canonicalized={:?}", canonicalized);
+ self.write_user_type_annotation(hir_id, canonicalized);
+ }
+ }
+
+ pub fn write_user_type_annotation(
+ &self,
+ hir_id: hir::HirId,
+ canonical_user_type_annotation: CanonicalUserType<'tcx>,
+ ) {
+ debug!(
+ "write_user_type_annotation: hir_id={:?} canonical_user_type_annotation={:?} tag={}",
+ hir_id,
+ canonical_user_type_annotation,
+ self.tag(),
+ );
+
+ if !canonical_user_type_annotation.is_identity() {
+ self.typeck_results
+ .borrow_mut()
+ .user_provided_types_mut()
+ .insert(hir_id, canonical_user_type_annotation);
+ } else {
+ debug!("write_user_type_annotation: skipping identity substs");
+ }
+ }
+
+ pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) {
+ debug!("apply_adjustments(expr={:?}, adj={:?})", expr, adj);
+
+ if adj.is_empty() {
+ return;
+ }
+
+ let autoborrow_mut = adj.iter().any(|adj| {
+ matches!(adj, &Adjustment {
+ kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })),
+ ..
+ })
+ });
+
+ match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) {
+ Entry::Vacant(entry) => {
+ entry.insert(adj);
+ }
+ Entry::Occupied(mut entry) => {
+ debug!(" - composing on top of {:?}", entry.get());
+ match (&entry.get()[..], &adj[..]) {
+ // Applying any adjustment on top of a NeverToAny
+ // is a valid NeverToAny adjustment, because it can't
+ // be reached.
+ (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return,
+ (&[
+ Adjustment { kind: Adjust::Deref(_), .. },
+ Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. },
+ ], &[
+ Adjustment { kind: Adjust::Deref(_), .. },
+ .. // Any following adjustments are allowed.
+ ]) => {
+ // A reborrow has no effect before a dereference.
+ }
+ // FIXME: currently we never try to compose autoderefs
+ // and ReifyFnPointer/UnsafeFnPointer, but we could.
+ _ =>
+ bug!("while adjusting {:?}, can't compose {:?} and {:?}",
+ expr, entry.get(), adj)
+ };
+ *entry.get_mut() = adj;
+ }
+ }
+
+ // If there is an mutable auto-borrow, it is equivalent to `&mut <expr>`.
+ // In this case implicit use of `Deref` and `Index` within `<expr>` should
+ // instead be `DerefMut` and `IndexMut`, so fix those up.
+ if autoborrow_mut {
+ self.convert_place_derefs_to_mutable(expr);
+ }
+ }
+
+ /// Basically whenever we are converting from a type scheme into
+ /// the fn body space, we always want to normalize associated
+ /// types as well. This function combines the two.
+ fn instantiate_type_scheme<T>(&self, span: Span, substs: SubstsRef<'tcx>, value: &T) -> T
+ where
+ T: TypeFoldable<'tcx>,
+ {
+ let value = value.subst(self.tcx, substs);
+ let result = self.normalize_associated_types_in(span, &value);
+ debug!("instantiate_type_scheme(value={:?}, substs={:?}) = {:?}", value, substs, result);
+ result
+ }
+
+ /// As `instantiate_type_scheme`, but for the bounds found in a
+ /// generic type scheme.
+ pub(in super::super) fn instantiate_bounds(
+ &self,
+ span: Span,
+ def_id: DefId,
+ substs: SubstsRef<'tcx>,
+ ) -> (ty::InstantiatedPredicates<'tcx>, Vec<Span>) {
+ let bounds = self.tcx.predicates_of(def_id);
+ let spans: Vec<Span> = bounds.predicates.iter().map(|(_, span)| *span).collect();
+ let result = bounds.instantiate(self.tcx, substs);
+ let result = self.normalize_associated_types_in(span, &result);
+ debug!(
+ "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}",
+ bounds, substs, result, spans,
+ );
+ (result, spans)
+ }
+
+ /// Replaces the opaque types from the given value with type variables,
+ /// and records the `OpaqueTypeMap` for later use during writeback. See
+ /// `InferCtxt::instantiate_opaque_types` for more details.
+ pub(in super::super) fn instantiate_opaque_types_from_value<T: TypeFoldable<'tcx>>(
+ &self,
+ parent_id: hir::HirId,
+ value: &T,
+ value_span: Span,
+ ) -> T {
+ let parent_def_id = self.tcx.hir().local_def_id(parent_id);
+ debug!(
+ "instantiate_opaque_types_from_value(parent_def_id={:?}, value={:?})",
+ parent_def_id, value
+ );
+
+ let (value, opaque_type_map) =
+ self.register_infer_ok_obligations(self.instantiate_opaque_types(
+ parent_def_id,
+ self.body_id,
+ self.param_env,
+ value,
+ value_span,
+ ));
+
+ let mut opaque_types = self.opaque_types.borrow_mut();
+ let mut opaque_types_vars = self.opaque_types_vars.borrow_mut();
+ for (ty, decl) in opaque_type_map {
+ let _ = opaque_types.insert(ty, decl);
+ let _ = opaque_types_vars.insert(decl.concrete_ty, decl.opaque_type);
+ }
+
+ value
+ }
+
+ pub(in super::super) fn normalize_associated_types_in<T>(&self, span: Span, value: &T) -> T
+ where
+ T: TypeFoldable<'tcx>,
+ {
+ self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value)
+ }
+
+ pub(in super::super) fn normalize_associated_types_in_as_infer_ok<T>(
+ &self,
+ span: Span,
+ value: &T,
+ ) -> InferOk<'tcx, T>
+ where
+ T: TypeFoldable<'tcx>,
+ {
+ self.inh.partially_normalize_associated_types_in(span, self.body_id, self.param_env, value)
+ }
+
+ pub fn require_type_meets(
+ &self,
+ ty: Ty<'tcx>,
+ span: Span,
+ code: traits::ObligationCauseCode<'tcx>,
+ def_id: DefId,
+ ) {
+ self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code));
+ }
+
+ pub fn require_type_is_sized(
+ &self,
+ ty: Ty<'tcx>,
+ span: Span,
+ code: traits::ObligationCauseCode<'tcx>,
+ ) {
+ if !ty.references_error() {
+ let lang_item = self.tcx.require_lang_item(LangItem::Sized, None);
+ self.require_type_meets(ty, span, code, lang_item);
+ }
+ }
+
+ pub fn require_type_is_sized_deferred(
+ &self,
+ ty: Ty<'tcx>,
+ span: Span,
+ code: traits::ObligationCauseCode<'tcx>,
+ ) {
+ if !ty.references_error() {
+ self.deferred_sized_obligations.borrow_mut().push((ty, span, code));
+ }
+ }
+
+ pub fn register_bound(
+ &self,
+ ty: Ty<'tcx>,
+ def_id: DefId,
+ cause: traits::ObligationCause<'tcx>,
+ ) {
+ if !ty.references_error() {
+ self.fulfillment_cx.borrow_mut().register_bound(
+ self,
+ self.param_env,
+ ty,
+ def_id,
+ cause,
+ );
+ }
+ }
+
+ pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> {
+ let t = AstConv::ast_ty_to_ty(self, ast_t);
+ self.register_wf_obligation(t.into(), ast_t.span, traits::MiscObligation);
+ t
+ }
+
+ pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
+ let ty = self.to_ty(ast_ty);
+ debug!("to_ty_saving_user_provided_ty: ty={:?}", ty);
+
+ if Self::can_contain_user_lifetime_bounds(ty) {
+ let c_ty = self.infcx.canonicalize_response(&UserType::Ty(ty));
+ debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty);
+ self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty);
+ }
+
+ ty
+ }
+
+ pub fn to_const(&self, ast_c: &hir::AnonConst) -> &'tcx ty::Const<'tcx> {
+ let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id);
+ let c = ty::Const::from_anon_const(self.tcx, const_def_id);
+ self.register_wf_obligation(
+ c.into(),
+ self.tcx.hir().span(ast_c.hir_id),
+ ObligationCauseCode::MiscObligation,
+ );
+ c
+ }
+
+ pub fn const_arg_to_const(
+ &self,
+ ast_c: &hir::AnonConst,
+ param_def_id: DefId,
+ ) -> &'tcx ty::Const<'tcx> {
+ let const_def = ty::WithOptConstParam {
+ did: self.tcx.hir().local_def_id(ast_c.hir_id),
+ const_param_did: Some(param_def_id),
+ };
+ let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def);
+ self.register_wf_obligation(
+ c.into(),
+ self.tcx.hir().span(ast_c.hir_id),
+ ObligationCauseCode::MiscObligation,
+ );
+ c
+ }
+
+ // If the type given by the user has free regions, save it for later, since
+ // NLL would like to enforce those. Also pass in types that involve
+ // projections, since those can resolve to `'static` bounds (modulo #54940,
+ // which hopefully will be fixed by the time you see this comment, dear
+ // reader, although I have my doubts). Also pass in types with inference
+ // types, because they may be repeated. Other sorts of things are already
+ // sufficiently enforced with erased regions. =)
+ fn can_contain_user_lifetime_bounds<T>(t: T) -> bool
+ where
+ T: TypeFoldable<'tcx>,
+ {
+ t.has_free_regions() || t.has_projections() || t.has_infer_types()
+ }
+
+ pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> {
+ match self.typeck_results.borrow().node_types().get(id) {
+ Some(&t) => t,
+ None if self.is_tainted_by_errors() => self.tcx.ty_error(),
+ None => {
+ bug!(
+ "no type for node {}: {} in fcx {}",
+ id,
+ self.tcx.hir().node_to_string(id),
+ self.tag()
+ );
+ }
+ }
+ }
+
+ /// Registers an obligation for checking later, during regionck, that `arg` is well-formed.
+ pub fn register_wf_obligation(
+ &self,
+ arg: subst::GenericArg<'tcx>,
+ span: Span,
+ code: traits::ObligationCauseCode<'tcx>,
+ ) {
+ // WF obligations never themselves fail, so no real need to give a detailed cause:
+ let cause = traits::ObligationCause::new(span, self.body_id, code);
+ self.register_predicate(traits::Obligation::new(
+ cause,
+ self.param_env,
+ ty::PredicateAtom::WellFormed(arg).to_predicate(self.tcx),
+ ));
+ }
+
+ /// Registers obligations that all `substs` are well-formed.
+ pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) {
+ for arg in substs.iter().filter(|arg| {
+ matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..))
+ }) {
+ self.register_wf_obligation(arg, expr.span, traits::MiscObligation);
+ }
+ }
+
+ /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each
+ /// type/region parameter was instantiated (`substs`), creates and registers suitable
+ /// trait/region obligations.
+ ///
+ /// For example, if there is a function:
+ ///
+ /// ```
+ /// fn foo<'a,T:'a>(...)
+ /// ```
+ ///
+ /// and a reference:
+ ///
+ /// ```
+ /// let f = foo;
+ /// ```
+ ///
+ /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a`
+ /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally.
+ pub fn add_obligations_for_parameters(
+ &self,
+ cause: traits::ObligationCause<'tcx>,
+ predicates: ty::InstantiatedPredicates<'tcx>,
+ ) {
+ assert!(!predicates.has_escaping_bound_vars());
+
+ debug!("add_obligations_for_parameters(predicates={:?})", predicates);
+
+ for obligation in traits::predicates_for_generics(cause, self.param_env, predicates) {
+ self.register_predicate(obligation);
+ }
+ }
+
+ // FIXME(arielb1): use this instead of field.ty everywhere
+ // Only for fields! Returns <none> for methods>
+ // Indifferent to privacy flags
+ pub fn field_ty(
+ &self,
+ span: Span,
+ field: &'tcx ty::FieldDef,
+ substs: SubstsRef<'tcx>,
+ ) -> Ty<'tcx> {
+ self.normalize_associated_types_in(span, &field.ty(self.tcx, substs))
+ }
+
+ pub(in super::super) fn resolve_generator_interiors(&self, def_id: DefId) {
+ let mut generators = self.deferred_generator_interiors.borrow_mut();
+ for (body_id, interior, kind) in generators.drain(..) {
+ self.select_obligations_where_possible(false, |_| {});
+ crate::check::generator_interior::resolve_interior(
+ self, def_id, body_id, interior, kind,
+ );
+ }
+ }
+
+ // Tries to apply a fallback to `ty` if it is an unsolved variable.
+ //
+ // - Unconstrained ints are replaced with `i32`.
+ //
+ // - Unconstrained floats are replaced with with `f64`.
+ //
+ // - Non-numerics get replaced with `!` when `#![feature(never_type_fallback)]`
+ // is enabled. Otherwise, they are replaced with `()`.
+ //
+ // Fallback becomes very dubious if we have encountered type-checking errors.
+ // In that case, fallback to Error.
+ // The return value indicates whether fallback has occurred.
+ pub(in super::super) fn fallback_if_possible(&self, ty: Ty<'tcx>, mode: FallbackMode) -> bool {
+ use rustc_middle::ty::error::UnconstrainedNumeric::Neither;
+ use rustc_middle::ty::error::UnconstrainedNumeric::{UnconstrainedFloat, UnconstrainedInt};
+
+ assert!(ty.is_ty_infer());
+ let fallback = match self.type_is_unconstrained_numeric(ty) {
+ _ if self.is_tainted_by_errors() => self.tcx().ty_error(),
+ UnconstrainedInt => self.tcx.types.i32,
+ UnconstrainedFloat => self.tcx.types.f64,
+ Neither if self.type_var_diverges(ty) => self.tcx.mk_diverging_default(),
+ Neither => {
+ // This type variable was created from the instantiation of an opaque
+ // type. The fact that we're attempting to perform fallback for it
+ // means that the function neither constrained it to a concrete
+ // type, nor to the opaque type itself.
+ //
+ // For example, in this code:
+ //
+ //```
+ // type MyType = impl Copy;
+ // fn defining_use() -> MyType { true }
+ // fn other_use() -> MyType { defining_use() }
+ // ```
+ //
+ // `defining_use` will constrain the instantiated inference
+ // variable to `bool`, while `other_use` will constrain
+ // the instantiated inference variable to `MyType`.
+ //
+ // When we process opaque types during writeback, we
+ // will handle cases like `other_use`, and not count
+ // them as defining usages
+ //
+ // However, we also need to handle cases like this:
+ //
+ // ```rust
+ // pub type Foo = impl Copy;
+ // fn produce() -> Option<Foo> {
+ // None
+ // }
+ // ```
+ //
+ // In the above snippet, the inference variable created by
+ // instantiating `Option<Foo>` will be completely unconstrained.
+ // We treat this as a non-defining use by making the inference
+ // variable fall back to the opaque type itself.
+ if let FallbackMode::All = mode {
+ if let Some(opaque_ty) = self.opaque_types_vars.borrow().get(ty) {
+ debug!(
+ "fallback_if_possible: falling back opaque type var {:?} to {:?}",
+ ty, opaque_ty
+ );
+ *opaque_ty
+ } else {
+ return false;
+ }
+ } else {
+ return false;
+ }
+ }
+ };
+ debug!("fallback_if_possible: defaulting `{:?}` to `{:?}`", ty, fallback);
+ self.demand_eqtype(rustc_span::DUMMY_SP, ty, fallback);
+ true
+ }
+
+ pub(in super::super) fn select_all_obligations_or_error(&self) {
+ debug!("select_all_obligations_or_error");
+ if let Err(errors) = self.fulfillment_cx.borrow_mut().select_all_or_error(&self) {
+ self.report_fulfillment_errors(&errors, self.inh.body_id, false);
+ }
+ }
+
+ /// Select as many obligations as we can at present.
+ pub(in super::super) fn select_obligations_where_possible(
+ &self,
+ fallback_has_occurred: bool,
+ mutate_fullfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
+ ) {
+ let result = self.fulfillment_cx.borrow_mut().select_where_possible(self);
+ if let Err(mut errors) = result {
+ mutate_fullfillment_errors(&mut errors);
+ self.report_fulfillment_errors(&errors, self.inh.body_id, fallback_has_occurred);
+ }
+ }
+
+ /// For the overloaded place expressions (`*x`, `x[3]`), the trait
+ /// returns a type of `&T`, but the actual type we assign to the
+ /// *expression* is `T`. So this function just peels off the return
+ /// type by one layer to yield `T`.
+ pub(in super::super) fn make_overloaded_place_return_type(
+ &self,
+ method: MethodCallee<'tcx>,
+ ) -> ty::TypeAndMut<'tcx> {
+ // extract method return type, which will be &T;
+ let ret_ty = method.sig.output();
+
+ // method returns &T, but the type as visible to user is T, so deref
+ ret_ty.builtin_deref(true).unwrap()
+ }
+
+ fn self_type_matches_expected_vid(
+ &self,
+ trait_ref: ty::PolyTraitRef<'tcx>,
+ expected_vid: ty::TyVid,
+ ) -> bool {
+ let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty());
+ debug!(
+ "self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?}, expected_vid={:?})",
+ trait_ref, self_ty, expected_vid
+ );
+ match *self_ty.kind() {
+ ty::Infer(ty::TyVar(found_vid)) => {
+ // FIXME: consider using `sub_root_var` here so we
+ // can see through subtyping.
+ let found_vid = self.root_var(found_vid);
+ debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid);
+ expected_vid == found_vid
+ }
+ _ => false,
+ }
+ }
+
+ pub(in super::super) fn obligations_for_self_ty<'b>(
+ &'b self,
+ self_ty: ty::TyVid,
+ ) -> impl Iterator<Item = (ty::PolyTraitRef<'tcx>, traits::PredicateObligation<'tcx>)>
+ + Captures<'tcx>
+ + 'b {
+ // FIXME: consider using `sub_root_var` here so we
+ // can see through subtyping.
+ let ty_var_root = self.root_var(self_ty);
+ debug!(
+ "obligations_for_self_ty: self_ty={:?} ty_var_root={:?} pending_obligations={:?}",
+ self_ty,
+ ty_var_root,
+ self.fulfillment_cx.borrow().pending_obligations()
+ );
+
+ self.fulfillment_cx
+ .borrow()
+ .pending_obligations()
+ .into_iter()
+ .filter_map(move |obligation| {
+ match obligation.predicate.skip_binders() {
+ ty::PredicateAtom::Projection(data) => {
+ Some((ty::Binder::bind(data).to_poly_trait_ref(self.tcx), obligation))
+ }
+ ty::PredicateAtom::Trait(data, _) => {
+ Some((ty::Binder::bind(data).to_poly_trait_ref(), obligation))
+ }
+ ty::PredicateAtom::Subtype(..) => None,
+ ty::PredicateAtom::RegionOutlives(..) => None,
+ ty::PredicateAtom::TypeOutlives(..) => None,
+ ty::PredicateAtom::WellFormed(..) => None,
+ ty::PredicateAtom::ObjectSafe(..) => None,
+ ty::PredicateAtom::ConstEvaluatable(..) => None,
+ ty::PredicateAtom::ConstEquate(..) => None,
+ // N.B., this predicate is created by breaking down a
+ // `ClosureType: FnFoo()` predicate, where
+ // `ClosureType` represents some `Closure`. It can't
+ // possibly be referring to the current closure,
+ // because we haven't produced the `Closure` for
+ // this closure yet; this is exactly why the other
+ // code is looking for a self type of a unresolved
+ // inference variable.
+ ty::PredicateAtom::ClosureKind(..) => None,
+ ty::PredicateAtom::TypeWellFormedFromEnv(..) => None,
+ }
+ })
+ .filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root))
+ }
+
+ pub(in super::super) fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool {
+ self.obligations_for_self_ty(self_ty)
+ .any(|(tr, _)| Some(tr.def_id()) == self.tcx.lang_items().sized_trait())
+ }
+
+ pub(in super::super) fn err_args(&self, len: usize) -> Vec<Ty<'tcx>> {
+ vec![self.tcx.ty_error(); len]
+ }
+
+ /// Unifies the output type with the expected type early, for more coercions
+ /// and forward type information on the input expressions.
+ pub(in super::super) fn expected_inputs_for_expected_output(
+ &self,
+ call_span: Span,
+ expected_ret: Expectation<'tcx>,
+ formal_ret: Ty<'tcx>,
+ formal_args: &[Ty<'tcx>],
+ ) -> Vec<Ty<'tcx>> {
+ let formal_ret = self.resolve_vars_with_obligations(formal_ret);
+ let ret_ty = match expected_ret.only_has_type(self) {
+ Some(ret) => ret,
+ None => return Vec::new(),
+ };
+ let expect_args = self
+ .fudge_inference_if_ok(|| {
+ // Attempt to apply a subtyping relationship between the formal
+ // return type (likely containing type variables if the function
+ // is polymorphic) and the expected return type.
+ // No argument expectations are produced if unification fails.
+ let origin = self.misc(call_span);
+ let ures = self.at(&origin, self.param_env).sup(ret_ty, &formal_ret);
+
+ // FIXME(#27336) can't use ? here, Try::from_error doesn't default
+ // to identity so the resulting type is not constrained.
+ match ures {
+ Ok(ok) => {
+ // Process any obligations locally as much as
+ // we can. We don't care if some things turn
+ // out unconstrained or ambiguous, as we're
+ // just trying to get hints here.
+ self.save_and_restore_in_snapshot_flag(|_| {
+ let mut fulfill = TraitEngine::new(self.tcx);
+ for obligation in ok.obligations {
+ fulfill.register_predicate_obligation(self, obligation);
+ }
+ fulfill.select_where_possible(self)
+ })
+ .map_err(|_| ())?;
+ }
+ Err(_) => return Err(()),
+ }
+
+ // Record all the argument types, with the substitutions
+ // produced from the above subtyping unification.
+ Ok(formal_args.iter().map(|ty| self.resolve_vars_if_possible(ty)).collect())
+ })
+ .unwrap_or_default();
+ debug!(
+ "expected_inputs_for_expected_output(formal={:?} -> {:?}, expected={:?} -> {:?})",
+ formal_args, formal_ret, expect_args, expected_ret
+ );
+ expect_args
+ }
+
+ pub(in super::super) fn resolve_lang_item_path(
+ &self,
+ lang_item: hir::LangItem,
+ span: Span,
+ hir_id: hir::HirId,
+ ) -> (Res, Ty<'tcx>) {
+ let def_id = self.tcx.require_lang_item(lang_item, Some(span));
+ let def_kind = self.tcx.def_kind(def_id);
+
+ let item_ty = if let DefKind::Variant = def_kind {
+ self.tcx.type_of(self.tcx.parent(def_id).expect("variant w/out parent"))
+ } else {
+ self.tcx.type_of(def_id)
+ };
+ let substs = self.infcx.fresh_substs_for_item(span, def_id);
+ let ty = item_ty.subst(self.tcx, substs);
+
+ self.write_resolution(hir_id, Ok((def_kind, def_id)));
+ self.add_required_obligations(span, def_id, &substs);
+ (Res::Def(def_kind, def_id), ty)
+ }
+
+ /// Resolves an associated value path into a base type and associated constant, or method
+ /// resolution. The newly resolved definition is written into `type_dependent_defs`.
+ pub fn resolve_ty_and_res_ufcs<'b>(
+ &self,
+ qpath: &'b QPath<'b>,
+ hir_id: hir::HirId,
+ span: Span,
+ ) -> (Res, Option<Ty<'tcx>>, &'b [hir::PathSegment<'b>]) {
+ debug!("resolve_ty_and_res_ufcs: qpath={:?} hir_id={:?} span={:?}", qpath, hir_id, span);
+ let (ty, qself, item_segment) = match *qpath {
+ QPath::Resolved(ref opt_qself, ref path) => {
+ return (
+ path.res,
+ opt_qself.as_ref().map(|qself| self.to_ty(qself)),
+ &path.segments[..],
+ );
+ }
+ QPath::TypeRelative(ref qself, ref segment) => (self.to_ty(qself), qself, segment),
+ QPath::LangItem(..) => bug!("`resolve_ty_and_res_ufcs` called on `LangItem`"),
+ };
+ if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id)
+ {
+ // Return directly on cache hit. This is useful to avoid doubly reporting
+ // errors with default match binding modes. See #44614.
+ let def =
+ cached_result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err);
+ return (def, Some(ty), slice::from_ref(&**item_segment));
+ }
+ let item_name = item_segment.ident;
+ let result = self.resolve_ufcs(span, item_name, ty, hir_id).or_else(|error| {
+ let result = match error {
+ method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
+ _ => Err(ErrorReported),
+ };
+ if item_name.name != kw::Invalid {
+ if let Some(mut e) = self.report_method_error(
+ span,
+ ty,
+ item_name,
+ SelfSource::QPath(qself),
+ error,
+ None,
+ ) {
+ e.emit();
+ }
+ }
+ result
+ });
+
+ // Write back the new resolution.
+ self.write_resolution(hir_id, result);
+ (
+ result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err),
+ Some(ty),
+ slice::from_ref(&**item_segment),
+ )
+ }
+
+ /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise.
+ pub(in super::super) fn get_node_fn_decl(
+ &self,
+ node: Node<'tcx>,
+ ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> {
+ match node {
+ Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => {
+ // This is less than ideal, it will not suggest a return type span on any
+ // method called `main`, regardless of whether it is actually the entry point,
+ // but it will still present it as the reason for the expected type.
+ Some((&sig.decl, ident, ident.name != sym::main))
+ }
+ Node::TraitItem(&hir::TraitItem {
+ ident,
+ kind: hir::TraitItemKind::Fn(ref sig, ..),
+ ..
+ }) => Some((&sig.decl, ident, true)),
+ Node::ImplItem(&hir::ImplItem {
+ ident,
+ kind: hir::ImplItemKind::Fn(ref sig, ..),
+ ..
+ }) => Some((&sig.decl, ident, false)),
+ _ => None,
+ }
+ }
+
+ /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a
+ /// suggestion can be made, `None` otherwise.
+ pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> {
+ // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or
+ // `while` before reaching it, as block tail returns are not available in them.
+ self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| {
+ let parent = self.tcx.hir().get(blk_id);
+ self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main))
+ })
+ }
+
+ pub(in super::super) fn note_internal_mutation_in_method(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ ) {
+ if found != self.tcx.types.unit {
+ return;
+ }
+ if let ExprKind::MethodCall(path_segment, _, [rcvr, ..], _) = expr.kind {
+ if self
+ .typeck_results
+ .borrow()
+ .expr_ty_adjusted_opt(rcvr)
+ .map_or(true, |ty| expected.peel_refs() != ty.peel_refs())
+ {
+ return;
+ }
+ let mut sp = MultiSpan::from_span(path_segment.ident.span);
+ sp.push_span_label(
+ path_segment.ident.span,
+ format!(
+ "this call modifies {} in-place",
+ match rcvr.kind {
+ ExprKind::Path(QPath::Resolved(
+ None,
+ hir::Path { segments: [segment], .. },
+ )) => format!("`{}`", segment.ident),
+ _ => "its receiver".to_string(),
+ }
+ ),
+ );
+ sp.push_span_label(
+ rcvr.span,
+ "you probably want to use this value after calling the method...".to_string(),
+ );
+ err.span_note(
+ sp,
+ &format!("method `{}` modifies its receiver in-place", path_segment.ident),
+ );
+ err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident));
+ }
+ }
+
+ pub(in super::super) fn note_need_for_fn_pointer(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ ) {
+ let (sig, did, substs) = match (&expected.kind(), &found.kind()) {
+ (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => {
+ let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1);
+ let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2);
+ if sig1 != sig2 {
+ return;
+ }
+ err.note(
+ "different `fn` items always have unique types, even if their signatures are \
+ the same",
+ );
+ (sig1, *did1, substs1)
+ }
+ (ty::FnDef(did, substs), ty::FnPtr(sig2)) => {
+ let sig1 = self.tcx.fn_sig(*did).subst(self.tcx, substs);
+ if sig1 != *sig2 {
+ return;
+ }
+ (sig1, *did, substs)
+ }
+ _ => return,
+ };
+ err.help(&format!("change the expected type to be function pointer `{}`", sig));
+ err.help(&format!(
+ "if the expected type is due to type inference, cast the expected `fn` to a function \
+ pointer: `{} as {}`",
+ self.tcx.def_path_str_with_substs(did, substs),
+ sig
+ ));
+ }
+
+ pub(in super::super) fn could_remove_semicolon(
+ &self,
+ blk: &'tcx hir::Block<'tcx>,
+ expected_ty: Ty<'tcx>,
+ ) -> Option<Span> {
+ // Be helpful when the user wrote `{... expr;}` and
+ // taking the `;` off is enough to fix the error.
+ let last_stmt = blk.stmts.last()?;
+ let last_expr = match last_stmt.kind {
+ hir::StmtKind::Semi(ref e) => e,
+ _ => return None,
+ };
+ let last_expr_ty = self.node_ty(last_expr.hir_id);
+ if matches!(last_expr_ty.kind(), ty::Error(_))
+ || self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err()
+ {
+ return None;
+ }
+ let original_span = original_sp(last_stmt.span, blk.span);
+ Some(original_span.with_lo(original_span.hi() - BytePos(1)))
+ }
+
+ // Instantiates the given path, which must refer to an item with the given
+ // number of type parameters and type.
+ pub fn instantiate_value_path(
+ &self,
+ segments: &[hir::PathSegment<'_>],
+ self_ty: Option<Ty<'tcx>>,
+ res: Res,
+ span: Span,
+ hir_id: hir::HirId,
+ ) -> (Ty<'tcx>, Res) {
+ debug!(
+ "instantiate_value_path(segments={:?}, self_ty={:?}, res={:?}, hir_id={})",
+ segments, self_ty, res, hir_id,
+ );
+
+ let tcx = self.tcx;
+
+ let path_segs = match res {
+ Res::Local(_) | Res::SelfCtor(_) => vec![],
+ Res::Def(kind, def_id) => {
+ AstConv::def_ids_for_value_path_segments(self, segments, self_ty, kind, def_id)
+ }
+ _ => bug!("instantiate_value_path on {:?}", res),
+ };
+
+ let mut user_self_ty = None;
+ let mut is_alias_variant_ctor = false;
+ match res {
+ Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) => {
+ if let Some(self_ty) = self_ty {
+ let adt_def = self_ty.ty_adt_def().unwrap();
+ user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did, self_ty });
+ is_alias_variant_ctor = true;
+ }
+ }
+ Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => {
+ let container = tcx.associated_item(def_id).container;
+ debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container);
+ match container {
+ ty::TraitContainer(trait_did) => {
+ callee::check_legal_trait_for_method_call(tcx, span, None, trait_did)
+ }
+ ty::ImplContainer(impl_def_id) => {
+ if segments.len() == 1 {
+ // `<T>::assoc` will end up here, and so
+ // can `T::assoc`. It this came from an
+ // inherent impl, we need to record the
+ // `T` for posterity (see `UserSelfTy` for
+ // details).
+ let self_ty = self_ty.expect("UFCS sugared assoc missing Self");
+ user_self_ty = Some(UserSelfTy { impl_def_id, self_ty });
+ }
+ }
+ }
+ }
+ _ => {}
+ }
+
+ // Now that we have categorized what space the parameters for each
+ // segment belong to, let's sort out the parameters that the user
+ // provided (if any) into their appropriate spaces. We'll also report
+ // errors if type parameters are provided in an inappropriate place.
+
+ let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect();
+ let generics_has_err = AstConv::prohibit_generics(
+ self,
+ segments.iter().enumerate().filter_map(|(index, seg)| {
+ if !generic_segs.contains(&index) || is_alias_variant_ctor {
+ Some(seg)
+ } else {
+ None
+ }
+ }),
+ );
+
+ if let Res::Local(hid) = res {
+ let ty = self.local_ty(span, hid).decl_ty;
+ let ty = self.normalize_associated_types_in(span, &ty);
+ self.write_ty(hir_id, ty);
+ return (ty, res);
+ }
+
+ if generics_has_err {
+ // Don't try to infer type parameters when prohibited generic arguments were given.
+ user_self_ty = None;
+ }
+
+ // Now we have to compare the types that the user *actually*
+ // provided against the types that were *expected*. If the user
+ // did not provide any types, then we want to substitute inference
+ // variables. If the user provided some types, we may still need
+ // to add defaults. If the user provided *too many* types, that's
+ // a problem.
+
+ let mut infer_args_for_err = FxHashSet::default();
+ for &PathSeg(def_id, index) in &path_segs {
+ let seg = &segments[index];
+ let generics = tcx.generics_of(def_id);
+ // Argument-position `impl Trait` is treated as a normal generic
+ // parameter internally, but we don't allow users to specify the
+ // parameter's value explicitly, so we have to do some error-
+ // checking here.
+ if let GenericArgCountResult {
+ correct: Err(GenericArgCountMismatch { reported: Some(ErrorReported), .. }),
+ ..
+ } = AstConv::check_generic_arg_count_for_call(
+ tcx, span, &generics, &seg, false, // `is_method_call`
+ ) {
+ infer_args_for_err.insert(index);
+ self.set_tainted_by_errors(); // See issue #53251.
+ }
+ }
+
+ let has_self = path_segs
+ .last()
+ .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self)
+ .unwrap_or(false);
+
+ let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res {
+ let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id));
+ match *ty.kind() {
+ ty::Adt(adt_def, substs) if adt_def.has_ctor() => {
+ let variant = adt_def.non_enum_variant();
+ let ctor_def_id = variant.ctor_def_id.unwrap();
+ (
+ Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id),
+ Some(substs),
+ )
+ }
+ _ => {
+ let mut err = tcx.sess.struct_span_err(
+ span,
+ "the `Self` constructor can only be used with tuple or unit structs",
+ );
+ if let Some(adt_def) = ty.ty_adt_def() {
+ match adt_def.adt_kind() {
+ AdtKind::Enum => {
+ err.help("did you mean to use one of the enum's variants?");
+ }
+ AdtKind::Struct | AdtKind::Union => {
+ err.span_suggestion(
+ span,
+ "use curly brackets",
+ String::from("Self { /* fields */ }"),
+ Applicability::HasPlaceholders,
+ );
+ }
+ }
+ }
+ err.emit();
+
+ return (tcx.ty_error(), res);
+ }
+ }
+ } else {
+ (res, None)
+ };
+ let def_id = res.def_id();
+
+ // The things we are substituting into the type should not contain
+ // escaping late-bound regions, and nor should the base type scheme.
+ let ty = tcx.type_of(def_id);
+
+ let arg_count = GenericArgCountResult {
+ explicit_late_bound: ExplicitLateBound::No,
+ correct: if infer_args_for_err.is_empty() {
+ Ok(())
+ } else {
+ Err(GenericArgCountMismatch::default())
+ },
+ };
+
+ let substs = self_ctor_substs.unwrap_or_else(|| {
+ AstConv::create_substs_for_generic_args(
+ tcx,
+ def_id,
+ &[][..],
+ has_self,
+ self_ty,
+ arg_count,
+ // Provide the generic args, and whether types should be inferred.
+ |def_id| {
+ if let Some(&PathSeg(_, index)) =
+ path_segs.iter().find(|&PathSeg(did, _)| *did == def_id)
+ {
+ // If we've encountered an `impl Trait`-related error, we're just
+ // going to infer the arguments for better error messages.
+ if !infer_args_for_err.contains(&index) {
+ // Check whether the user has provided generic arguments.
+ if let Some(ref data) = segments[index].args {
+ return (Some(data), segments[index].infer_args);
+ }
+ }
+ return (None, segments[index].infer_args);
+ }
+
+ (None, true)
+ },
+ // Provide substitutions for parameters for which (valid) arguments have been provided.
+ |param, arg| match (¶m.kind, arg) {
+ (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
+ AstConv::ast_region_to_region(self, lt, Some(param)).into()
+ }
+ (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
+ self.to_ty(ty).into()
+ }
+ (GenericParamDefKind::Const, GenericArg::Const(ct)) => {
+ self.const_arg_to_const(&ct.value, param.def_id).into()
+ }
+ _ => unreachable!(),
+ },
+ // Provide substitutions for parameters for which arguments are inferred.
+ |substs, param, infer_args| {
+ match param.kind {
+ GenericParamDefKind::Lifetime => {
+ self.re_infer(Some(param), span).unwrap().into()
+ }
+ GenericParamDefKind::Type { has_default, .. } => {
+ if !infer_args && has_default {
+ // If we have a default, then we it doesn't matter that we're not
+ // inferring the type arguments: we provide the default where any
+ // is missing.
+ let default = tcx.type_of(param.def_id);
+ self.normalize_ty(
+ span,
+ default.subst_spanned(tcx, substs.unwrap(), Some(span)),
+ )
+ .into()
+ } else {
+ // If no type arguments were provided, we have to infer them.
+ // This case also occurs as a result of some malformed input, e.g.
+ // a lifetime argument being given instead of a type parameter.
+ // Using inference instead of `Error` gives better error messages.
+ self.var_for_def(span, param)
+ }
+ }
+ GenericParamDefKind::Const => {
+ // FIXME(const_generics:defaults)
+ // No const parameters were provided, we have to infer them.
+ self.var_for_def(span, param)
+ }
+ }
+ },
+ )
+ });
+ assert!(!substs.has_escaping_bound_vars());
+ assert!(!ty.has_escaping_bound_vars());
+
+ // First, store the "user substs" for later.
+ self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty);
+
+ self.add_required_obligations(span, def_id, &substs);
+
+ // Substitute the values for the type parameters into the type of
+ // the referenced item.
+ let ty_substituted = self.instantiate_type_scheme(span, &substs, &ty);
+
+ if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
+ // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
+ // is inherent, there is no `Self` parameter; instead, the impl needs
+ // type parameters, which we can infer by unifying the provided `Self`
+ // with the substituted impl type.
+ // This also occurs for an enum variant on a type alias.
+ let ty = tcx.type_of(impl_def_id);
+
+ let impl_ty = self.instantiate_type_scheme(span, &substs, &ty);
+ match self.at(&self.misc(span), self.param_env).sup(impl_ty, self_ty) {
+ Ok(ok) => self.register_infer_ok_obligations(ok),
+ Err(_) => {
+ self.tcx.sess.delay_span_bug(
+ span,
+ &format!(
+ "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?",
+ self_ty,
+ impl_ty,
+ ),
+ );
+ }
+ }
+ }
+
+ self.check_rustc_args_require_const(def_id, hir_id, span);
+
+ debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted);
+ self.write_substs(hir_id, substs);
+
+ (ty_substituted, res)
+ }
+
+ /// Add all the obligations that are required, substituting and normalized appropriately.
+ fn add_required_obligations(&self, span: Span, def_id: DefId, substs: &SubstsRef<'tcx>) {
+ let (bounds, spans) = self.instantiate_bounds(span, def_id, &substs);
+
+ for (i, mut obligation) in traits::predicates_for_generics(
+ traits::ObligationCause::new(span, self.body_id, traits::ItemObligation(def_id)),
+ self.param_env,
+ bounds,
+ )
+ .enumerate()
+ {
+ // This makes the error point at the bound, but we want to point at the argument
+ if let Some(span) = spans.get(i) {
+ obligation.cause.make_mut().code = traits::BindingObligation(def_id, *span);
+ }
+ self.register_predicate(obligation);
+ }
+ }
+
+ /// Resolves `typ` by a single level if `typ` is a type variable.
+ /// If no resolution is possible, then an error is reported.
+ /// Numeric inference variables may be left unresolved.
+ pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
+ let ty = self.resolve_vars_with_obligations(ty);
+ if !ty.is_ty_var() {
+ ty
+ } else {
+ if !self.is_tainted_by_errors() {
+ self.emit_inference_failure_err((**self).body_id, sp, ty.into(), E0282)
+ .note("type must be known at this point")
+ .emit();
+ }
+ let err = self.tcx.ty_error();
+ self.demand_suptype(sp, err, ty);
+ err
+ }
+ }
+
+ pub(in super::super) fn with_breakable_ctxt<F: FnOnce() -> R, R>(
+ &self,
+ id: hir::HirId,
+ ctxt: BreakableCtxt<'tcx>,
+ f: F,
+ ) -> (BreakableCtxt<'tcx>, R) {
+ let index;
+ {
+ let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
+ index = enclosing_breakables.stack.len();
+ enclosing_breakables.by_id.insert(id, index);
+ enclosing_breakables.stack.push(ctxt);
+ }
+ let result = f();
+ let ctxt = {
+ let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
+ debug_assert!(enclosing_breakables.stack.len() == index + 1);
+ enclosing_breakables.by_id.remove(&id).expect("missing breakable context");
+ enclosing_breakables.stack.pop().expect("missing breakable context")
+ };
+ (ctxt, result)
+ }
+
+ /// Instantiate a QueryResponse in a probe context, without a
+ /// good ObligationCause.
+ pub(in super::super) fn probe_instantiate_query_response(
+ &self,
+ span: Span,
+ original_values: &OriginalQueryValues<'tcx>,
+ query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
+ ) -> InferResult<'tcx, Ty<'tcx>> {
+ self.instantiate_query_response_and_region_obligations(
+ &traits::ObligationCause::misc(span, self.body_id),
+ self.param_env,
+ original_values,
+ query_result,
+ )
+ }
+
+ /// Returns `true` if an expression is contained inside the LHS of an assignment expression.
+ pub(in super::super) fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool {
+ let mut contained_in_place = false;
+
+ while let hir::Node::Expr(parent_expr) =
+ self.tcx.hir().get(self.tcx.hir().get_parent_node(expr_id))
+ {
+ match &parent_expr.kind {
+ hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => {
+ if lhs.hir_id == expr_id {
+ contained_in_place = true;
+ break;
+ }
+ }
+ _ => (),
+ }
+ expr_id = parent_expr.hir_id;
+ }
+
+ contained_in_place
+ }
+}
--- /dev/null
+use crate::astconv::AstConv;
+use crate::check::coercion::CoerceMany;
+use crate::check::method::MethodCallee;
+use crate::check::Expectation::*;
+use crate::check::TupleArgumentsFlag::*;
+use crate::check::{
+ potentially_plural_count, struct_span_err, BreakableCtxt, Diverges, Expectation, FnCtxt,
+ LocalTy, Needs, TupleArgumentsFlag,
+};
+
+use rustc_ast as ast;
+use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticId};
+use rustc_hir as hir;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def_id::DefId;
+use rustc_hir::{ExprKind, Node, QPath};
+use rustc_middle::ty::adjustment::AllowTwoPhase;
+use rustc_middle::ty::fold::TypeFoldable;
+use rustc_middle::ty::{self, Ty};
+use rustc_session::Session;
+use rustc_span::symbol::{sym, Ident};
+use rustc_span::{self, Span};
+use rustc_trait_selection::traits::{self, ObligationCauseCode};
+
+use std::mem::replace;
+use std::slice;
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+ pub(in super::super) fn check_casts(&self) {
+ let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
+ for cast in deferred_cast_checks.drain(..) {
+ cast.check(self);
+ }
+ }
+
+ pub(in super::super) fn check_method_argument_types(
+ &self,
+ sp: Span,
+ expr: &'tcx hir::Expr<'tcx>,
+ method: Result<MethodCallee<'tcx>, ()>,
+ args_no_rcvr: &'tcx [hir::Expr<'tcx>],
+ tuple_arguments: TupleArgumentsFlag,
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ let has_error = match method {
+ Ok(method) => method.substs.references_error() || method.sig.references_error(),
+ Err(_) => true,
+ };
+ if has_error {
+ let err_inputs = self.err_args(args_no_rcvr.len());
+
+ let err_inputs = match tuple_arguments {
+ DontTupleArguments => err_inputs,
+ TupleArguments => vec![self.tcx.intern_tup(&err_inputs[..])],
+ };
+
+ self.check_argument_types(
+ sp,
+ expr,
+ &err_inputs[..],
+ &[],
+ args_no_rcvr,
+ false,
+ tuple_arguments,
+ None,
+ );
+ return self.tcx.ty_error();
+ }
+
+ let method = method.unwrap();
+ // HACK(eddyb) ignore self in the definition (see above).
+ let expected_arg_tys = self.expected_inputs_for_expected_output(
+ sp,
+ expected,
+ method.sig.output(),
+ &method.sig.inputs()[1..],
+ );
+ self.check_argument_types(
+ sp,
+ expr,
+ &method.sig.inputs()[1..],
+ &expected_arg_tys[..],
+ args_no_rcvr,
+ method.sig.c_variadic,
+ tuple_arguments,
+ self.tcx.hir().span_if_local(method.def_id),
+ );
+ method.sig.output()
+ }
+
+ /// Generic function that factors out common logic from function calls,
+ /// method calls and overloaded operators.
+ pub(in super::super) fn check_argument_types(
+ &self,
+ sp: Span,
+ expr: &'tcx hir::Expr<'tcx>,
+ fn_inputs: &[Ty<'tcx>],
+ expected_arg_tys: &[Ty<'tcx>],
+ args: &'tcx [hir::Expr<'tcx>],
+ c_variadic: bool,
+ tuple_arguments: TupleArgumentsFlag,
+ def_span: Option<Span>,
+ ) {
+ let tcx = self.tcx;
+ // Grab the argument types, supplying fresh type variables
+ // if the wrong number of arguments were supplied
+ let supplied_arg_count = if tuple_arguments == DontTupleArguments { args.len() } else { 1 };
+
+ // All the input types from the fn signature must outlive the call
+ // so as to validate implied bounds.
+ for (&fn_input_ty, arg_expr) in fn_inputs.iter().zip(args.iter()) {
+ self.register_wf_obligation(fn_input_ty.into(), arg_expr.span, traits::MiscObligation);
+ }
+
+ let expected_arg_count = fn_inputs.len();
+
+ let param_count_error = |expected_count: usize,
+ arg_count: usize,
+ error_code: &str,
+ c_variadic: bool,
+ sugg_unit: bool| {
+ let (span, start_span, args) = match &expr.kind {
+ hir::ExprKind::Call(hir::Expr { span, .. }, args) => (*span, *span, &args[..]),
+ hir::ExprKind::MethodCall(path_segment, span, args, _) => (
+ *span,
+ // `sp` doesn't point at the whole `foo.bar()`, only at `bar`.
+ path_segment
+ .args
+ .and_then(|args| args.args.iter().last())
+ // Account for `foo.bar::<T>()`.
+ .map(|arg| {
+ // Skip the closing `>`.
+ tcx.sess
+ .source_map()
+ .next_point(tcx.sess.source_map().next_point(arg.span()))
+ })
+ .unwrap_or(*span),
+ &args[1..], // Skip the receiver.
+ ),
+ k => span_bug!(sp, "checking argument types on a non-call: `{:?}`", k),
+ };
+ let arg_spans = if args.is_empty() {
+ // foo()
+ // ^^^-- supplied 0 arguments
+ // |
+ // expected 2 arguments
+ vec![tcx.sess.source_map().next_point(start_span).with_hi(sp.hi())]
+ } else {
+ // foo(1, 2, 3)
+ // ^^^ - - - supplied 3 arguments
+ // |
+ // expected 2 arguments
+ args.iter().map(|arg| arg.span).collect::<Vec<Span>>()
+ };
+
+ let mut err = tcx.sess.struct_span_err_with_code(
+ span,
+ &format!(
+ "this function takes {}{} but {} {} supplied",
+ if c_variadic { "at least " } else { "" },
+ potentially_plural_count(expected_count, "argument"),
+ potentially_plural_count(arg_count, "argument"),
+ if arg_count == 1 { "was" } else { "were" }
+ ),
+ DiagnosticId::Error(error_code.to_owned()),
+ );
+ let label = format!("supplied {}", potentially_plural_count(arg_count, "argument"));
+ for (i, span) in arg_spans.into_iter().enumerate() {
+ err.span_label(
+ span,
+ if arg_count == 0 || i + 1 == arg_count { &label } else { "" },
+ );
+ }
+
+ if let Some(def_s) = def_span.map(|sp| tcx.sess.source_map().guess_head_span(sp)) {
+ err.span_label(def_s, "defined here");
+ }
+ if sugg_unit {
+ let sugg_span = tcx.sess.source_map().end_point(expr.span);
+ // remove closing `)` from the span
+ let sugg_span = sugg_span.shrink_to_lo();
+ err.span_suggestion(
+ sugg_span,
+ "expected the unit value `()`; create it with empty parentheses",
+ String::from("()"),
+ Applicability::MachineApplicable,
+ );
+ } else {
+ err.span_label(
+ span,
+ format!(
+ "expected {}{}",
+ if c_variadic { "at least " } else { "" },
+ potentially_plural_count(expected_count, "argument")
+ ),
+ );
+ }
+ err.emit();
+ };
+
+ let mut expected_arg_tys = expected_arg_tys.to_vec();
+
+ let formal_tys = if tuple_arguments == TupleArguments {
+ let tuple_type = self.structurally_resolved_type(sp, fn_inputs[0]);
+ match tuple_type.kind() {
+ ty::Tuple(arg_types) if arg_types.len() != args.len() => {
+ param_count_error(arg_types.len(), args.len(), "E0057", false, false);
+ expected_arg_tys = vec![];
+ self.err_args(args.len())
+ }
+ ty::Tuple(arg_types) => {
+ expected_arg_tys = match expected_arg_tys.get(0) {
+ Some(&ty) => match ty.kind() {
+ ty::Tuple(ref tys) => tys.iter().map(|k| k.expect_ty()).collect(),
+ _ => vec![],
+ },
+ None => vec![],
+ };
+ arg_types.iter().map(|k| k.expect_ty()).collect()
+ }
+ _ => {
+ struct_span_err!(
+ tcx.sess,
+ sp,
+ E0059,
+ "cannot use call notation; the first type parameter \
+ for the function trait is neither a tuple nor unit"
+ )
+ .emit();
+ expected_arg_tys = vec![];
+ self.err_args(args.len())
+ }
+ }
+ } else if expected_arg_count == supplied_arg_count {
+ fn_inputs.to_vec()
+ } else if c_variadic {
+ if supplied_arg_count >= expected_arg_count {
+ fn_inputs.to_vec()
+ } else {
+ param_count_error(expected_arg_count, supplied_arg_count, "E0060", true, false);
+ expected_arg_tys = vec![];
+ self.err_args(supplied_arg_count)
+ }
+ } else {
+ // is the missing argument of type `()`?
+ let sugg_unit = if expected_arg_tys.len() == 1 && supplied_arg_count == 0 {
+ self.resolve_vars_if_possible(&expected_arg_tys[0]).is_unit()
+ } else if fn_inputs.len() == 1 && supplied_arg_count == 0 {
+ self.resolve_vars_if_possible(&fn_inputs[0]).is_unit()
+ } else {
+ false
+ };
+ param_count_error(expected_arg_count, supplied_arg_count, "E0061", false, sugg_unit);
+
+ expected_arg_tys = vec![];
+ self.err_args(supplied_arg_count)
+ };
+
+ debug!(
+ "check_argument_types: formal_tys={:?}",
+ formal_tys.iter().map(|t| self.ty_to_string(*t)).collect::<Vec<String>>()
+ );
+
+ // If there is no expectation, expect formal_tys.
+ let expected_arg_tys =
+ if !expected_arg_tys.is_empty() { expected_arg_tys } else { formal_tys.clone() };
+
+ let mut final_arg_types: Vec<(usize, Ty<'_>, Ty<'_>)> = vec![];
+
+ // Check the arguments.
+ // We do this in a pretty awful way: first we type-check any arguments
+ // that are not closures, then we type-check the closures. This is so
+ // that we have more information about the types of arguments when we
+ // type-check the functions. This isn't really the right way to do this.
+ for &check_closures in &[false, true] {
+ debug!("check_closures={}", check_closures);
+
+ // More awful hacks: before we check argument types, try to do
+ // an "opportunistic" trait resolution of any trait bounds on
+ // the call. This helps coercions.
+ if check_closures {
+ self.select_obligations_where_possible(false, |errors| {
+ self.point_at_type_arg_instead_of_call_if_possible(errors, expr);
+ self.point_at_arg_instead_of_call_if_possible(
+ errors,
+ &final_arg_types[..],
+ sp,
+ &args,
+ );
+ })
+ }
+
+ // For C-variadic functions, we don't have a declared type for all of
+ // the arguments hence we only do our usual type checking with
+ // the arguments who's types we do know.
+ let t = if c_variadic {
+ expected_arg_count
+ } else if tuple_arguments == TupleArguments {
+ args.len()
+ } else {
+ supplied_arg_count
+ };
+ for (i, arg) in args.iter().take(t).enumerate() {
+ // Warn only for the first loop (the "no closures" one).
+ // Closure arguments themselves can't be diverging, but
+ // a previous argument can, e.g., `foo(panic!(), || {})`.
+ if !check_closures {
+ self.warn_if_unreachable(arg.hir_id, arg.span, "expression");
+ }
+
+ let is_closure = match arg.kind {
+ ExprKind::Closure(..) => true,
+ _ => false,
+ };
+
+ if is_closure != check_closures {
+ continue;
+ }
+
+ debug!("checking the argument");
+ let formal_ty = formal_tys[i];
+
+ // The special-cased logic below has three functions:
+ // 1. Provide as good of an expected type as possible.
+ let expected = Expectation::rvalue_hint(self, expected_arg_tys[i]);
+
+ let checked_ty = self.check_expr_with_expectation(&arg, expected);
+
+ // 2. Coerce to the most detailed type that could be coerced
+ // to, which is `expected_ty` if `rvalue_hint` returns an
+ // `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise.
+ let coerce_ty = expected.only_has_type(self).unwrap_or(formal_ty);
+ // We're processing function arguments so we definitely want to use
+ // two-phase borrows.
+ self.demand_coerce(&arg, checked_ty, coerce_ty, None, AllowTwoPhase::Yes);
+ final_arg_types.push((i, checked_ty, coerce_ty));
+
+ // 3. Relate the expected type and the formal one,
+ // if the expected type was used for the coercion.
+ self.demand_suptype(arg.span, formal_ty, coerce_ty);
+ }
+ }
+
+ // We also need to make sure we at least write the ty of the other
+ // arguments which we skipped above.
+ if c_variadic {
+ fn variadic_error<'tcx>(s: &Session, span: Span, t: Ty<'tcx>, cast_ty: &str) {
+ use crate::structured_errors::{StructuredDiagnostic, VariadicError};
+ VariadicError::new(s, span, t, cast_ty).diagnostic().emit();
+ }
+
+ for arg in args.iter().skip(expected_arg_count) {
+ let arg_ty = self.check_expr(&arg);
+
+ // There are a few types which get autopromoted when passed via varargs
+ // in C but we just error out instead and require explicit casts.
+ let arg_ty = self.structurally_resolved_type(arg.span, arg_ty);
+ match arg_ty.kind() {
+ ty::Float(ast::FloatTy::F32) => {
+ variadic_error(tcx.sess, arg.span, arg_ty, "c_double");
+ }
+ ty::Int(ast::IntTy::I8 | ast::IntTy::I16) | ty::Bool => {
+ variadic_error(tcx.sess, arg.span, arg_ty, "c_int");
+ }
+ ty::Uint(ast::UintTy::U8 | ast::UintTy::U16) => {
+ variadic_error(tcx.sess, arg.span, arg_ty, "c_uint");
+ }
+ ty::FnDef(..) => {
+ let ptr_ty = self.tcx.mk_fn_ptr(arg_ty.fn_sig(self.tcx));
+ let ptr_ty = self.resolve_vars_if_possible(&ptr_ty);
+ variadic_error(tcx.sess, arg.span, arg_ty, &ptr_ty.to_string());
+ }
+ _ => {}
+ }
+ }
+ }
+ }
+
+ // AST fragment checking
+ pub(in super::super) fn check_lit(
+ &self,
+ lit: &hir::Lit,
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ let tcx = self.tcx;
+
+ match lit.node {
+ ast::LitKind::Str(..) => tcx.mk_static_str(),
+ ast::LitKind::ByteStr(ref v) => {
+ tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.u8, v.len() as u64))
+ }
+ ast::LitKind::Byte(_) => tcx.types.u8,
+ ast::LitKind::Char(_) => tcx.types.char,
+ ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(t),
+ ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(t),
+ ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => {
+ let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() {
+ ty::Int(_) | ty::Uint(_) => Some(ty),
+ ty::Char => Some(tcx.types.u8),
+ ty::RawPtr(..) => Some(tcx.types.usize),
+ ty::FnDef(..) | ty::FnPtr(_) => Some(tcx.types.usize),
+ _ => None,
+ });
+ opt_ty.unwrap_or_else(|| self.next_int_var())
+ }
+ ast::LitKind::Float(_, ast::LitFloatType::Suffixed(t)) => tcx.mk_mach_float(t),
+ ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) => {
+ let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() {
+ ty::Float(_) => Some(ty),
+ _ => None,
+ });
+ opt_ty.unwrap_or_else(|| self.next_float_var())
+ }
+ ast::LitKind::Bool(_) => tcx.types.bool,
+ ast::LitKind::Err(_) => tcx.ty_error(),
+ }
+ }
+
+ pub fn check_struct_path(
+ &self,
+ qpath: &QPath<'_>,
+ hir_id: hir::HirId,
+ ) -> Option<(&'tcx ty::VariantDef, Ty<'tcx>)> {
+ let path_span = qpath.qself_span();
+ let (def, ty) = self.finish_resolving_struct_path(qpath, path_span, hir_id);
+ let variant = match def {
+ Res::Err => {
+ self.set_tainted_by_errors();
+ return None;
+ }
+ Res::Def(DefKind::Variant, _) => match ty.kind() {
+ ty::Adt(adt, substs) => Some((adt.variant_of_res(def), adt.did, substs)),
+ _ => bug!("unexpected type: {:?}", ty),
+ },
+ Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _)
+ | Res::SelfTy(..) => match ty.kind() {
+ ty::Adt(adt, substs) if !adt.is_enum() => {
+ Some((adt.non_enum_variant(), adt.did, substs))
+ }
+ _ => None,
+ },
+ _ => bug!("unexpected definition: {:?}", def),
+ };
+
+ if let Some((variant, did, substs)) = variant {
+ debug!("check_struct_path: did={:?} substs={:?}", did, substs);
+ self.write_user_type_annotation_from_substs(hir_id, did, substs, None);
+
+ // Check bounds on type arguments used in the path.
+ let (bounds, _) = self.instantiate_bounds(path_span, did, substs);
+ let cause =
+ traits::ObligationCause::new(path_span, self.body_id, traits::ItemObligation(did));
+ self.add_obligations_for_parameters(cause, bounds);
+
+ Some((variant, ty))
+ } else {
+ struct_span_err!(
+ self.tcx.sess,
+ path_span,
+ E0071,
+ "expected struct, variant or union type, found {}",
+ ty.sort_string(self.tcx)
+ )
+ .span_label(path_span, "not a struct")
+ .emit();
+ None
+ }
+ }
+
+ pub fn check_decl_initializer(
+ &self,
+ local: &'tcx hir::Local<'tcx>,
+ init: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ // FIXME(tschottdorf): `contains_explicit_ref_binding()` must be removed
+ // for #42640 (default match binding modes).
+ //
+ // See #44848.
+ let ref_bindings = local.pat.contains_explicit_ref_binding();
+
+ let local_ty = self.local_ty(init.span, local.hir_id).revealed_ty;
+ if let Some(m) = ref_bindings {
+ // Somewhat subtle: if we have a `ref` binding in the pattern,
+ // we want to avoid introducing coercions for the RHS. This is
+ // both because it helps preserve sanity and, in the case of
+ // ref mut, for soundness (issue #23116). In particular, in
+ // the latter case, we need to be clear that the type of the
+ // referent for the reference that results is *equal to* the
+ // type of the place it is referencing, and not some
+ // supertype thereof.
+ let init_ty = self.check_expr_with_needs(init, Needs::maybe_mut_place(m));
+ self.demand_eqtype(init.span, local_ty, init_ty);
+ init_ty
+ } else {
+ self.check_expr_coercable_to_type(init, local_ty, None)
+ }
+ }
+
+ /// Type check a `let` statement.
+ pub fn check_decl_local(&self, local: &'tcx hir::Local<'tcx>) {
+ // Determine and write the type which we'll check the pattern against.
+ let ty = self.local_ty(local.span, local.hir_id).decl_ty;
+ self.write_ty(local.hir_id, ty);
+
+ // Type check the initializer.
+ if let Some(ref init) = local.init {
+ let init_ty = self.check_decl_initializer(local, &init);
+ self.overwrite_local_ty_if_err(local, ty, init_ty);
+ }
+
+ // Does the expected pattern type originate from an expression and what is the span?
+ let (origin_expr, ty_span) = match (local.ty, local.init) {
+ (Some(ty), _) => (false, Some(ty.span)), // Bias towards the explicit user type.
+ (_, Some(init)) => (true, Some(init.span)), // No explicit type; so use the scrutinee.
+ _ => (false, None), // We have `let $pat;`, so the expected type is unconstrained.
+ };
+
+ // Type check the pattern. Override if necessary to avoid knock-on errors.
+ self.check_pat_top(&local.pat, ty, ty_span, origin_expr);
+ let pat_ty = self.node_ty(local.pat.hir_id);
+ self.overwrite_local_ty_if_err(local, ty, pat_ty);
+ }
+
+ pub fn check_stmt(&self, stmt: &'tcx hir::Stmt<'tcx>) {
+ // Don't do all the complex logic below for `DeclItem`.
+ match stmt.kind {
+ hir::StmtKind::Item(..) => return,
+ hir::StmtKind::Local(..) | hir::StmtKind::Expr(..) | hir::StmtKind::Semi(..) => {}
+ }
+
+ self.warn_if_unreachable(stmt.hir_id, stmt.span, "statement");
+
+ // Hide the outer diverging and `has_errors` flags.
+ let old_diverges = self.diverges.replace(Diverges::Maybe);
+ let old_has_errors = self.has_errors.replace(false);
+
+ match stmt.kind {
+ hir::StmtKind::Local(ref l) => {
+ self.check_decl_local(&l);
+ }
+ // Ignore for now.
+ hir::StmtKind::Item(_) => {}
+ hir::StmtKind::Expr(ref expr) => {
+ // Check with expected type of `()`.
+ self.check_expr_has_type_or_error(&expr, self.tcx.mk_unit(), |err| {
+ self.suggest_semicolon_at_end(expr.span, err);
+ });
+ }
+ hir::StmtKind::Semi(ref expr) => {
+ self.check_expr(&expr);
+ }
+ }
+
+ // Combine the diverging and `has_error` flags.
+ self.diverges.set(self.diverges.get() | old_diverges);
+ self.has_errors.set(self.has_errors.get() | old_has_errors);
+ }
+
+ pub fn check_block_no_value(&self, blk: &'tcx hir::Block<'tcx>) {
+ let unit = self.tcx.mk_unit();
+ let ty = self.check_block_with_expected(blk, ExpectHasType(unit));
+
+ // if the block produces a `!` value, that can always be
+ // (effectively) coerced to unit.
+ if !ty.is_never() {
+ self.demand_suptype(blk.span, unit, ty);
+ }
+ }
+
+ pub(in super::super) fn check_block_with_expected(
+ &self,
+ blk: &'tcx hir::Block<'tcx>,
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ let prev = {
+ let mut fcx_ps = self.ps.borrow_mut();
+ let unsafety_state = fcx_ps.recurse(blk);
+ replace(&mut *fcx_ps, unsafety_state)
+ };
+
+ // In some cases, blocks have just one exit, but other blocks
+ // can be targeted by multiple breaks. This can happen both
+ // with labeled blocks as well as when we desugar
+ // a `try { ... }` expression.
+ //
+ // Example 1:
+ //
+ // 'a: { if true { break 'a Err(()); } Ok(()) }
+ //
+ // Here we would wind up with two coercions, one from
+ // `Err(())` and the other from the tail expression
+ // `Ok(())`. If the tail expression is omitted, that's a
+ // "forced unit" -- unless the block diverges, in which
+ // case we can ignore the tail expression (e.g., `'a: {
+ // break 'a 22; }` would not force the type of the block
+ // to be `()`).
+ let tail_expr = blk.expr.as_ref();
+ let coerce_to_ty = expected.coercion_target_type(self, blk.span);
+ let coerce = if blk.targeted_by_break {
+ CoerceMany::new(coerce_to_ty)
+ } else {
+ let tail_expr: &[&hir::Expr<'_>] = match tail_expr {
+ Some(e) => slice::from_ref(e),
+ None => &[],
+ };
+ CoerceMany::with_coercion_sites(coerce_to_ty, tail_expr)
+ };
+
+ let prev_diverges = self.diverges.get();
+ let ctxt = BreakableCtxt { coerce: Some(coerce), may_break: false };
+
+ let (ctxt, ()) = self.with_breakable_ctxt(blk.hir_id, ctxt, || {
+ for s in blk.stmts {
+ self.check_stmt(s);
+ }
+
+ // check the tail expression **without** holding the
+ // `enclosing_breakables` lock below.
+ let tail_expr_ty = tail_expr.map(|t| self.check_expr_with_expectation(t, expected));
+
+ let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
+ let ctxt = enclosing_breakables.find_breakable(blk.hir_id);
+ let coerce = ctxt.coerce.as_mut().unwrap();
+ if let Some(tail_expr_ty) = tail_expr_ty {
+ let tail_expr = tail_expr.unwrap();
+ let span = self.get_expr_coercion_span(tail_expr);
+ let cause = self.cause(span, ObligationCauseCode::BlockTailExpression(blk.hir_id));
+ coerce.coerce(self, &cause, tail_expr, tail_expr_ty);
+ } else {
+ // Subtle: if there is no explicit tail expression,
+ // that is typically equivalent to a tail expression
+ // of `()` -- except if the block diverges. In that
+ // case, there is no value supplied from the tail
+ // expression (assuming there are no other breaks,
+ // this implies that the type of the block will be
+ // `!`).
+ //
+ // #41425 -- label the implicit `()` as being the
+ // "found type" here, rather than the "expected type".
+ if !self.diverges.get().is_always() {
+ // #50009 -- Do not point at the entire fn block span, point at the return type
+ // span, as it is the cause of the requirement, and
+ // `consider_hint_about_removing_semicolon` will point at the last expression
+ // if it were a relevant part of the error. This improves usability in editors
+ // that highlight errors inline.
+ let mut sp = blk.span;
+ let mut fn_span = None;
+ if let Some((decl, ident)) = self.get_parent_fn_decl(blk.hir_id) {
+ let ret_sp = decl.output.span();
+ if let Some(block_sp) = self.parent_item_span(blk.hir_id) {
+ // HACK: on some cases (`ui/liveness/liveness-issue-2163.rs`) the
+ // output would otherwise be incorrect and even misleading. Make sure
+ // the span we're aiming at correspond to a `fn` body.
+ if block_sp == blk.span {
+ sp = ret_sp;
+ fn_span = Some(ident.span);
+ }
+ }
+ }
+ coerce.coerce_forced_unit(
+ self,
+ &self.misc(sp),
+ &mut |err| {
+ if let Some(expected_ty) = expected.only_has_type(self) {
+ self.consider_hint_about_removing_semicolon(blk, expected_ty, err);
+ }
+ if let Some(fn_span) = fn_span {
+ err.span_label(
+ fn_span,
+ "implicitly returns `()` as its body has no tail or `return` \
+ expression",
+ );
+ }
+ },
+ false,
+ );
+ }
+ }
+ });
+
+ if ctxt.may_break {
+ // If we can break from the block, then the block's exit is always reachable
+ // (... as long as the entry is reachable) - regardless of the tail of the block.
+ self.diverges.set(prev_diverges);
+ }
+
+ let mut ty = ctxt.coerce.unwrap().complete(self);
+
+ if self.has_errors.get() || ty.references_error() {
+ ty = self.tcx.ty_error()
+ }
+
+ self.write_ty(blk.hir_id, ty);
+
+ *self.ps.borrow_mut() = prev;
+ ty
+ }
+
+ pub(in super::super) fn check_rustc_args_require_const(
+ &self,
+ def_id: DefId,
+ hir_id: hir::HirId,
+ span: Span,
+ ) {
+ // We're only interested in functions tagged with
+ // #[rustc_args_required_const], so ignore anything that's not.
+ if !self.tcx.has_attr(def_id, sym::rustc_args_required_const) {
+ return;
+ }
+
+ // If our calling expression is indeed the function itself, we're good!
+ // If not, generate an error that this can only be called directly.
+ if let Node::Expr(expr) = self.tcx.hir().get(self.tcx.hir().get_parent_node(hir_id)) {
+ if let ExprKind::Call(ref callee, ..) = expr.kind {
+ if callee.hir_id == hir_id {
+ return;
+ }
+ }
+ }
+
+ self.tcx.sess.span_err(
+ span,
+ "this function can only be invoked directly, not through a function pointer",
+ );
+ }
+
+ /// A common error is to add an extra semicolon:
+ ///
+ /// ```
+ /// fn foo() -> usize {
+ /// 22;
+ /// }
+ /// ```
+ ///
+ /// This routine checks if the final statement in a block is an
+ /// expression with an explicit semicolon whose type is compatible
+ /// with `expected_ty`. If so, it suggests removing the semicolon.
+ fn consider_hint_about_removing_semicolon(
+ &self,
+ blk: &'tcx hir::Block<'tcx>,
+ expected_ty: Ty<'tcx>,
+ err: &mut DiagnosticBuilder<'_>,
+ ) {
+ if let Some(span_semi) = self.could_remove_semicolon(blk, expected_ty) {
+ err.span_suggestion(
+ span_semi,
+ "consider removing this semicolon",
+ String::new(),
+ Applicability::MachineApplicable,
+ );
+ }
+ }
+
+ fn parent_item_span(&self, id: hir::HirId) -> Option<Span> {
+ let node = self.tcx.hir().get(self.tcx.hir().get_parent_item(id));
+ match node {
+ Node::Item(&hir::Item { kind: hir::ItemKind::Fn(_, _, body_id), .. })
+ | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(_, body_id), .. }) => {
+ let body = self.tcx.hir().body(body_id);
+ if let ExprKind::Block(block, _) = &body.value.kind {
+ return Some(block.span);
+ }
+ }
+ _ => {}
+ }
+ None
+ }
+
+ /// Given a function block's `HirId`, returns its `FnDecl` if it exists, or `None` otherwise.
+ fn get_parent_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident)> {
+ let parent = self.tcx.hir().get(self.tcx.hir().get_parent_item(blk_id));
+ self.get_node_fn_decl(parent).map(|(fn_decl, ident, _)| (fn_decl, ident))
+ }
+
+ /// If `expr` is a `match` expression that has only one non-`!` arm, use that arm's tail
+ /// expression's `Span`, otherwise return `expr.span`. This is done to give better errors
+ /// when given code like the following:
+ /// ```text
+ /// if false { return 0i32; } else { 1u32 }
+ /// // ^^^^ point at this instead of the whole `if` expression
+ /// ```
+ fn get_expr_coercion_span(&self, expr: &hir::Expr<'_>) -> rustc_span::Span {
+ if let hir::ExprKind::Match(_, arms, _) = &expr.kind {
+ let arm_spans: Vec<Span> = arms
+ .iter()
+ .filter_map(|arm| {
+ self.in_progress_typeck_results
+ .and_then(|typeck_results| {
+ typeck_results.borrow().node_type_opt(arm.body.hir_id)
+ })
+ .and_then(|arm_ty| {
+ if arm_ty.is_never() {
+ None
+ } else {
+ Some(match &arm.body.kind {
+ // Point at the tail expression when possible.
+ hir::ExprKind::Block(block, _) => {
+ block.expr.as_ref().map(|e| e.span).unwrap_or(block.span)
+ }
+ _ => arm.body.span,
+ })
+ }
+ })
+ })
+ .collect();
+ if arm_spans.len() == 1 {
+ return arm_spans[0];
+ }
+ }
+ expr.span
+ }
+
+ fn overwrite_local_ty_if_err(
+ &self,
+ local: &'tcx hir::Local<'tcx>,
+ decl_ty: Ty<'tcx>,
+ ty: Ty<'tcx>,
+ ) {
+ if ty.references_error() {
+ // Override the types everywhere with `err()` to avoid knock on errors.
+ self.write_ty(local.hir_id, ty);
+ self.write_ty(local.pat.hir_id, ty);
+ let local_ty = LocalTy { decl_ty, revealed_ty: ty };
+ self.locals.borrow_mut().insert(local.hir_id, local_ty);
+ self.locals.borrow_mut().insert(local.pat.hir_id, local_ty);
+ }
+ }
+
+ // Finish resolving a path in a struct expression or pattern `S::A { .. }` if necessary.
+ // The newly resolved definition is written into `type_dependent_defs`.
+ fn finish_resolving_struct_path(
+ &self,
+ qpath: &QPath<'_>,
+ path_span: Span,
+ hir_id: hir::HirId,
+ ) -> (Res, Ty<'tcx>) {
+ match *qpath {
+ QPath::Resolved(ref maybe_qself, ref path) => {
+ let self_ty = maybe_qself.as_ref().map(|qself| self.to_ty(qself));
+ let ty = AstConv::res_to_ty(self, self_ty, path, true);
+ (path.res, ty)
+ }
+ QPath::TypeRelative(ref qself, ref segment) => {
+ let ty = self.to_ty(qself);
+
+ let res = if let hir::TyKind::Path(QPath::Resolved(_, ref path)) = qself.kind {
+ path.res
+ } else {
+ Res::Err
+ };
+ let result =
+ AstConv::associated_path_to_ty(self, hir_id, path_span, ty, res, segment, true);
+ let ty = result.map(|(ty, _, _)| ty).unwrap_or_else(|_| self.tcx().ty_error());
+ let result = result.map(|(_, kind, def_id)| (kind, def_id));
+
+ // Write back the new resolution.
+ self.write_resolution(hir_id, result);
+
+ (result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), ty)
+ }
+ QPath::LangItem(lang_item, span) => {
+ self.resolve_lang_item_path(lang_item, span, hir_id)
+ }
+ }
+ }
+
+ /// Given a vec of evaluated `FulfillmentError`s and an `fn` call argument expressions, we walk
+ /// the checked and coerced types for each argument to see if any of the `FulfillmentError`s
+ /// reference a type argument. The reason to walk also the checked type is that the coerced type
+ /// can be not easily comparable with predicate type (because of coercion). If the types match
+ /// for either checked or coerced type, and there's only *one* argument that does, we point at
+ /// the corresponding argument's expression span instead of the `fn` call path span.
+ fn point_at_arg_instead_of_call_if_possible(
+ &self,
+ errors: &mut Vec<traits::FulfillmentError<'tcx>>,
+ final_arg_types: &[(usize, Ty<'tcx>, Ty<'tcx>)],
+ call_sp: Span,
+ args: &'tcx [hir::Expr<'tcx>],
+ ) {
+ // We *do not* do this for desugared call spans to keep good diagnostics when involving
+ // the `?` operator.
+ if call_sp.desugaring_kind().is_some() {
+ return;
+ }
+
+ for error in errors {
+ // Only if the cause is somewhere inside the expression we want try to point at arg.
+ // Otherwise, it means that the cause is somewhere else and we should not change
+ // anything because we can break the correct span.
+ if !call_sp.contains(error.obligation.cause.span) {
+ continue;
+ }
+
+ if let ty::PredicateAtom::Trait(predicate, _) =
+ error.obligation.predicate.skip_binders()
+ {
+ // Collect the argument position for all arguments that could have caused this
+ // `FulfillmentError`.
+ let mut referenced_in = final_arg_types
+ .iter()
+ .map(|&(i, checked_ty, _)| (i, checked_ty))
+ .chain(final_arg_types.iter().map(|&(i, _, coerced_ty)| (i, coerced_ty)))
+ .flat_map(|(i, ty)| {
+ let ty = self.resolve_vars_if_possible(&ty);
+ // We walk the argument type because the argument's type could have
+ // been `Option<T>`, but the `FulfillmentError` references `T`.
+ if ty.walk().any(|arg| arg == predicate.self_ty().into()) {
+ Some(i)
+ } else {
+ None
+ }
+ })
+ .collect::<Vec<usize>>();
+
+ // Both checked and coerced types could have matched, thus we need to remove
+ // duplicates.
+
+ // We sort primitive type usize here and can use unstable sort
+ referenced_in.sort_unstable();
+ referenced_in.dedup();
+
+ if let (Some(ref_in), None) = (referenced_in.pop(), referenced_in.pop()) {
+ // We make sure that only *one* argument matches the obligation failure
+ // and we assign the obligation's span to its expression's.
+ error.obligation.cause.make_mut().span = args[ref_in].span;
+ error.points_at_arg_span = true;
+ }
+ }
+ }
+ }
+
+ /// Given a vec of evaluated `FulfillmentError`s and an `fn` call expression, we walk the
+ /// `PathSegment`s and resolve their type parameters to see if any of the `FulfillmentError`s
+ /// were caused by them. If they were, we point at the corresponding type argument's span
+ /// instead of the `fn` call path span.
+ fn point_at_type_arg_instead_of_call_if_possible(
+ &self,
+ errors: &mut Vec<traits::FulfillmentError<'tcx>>,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ ) {
+ if let hir::ExprKind::Call(path, _) = &call_expr.kind {
+ if let hir::ExprKind::Path(qpath) = &path.kind {
+ if let hir::QPath::Resolved(_, path) = &qpath {
+ for error in errors {
+ if let ty::PredicateAtom::Trait(predicate, _) =
+ error.obligation.predicate.skip_binders()
+ {
+ // If any of the type arguments in this path segment caused the
+ // `FullfillmentError`, point at its span (#61860).
+ for arg in path
+ .segments
+ .iter()
+ .filter_map(|seg| seg.args.as_ref())
+ .flat_map(|a| a.args.iter())
+ {
+ if let hir::GenericArg::Type(hir_ty) = &arg {
+ if let hir::TyKind::Path(hir::QPath::TypeRelative(..)) =
+ &hir_ty.kind
+ {
+ // Avoid ICE with associated types. As this is best
+ // effort only, it's ok to ignore the case. It
+ // would trigger in `is_send::<T::AssocType>();`
+ // from `typeck-default-trait-impl-assoc-type.rs`.
+ } else {
+ let ty = AstConv::ast_ty_to_ty(self, hir_ty);
+ let ty = self.resolve_vars_if_possible(&ty);
+ if ty == predicate.self_ty() {
+ error.obligation.cause.make_mut().span = hir_ty.span;
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+}
--- /dev/null
+mod _impl;
+mod checks;
+mod suggestions;
+
+pub use _impl::*;
+pub use checks::*;
+pub use suggestions::*;
+
+use crate::astconv::AstConv;
+use crate::check::coercion::DynamicCoerceMany;
+use crate::check::{Diverges, EnclosingBreakables, Inherited, UnsafetyState};
+
+use rustc_hir as hir;
+use rustc_hir::def_id::DefId;
+use rustc_infer::infer;
+use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
+use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
+use rustc_middle::hir::map::blocks::FnLikeNode;
+use rustc_middle::ty::fold::TypeFoldable;
+use rustc_middle::ty::subst::GenericArgKind;
+use rustc_middle::ty::{self, Const, Ty, TyCtxt};
+use rustc_session::Session;
+use rustc_span::{self, Span};
+use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode};
+
+use std::cell::{Cell, RefCell};
+use std::ops::Deref;
+
+pub struct FnCtxt<'a, 'tcx> {
+ pub(super) body_id: hir::HirId,
+
+ /// The parameter environment used for proving trait obligations
+ /// in this function. This can change when we descend into
+ /// closures (as they bring new things into scope), hence it is
+ /// not part of `Inherited` (as of the time of this writing,
+ /// closures do not yet change the environment, but they will
+ /// eventually).
+ pub(super) param_env: ty::ParamEnv<'tcx>,
+
+ /// Number of errors that had been reported when we started
+ /// checking this function. On exit, if we find that *more* errors
+ /// have been reported, we will skip regionck and other work that
+ /// expects the types within the function to be consistent.
+ // FIXME(matthewjasper) This should not exist, and it's not correct
+ // if type checking is run in parallel.
+ err_count_on_creation: usize,
+
+ /// If `Some`, this stores coercion information for returned
+ /// expressions. If `None`, this is in a context where return is
+ /// inappropriate, such as a const expression.
+ ///
+ /// This is a `RefCell<DynamicCoerceMany>`, which means that we
+ /// can track all the return expressions and then use them to
+ /// compute a useful coercion from the set, similar to a match
+ /// expression or other branching context. You can use methods
+ /// like `expected_ty` to access the declared return type (if
+ /// any).
+ pub(super) ret_coercion: Option<RefCell<DynamicCoerceMany<'tcx>>>,
+
+ pub(super) ret_coercion_impl_trait: Option<Ty<'tcx>>,
+
+ pub(super) ret_type_span: Option<Span>,
+
+ /// Used exclusively to reduce cost of advanced evaluation used for
+ /// more helpful diagnostics.
+ pub(super) in_tail_expr: bool,
+
+ /// First span of a return site that we find. Used in error messages.
+ pub(super) ret_coercion_span: RefCell<Option<Span>>,
+
+ pub(super) resume_yield_tys: Option<(Ty<'tcx>, Ty<'tcx>)>,
+
+ pub(super) ps: RefCell<UnsafetyState>,
+
+ /// Whether the last checked node generates a divergence (e.g.,
+ /// `return` will set this to `Always`). In general, when entering
+ /// an expression or other node in the tree, the initial value
+ /// indicates whether prior parts of the containing expression may
+ /// have diverged. It is then typically set to `Maybe` (and the
+ /// old value remembered) for processing the subparts of the
+ /// current expression. As each subpart is processed, they may set
+ /// the flag to `Always`, etc. Finally, at the end, we take the
+ /// result and "union" it with the original value, so that when we
+ /// return the flag indicates if any subpart of the parent
+ /// expression (up to and including this part) has diverged. So,
+ /// if you read it after evaluating a subexpression `X`, the value
+ /// you get indicates whether any subexpression that was
+ /// evaluating up to and including `X` diverged.
+ ///
+ /// We currently use this flag only for diagnostic purposes:
+ ///
+ /// - To warn about unreachable code: if, after processing a
+ /// sub-expression but before we have applied the effects of the
+ /// current node, we see that the flag is set to `Always`, we
+ /// can issue a warning. This corresponds to something like
+ /// `foo(return)`; we warn on the `foo()` expression. (We then
+ /// update the flag to `WarnedAlways` to suppress duplicate
+ /// reports.) Similarly, if we traverse to a fresh statement (or
+ /// tail expression) from a `Always` setting, we will issue a
+ /// warning. This corresponds to something like `{return;
+ /// foo();}` or `{return; 22}`, where we would warn on the
+ /// `foo()` or `22`.
+ ///
+ /// An expression represents dead code if, after checking it,
+ /// the diverges flag is set to something other than `Maybe`.
+ pub(super) diverges: Cell<Diverges>,
+
+ /// Whether any child nodes have any type errors.
+ pub(super) has_errors: Cell<bool>,
+
+ pub(super) enclosing_breakables: RefCell<EnclosingBreakables<'tcx>>,
+
+ pub(super) inh: &'a Inherited<'a, 'tcx>,
+}
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+ pub fn new(
+ inh: &'a Inherited<'a, 'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+ body_id: hir::HirId,
+ ) -> FnCtxt<'a, 'tcx> {
+ FnCtxt {
+ body_id,
+ param_env,
+ err_count_on_creation: inh.tcx.sess.err_count(),
+ ret_coercion: None,
+ ret_coercion_impl_trait: None,
+ ret_type_span: None,
+ in_tail_expr: false,
+ ret_coercion_span: RefCell::new(None),
+ resume_yield_tys: None,
+ ps: RefCell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)),
+ diverges: Cell::new(Diverges::Maybe),
+ has_errors: Cell::new(false),
+ enclosing_breakables: RefCell::new(EnclosingBreakables {
+ stack: Vec::new(),
+ by_id: Default::default(),
+ }),
+ inh,
+ }
+ }
+
+ pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> {
+ ObligationCause::new(span, self.body_id, code)
+ }
+
+ pub fn misc(&self, span: Span) -> ObligationCause<'tcx> {
+ self.cause(span, ObligationCauseCode::MiscObligation)
+ }
+
+ pub fn sess(&self) -> &Session {
+ &self.tcx.sess
+ }
+
+ pub fn errors_reported_since_creation(&self) -> bool {
+ self.tcx.sess.err_count() > self.err_count_on_creation
+ }
+}
+
+impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> {
+ type Target = Inherited<'a, 'tcx>;
+ fn deref(&self) -> &Self::Target {
+ &self.inh
+ }
+}
+
+impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
+ fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
+ self.tcx
+ }
+
+ fn item_def_id(&self) -> Option<DefId> {
+ None
+ }
+
+ fn default_constness_for_trait_bounds(&self) -> hir::Constness {
+ // FIXME: refactor this into a method
+ let node = self.tcx.hir().get(self.body_id);
+ if let Some(fn_like) = FnLikeNode::from_node(node) {
+ fn_like.constness()
+ } else {
+ hir::Constness::NotConst
+ }
+ }
+
+ fn get_type_parameter_bounds(&self, _: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
+ let tcx = self.tcx;
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+ let item_id = tcx.hir().ty_param_owner(hir_id);
+ let item_def_id = tcx.hir().local_def_id(item_id);
+ let generics = tcx.generics_of(item_def_id);
+ let index = generics.param_def_id_to_index[&def_id];
+ ty::GenericPredicates {
+ parent: None,
+ predicates: tcx.arena.alloc_from_iter(
+ self.param_env.caller_bounds().iter().filter_map(|predicate| {
+ match predicate.skip_binders() {
+ ty::PredicateAtom::Trait(data, _) if data.self_ty().is_param(index) => {
+ // HACK(eddyb) should get the original `Span`.
+ let span = tcx.def_span(def_id);
+ Some((predicate, span))
+ }
+ _ => None,
+ }
+ }),
+ ),
+ }
+ }
+
+ fn re_infer(&self, def: Option<&ty::GenericParamDef>, span: Span) -> Option<ty::Region<'tcx>> {
+ let v = match def {
+ Some(def) => infer::EarlyBoundRegion(span, def.name),
+ None => infer::MiscVariable(span),
+ };
+ Some(self.next_region_var(v))
+ }
+
+ fn allow_ty_infer(&self) -> bool {
+ true
+ }
+
+ fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
+ if let Some(param) = param {
+ if let GenericArgKind::Type(ty) = self.var_for_def(span, param).unpack() {
+ return ty;
+ }
+ unreachable!()
+ } else {
+ self.next_ty_var(TypeVariableOrigin {
+ kind: TypeVariableOriginKind::TypeInference,
+ span,
+ })
+ }
+ }
+
+ fn ct_infer(
+ &self,
+ ty: Ty<'tcx>,
+ param: Option<&ty::GenericParamDef>,
+ span: Span,
+ ) -> &'tcx Const<'tcx> {
+ if let Some(param) = param {
+ if let GenericArgKind::Const(ct) = self.var_for_def(span, param).unpack() {
+ return ct;
+ }
+ unreachable!()
+ } else {
+ self.next_const_var(
+ ty,
+ ConstVariableOrigin { kind: ConstVariableOriginKind::ConstInference, span },
+ )
+ }
+ }
+
+ fn projected_ty_from_poly_trait_ref(
+ &self,
+ span: Span,
+ item_def_id: DefId,
+ item_segment: &hir::PathSegment<'_>,
+ poly_trait_ref: ty::PolyTraitRef<'tcx>,
+ ) -> Ty<'tcx> {
+ let (trait_ref, _) = self.replace_bound_vars_with_fresh_vars(
+ span,
+ infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id),
+ &poly_trait_ref,
+ );
+
+ let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
+ self,
+ self.tcx,
+ span,
+ item_def_id,
+ item_segment,
+ trait_ref.substs,
+ );
+
+ self.tcx().mk_projection(item_def_id, item_substs)
+ }
+
+ fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
+ if ty.has_escaping_bound_vars() {
+ ty // FIXME: normalization and escaping regions
+ } else {
+ self.normalize_associated_types_in(span, &ty)
+ }
+ }
+
+ fn set_tainted_by_errors(&self) {
+ self.infcx.set_tainted_by_errors()
+ }
+
+ fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, _span: Span) {
+ self.write_ty(hir_id, ty)
+ }
+}
--- /dev/null
+use super::FnCtxt;
+use crate::astconv::AstConv;
+
+use rustc_ast::util::parser::ExprPrecedence;
+use rustc_span::{self, Span};
+use rustc_trait_selection::traits;
+
+use rustc_errors::{Applicability, DiagnosticBuilder};
+use rustc_hir as hir;
+use rustc_hir::def::{CtorOf, DefKind};
+use rustc_hir::lang_items::LangItem;
+use rustc_hir::{ExprKind, ItemKind, Node};
+use rustc_infer::infer;
+use rustc_middle::ty::{self, Ty};
+use rustc_span::symbol::kw;
+use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
+
+use std::iter;
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+ pub(in super::super) fn suggest_semicolon_at_end(
+ &self,
+ span: Span,
+ err: &mut DiagnosticBuilder<'_>,
+ ) {
+ err.span_suggestion_short(
+ span.shrink_to_hi(),
+ "consider using a semicolon here",
+ ";".to_string(),
+ Applicability::MachineApplicable,
+ );
+ }
+
+ /// On implicit return expressions with mismatched types, provides the following suggestions:
+ ///
+ /// - Points out the method's return type as the reason for the expected type.
+ /// - Possible missing semicolon.
+ /// - Possible missing return type if the return type is the default, and not `fn main()`.
+ pub fn suggest_mismatched_types_on_tail(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ cause_span: Span,
+ blk_id: hir::HirId,
+ ) -> bool {
+ let expr = expr.peel_drop_temps();
+ self.suggest_missing_semicolon(err, expr, expected, cause_span);
+ let mut pointing_at_return_type = false;
+ if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) {
+ pointing_at_return_type =
+ self.suggest_missing_return_type(err, &fn_decl, expected, found, can_suggest);
+ }
+ pointing_at_return_type
+ }
+
+ /// When encountering an fn-like ctor that needs to unify with a value, check whether calling
+ /// the ctor would successfully solve the type mismatch and if so, suggest it:
+ /// ```
+ /// fn foo(x: usize) -> usize { x }
+ /// let x: usize = foo; // suggest calling the `foo` function: `foo(42)`
+ /// ```
+ fn suggest_fn_call(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ ) -> bool {
+ let hir = self.tcx.hir();
+ let (def_id, sig) = match *found.kind() {
+ ty::FnDef(def_id, _) => (def_id, found.fn_sig(self.tcx)),
+ ty::Closure(def_id, substs) => (def_id, substs.as_closure().sig()),
+ _ => return false,
+ };
+
+ let sig = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, &sig).0;
+ let sig = self.normalize_associated_types_in(expr.span, &sig);
+ if self.can_coerce(sig.output(), expected) {
+ let (mut sugg_call, applicability) = if sig.inputs().is_empty() {
+ (String::new(), Applicability::MachineApplicable)
+ } else {
+ ("...".to_string(), Applicability::HasPlaceholders)
+ };
+ let mut msg = "call this function";
+ match hir.get_if_local(def_id) {
+ Some(
+ Node::Item(hir::Item { kind: ItemKind::Fn(.., body_id), .. })
+ | Node::ImplItem(hir::ImplItem {
+ kind: hir::ImplItemKind::Fn(_, body_id), ..
+ })
+ | Node::TraitItem(hir::TraitItem {
+ kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Provided(body_id)),
+ ..
+ }),
+ ) => {
+ let body = hir.body(*body_id);
+ sugg_call = body
+ .params
+ .iter()
+ .map(|param| match ¶m.pat.kind {
+ hir::PatKind::Binding(_, _, ident, None)
+ if ident.name != kw::SelfLower =>
+ {
+ ident.to_string()
+ }
+ _ => "_".to_string(),
+ })
+ .collect::<Vec<_>>()
+ .join(", ");
+ }
+ Some(Node::Expr(hir::Expr {
+ kind: ExprKind::Closure(_, _, body_id, _, _),
+ span: full_closure_span,
+ ..
+ })) => {
+ if *full_closure_span == expr.span {
+ return false;
+ }
+ msg = "call this closure";
+ let body = hir.body(*body_id);
+ sugg_call = body
+ .params
+ .iter()
+ .map(|param| match ¶m.pat.kind {
+ hir::PatKind::Binding(_, _, ident, None)
+ if ident.name != kw::SelfLower =>
+ {
+ ident.to_string()
+ }
+ _ => "_".to_string(),
+ })
+ .collect::<Vec<_>>()
+ .join(", ");
+ }
+ Some(Node::Ctor(hir::VariantData::Tuple(fields, _))) => {
+ sugg_call = fields.iter().map(|_| "_").collect::<Vec<_>>().join(", ");
+ match def_id.as_local().map(|def_id| hir.def_kind(def_id)) {
+ Some(DefKind::Ctor(hir::def::CtorOf::Variant, _)) => {
+ msg = "instantiate this tuple variant";
+ }
+ Some(DefKind::Ctor(CtorOf::Struct, _)) => {
+ msg = "instantiate this tuple struct";
+ }
+ _ => {}
+ }
+ }
+ Some(Node::ForeignItem(hir::ForeignItem {
+ kind: hir::ForeignItemKind::Fn(_, idents, _),
+ ..
+ })) => {
+ sugg_call = idents
+ .iter()
+ .map(|ident| {
+ if ident.name != kw::SelfLower {
+ ident.to_string()
+ } else {
+ "_".to_string()
+ }
+ })
+ .collect::<Vec<_>>()
+ .join(", ")
+ }
+ Some(Node::TraitItem(hir::TraitItem {
+ kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Required(idents)),
+ ..
+ })) => {
+ sugg_call = idents
+ .iter()
+ .map(|ident| {
+ if ident.name != kw::SelfLower {
+ ident.to_string()
+ } else {
+ "_".to_string()
+ }
+ })
+ .collect::<Vec<_>>()
+ .join(", ")
+ }
+ _ => {}
+ }
+ err.span_suggestion_verbose(
+ expr.span.shrink_to_hi(),
+ &format!("use parentheses to {}", msg),
+ format!("({})", sugg_call),
+ applicability,
+ );
+ return true;
+ }
+ false
+ }
+
+ pub fn suggest_deref_ref_or_into(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
+ ) {
+ if let Some((sp, msg, suggestion, applicability)) = self.check_ref(expr, found, expected) {
+ err.span_suggestion(sp, msg, suggestion, applicability);
+ } else if let (ty::FnDef(def_id, ..), true) =
+ (&found.kind(), self.suggest_fn_call(err, expr, expected, found))
+ {
+ if let Some(sp) = self.tcx.hir().span_if_local(*def_id) {
+ let sp = self.sess().source_map().guess_head_span(sp);
+ err.span_label(sp, &format!("{} defined here", found));
+ }
+ } else if !self.check_for_cast(err, expr, found, expected, expected_ty_expr) {
+ let is_struct_pat_shorthand_field =
+ self.is_hir_id_from_struct_pattern_shorthand_field(expr.hir_id, expr.span);
+ let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id);
+ if let Ok(expr_text) = self.sess().source_map().span_to_snippet(expr.span) {
+ let mut suggestions = iter::repeat(&expr_text)
+ .zip(methods.iter())
+ .filter_map(|(receiver, method)| {
+ let method_call = format!(".{}()", method.ident);
+ if receiver.ends_with(&method_call) {
+ None // do not suggest code that is already there (#53348)
+ } else {
+ let method_call_list = [".to_vec()", ".to_string()"];
+ let sugg = if receiver.ends_with(".clone()")
+ && method_call_list.contains(&method_call.as_str())
+ {
+ let max_len = receiver.rfind('.').unwrap();
+ format!("{}{}", &receiver[..max_len], method_call)
+ } else {
+ if expr.precedence().order() < ExprPrecedence::MethodCall.order() {
+ format!("({}){}", receiver, method_call)
+ } else {
+ format!("{}{}", receiver, method_call)
+ }
+ };
+ Some(if is_struct_pat_shorthand_field {
+ format!("{}: {}", receiver, sugg)
+ } else {
+ sugg
+ })
+ }
+ })
+ .peekable();
+ if suggestions.peek().is_some() {
+ err.span_suggestions(
+ expr.span,
+ "try using a conversion method",
+ suggestions,
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+ }
+ }
+
+ /// When encountering the expected boxed value allocated in the stack, suggest allocating it
+ /// in the heap by calling `Box::new()`.
+ pub(in super::super) fn suggest_boxing_when_appropriate(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ ) {
+ if self.tcx.hir().is_inside_const_context(expr.hir_id) {
+ // Do not suggest `Box::new` in const context.
+ return;
+ }
+ if !expected.is_box() || found.is_box() {
+ return;
+ }
+ let boxed_found = self.tcx.mk_box(found);
+ if let (true, Ok(snippet)) = (
+ self.can_coerce(boxed_found, expected),
+ self.sess().source_map().span_to_snippet(expr.span),
+ ) {
+ err.span_suggestion(
+ expr.span,
+ "store this in the heap by calling `Box::new`",
+ format!("Box::new({})", snippet),
+ Applicability::MachineApplicable,
+ );
+ err.note(
+ "for more on the distinction between the stack and the heap, read \
+ https://doc.rust-lang.org/book/ch15-01-box.html, \
+ https://doc.rust-lang.org/rust-by-example/std/box.html, and \
+ https://doc.rust-lang.org/std/boxed/index.html",
+ );
+ }
+ }
+
+ /// When encountering an `impl Future` where `BoxFuture` is expected, suggest `Box::pin`.
+ pub(in super::super) fn suggest_calling_boxed_future_when_appropriate(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ ) -> bool {
+ // Handle #68197.
+
+ if self.tcx.hir().is_inside_const_context(expr.hir_id) {
+ // Do not suggest `Box::new` in const context.
+ return false;
+ }
+ let pin_did = self.tcx.lang_items().pin_type();
+ match expected.kind() {
+ ty::Adt(def, _) if Some(def.did) != pin_did => return false,
+ // This guards the `unwrap` and `mk_box` below.
+ _ if pin_did.is_none() || self.tcx.lang_items().owned_box().is_none() => return false,
+ _ => {}
+ }
+ let boxed_found = self.tcx.mk_box(found);
+ let new_found = self.tcx.mk_lang_item(boxed_found, LangItem::Pin).unwrap();
+ if let (true, Ok(snippet)) = (
+ self.can_coerce(new_found, expected),
+ self.sess().source_map().span_to_snippet(expr.span),
+ ) {
+ match found.kind() {
+ ty::Adt(def, _) if def.is_box() => {
+ err.help("use `Box::pin`");
+ }
+ _ => {
+ err.span_suggestion(
+ expr.span,
+ "you need to pin and box this expression",
+ format!("Box::pin({})", snippet),
+ Applicability::MachineApplicable,
+ );
+ }
+ }
+ true
+ } else {
+ false
+ }
+ }
+
+ /// A common error is to forget to add a semicolon at the end of a block, e.g.,
+ ///
+ /// ```
+ /// fn foo() {
+ /// bar_that_returns_u32()
+ /// }
+ /// ```
+ ///
+ /// This routine checks if the return expression in a block would make sense on its own as a
+ /// statement and the return type has been left as default or has been specified as `()`. If so,
+ /// it suggests adding a semicolon.
+ fn suggest_missing_semicolon(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expression: &'tcx hir::Expr<'tcx>,
+ expected: Ty<'tcx>,
+ cause_span: Span,
+ ) {
+ if expected.is_unit() {
+ // `BlockTailExpression` only relevant if the tail expr would be
+ // useful on its own.
+ match expression.kind {
+ ExprKind::Call(..)
+ | ExprKind::MethodCall(..)
+ | ExprKind::Loop(..)
+ | ExprKind::Match(..)
+ | ExprKind::Block(..) => {
+ err.span_suggestion(
+ cause_span.shrink_to_hi(),
+ "try adding a semicolon",
+ ";".to_string(),
+ Applicability::MachineApplicable,
+ );
+ }
+ _ => (),
+ }
+ }
+ }
+
+ /// A possible error is to forget to add a return type that is needed:
+ ///
+ /// ```
+ /// fn foo() {
+ /// bar_that_returns_u32()
+ /// }
+ /// ```
+ ///
+ /// This routine checks if the return type is left as default, the method is not part of an
+ /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return
+ /// type.
+ pub(in super::super) fn suggest_missing_return_type(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ fn_decl: &hir::FnDecl<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ can_suggest: bool,
+ ) -> bool {
+ // Only suggest changing the return type for methods that
+ // haven't set a return type at all (and aren't `fn main()` or an impl).
+ match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) {
+ (&hir::FnRetTy::DefaultReturn(span), true, true, true) => {
+ err.span_suggestion(
+ span,
+ "try adding a return type",
+ format!("-> {} ", self.resolve_vars_with_obligations(found)),
+ Applicability::MachineApplicable,
+ );
+ true
+ }
+ (&hir::FnRetTy::DefaultReturn(span), false, true, true) => {
+ err.span_label(span, "possibly return type missing here?");
+ true
+ }
+ (&hir::FnRetTy::DefaultReturn(span), _, false, true) => {
+ // `fn main()` must return `()`, do not suggest changing return type
+ err.span_label(span, "expected `()` because of default return type");
+ true
+ }
+ // expectation was caused by something else, not the default return
+ (&hir::FnRetTy::DefaultReturn(_), _, _, false) => false,
+ (&hir::FnRetTy::Return(ref ty), _, _, _) => {
+ // Only point to return type if the expected type is the return type, as if they
+ // are not, the expectation must have been caused by something else.
+ debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind);
+ let sp = ty.span;
+ let ty = AstConv::ast_ty_to_ty(self, ty);
+ debug!("suggest_missing_return_type: return type {:?}", ty);
+ debug!("suggest_missing_return_type: expected type {:?}", ty);
+ if ty.kind() == expected.kind() {
+ err.span_label(sp, format!("expected `{}` because of return type", expected));
+ return true;
+ }
+ false
+ }
+ }
+ }
+
+ /// A possible error is to forget to add `.await` when using futures:
+ ///
+ /// ```
+ /// async fn make_u32() -> u32 {
+ /// 22
+ /// }
+ ///
+ /// fn take_u32(x: u32) {}
+ ///
+ /// async fn foo() {
+ /// let x = make_u32();
+ /// take_u32(x);
+ /// }
+ /// ```
+ ///
+ /// This routine checks if the found type `T` implements `Future<Output=U>` where `U` is the
+ /// expected type. If this is the case, and we are inside of an async body, it suggests adding
+ /// `.await` to the tail of the expression.
+ pub(in super::super) fn suggest_missing_await(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ ) {
+ debug!("suggest_missing_await: expr={:?} expected={:?}, found={:?}", expr, expected, found);
+ // `.await` is not permitted outside of `async` bodies, so don't bother to suggest if the
+ // body isn't `async`.
+ let item_id = self.tcx().hir().get_parent_node(self.body_id);
+ if let Some(body_id) = self.tcx().hir().maybe_body_owned_by(item_id) {
+ let body = self.tcx().hir().body(body_id);
+ if let Some(hir::GeneratorKind::Async(_)) = body.generator_kind {
+ let sp = expr.span;
+ // Check for `Future` implementations by constructing a predicate to
+ // prove: `<T as Future>::Output == U`
+ let future_trait = self.tcx.require_lang_item(LangItem::Future, Some(sp));
+ let item_def_id = self
+ .tcx
+ .associated_items(future_trait)
+ .in_definition_order()
+ .next()
+ .unwrap()
+ .def_id;
+ // `<T as Future>::Output`
+ let projection_ty = ty::ProjectionTy {
+ // `T`
+ substs: self
+ .tcx
+ .mk_substs_trait(found, self.fresh_substs_for_item(sp, item_def_id)),
+ // `Future::Output`
+ item_def_id,
+ };
+
+ let predicate = ty::PredicateAtom::Projection(ty::ProjectionPredicate {
+ projection_ty,
+ ty: expected,
+ })
+ .potentially_quantified(self.tcx, ty::PredicateKind::ForAll);
+ let obligation = traits::Obligation::new(self.misc(sp), self.param_env, predicate);
+
+ debug!("suggest_missing_await: trying obligation {:?}", obligation);
+
+ if self.infcx.predicate_may_hold(&obligation) {
+ debug!("suggest_missing_await: obligation held: {:?}", obligation);
+ if let Ok(code) = self.sess().source_map().span_to_snippet(sp) {
+ err.span_suggestion(
+ sp,
+ "consider using `.await` here",
+ format!("{}.await", code),
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ debug!("suggest_missing_await: no snippet for {:?}", sp);
+ }
+ } else {
+ debug!("suggest_missing_await: obligation did not hold: {:?}", obligation)
+ }
+ }
+ }
+ }
+
+ pub(in super::super) fn suggest_missing_parentheses(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ expr: &hir::Expr<'_>,
+ ) {
+ let sp = self.tcx.sess.source_map().start_point(expr.span);
+ if let Some(sp) = self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) {
+ // `{ 42 } &&x` (#61475) or `{ 42 } && if x { 1 } else { 0 }`
+ self.tcx.sess.parse_sess.expr_parentheses_needed(err, *sp, None);
+ }
+ }
+}
+++ /dev/null
-use super::coercion::CoerceMany;
-use super::method::MethodCallee;
-use super::Expectation::*;
-use super::TupleArgumentsFlag::*;
-use super::{
- potentially_plural_count, struct_span_err, BreakableCtxt, Diverges, Expectation, FnCtxt,
- LocalTy, Needs, TupleArgumentsFlag,
-};
-use crate::astconv::AstConv;
-
-use rustc_ast as ast;
-use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticId};
-use rustc_hir as hir;
-use rustc_hir::def::{DefKind, Res};
-use rustc_hir::def_id::DefId;
-use rustc_hir::{ExprKind, Node, QPath};
-use rustc_middle::ty::adjustment::AllowTwoPhase;
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::{self, Ty};
-use rustc_session::Session;
-use rustc_span::symbol::{sym, Ident};
-use rustc_span::{self, Span};
-use rustc_trait_selection::traits::{self, ObligationCauseCode};
-
-use std::mem::replace;
-use std::slice;
-
-impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
- pub(super) fn check_casts(&self) {
- let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
- for cast in deferred_cast_checks.drain(..) {
- cast.check(self);
- }
- }
-
- pub(super) fn check_method_argument_types(
- &self,
- sp: Span,
- expr: &'tcx hir::Expr<'tcx>,
- method: Result<MethodCallee<'tcx>, ()>,
- args_no_rcvr: &'tcx [hir::Expr<'tcx>],
- tuple_arguments: TupleArgumentsFlag,
- expected: Expectation<'tcx>,
- ) -> Ty<'tcx> {
- let has_error = match method {
- Ok(method) => method.substs.references_error() || method.sig.references_error(),
- Err(_) => true,
- };
- if has_error {
- let err_inputs = self.err_args(args_no_rcvr.len());
-
- let err_inputs = match tuple_arguments {
- DontTupleArguments => err_inputs,
- TupleArguments => vec![self.tcx.intern_tup(&err_inputs[..])],
- };
-
- self.check_argument_types(
- sp,
- expr,
- &err_inputs[..],
- &[],
- args_no_rcvr,
- false,
- tuple_arguments,
- None,
- );
- return self.tcx.ty_error();
- }
-
- let method = method.unwrap();
- // HACK(eddyb) ignore self in the definition (see above).
- let expected_arg_tys = self.expected_inputs_for_expected_output(
- sp,
- expected,
- method.sig.output(),
- &method.sig.inputs()[1..],
- );
- self.check_argument_types(
- sp,
- expr,
- &method.sig.inputs()[1..],
- &expected_arg_tys[..],
- args_no_rcvr,
- method.sig.c_variadic,
- tuple_arguments,
- self.tcx.hir().span_if_local(method.def_id),
- );
- method.sig.output()
- }
-
- /// Generic function that factors out common logic from function calls,
- /// method calls and overloaded operators.
- pub(super) fn check_argument_types(
- &self,
- sp: Span,
- expr: &'tcx hir::Expr<'tcx>,
- fn_inputs: &[Ty<'tcx>],
- expected_arg_tys: &[Ty<'tcx>],
- args: &'tcx [hir::Expr<'tcx>],
- c_variadic: bool,
- tuple_arguments: TupleArgumentsFlag,
- def_span: Option<Span>,
- ) {
- let tcx = self.tcx;
- // Grab the argument types, supplying fresh type variables
- // if the wrong number of arguments were supplied
- let supplied_arg_count = if tuple_arguments == DontTupleArguments { args.len() } else { 1 };
-
- // All the input types from the fn signature must outlive the call
- // so as to validate implied bounds.
- for (&fn_input_ty, arg_expr) in fn_inputs.iter().zip(args.iter()) {
- self.register_wf_obligation(fn_input_ty.into(), arg_expr.span, traits::MiscObligation);
- }
-
- let expected_arg_count = fn_inputs.len();
-
- let param_count_error = |expected_count: usize,
- arg_count: usize,
- error_code: &str,
- c_variadic: bool,
- sugg_unit: bool| {
- let (span, start_span, args) = match &expr.kind {
- hir::ExprKind::Call(hir::Expr { span, .. }, args) => (*span, *span, &args[..]),
- hir::ExprKind::MethodCall(path_segment, span, args, _) => (
- *span,
- // `sp` doesn't point at the whole `foo.bar()`, only at `bar`.
- path_segment
- .args
- .and_then(|args| args.args.iter().last())
- // Account for `foo.bar::<T>()`.
- .map(|arg| {
- // Skip the closing `>`.
- tcx.sess
- .source_map()
- .next_point(tcx.sess.source_map().next_point(arg.span()))
- })
- .unwrap_or(*span),
- &args[1..], // Skip the receiver.
- ),
- k => span_bug!(sp, "checking argument types on a non-call: `{:?}`", k),
- };
- let arg_spans = if args.is_empty() {
- // foo()
- // ^^^-- supplied 0 arguments
- // |
- // expected 2 arguments
- vec![tcx.sess.source_map().next_point(start_span).with_hi(sp.hi())]
- } else {
- // foo(1, 2, 3)
- // ^^^ - - - supplied 3 arguments
- // |
- // expected 2 arguments
- args.iter().map(|arg| arg.span).collect::<Vec<Span>>()
- };
-
- let mut err = tcx.sess.struct_span_err_with_code(
- span,
- &format!(
- "this function takes {}{} but {} {} supplied",
- if c_variadic { "at least " } else { "" },
- potentially_plural_count(expected_count, "argument"),
- potentially_plural_count(arg_count, "argument"),
- if arg_count == 1 { "was" } else { "were" }
- ),
- DiagnosticId::Error(error_code.to_owned()),
- );
- let label = format!("supplied {}", potentially_plural_count(arg_count, "argument"));
- for (i, span) in arg_spans.into_iter().enumerate() {
- err.span_label(
- span,
- if arg_count == 0 || i + 1 == arg_count { &label } else { "" },
- );
- }
-
- if let Some(def_s) = def_span.map(|sp| tcx.sess.source_map().guess_head_span(sp)) {
- err.span_label(def_s, "defined here");
- }
- if sugg_unit {
- let sugg_span = tcx.sess.source_map().end_point(expr.span);
- // remove closing `)` from the span
- let sugg_span = sugg_span.shrink_to_lo();
- err.span_suggestion(
- sugg_span,
- "expected the unit value `()`; create it with empty parentheses",
- String::from("()"),
- Applicability::MachineApplicable,
- );
- } else {
- err.span_label(
- span,
- format!(
- "expected {}{}",
- if c_variadic { "at least " } else { "" },
- potentially_plural_count(expected_count, "argument")
- ),
- );
- }
- err.emit();
- };
-
- let mut expected_arg_tys = expected_arg_tys.to_vec();
-
- let formal_tys = if tuple_arguments == TupleArguments {
- let tuple_type = self.structurally_resolved_type(sp, fn_inputs[0]);
- match tuple_type.kind() {
- ty::Tuple(arg_types) if arg_types.len() != args.len() => {
- param_count_error(arg_types.len(), args.len(), "E0057", false, false);
- expected_arg_tys = vec![];
- self.err_args(args.len())
- }
- ty::Tuple(arg_types) => {
- expected_arg_tys = match expected_arg_tys.get(0) {
- Some(&ty) => match ty.kind() {
- ty::Tuple(ref tys) => tys.iter().map(|k| k.expect_ty()).collect(),
- _ => vec![],
- },
- None => vec![],
- };
- arg_types.iter().map(|k| k.expect_ty()).collect()
- }
- _ => {
- struct_span_err!(
- tcx.sess,
- sp,
- E0059,
- "cannot use call notation; the first type parameter \
- for the function trait is neither a tuple nor unit"
- )
- .emit();
- expected_arg_tys = vec![];
- self.err_args(args.len())
- }
- }
- } else if expected_arg_count == supplied_arg_count {
- fn_inputs.to_vec()
- } else if c_variadic {
- if supplied_arg_count >= expected_arg_count {
- fn_inputs.to_vec()
- } else {
- param_count_error(expected_arg_count, supplied_arg_count, "E0060", true, false);
- expected_arg_tys = vec![];
- self.err_args(supplied_arg_count)
- }
- } else {
- // is the missing argument of type `()`?
- let sugg_unit = if expected_arg_tys.len() == 1 && supplied_arg_count == 0 {
- self.resolve_vars_if_possible(&expected_arg_tys[0]).is_unit()
- } else if fn_inputs.len() == 1 && supplied_arg_count == 0 {
- self.resolve_vars_if_possible(&fn_inputs[0]).is_unit()
- } else {
- false
- };
- param_count_error(expected_arg_count, supplied_arg_count, "E0061", false, sugg_unit);
-
- expected_arg_tys = vec![];
- self.err_args(supplied_arg_count)
- };
-
- debug!(
- "check_argument_types: formal_tys={:?}",
- formal_tys.iter().map(|t| self.ty_to_string(*t)).collect::<Vec<String>>()
- );
-
- // If there is no expectation, expect formal_tys.
- let expected_arg_tys =
- if !expected_arg_tys.is_empty() { expected_arg_tys } else { formal_tys.clone() };
-
- let mut final_arg_types: Vec<(usize, Ty<'_>, Ty<'_>)> = vec![];
-
- // Check the arguments.
- // We do this in a pretty awful way: first we type-check any arguments
- // that are not closures, then we type-check the closures. This is so
- // that we have more information about the types of arguments when we
- // type-check the functions. This isn't really the right way to do this.
- for &check_closures in &[false, true] {
- debug!("check_closures={}", check_closures);
-
- // More awful hacks: before we check argument types, try to do
- // an "opportunistic" trait resolution of any trait bounds on
- // the call. This helps coercions.
- if check_closures {
- self.select_obligations_where_possible(false, |errors| {
- self.point_at_type_arg_instead_of_call_if_possible(errors, expr);
- self.point_at_arg_instead_of_call_if_possible(
- errors,
- &final_arg_types[..],
- sp,
- &args,
- );
- })
- }
-
- // For C-variadic functions, we don't have a declared type for all of
- // the arguments hence we only do our usual type checking with
- // the arguments who's types we do know.
- let t = if c_variadic {
- expected_arg_count
- } else if tuple_arguments == TupleArguments {
- args.len()
- } else {
- supplied_arg_count
- };
- for (i, arg) in args.iter().take(t).enumerate() {
- // Warn only for the first loop (the "no closures" one).
- // Closure arguments themselves can't be diverging, but
- // a previous argument can, e.g., `foo(panic!(), || {})`.
- if !check_closures {
- self.warn_if_unreachable(arg.hir_id, arg.span, "expression");
- }
-
- let is_closure = match arg.kind {
- ExprKind::Closure(..) => true,
- _ => false,
- };
-
- if is_closure != check_closures {
- continue;
- }
-
- debug!("checking the argument");
- let formal_ty = formal_tys[i];
-
- // The special-cased logic below has three functions:
- // 1. Provide as good of an expected type as possible.
- let expected = Expectation::rvalue_hint(self, expected_arg_tys[i]);
-
- let checked_ty = self.check_expr_with_expectation(&arg, expected);
-
- // 2. Coerce to the most detailed type that could be coerced
- // to, which is `expected_ty` if `rvalue_hint` returns an
- // `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise.
- let coerce_ty = expected.only_has_type(self).unwrap_or(formal_ty);
- // We're processing function arguments so we definitely want to use
- // two-phase borrows.
- self.demand_coerce(&arg, checked_ty, coerce_ty, None, AllowTwoPhase::Yes);
- final_arg_types.push((i, checked_ty, coerce_ty));
-
- // 3. Relate the expected type and the formal one,
- // if the expected type was used for the coercion.
- self.demand_suptype(arg.span, formal_ty, coerce_ty);
- }
- }
-
- // We also need to make sure we at least write the ty of the other
- // arguments which we skipped above.
- if c_variadic {
- fn variadic_error<'tcx>(s: &Session, span: Span, t: Ty<'tcx>, cast_ty: &str) {
- use crate::structured_errors::{StructuredDiagnostic, VariadicError};
- VariadicError::new(s, span, t, cast_ty).diagnostic().emit();
- }
-
- for arg in args.iter().skip(expected_arg_count) {
- let arg_ty = self.check_expr(&arg);
-
- // There are a few types which get autopromoted when passed via varargs
- // in C but we just error out instead and require explicit casts.
- let arg_ty = self.structurally_resolved_type(arg.span, arg_ty);
- match arg_ty.kind() {
- ty::Float(ast::FloatTy::F32) => {
- variadic_error(tcx.sess, arg.span, arg_ty, "c_double");
- }
- ty::Int(ast::IntTy::I8 | ast::IntTy::I16) | ty::Bool => {
- variadic_error(tcx.sess, arg.span, arg_ty, "c_int");
- }
- ty::Uint(ast::UintTy::U8 | ast::UintTy::U16) => {
- variadic_error(tcx.sess, arg.span, arg_ty, "c_uint");
- }
- ty::FnDef(..) => {
- let ptr_ty = self.tcx.mk_fn_ptr(arg_ty.fn_sig(self.tcx));
- let ptr_ty = self.resolve_vars_if_possible(&ptr_ty);
- variadic_error(tcx.sess, arg.span, arg_ty, &ptr_ty.to_string());
- }
- _ => {}
- }
- }
- }
- }
-
- // AST fragment checking
- pub(super) fn check_lit(&self, lit: &hir::Lit, expected: Expectation<'tcx>) -> Ty<'tcx> {
- let tcx = self.tcx;
-
- match lit.node {
- ast::LitKind::Str(..) => tcx.mk_static_str(),
- ast::LitKind::ByteStr(ref v) => {
- tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.u8, v.len() as u64))
- }
- ast::LitKind::Byte(_) => tcx.types.u8,
- ast::LitKind::Char(_) => tcx.types.char,
- ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(t),
- ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(t),
- ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => {
- let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() {
- ty::Int(_) | ty::Uint(_) => Some(ty),
- ty::Char => Some(tcx.types.u8),
- ty::RawPtr(..) => Some(tcx.types.usize),
- ty::FnDef(..) | ty::FnPtr(_) => Some(tcx.types.usize),
- _ => None,
- });
- opt_ty.unwrap_or_else(|| self.next_int_var())
- }
- ast::LitKind::Float(_, ast::LitFloatType::Suffixed(t)) => tcx.mk_mach_float(t),
- ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) => {
- let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() {
- ty::Float(_) => Some(ty),
- _ => None,
- });
- opt_ty.unwrap_or_else(|| self.next_float_var())
- }
- ast::LitKind::Bool(_) => tcx.types.bool,
- ast::LitKind::Err(_) => tcx.ty_error(),
- }
- }
-
- pub fn check_struct_path(
- &self,
- qpath: &QPath<'_>,
- hir_id: hir::HirId,
- ) -> Option<(&'tcx ty::VariantDef, Ty<'tcx>)> {
- let path_span = qpath.qself_span();
- let (def, ty) = self.finish_resolving_struct_path(qpath, path_span, hir_id);
- let variant = match def {
- Res::Err => {
- self.set_tainted_by_errors();
- return None;
- }
- Res::Def(DefKind::Variant, _) => match ty.kind() {
- ty::Adt(adt, substs) => Some((adt.variant_of_res(def), adt.did, substs)),
- _ => bug!("unexpected type: {:?}", ty),
- },
- Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _)
- | Res::SelfTy(..) => match ty.kind() {
- ty::Adt(adt, substs) if !adt.is_enum() => {
- Some((adt.non_enum_variant(), adt.did, substs))
- }
- _ => None,
- },
- _ => bug!("unexpected definition: {:?}", def),
- };
-
- if let Some((variant, did, substs)) = variant {
- debug!("check_struct_path: did={:?} substs={:?}", did, substs);
- self.write_user_type_annotation_from_substs(hir_id, did, substs, None);
-
- // Check bounds on type arguments used in the path.
- let (bounds, _) = self.instantiate_bounds(path_span, did, substs);
- let cause =
- traits::ObligationCause::new(path_span, self.body_id, traits::ItemObligation(did));
- self.add_obligations_for_parameters(cause, bounds);
-
- Some((variant, ty))
- } else {
- struct_span_err!(
- self.tcx.sess,
- path_span,
- E0071,
- "expected struct, variant or union type, found {}",
- ty.sort_string(self.tcx)
- )
- .span_label(path_span, "not a struct")
- .emit();
- None
- }
- }
-
- pub fn check_decl_initializer(
- &self,
- local: &'tcx hir::Local<'tcx>,
- init: &'tcx hir::Expr<'tcx>,
- ) -> Ty<'tcx> {
- // FIXME(tschottdorf): `contains_explicit_ref_binding()` must be removed
- // for #42640 (default match binding modes).
- //
- // See #44848.
- let ref_bindings = local.pat.contains_explicit_ref_binding();
-
- let local_ty = self.local_ty(init.span, local.hir_id).revealed_ty;
- if let Some(m) = ref_bindings {
- // Somewhat subtle: if we have a `ref` binding in the pattern,
- // we want to avoid introducing coercions for the RHS. This is
- // both because it helps preserve sanity and, in the case of
- // ref mut, for soundness (issue #23116). In particular, in
- // the latter case, we need to be clear that the type of the
- // referent for the reference that results is *equal to* the
- // type of the place it is referencing, and not some
- // supertype thereof.
- let init_ty = self.check_expr_with_needs(init, Needs::maybe_mut_place(m));
- self.demand_eqtype(init.span, local_ty, init_ty);
- init_ty
- } else {
- self.check_expr_coercable_to_type(init, local_ty, None)
- }
- }
-
- /// Type check a `let` statement.
- pub fn check_decl_local(&self, local: &'tcx hir::Local<'tcx>) {
- // Determine and write the type which we'll check the pattern against.
- let ty = self.local_ty(local.span, local.hir_id).decl_ty;
- self.write_ty(local.hir_id, ty);
-
- // Type check the initializer.
- if let Some(ref init) = local.init {
- let init_ty = self.check_decl_initializer(local, &init);
- self.overwrite_local_ty_if_err(local, ty, init_ty);
- }
-
- // Does the expected pattern type originate from an expression and what is the span?
- let (origin_expr, ty_span) = match (local.ty, local.init) {
- (Some(ty), _) => (false, Some(ty.span)), // Bias towards the explicit user type.
- (_, Some(init)) => (true, Some(init.span)), // No explicit type; so use the scrutinee.
- _ => (false, None), // We have `let $pat;`, so the expected type is unconstrained.
- };
-
- // Type check the pattern. Override if necessary to avoid knock-on errors.
- self.check_pat_top(&local.pat, ty, ty_span, origin_expr);
- let pat_ty = self.node_ty(local.pat.hir_id);
- self.overwrite_local_ty_if_err(local, ty, pat_ty);
- }
-
- pub fn check_stmt(&self, stmt: &'tcx hir::Stmt<'tcx>) {
- // Don't do all the complex logic below for `DeclItem`.
- match stmt.kind {
- hir::StmtKind::Item(..) => return,
- hir::StmtKind::Local(..) | hir::StmtKind::Expr(..) | hir::StmtKind::Semi(..) => {}
- }
-
- self.warn_if_unreachable(stmt.hir_id, stmt.span, "statement");
-
- // Hide the outer diverging and `has_errors` flags.
- let old_diverges = self.diverges.replace(Diverges::Maybe);
- let old_has_errors = self.has_errors.replace(false);
-
- match stmt.kind {
- hir::StmtKind::Local(ref l) => {
- self.check_decl_local(&l);
- }
- // Ignore for now.
- hir::StmtKind::Item(_) => {}
- hir::StmtKind::Expr(ref expr) => {
- // Check with expected type of `()`.
- self.check_expr_has_type_or_error(&expr, self.tcx.mk_unit(), |err| {
- self.suggest_semicolon_at_end(expr.span, err);
- });
- }
- hir::StmtKind::Semi(ref expr) => {
- self.check_expr(&expr);
- }
- }
-
- // Combine the diverging and `has_error` flags.
- self.diverges.set(self.diverges.get() | old_diverges);
- self.has_errors.set(self.has_errors.get() | old_has_errors);
- }
-
- pub fn check_block_no_value(&self, blk: &'tcx hir::Block<'tcx>) {
- let unit = self.tcx.mk_unit();
- let ty = self.check_block_with_expected(blk, ExpectHasType(unit));
-
- // if the block produces a `!` value, that can always be
- // (effectively) coerced to unit.
- if !ty.is_never() {
- self.demand_suptype(blk.span, unit, ty);
- }
- }
-
- pub(super) fn check_block_with_expected(
- &self,
- blk: &'tcx hir::Block<'tcx>,
- expected: Expectation<'tcx>,
- ) -> Ty<'tcx> {
- let prev = {
- let mut fcx_ps = self.ps.borrow_mut();
- let unsafety_state = fcx_ps.recurse(blk);
- replace(&mut *fcx_ps, unsafety_state)
- };
-
- // In some cases, blocks have just one exit, but other blocks
- // can be targeted by multiple breaks. This can happen both
- // with labeled blocks as well as when we desugar
- // a `try { ... }` expression.
- //
- // Example 1:
- //
- // 'a: { if true { break 'a Err(()); } Ok(()) }
- //
- // Here we would wind up with two coercions, one from
- // `Err(())` and the other from the tail expression
- // `Ok(())`. If the tail expression is omitted, that's a
- // "forced unit" -- unless the block diverges, in which
- // case we can ignore the tail expression (e.g., `'a: {
- // break 'a 22; }` would not force the type of the block
- // to be `()`).
- let tail_expr = blk.expr.as_ref();
- let coerce_to_ty = expected.coercion_target_type(self, blk.span);
- let coerce = if blk.targeted_by_break {
- CoerceMany::new(coerce_to_ty)
- } else {
- let tail_expr: &[&hir::Expr<'_>] = match tail_expr {
- Some(e) => slice::from_ref(e),
- None => &[],
- };
- CoerceMany::with_coercion_sites(coerce_to_ty, tail_expr)
- };
-
- let prev_diverges = self.diverges.get();
- let ctxt = BreakableCtxt { coerce: Some(coerce), may_break: false };
-
- let (ctxt, ()) = self.with_breakable_ctxt(blk.hir_id, ctxt, || {
- for s in blk.stmts {
- self.check_stmt(s);
- }
-
- // check the tail expression **without** holding the
- // `enclosing_breakables` lock below.
- let tail_expr_ty = tail_expr.map(|t| self.check_expr_with_expectation(t, expected));
-
- let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
- let ctxt = enclosing_breakables.find_breakable(blk.hir_id);
- let coerce = ctxt.coerce.as_mut().unwrap();
- if let Some(tail_expr_ty) = tail_expr_ty {
- let tail_expr = tail_expr.unwrap();
- let span = self.get_expr_coercion_span(tail_expr);
- let cause = self.cause(span, ObligationCauseCode::BlockTailExpression(blk.hir_id));
- coerce.coerce(self, &cause, tail_expr, tail_expr_ty);
- } else {
- // Subtle: if there is no explicit tail expression,
- // that is typically equivalent to a tail expression
- // of `()` -- except if the block diverges. In that
- // case, there is no value supplied from the tail
- // expression (assuming there are no other breaks,
- // this implies that the type of the block will be
- // `!`).
- //
- // #41425 -- label the implicit `()` as being the
- // "found type" here, rather than the "expected type".
- if !self.diverges.get().is_always() {
- // #50009 -- Do not point at the entire fn block span, point at the return type
- // span, as it is the cause of the requirement, and
- // `consider_hint_about_removing_semicolon` will point at the last expression
- // if it were a relevant part of the error. This improves usability in editors
- // that highlight errors inline.
- let mut sp = blk.span;
- let mut fn_span = None;
- if let Some((decl, ident)) = self.get_parent_fn_decl(blk.hir_id) {
- let ret_sp = decl.output.span();
- if let Some(block_sp) = self.parent_item_span(blk.hir_id) {
- // HACK: on some cases (`ui/liveness/liveness-issue-2163.rs`) the
- // output would otherwise be incorrect and even misleading. Make sure
- // the span we're aiming at correspond to a `fn` body.
- if block_sp == blk.span {
- sp = ret_sp;
- fn_span = Some(ident.span);
- }
- }
- }
- coerce.coerce_forced_unit(
- self,
- &self.misc(sp),
- &mut |err| {
- if let Some(expected_ty) = expected.only_has_type(self) {
- self.consider_hint_about_removing_semicolon(blk, expected_ty, err);
- }
- if let Some(fn_span) = fn_span {
- err.span_label(
- fn_span,
- "implicitly returns `()` as its body has no tail or `return` \
- expression",
- );
- }
- },
- false,
- );
- }
- }
- });
-
- if ctxt.may_break {
- // If we can break from the block, then the block's exit is always reachable
- // (... as long as the entry is reachable) - regardless of the tail of the block.
- self.diverges.set(prev_diverges);
- }
-
- let mut ty = ctxt.coerce.unwrap().complete(self);
-
- if self.has_errors.get() || ty.references_error() {
- ty = self.tcx.ty_error()
- }
-
- self.write_ty(blk.hir_id, ty);
-
- *self.ps.borrow_mut() = prev;
- ty
- }
-
- pub(super) fn check_rustc_args_require_const(
- &self,
- def_id: DefId,
- hir_id: hir::HirId,
- span: Span,
- ) {
- // We're only interested in functions tagged with
- // #[rustc_args_required_const], so ignore anything that's not.
- if !self.tcx.has_attr(def_id, sym::rustc_args_required_const) {
- return;
- }
-
- // If our calling expression is indeed the function itself, we're good!
- // If not, generate an error that this can only be called directly.
- if let Node::Expr(expr) = self.tcx.hir().get(self.tcx.hir().get_parent_node(hir_id)) {
- if let ExprKind::Call(ref callee, ..) = expr.kind {
- if callee.hir_id == hir_id {
- return;
- }
- }
- }
-
- self.tcx.sess.span_err(
- span,
- "this function can only be invoked directly, not through a function pointer",
- );
- }
-
- /// A common error is to add an extra semicolon:
- ///
- /// ```
- /// fn foo() -> usize {
- /// 22;
- /// }
- /// ```
- ///
- /// This routine checks if the final statement in a block is an
- /// expression with an explicit semicolon whose type is compatible
- /// with `expected_ty`. If so, it suggests removing the semicolon.
- fn consider_hint_about_removing_semicolon(
- &self,
- blk: &'tcx hir::Block<'tcx>,
- expected_ty: Ty<'tcx>,
- err: &mut DiagnosticBuilder<'_>,
- ) {
- if let Some(span_semi) = self.could_remove_semicolon(blk, expected_ty) {
- err.span_suggestion(
- span_semi,
- "consider removing this semicolon",
- String::new(),
- Applicability::MachineApplicable,
- );
- }
- }
-
- fn parent_item_span(&self, id: hir::HirId) -> Option<Span> {
- let node = self.tcx.hir().get(self.tcx.hir().get_parent_item(id));
- match node {
- Node::Item(&hir::Item { kind: hir::ItemKind::Fn(_, _, body_id), .. })
- | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(_, body_id), .. }) => {
- let body = self.tcx.hir().body(body_id);
- if let ExprKind::Block(block, _) = &body.value.kind {
- return Some(block.span);
- }
- }
- _ => {}
- }
- None
- }
-
- /// Given a function block's `HirId`, returns its `FnDecl` if it exists, or `None` otherwise.
- fn get_parent_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident)> {
- let parent = self.tcx.hir().get(self.tcx.hir().get_parent_item(blk_id));
- self.get_node_fn_decl(parent).map(|(fn_decl, ident, _)| (fn_decl, ident))
- }
-
- /// If `expr` is a `match` expression that has only one non-`!` arm, use that arm's tail
- /// expression's `Span`, otherwise return `expr.span`. This is done to give better errors
- /// when given code like the following:
- /// ```text
- /// if false { return 0i32; } else { 1u32 }
- /// // ^^^^ point at this instead of the whole `if` expression
- /// ```
- fn get_expr_coercion_span(&self, expr: &hir::Expr<'_>) -> rustc_span::Span {
- if let hir::ExprKind::Match(_, arms, _) = &expr.kind {
- let arm_spans: Vec<Span> = arms
- .iter()
- .filter_map(|arm| {
- self.in_progress_typeck_results
- .and_then(|typeck_results| {
- typeck_results.borrow().node_type_opt(arm.body.hir_id)
- })
- .and_then(|arm_ty| {
- if arm_ty.is_never() {
- None
- } else {
- Some(match &arm.body.kind {
- // Point at the tail expression when possible.
- hir::ExprKind::Block(block, _) => {
- block.expr.as_ref().map(|e| e.span).unwrap_or(block.span)
- }
- _ => arm.body.span,
- })
- }
- })
- })
- .collect();
- if arm_spans.len() == 1 {
- return arm_spans[0];
- }
- }
- expr.span
- }
-
- fn overwrite_local_ty_if_err(
- &self,
- local: &'tcx hir::Local<'tcx>,
- decl_ty: Ty<'tcx>,
- ty: Ty<'tcx>,
- ) {
- if ty.references_error() {
- // Override the types everywhere with `err()` to avoid knock on errors.
- self.write_ty(local.hir_id, ty);
- self.write_ty(local.pat.hir_id, ty);
- let local_ty = LocalTy { decl_ty, revealed_ty: ty };
- self.locals.borrow_mut().insert(local.hir_id, local_ty);
- self.locals.borrow_mut().insert(local.pat.hir_id, local_ty);
- }
- }
-
- // Finish resolving a path in a struct expression or pattern `S::A { .. }` if necessary.
- // The newly resolved definition is written into `type_dependent_defs`.
- fn finish_resolving_struct_path(
- &self,
- qpath: &QPath<'_>,
- path_span: Span,
- hir_id: hir::HirId,
- ) -> (Res, Ty<'tcx>) {
- match *qpath {
- QPath::Resolved(ref maybe_qself, ref path) => {
- let self_ty = maybe_qself.as_ref().map(|qself| self.to_ty(qself));
- let ty = AstConv::res_to_ty(self, self_ty, path, true);
- (path.res, ty)
- }
- QPath::TypeRelative(ref qself, ref segment) => {
- let ty = self.to_ty(qself);
-
- let res = if let hir::TyKind::Path(QPath::Resolved(_, ref path)) = qself.kind {
- path.res
- } else {
- Res::Err
- };
- let result =
- AstConv::associated_path_to_ty(self, hir_id, path_span, ty, res, segment, true);
- let ty = result.map(|(ty, _, _)| ty).unwrap_or_else(|_| self.tcx().ty_error());
- let result = result.map(|(_, kind, def_id)| (kind, def_id));
-
- // Write back the new resolution.
- self.write_resolution(hir_id, result);
-
- (result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), ty)
- }
- QPath::LangItem(lang_item, span) => {
- self.resolve_lang_item_path(lang_item, span, hir_id)
- }
- }
- }
-
- /// Given a vec of evaluated `FulfillmentError`s and an `fn` call argument expressions, we walk
- /// the checked and coerced types for each argument to see if any of the `FulfillmentError`s
- /// reference a type argument. The reason to walk also the checked type is that the coerced type
- /// can be not easily comparable with predicate type (because of coercion). If the types match
- /// for either checked or coerced type, and there's only *one* argument that does, we point at
- /// the corresponding argument's expression span instead of the `fn` call path span.
- fn point_at_arg_instead_of_call_if_possible(
- &self,
- errors: &mut Vec<traits::FulfillmentError<'tcx>>,
- final_arg_types: &[(usize, Ty<'tcx>, Ty<'tcx>)],
- call_sp: Span,
- args: &'tcx [hir::Expr<'tcx>],
- ) {
- // We *do not* do this for desugared call spans to keep good diagnostics when involving
- // the `?` operator.
- if call_sp.desugaring_kind().is_some() {
- return;
- }
-
- for error in errors {
- // Only if the cause is somewhere inside the expression we want try to point at arg.
- // Otherwise, it means that the cause is somewhere else and we should not change
- // anything because we can break the correct span.
- if !call_sp.contains(error.obligation.cause.span) {
- continue;
- }
-
- if let ty::PredicateAtom::Trait(predicate, _) =
- error.obligation.predicate.skip_binders()
- {
- // Collect the argument position for all arguments that could have caused this
- // `FulfillmentError`.
- let mut referenced_in = final_arg_types
- .iter()
- .map(|&(i, checked_ty, _)| (i, checked_ty))
- .chain(final_arg_types.iter().map(|&(i, _, coerced_ty)| (i, coerced_ty)))
- .flat_map(|(i, ty)| {
- let ty = self.resolve_vars_if_possible(&ty);
- // We walk the argument type because the argument's type could have
- // been `Option<T>`, but the `FulfillmentError` references `T`.
- if ty.walk().any(|arg| arg == predicate.self_ty().into()) {
- Some(i)
- } else {
- None
- }
- })
- .collect::<Vec<usize>>();
-
- // Both checked and coerced types could have matched, thus we need to remove
- // duplicates.
-
- // We sort primitive type usize here and can use unstable sort
- referenced_in.sort_unstable();
- referenced_in.dedup();
-
- if let (Some(ref_in), None) = (referenced_in.pop(), referenced_in.pop()) {
- // We make sure that only *one* argument matches the obligation failure
- // and we assign the obligation's span to its expression's.
- error.obligation.cause.make_mut().span = args[ref_in].span;
- error.points_at_arg_span = true;
- }
- }
- }
- }
-
- /// Given a vec of evaluated `FulfillmentError`s and an `fn` call expression, we walk the
- /// `PathSegment`s and resolve their type parameters to see if any of the `FulfillmentError`s
- /// were caused by them. If they were, we point at the corresponding type argument's span
- /// instead of the `fn` call path span.
- fn point_at_type_arg_instead_of_call_if_possible(
- &self,
- errors: &mut Vec<traits::FulfillmentError<'tcx>>,
- call_expr: &'tcx hir::Expr<'tcx>,
- ) {
- if let hir::ExprKind::Call(path, _) = &call_expr.kind {
- if let hir::ExprKind::Path(qpath) = &path.kind {
- if let hir::QPath::Resolved(_, path) = &qpath {
- for error in errors {
- if let ty::PredicateAtom::Trait(predicate, _) =
- error.obligation.predicate.skip_binders()
- {
- // If any of the type arguments in this path segment caused the
- // `FullfillmentError`, point at its span (#61860).
- for arg in path
- .segments
- .iter()
- .filter_map(|seg| seg.args.as_ref())
- .flat_map(|a| a.args.iter())
- {
- if let hir::GenericArg::Type(hir_ty) = &arg {
- if let hir::TyKind::Path(hir::QPath::TypeRelative(..)) =
- &hir_ty.kind
- {
- // Avoid ICE with associated types. As this is best
- // effort only, it's ok to ignore the case. It
- // would trigger in `is_send::<T::AssocType>();`
- // from `typeck-default-trait-impl-assoc-type.rs`.
- } else {
- let ty = AstConv::ast_ty_to_ty(self, hir_ty);
- let ty = self.resolve_vars_if_possible(&ty);
- if ty == predicate.self_ty() {
- error.obligation.cause.make_mut().span = hir_ty.span;
- }
- }
- }
- }
- }
- }
- }
- }
- }
- }
-}
+++ /dev/null
-use super::callee::{self, DeferredCallResolution};
-use super::method::{self, MethodCallee, SelfSource};
-use super::{BreakableCtxt, Diverges, Expectation, FallbackMode, FnCtxt, LocalTy};
-use crate::astconv::{
- AstConv, ExplicitLateBound, GenericArgCountMismatch, GenericArgCountResult, PathSeg,
-};
-
-use rustc_data_structures::captures::Captures;
-use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::{Applicability, DiagnosticBuilder, ErrorReported};
-use rustc_hir as hir;
-use rustc_hir::def::{CtorOf, DefKind, Res};
-use rustc_hir::def_id::DefId;
-use rustc_hir::lang_items::LangItem;
-use rustc_hir::{ExprKind, GenericArg, Node, QPath};
-use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
-use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
-use rustc_infer::infer::{InferOk, InferResult};
-use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::subst::{
- self, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSelfTy, UserSubsts,
-};
-use rustc_middle::ty::{
- self, AdtKind, CanonicalUserType, DefIdTree, GenericParamDefKind, ToPolyTraitRef, ToPredicate,
- Ty, UserType,
-};
-use rustc_session::lint;
-use rustc_span::hygiene::DesugaringKind;
-use rustc_span::source_map::{original_sp, DUMMY_SP};
-use rustc_span::symbol::{kw, sym, Ident};
-use rustc_span::{self, BytePos, MultiSpan, Span};
-use rustc_trait_selection::infer::InferCtxtExt as _;
-use rustc_trait_selection::opaque_types::InferCtxtExt as _;
-use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
-use rustc_trait_selection::traits::{self, ObligationCauseCode, TraitEngine, TraitEngineExt};
-
-use std::collections::hash_map::Entry;
-use std::slice;
-
-impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
- /// Produces warning on the given node, if the current point in the
- /// function is unreachable, and there hasn't been another warning.
- pub(super) fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) {
- // FIXME: Combine these two 'if' expressions into one once
- // let chains are implemented
- if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() {
- // If span arose from a desugaring of `if` or `while`, then it is the condition itself,
- // which diverges, that we are about to lint on. This gives suboptimal diagnostics.
- // Instead, stop here so that the `if`- or `while`-expression's block is linted instead.
- if !span.is_desugaring(DesugaringKind::CondTemporary)
- && !span.is_desugaring(DesugaringKind::Async)
- && !orig_span.is_desugaring(DesugaringKind::Await)
- {
- self.diverges.set(Diverges::WarnedAlways);
-
- debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind);
-
- self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, |lint| {
- let msg = format!("unreachable {}", kind);
- lint.build(&msg)
- .span_label(span, &msg)
- .span_label(
- orig_span,
- custom_note
- .unwrap_or("any code following this expression is unreachable"),
- )
- .emit();
- })
- }
- }
- }
-
- /// Resolves type and const variables in `ty` if possible. Unlike the infcx
- /// version (resolve_vars_if_possible), this version will
- /// also select obligations if it seems useful, in an effort
- /// to get more type information.
- pub(super) fn resolve_vars_with_obligations(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
- debug!("resolve_vars_with_obligations(ty={:?})", ty);
-
- // No Infer()? Nothing needs doing.
- if !ty.has_infer_types_or_consts() {
- debug!("resolve_vars_with_obligations: ty={:?}", ty);
- return ty;
- }
-
- // If `ty` is a type variable, see whether we already know what it is.
- ty = self.resolve_vars_if_possible(&ty);
- if !ty.has_infer_types_or_consts() {
- debug!("resolve_vars_with_obligations: ty={:?}", ty);
- return ty;
- }
-
- // If not, try resolving pending obligations as much as
- // possible. This can help substantially when there are
- // indirect dependencies that don't seem worth tracking
- // precisely.
- self.select_obligations_where_possible(false, |_| {});
- ty = self.resolve_vars_if_possible(&ty);
-
- debug!("resolve_vars_with_obligations: ty={:?}", ty);
- ty
- }
-
- pub(super) fn record_deferred_call_resolution(
- &self,
- closure_def_id: DefId,
- r: DeferredCallResolution<'tcx>,
- ) {
- let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
- deferred_call_resolutions.entry(closure_def_id).or_default().push(r);
- }
-
- pub(super) fn remove_deferred_call_resolutions(
- &self,
- closure_def_id: DefId,
- ) -> Vec<DeferredCallResolution<'tcx>> {
- let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
- deferred_call_resolutions.remove(&closure_def_id).unwrap_or(vec![])
- }
-
- pub fn tag(&self) -> String {
- format!("{:p}", self)
- }
-
- pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> {
- self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| {
- span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid))
- })
- }
-
- #[inline]
- pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) {
- debug!(
- "write_ty({:?}, {:?}) in fcx {}",
- id,
- self.resolve_vars_if_possible(&ty),
- self.tag()
- );
- self.typeck_results.borrow_mut().node_types_mut().insert(id, ty);
-
- if ty.references_error() {
- self.has_errors.set(true);
- self.set_tainted_by_errors();
- }
- }
-
- pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) {
- self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index);
- }
-
- pub(super) fn write_resolution(
- &self,
- hir_id: hir::HirId,
- r: Result<(DefKind, DefId), ErrorReported>,
- ) {
- self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r);
- }
-
- pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) {
- debug!("write_method_call(hir_id={:?}, method={:?})", hir_id, method);
- self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id)));
- self.write_substs(hir_id, method.substs);
-
- // When the method is confirmed, the `method.substs` includes
- // parameters from not just the method, but also the impl of
- // the method -- in particular, the `Self` type will be fully
- // resolved. However, those are not something that the "user
- // specified" -- i.e., those types come from the inferred type
- // of the receiver, not something the user wrote. So when we
- // create the user-substs, we want to replace those earlier
- // types with just the types that the user actually wrote --
- // that is, those that appear on the *method itself*.
- //
- // As an example, if the user wrote something like
- // `foo.bar::<u32>(...)` -- the `Self` type here will be the
- // type of `foo` (possibly adjusted), but we don't want to
- // include that. We want just the `[_, u32]` part.
- if !method.substs.is_noop() {
- let method_generics = self.tcx.generics_of(method.def_id);
- if !method_generics.params.is_empty() {
- let user_type_annotation = self.infcx.probe(|_| {
- let user_substs = UserSubsts {
- substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| {
- let i = param.index as usize;
- if i < method_generics.parent_count {
- self.infcx.var_for_def(DUMMY_SP, param)
- } else {
- method.substs[i]
- }
- }),
- user_self_ty: None, // not relevant here
- };
-
- self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf(
- method.def_id,
- user_substs,
- ))
- });
-
- debug!("write_method_call: user_type_annotation={:?}", user_type_annotation);
- self.write_user_type_annotation(hir_id, user_type_annotation);
- }
- }
- }
-
- pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) {
- if !substs.is_noop() {
- debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag());
-
- self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs);
- }
- }
-
- /// Given the substs that we just converted from the HIR, try to
- /// canonicalize them and store them as user-given substitutions
- /// (i.e., substitutions that must be respected by the NLL check).
- ///
- /// This should be invoked **before any unifications have
- /// occurred**, so that annotations like `Vec<_>` are preserved
- /// properly.
- pub fn write_user_type_annotation_from_substs(
- &self,
- hir_id: hir::HirId,
- def_id: DefId,
- substs: SubstsRef<'tcx>,
- user_self_ty: Option<UserSelfTy<'tcx>>,
- ) {
- debug!(
- "write_user_type_annotation_from_substs: hir_id={:?} def_id={:?} substs={:?} \
- user_self_ty={:?} in fcx {}",
- hir_id,
- def_id,
- substs,
- user_self_ty,
- self.tag(),
- );
-
- if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) {
- let canonicalized = self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf(
- def_id,
- UserSubsts { substs, user_self_ty },
- ));
- debug!("write_user_type_annotation_from_substs: canonicalized={:?}", canonicalized);
- self.write_user_type_annotation(hir_id, canonicalized);
- }
- }
-
- pub fn write_user_type_annotation(
- &self,
- hir_id: hir::HirId,
- canonical_user_type_annotation: CanonicalUserType<'tcx>,
- ) {
- debug!(
- "write_user_type_annotation: hir_id={:?} canonical_user_type_annotation={:?} tag={}",
- hir_id,
- canonical_user_type_annotation,
- self.tag(),
- );
-
- if !canonical_user_type_annotation.is_identity() {
- self.typeck_results
- .borrow_mut()
- .user_provided_types_mut()
- .insert(hir_id, canonical_user_type_annotation);
- } else {
- debug!("write_user_type_annotation: skipping identity substs");
- }
- }
-
- pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) {
- debug!("apply_adjustments(expr={:?}, adj={:?})", expr, adj);
-
- if adj.is_empty() {
- return;
- }
-
- let autoborrow_mut = adj.iter().any(|adj| {
- matches!(adj, &Adjustment {
- kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })),
- ..
- })
- });
-
- match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) {
- Entry::Vacant(entry) => {
- entry.insert(adj);
- }
- Entry::Occupied(mut entry) => {
- debug!(" - composing on top of {:?}", entry.get());
- match (&entry.get()[..], &adj[..]) {
- // Applying any adjustment on top of a NeverToAny
- // is a valid NeverToAny adjustment, because it can't
- // be reached.
- (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return,
- (&[
- Adjustment { kind: Adjust::Deref(_), .. },
- Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. },
- ], &[
- Adjustment { kind: Adjust::Deref(_), .. },
- .. // Any following adjustments are allowed.
- ]) => {
- // A reborrow has no effect before a dereference.
- }
- // FIXME: currently we never try to compose autoderefs
- // and ReifyFnPointer/UnsafeFnPointer, but we could.
- _ =>
- bug!("while adjusting {:?}, can't compose {:?} and {:?}",
- expr, entry.get(), adj)
- };
- *entry.get_mut() = adj;
- }
- }
-
- // If there is an mutable auto-borrow, it is equivalent to `&mut <expr>`.
- // In this case implicit use of `Deref` and `Index` within `<expr>` should
- // instead be `DerefMut` and `IndexMut`, so fix those up.
- if autoborrow_mut {
- self.convert_place_derefs_to_mutable(expr);
- }
- }
-
- /// Basically whenever we are converting from a type scheme into
- /// the fn body space, we always want to normalize associated
- /// types as well. This function combines the two.
- fn instantiate_type_scheme<T>(&self, span: Span, substs: SubstsRef<'tcx>, value: &T) -> T
- where
- T: TypeFoldable<'tcx>,
- {
- let value = value.subst(self.tcx, substs);
- let result = self.normalize_associated_types_in(span, &value);
- debug!("instantiate_type_scheme(value={:?}, substs={:?}) = {:?}", value, substs, result);
- result
- }
-
- /// As `instantiate_type_scheme`, but for the bounds found in a
- /// generic type scheme.
- pub(super) fn instantiate_bounds(
- &self,
- span: Span,
- def_id: DefId,
- substs: SubstsRef<'tcx>,
- ) -> (ty::InstantiatedPredicates<'tcx>, Vec<Span>) {
- let bounds = self.tcx.predicates_of(def_id);
- let spans: Vec<Span> = bounds.predicates.iter().map(|(_, span)| *span).collect();
- let result = bounds.instantiate(self.tcx, substs);
- let result = self.normalize_associated_types_in(span, &result);
- debug!(
- "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}",
- bounds, substs, result, spans,
- );
- (result, spans)
- }
-
- /// Replaces the opaque types from the given value with type variables,
- /// and records the `OpaqueTypeMap` for later use during writeback. See
- /// `InferCtxt::instantiate_opaque_types` for more details.
- pub(super) fn instantiate_opaque_types_from_value<T: TypeFoldable<'tcx>>(
- &self,
- parent_id: hir::HirId,
- value: &T,
- value_span: Span,
- ) -> T {
- let parent_def_id = self.tcx.hir().local_def_id(parent_id);
- debug!(
- "instantiate_opaque_types_from_value(parent_def_id={:?}, value={:?})",
- parent_def_id, value
- );
-
- let (value, opaque_type_map) =
- self.register_infer_ok_obligations(self.instantiate_opaque_types(
- parent_def_id,
- self.body_id,
- self.param_env,
- value,
- value_span,
- ));
-
- let mut opaque_types = self.opaque_types.borrow_mut();
- let mut opaque_types_vars = self.opaque_types_vars.borrow_mut();
- for (ty, decl) in opaque_type_map {
- let _ = opaque_types.insert(ty, decl);
- let _ = opaque_types_vars.insert(decl.concrete_ty, decl.opaque_type);
- }
-
- value
- }
-
- pub(super) fn normalize_associated_types_in<T>(&self, span: Span, value: &T) -> T
- where
- T: TypeFoldable<'tcx>,
- {
- self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value)
- }
-
- pub(super) fn normalize_associated_types_in_as_infer_ok<T>(
- &self,
- span: Span,
- value: &T,
- ) -> InferOk<'tcx, T>
- where
- T: TypeFoldable<'tcx>,
- {
- self.inh.partially_normalize_associated_types_in(span, self.body_id, self.param_env, value)
- }
-
- pub fn require_type_meets(
- &self,
- ty: Ty<'tcx>,
- span: Span,
- code: traits::ObligationCauseCode<'tcx>,
- def_id: DefId,
- ) {
- self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code));
- }
-
- pub fn require_type_is_sized(
- &self,
- ty: Ty<'tcx>,
- span: Span,
- code: traits::ObligationCauseCode<'tcx>,
- ) {
- if !ty.references_error() {
- let lang_item = self.tcx.require_lang_item(LangItem::Sized, None);
- self.require_type_meets(ty, span, code, lang_item);
- }
- }
-
- pub fn require_type_is_sized_deferred(
- &self,
- ty: Ty<'tcx>,
- span: Span,
- code: traits::ObligationCauseCode<'tcx>,
- ) {
- if !ty.references_error() {
- self.deferred_sized_obligations.borrow_mut().push((ty, span, code));
- }
- }
-
- pub fn register_bound(
- &self,
- ty: Ty<'tcx>,
- def_id: DefId,
- cause: traits::ObligationCause<'tcx>,
- ) {
- if !ty.references_error() {
- self.fulfillment_cx.borrow_mut().register_bound(
- self,
- self.param_env,
- ty,
- def_id,
- cause,
- );
- }
- }
-
- pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> {
- let t = AstConv::ast_ty_to_ty(self, ast_t);
- self.register_wf_obligation(t.into(), ast_t.span, traits::MiscObligation);
- t
- }
-
- pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
- let ty = self.to_ty(ast_ty);
- debug!("to_ty_saving_user_provided_ty: ty={:?}", ty);
-
- if Self::can_contain_user_lifetime_bounds(ty) {
- let c_ty = self.infcx.canonicalize_response(&UserType::Ty(ty));
- debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty);
- self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty);
- }
-
- ty
- }
-
- pub fn to_const(&self, ast_c: &hir::AnonConst) -> &'tcx ty::Const<'tcx> {
- let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id);
- let c = ty::Const::from_anon_const(self.tcx, const_def_id);
- self.register_wf_obligation(
- c.into(),
- self.tcx.hir().span(ast_c.hir_id),
- ObligationCauseCode::MiscObligation,
- );
- c
- }
-
- pub fn const_arg_to_const(
- &self,
- ast_c: &hir::AnonConst,
- param_def_id: DefId,
- ) -> &'tcx ty::Const<'tcx> {
- let const_def = ty::WithOptConstParam {
- did: self.tcx.hir().local_def_id(ast_c.hir_id),
- const_param_did: Some(param_def_id),
- };
- let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def);
- self.register_wf_obligation(
- c.into(),
- self.tcx.hir().span(ast_c.hir_id),
- ObligationCauseCode::MiscObligation,
- );
- c
- }
-
- // If the type given by the user has free regions, save it for later, since
- // NLL would like to enforce those. Also pass in types that involve
- // projections, since those can resolve to `'static` bounds (modulo #54940,
- // which hopefully will be fixed by the time you see this comment, dear
- // reader, although I have my doubts). Also pass in types with inference
- // types, because they may be repeated. Other sorts of things are already
- // sufficiently enforced with erased regions. =)
- fn can_contain_user_lifetime_bounds<T>(t: T) -> bool
- where
- T: TypeFoldable<'tcx>,
- {
- t.has_free_regions() || t.has_projections() || t.has_infer_types()
- }
-
- pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> {
- match self.typeck_results.borrow().node_types().get(id) {
- Some(&t) => t,
- None if self.is_tainted_by_errors() => self.tcx.ty_error(),
- None => {
- bug!(
- "no type for node {}: {} in fcx {}",
- id,
- self.tcx.hir().node_to_string(id),
- self.tag()
- );
- }
- }
- }
-
- /// Registers an obligation for checking later, during regionck, that `arg` is well-formed.
- pub fn register_wf_obligation(
- &self,
- arg: subst::GenericArg<'tcx>,
- span: Span,
- code: traits::ObligationCauseCode<'tcx>,
- ) {
- // WF obligations never themselves fail, so no real need to give a detailed cause:
- let cause = traits::ObligationCause::new(span, self.body_id, code);
- self.register_predicate(traits::Obligation::new(
- cause,
- self.param_env,
- ty::PredicateAtom::WellFormed(arg).to_predicate(self.tcx),
- ));
- }
-
- /// Registers obligations that all `substs` are well-formed.
- pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) {
- for arg in substs.iter().filter(|arg| {
- matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..))
- }) {
- self.register_wf_obligation(arg, expr.span, traits::MiscObligation);
- }
- }
-
- /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each
- /// type/region parameter was instantiated (`substs`), creates and registers suitable
- /// trait/region obligations.
- ///
- /// For example, if there is a function:
- ///
- /// ```
- /// fn foo<'a,T:'a>(...)
- /// ```
- ///
- /// and a reference:
- ///
- /// ```
- /// let f = foo;
- /// ```
- ///
- /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a`
- /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally.
- pub fn add_obligations_for_parameters(
- &self,
- cause: traits::ObligationCause<'tcx>,
- predicates: ty::InstantiatedPredicates<'tcx>,
- ) {
- assert!(!predicates.has_escaping_bound_vars());
-
- debug!("add_obligations_for_parameters(predicates={:?})", predicates);
-
- for obligation in traits::predicates_for_generics(cause, self.param_env, predicates) {
- self.register_predicate(obligation);
- }
- }
-
- // FIXME(arielb1): use this instead of field.ty everywhere
- // Only for fields! Returns <none> for methods>
- // Indifferent to privacy flags
- pub fn field_ty(
- &self,
- span: Span,
- field: &'tcx ty::FieldDef,
- substs: SubstsRef<'tcx>,
- ) -> Ty<'tcx> {
- self.normalize_associated_types_in(span, &field.ty(self.tcx, substs))
- }
-
- pub(super) fn resolve_generator_interiors(&self, def_id: DefId) {
- let mut generators = self.deferred_generator_interiors.borrow_mut();
- for (body_id, interior, kind) in generators.drain(..) {
- self.select_obligations_where_possible(false, |_| {});
- super::generator_interior::resolve_interior(self, def_id, body_id, interior, kind);
- }
- }
-
- // Tries to apply a fallback to `ty` if it is an unsolved variable.
- //
- // - Unconstrained ints are replaced with `i32`.
- //
- // - Unconstrained floats are replaced with with `f64`.
- //
- // - Non-numerics get replaced with `!` when `#![feature(never_type_fallback)]`
- // is enabled. Otherwise, they are replaced with `()`.
- //
- // Fallback becomes very dubious if we have encountered type-checking errors.
- // In that case, fallback to Error.
- // The return value indicates whether fallback has occurred.
- pub(super) fn fallback_if_possible(&self, ty: Ty<'tcx>, mode: FallbackMode) -> bool {
- use rustc_middle::ty::error::UnconstrainedNumeric::Neither;
- use rustc_middle::ty::error::UnconstrainedNumeric::{UnconstrainedFloat, UnconstrainedInt};
-
- assert!(ty.is_ty_infer());
- let fallback = match self.type_is_unconstrained_numeric(ty) {
- _ if self.is_tainted_by_errors() => self.tcx().ty_error(),
- UnconstrainedInt => self.tcx.types.i32,
- UnconstrainedFloat => self.tcx.types.f64,
- Neither if self.type_var_diverges(ty) => self.tcx.mk_diverging_default(),
- Neither => {
- // This type variable was created from the instantiation of an opaque
- // type. The fact that we're attempting to perform fallback for it
- // means that the function neither constrained it to a concrete
- // type, nor to the opaque type itself.
- //
- // For example, in this code:
- //
- //```
- // type MyType = impl Copy;
- // fn defining_use() -> MyType { true }
- // fn other_use() -> MyType { defining_use() }
- // ```
- //
- // `defining_use` will constrain the instantiated inference
- // variable to `bool`, while `other_use` will constrain
- // the instantiated inference variable to `MyType`.
- //
- // When we process opaque types during writeback, we
- // will handle cases like `other_use`, and not count
- // them as defining usages
- //
- // However, we also need to handle cases like this:
- //
- // ```rust
- // pub type Foo = impl Copy;
- // fn produce() -> Option<Foo> {
- // None
- // }
- // ```
- //
- // In the above snippet, the inference variable created by
- // instantiating `Option<Foo>` will be completely unconstrained.
- // We treat this as a non-defining use by making the inference
- // variable fall back to the opaque type itself.
- if let FallbackMode::All = mode {
- if let Some(opaque_ty) = self.opaque_types_vars.borrow().get(ty) {
- debug!(
- "fallback_if_possible: falling back opaque type var {:?} to {:?}",
- ty, opaque_ty
- );
- *opaque_ty
- } else {
- return false;
- }
- } else {
- return false;
- }
- }
- };
- debug!("fallback_if_possible: defaulting `{:?}` to `{:?}`", ty, fallback);
- self.demand_eqtype(rustc_span::DUMMY_SP, ty, fallback);
- true
- }
-
- pub(super) fn select_all_obligations_or_error(&self) {
- debug!("select_all_obligations_or_error");
- if let Err(errors) = self.fulfillment_cx.borrow_mut().select_all_or_error(&self) {
- self.report_fulfillment_errors(&errors, self.inh.body_id, false);
- }
- }
-
- /// Select as many obligations as we can at present.
- pub(super) fn select_obligations_where_possible(
- &self,
- fallback_has_occurred: bool,
- mutate_fullfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
- ) {
- let result = self.fulfillment_cx.borrow_mut().select_where_possible(self);
- if let Err(mut errors) = result {
- mutate_fullfillment_errors(&mut errors);
- self.report_fulfillment_errors(&errors, self.inh.body_id, fallback_has_occurred);
- }
- }
-
- /// For the overloaded place expressions (`*x`, `x[3]`), the trait
- /// returns a type of `&T`, but the actual type we assign to the
- /// *expression* is `T`. So this function just peels off the return
- /// type by one layer to yield `T`.
- pub(super) fn make_overloaded_place_return_type(
- &self,
- method: MethodCallee<'tcx>,
- ) -> ty::TypeAndMut<'tcx> {
- // extract method return type, which will be &T;
- let ret_ty = method.sig.output();
-
- // method returns &T, but the type as visible to user is T, so deref
- ret_ty.builtin_deref(true).unwrap()
- }
-
- fn self_type_matches_expected_vid(
- &self,
- trait_ref: ty::PolyTraitRef<'tcx>,
- expected_vid: ty::TyVid,
- ) -> bool {
- let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty());
- debug!(
- "self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?}, expected_vid={:?})",
- trait_ref, self_ty, expected_vid
- );
- match *self_ty.kind() {
- ty::Infer(ty::TyVar(found_vid)) => {
- // FIXME: consider using `sub_root_var` here so we
- // can see through subtyping.
- let found_vid = self.root_var(found_vid);
- debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid);
- expected_vid == found_vid
- }
- _ => false,
- }
- }
-
- pub(super) fn obligations_for_self_ty<'b>(
- &'b self,
- self_ty: ty::TyVid,
- ) -> impl Iterator<Item = (ty::PolyTraitRef<'tcx>, traits::PredicateObligation<'tcx>)>
- + Captures<'tcx>
- + 'b {
- // FIXME: consider using `sub_root_var` here so we
- // can see through subtyping.
- let ty_var_root = self.root_var(self_ty);
- debug!(
- "obligations_for_self_ty: self_ty={:?} ty_var_root={:?} pending_obligations={:?}",
- self_ty,
- ty_var_root,
- self.fulfillment_cx.borrow().pending_obligations()
- );
-
- self.fulfillment_cx
- .borrow()
- .pending_obligations()
- .into_iter()
- .filter_map(move |obligation| {
- match obligation.predicate.skip_binders() {
- ty::PredicateAtom::Projection(data) => {
- Some((ty::Binder::bind(data).to_poly_trait_ref(self.tcx), obligation))
- }
- ty::PredicateAtom::Trait(data, _) => {
- Some((ty::Binder::bind(data).to_poly_trait_ref(), obligation))
- }
- ty::PredicateAtom::Subtype(..) => None,
- ty::PredicateAtom::RegionOutlives(..) => None,
- ty::PredicateAtom::TypeOutlives(..) => None,
- ty::PredicateAtom::WellFormed(..) => None,
- ty::PredicateAtom::ObjectSafe(..) => None,
- ty::PredicateAtom::ConstEvaluatable(..) => None,
- ty::PredicateAtom::ConstEquate(..) => None,
- // N.B., this predicate is created by breaking down a
- // `ClosureType: FnFoo()` predicate, where
- // `ClosureType` represents some `Closure`. It can't
- // possibly be referring to the current closure,
- // because we haven't produced the `Closure` for
- // this closure yet; this is exactly why the other
- // code is looking for a self type of a unresolved
- // inference variable.
- ty::PredicateAtom::ClosureKind(..) => None,
- ty::PredicateAtom::TypeWellFormedFromEnv(..) => None,
- }
- })
- .filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root))
- }
-
- pub(super) fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool {
- self.obligations_for_self_ty(self_ty)
- .any(|(tr, _)| Some(tr.def_id()) == self.tcx.lang_items().sized_trait())
- }
-
- pub(super) fn err_args(&self, len: usize) -> Vec<Ty<'tcx>> {
- vec![self.tcx.ty_error(); len]
- }
-
- /// Unifies the output type with the expected type early, for more coercions
- /// and forward type information on the input expressions.
- pub(super) fn expected_inputs_for_expected_output(
- &self,
- call_span: Span,
- expected_ret: Expectation<'tcx>,
- formal_ret: Ty<'tcx>,
- formal_args: &[Ty<'tcx>],
- ) -> Vec<Ty<'tcx>> {
- let formal_ret = self.resolve_vars_with_obligations(formal_ret);
- let ret_ty = match expected_ret.only_has_type(self) {
- Some(ret) => ret,
- None => return Vec::new(),
- };
- let expect_args = self
- .fudge_inference_if_ok(|| {
- // Attempt to apply a subtyping relationship between the formal
- // return type (likely containing type variables if the function
- // is polymorphic) and the expected return type.
- // No argument expectations are produced if unification fails.
- let origin = self.misc(call_span);
- let ures = self.at(&origin, self.param_env).sup(ret_ty, &formal_ret);
-
- // FIXME(#27336) can't use ? here, Try::from_error doesn't default
- // to identity so the resulting type is not constrained.
- match ures {
- Ok(ok) => {
- // Process any obligations locally as much as
- // we can. We don't care if some things turn
- // out unconstrained or ambiguous, as we're
- // just trying to get hints here.
- self.save_and_restore_in_snapshot_flag(|_| {
- let mut fulfill = TraitEngine::new(self.tcx);
- for obligation in ok.obligations {
- fulfill.register_predicate_obligation(self, obligation);
- }
- fulfill.select_where_possible(self)
- })
- .map_err(|_| ())?;
- }
- Err(_) => return Err(()),
- }
-
- // Record all the argument types, with the substitutions
- // produced from the above subtyping unification.
- Ok(formal_args.iter().map(|ty| self.resolve_vars_if_possible(ty)).collect())
- })
- .unwrap_or_default();
- debug!(
- "expected_inputs_for_expected_output(formal={:?} -> {:?}, expected={:?} -> {:?})",
- formal_args, formal_ret, expect_args, expected_ret
- );
- expect_args
- }
-
- pub(super) fn resolve_lang_item_path(
- &self,
- lang_item: hir::LangItem,
- span: Span,
- hir_id: hir::HirId,
- ) -> (Res, Ty<'tcx>) {
- let def_id = self.tcx.require_lang_item(lang_item, Some(span));
- let def_kind = self.tcx.def_kind(def_id);
-
- let item_ty = if let DefKind::Variant = def_kind {
- self.tcx.type_of(self.tcx.parent(def_id).expect("variant w/out parent"))
- } else {
- self.tcx.type_of(def_id)
- };
- let substs = self.infcx.fresh_substs_for_item(span, def_id);
- let ty = item_ty.subst(self.tcx, substs);
-
- self.write_resolution(hir_id, Ok((def_kind, def_id)));
- self.add_required_obligations(span, def_id, &substs);
- (Res::Def(def_kind, def_id), ty)
- }
-
- /// Resolves an associated value path into a base type and associated constant, or method
- /// resolution. The newly resolved definition is written into `type_dependent_defs`.
- pub fn resolve_ty_and_res_ufcs<'b>(
- &self,
- qpath: &'b QPath<'b>,
- hir_id: hir::HirId,
- span: Span,
- ) -> (Res, Option<Ty<'tcx>>, &'b [hir::PathSegment<'b>]) {
- debug!("resolve_ty_and_res_ufcs: qpath={:?} hir_id={:?} span={:?}", qpath, hir_id, span);
- let (ty, qself, item_segment) = match *qpath {
- QPath::Resolved(ref opt_qself, ref path) => {
- return (
- path.res,
- opt_qself.as_ref().map(|qself| self.to_ty(qself)),
- &path.segments[..],
- );
- }
- QPath::TypeRelative(ref qself, ref segment) => (self.to_ty(qself), qself, segment),
- QPath::LangItem(..) => bug!("`resolve_ty_and_res_ufcs` called on `LangItem`"),
- };
- if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id)
- {
- // Return directly on cache hit. This is useful to avoid doubly reporting
- // errors with default match binding modes. See #44614.
- let def =
- cached_result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err);
- return (def, Some(ty), slice::from_ref(&**item_segment));
- }
- let item_name = item_segment.ident;
- let result = self.resolve_ufcs(span, item_name, ty, hir_id).or_else(|error| {
- let result = match error {
- method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
- _ => Err(ErrorReported),
- };
- if item_name.name != kw::Invalid {
- if let Some(mut e) = self.report_method_error(
- span,
- ty,
- item_name,
- SelfSource::QPath(qself),
- error,
- None,
- ) {
- e.emit();
- }
- }
- result
- });
-
- // Write back the new resolution.
- self.write_resolution(hir_id, result);
- (
- result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err),
- Some(ty),
- slice::from_ref(&**item_segment),
- )
- }
-
- /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise.
- pub(super) fn get_node_fn_decl(
- &self,
- node: Node<'tcx>,
- ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> {
- match node {
- Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => {
- // This is less than ideal, it will not suggest a return type span on any
- // method called `main`, regardless of whether it is actually the entry point,
- // but it will still present it as the reason for the expected type.
- Some((&sig.decl, ident, ident.name != sym::main))
- }
- Node::TraitItem(&hir::TraitItem {
- ident,
- kind: hir::TraitItemKind::Fn(ref sig, ..),
- ..
- }) => Some((&sig.decl, ident, true)),
- Node::ImplItem(&hir::ImplItem {
- ident,
- kind: hir::ImplItemKind::Fn(ref sig, ..),
- ..
- }) => Some((&sig.decl, ident, false)),
- _ => None,
- }
- }
-
- /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a
- /// suggestion can be made, `None` otherwise.
- pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> {
- // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or
- // `while` before reaching it, as block tail returns are not available in them.
- self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| {
- let parent = self.tcx.hir().get(blk_id);
- self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main))
- })
- }
-
- pub(super) fn note_internal_mutation_in_method(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) {
- if found != self.tcx.types.unit {
- return;
- }
- if let ExprKind::MethodCall(path_segment, _, [rcvr, ..], _) = expr.kind {
- if self
- .typeck_results
- .borrow()
- .expr_ty_adjusted_opt(rcvr)
- .map_or(true, |ty| expected.peel_refs() != ty.peel_refs())
- {
- return;
- }
- let mut sp = MultiSpan::from_span(path_segment.ident.span);
- sp.push_span_label(
- path_segment.ident.span,
- format!(
- "this call modifies {} in-place",
- match rcvr.kind {
- ExprKind::Path(QPath::Resolved(
- None,
- hir::Path { segments: [segment], .. },
- )) => format!("`{}`", segment.ident),
- _ => "its receiver".to_string(),
- }
- ),
- );
- sp.push_span_label(
- rcvr.span,
- "you probably want to use this value after calling the method...".to_string(),
- );
- err.span_note(
- sp,
- &format!("method `{}` modifies its receiver in-place", path_segment.ident),
- );
- err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident));
- }
- }
-
- pub(super) fn note_need_for_fn_pointer(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) {
- let (sig, did, substs) = match (&expected.kind(), &found.kind()) {
- (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => {
- let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1);
- let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2);
- if sig1 != sig2 {
- return;
- }
- err.note(
- "different `fn` items always have unique types, even if their signatures are \
- the same",
- );
- (sig1, *did1, substs1)
- }
- (ty::FnDef(did, substs), ty::FnPtr(sig2)) => {
- let sig1 = self.tcx.fn_sig(*did).subst(self.tcx, substs);
- if sig1 != *sig2 {
- return;
- }
- (sig1, *did, substs)
- }
- _ => return,
- };
- err.help(&format!("change the expected type to be function pointer `{}`", sig));
- err.help(&format!(
- "if the expected type is due to type inference, cast the expected `fn` to a function \
- pointer: `{} as {}`",
- self.tcx.def_path_str_with_substs(did, substs),
- sig
- ));
- }
-
- pub(super) fn could_remove_semicolon(
- &self,
- blk: &'tcx hir::Block<'tcx>,
- expected_ty: Ty<'tcx>,
- ) -> Option<Span> {
- // Be helpful when the user wrote `{... expr;}` and
- // taking the `;` off is enough to fix the error.
- let last_stmt = blk.stmts.last()?;
- let last_expr = match last_stmt.kind {
- hir::StmtKind::Semi(ref e) => e,
- _ => return None,
- };
- let last_expr_ty = self.node_ty(last_expr.hir_id);
- if matches!(last_expr_ty.kind(), ty::Error(_))
- || self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err()
- {
- return None;
- }
- let original_span = original_sp(last_stmt.span, blk.span);
- Some(original_span.with_lo(original_span.hi() - BytePos(1)))
- }
-
- // Instantiates the given path, which must refer to an item with the given
- // number of type parameters and type.
- pub fn instantiate_value_path(
- &self,
- segments: &[hir::PathSegment<'_>],
- self_ty: Option<Ty<'tcx>>,
- res: Res,
- span: Span,
- hir_id: hir::HirId,
- ) -> (Ty<'tcx>, Res) {
- debug!(
- "instantiate_value_path(segments={:?}, self_ty={:?}, res={:?}, hir_id={})",
- segments, self_ty, res, hir_id,
- );
-
- let tcx = self.tcx;
-
- let path_segs = match res {
- Res::Local(_) | Res::SelfCtor(_) => vec![],
- Res::Def(kind, def_id) => {
- AstConv::def_ids_for_value_path_segments(self, segments, self_ty, kind, def_id)
- }
- _ => bug!("instantiate_value_path on {:?}", res),
- };
-
- let mut user_self_ty = None;
- let mut is_alias_variant_ctor = false;
- match res {
- Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) => {
- if let Some(self_ty) = self_ty {
- let adt_def = self_ty.ty_adt_def().unwrap();
- user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did, self_ty });
- is_alias_variant_ctor = true;
- }
- }
- Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => {
- let container = tcx.associated_item(def_id).container;
- debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container);
- match container {
- ty::TraitContainer(trait_did) => {
- callee::check_legal_trait_for_method_call(tcx, span, None, trait_did)
- }
- ty::ImplContainer(impl_def_id) => {
- if segments.len() == 1 {
- // `<T>::assoc` will end up here, and so
- // can `T::assoc`. It this came from an
- // inherent impl, we need to record the
- // `T` for posterity (see `UserSelfTy` for
- // details).
- let self_ty = self_ty.expect("UFCS sugared assoc missing Self");
- user_self_ty = Some(UserSelfTy { impl_def_id, self_ty });
- }
- }
- }
- }
- _ => {}
- }
-
- // Now that we have categorized what space the parameters for each
- // segment belong to, let's sort out the parameters that the user
- // provided (if any) into their appropriate spaces. We'll also report
- // errors if type parameters are provided in an inappropriate place.
-
- let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect();
- let generics_has_err = AstConv::prohibit_generics(
- self,
- segments.iter().enumerate().filter_map(|(index, seg)| {
- if !generic_segs.contains(&index) || is_alias_variant_ctor {
- Some(seg)
- } else {
- None
- }
- }),
- );
-
- if let Res::Local(hid) = res {
- let ty = self.local_ty(span, hid).decl_ty;
- let ty = self.normalize_associated_types_in(span, &ty);
- self.write_ty(hir_id, ty);
- return (ty, res);
- }
-
- if generics_has_err {
- // Don't try to infer type parameters when prohibited generic arguments were given.
- user_self_ty = None;
- }
-
- // Now we have to compare the types that the user *actually*
- // provided against the types that were *expected*. If the user
- // did not provide any types, then we want to substitute inference
- // variables. If the user provided some types, we may still need
- // to add defaults. If the user provided *too many* types, that's
- // a problem.
-
- let mut infer_args_for_err = FxHashSet::default();
- for &PathSeg(def_id, index) in &path_segs {
- let seg = &segments[index];
- let generics = tcx.generics_of(def_id);
- // Argument-position `impl Trait` is treated as a normal generic
- // parameter internally, but we don't allow users to specify the
- // parameter's value explicitly, so we have to do some error-
- // checking here.
- if let GenericArgCountResult {
- correct: Err(GenericArgCountMismatch { reported: Some(ErrorReported), .. }),
- ..
- } = AstConv::check_generic_arg_count_for_call(
- tcx, span, &generics, &seg, false, // `is_method_call`
- ) {
- infer_args_for_err.insert(index);
- self.set_tainted_by_errors(); // See issue #53251.
- }
- }
-
- let has_self = path_segs
- .last()
- .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self)
- .unwrap_or(false);
-
- let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res {
- let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id));
- match *ty.kind() {
- ty::Adt(adt_def, substs) if adt_def.has_ctor() => {
- let variant = adt_def.non_enum_variant();
- let ctor_def_id = variant.ctor_def_id.unwrap();
- (
- Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id),
- Some(substs),
- )
- }
- _ => {
- let mut err = tcx.sess.struct_span_err(
- span,
- "the `Self` constructor can only be used with tuple or unit structs",
- );
- if let Some(adt_def) = ty.ty_adt_def() {
- match adt_def.adt_kind() {
- AdtKind::Enum => {
- err.help("did you mean to use one of the enum's variants?");
- }
- AdtKind::Struct | AdtKind::Union => {
- err.span_suggestion(
- span,
- "use curly brackets",
- String::from("Self { /* fields */ }"),
- Applicability::HasPlaceholders,
- );
- }
- }
- }
- err.emit();
-
- return (tcx.ty_error(), res);
- }
- }
- } else {
- (res, None)
- };
- let def_id = res.def_id();
-
- // The things we are substituting into the type should not contain
- // escaping late-bound regions, and nor should the base type scheme.
- let ty = tcx.type_of(def_id);
-
- let arg_count = GenericArgCountResult {
- explicit_late_bound: ExplicitLateBound::No,
- correct: if infer_args_for_err.is_empty() {
- Ok(())
- } else {
- Err(GenericArgCountMismatch::default())
- },
- };
-
- let substs = self_ctor_substs.unwrap_or_else(|| {
- AstConv::create_substs_for_generic_args(
- tcx,
- def_id,
- &[][..],
- has_self,
- self_ty,
- arg_count,
- // Provide the generic args, and whether types should be inferred.
- |def_id| {
- if let Some(&PathSeg(_, index)) =
- path_segs.iter().find(|&PathSeg(did, _)| *did == def_id)
- {
- // If we've encountered an `impl Trait`-related error, we're just
- // going to infer the arguments for better error messages.
- if !infer_args_for_err.contains(&index) {
- // Check whether the user has provided generic arguments.
- if let Some(ref data) = segments[index].args {
- return (Some(data), segments[index].infer_args);
- }
- }
- return (None, segments[index].infer_args);
- }
-
- (None, true)
- },
- // Provide substitutions for parameters for which (valid) arguments have been provided.
- |param, arg| match (¶m.kind, arg) {
- (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
- AstConv::ast_region_to_region(self, lt, Some(param)).into()
- }
- (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
- self.to_ty(ty).into()
- }
- (GenericParamDefKind::Const, GenericArg::Const(ct)) => {
- self.const_arg_to_const(&ct.value, param.def_id).into()
- }
- _ => unreachable!(),
- },
- // Provide substitutions for parameters for which arguments are inferred.
- |substs, param, infer_args| {
- match param.kind {
- GenericParamDefKind::Lifetime => {
- self.re_infer(Some(param), span).unwrap().into()
- }
- GenericParamDefKind::Type { has_default, .. } => {
- if !infer_args && has_default {
- // If we have a default, then we it doesn't matter that we're not
- // inferring the type arguments: we provide the default where any
- // is missing.
- let default = tcx.type_of(param.def_id);
- self.normalize_ty(
- span,
- default.subst_spanned(tcx, substs.unwrap(), Some(span)),
- )
- .into()
- } else {
- // If no type arguments were provided, we have to infer them.
- // This case also occurs as a result of some malformed input, e.g.
- // a lifetime argument being given instead of a type parameter.
- // Using inference instead of `Error` gives better error messages.
- self.var_for_def(span, param)
- }
- }
- GenericParamDefKind::Const => {
- // FIXME(const_generics:defaults)
- // No const parameters were provided, we have to infer them.
- self.var_for_def(span, param)
- }
- }
- },
- )
- });
- assert!(!substs.has_escaping_bound_vars());
- assert!(!ty.has_escaping_bound_vars());
-
- // First, store the "user substs" for later.
- self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty);
-
- self.add_required_obligations(span, def_id, &substs);
-
- // Substitute the values for the type parameters into the type of
- // the referenced item.
- let ty_substituted = self.instantiate_type_scheme(span, &substs, &ty);
-
- if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
- // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
- // is inherent, there is no `Self` parameter; instead, the impl needs
- // type parameters, which we can infer by unifying the provided `Self`
- // with the substituted impl type.
- // This also occurs for an enum variant on a type alias.
- let ty = tcx.type_of(impl_def_id);
-
- let impl_ty = self.instantiate_type_scheme(span, &substs, &ty);
- match self.at(&self.misc(span), self.param_env).sup(impl_ty, self_ty) {
- Ok(ok) => self.register_infer_ok_obligations(ok),
- Err(_) => {
- self.tcx.sess.delay_span_bug(
- span,
- &format!(
- "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?",
- self_ty,
- impl_ty,
- ),
- );
- }
- }
- }
-
- self.check_rustc_args_require_const(def_id, hir_id, span);
-
- debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted);
- self.write_substs(hir_id, substs);
-
- (ty_substituted, res)
- }
-
- /// Add all the obligations that are required, substituting and normalized appropriately.
- fn add_required_obligations(&self, span: Span, def_id: DefId, substs: &SubstsRef<'tcx>) {
- let (bounds, spans) = self.instantiate_bounds(span, def_id, &substs);
-
- for (i, mut obligation) in traits::predicates_for_generics(
- traits::ObligationCause::new(span, self.body_id, traits::ItemObligation(def_id)),
- self.param_env,
- bounds,
- )
- .enumerate()
- {
- // This makes the error point at the bound, but we want to point at the argument
- if let Some(span) = spans.get(i) {
- obligation.cause.make_mut().code = traits::BindingObligation(def_id, *span);
- }
- self.register_predicate(obligation);
- }
- }
-
- /// Resolves `typ` by a single level if `typ` is a type variable.
- /// If no resolution is possible, then an error is reported.
- /// Numeric inference variables may be left unresolved.
- pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
- let ty = self.resolve_vars_with_obligations(ty);
- if !ty.is_ty_var() {
- ty
- } else {
- if !self.is_tainted_by_errors() {
- self.emit_inference_failure_err((**self).body_id, sp, ty.into(), E0282)
- .note("type must be known at this point")
- .emit();
- }
- let err = self.tcx.ty_error();
- self.demand_suptype(sp, err, ty);
- err
- }
- }
-
- pub(super) fn with_breakable_ctxt<F: FnOnce() -> R, R>(
- &self,
- id: hir::HirId,
- ctxt: BreakableCtxt<'tcx>,
- f: F,
- ) -> (BreakableCtxt<'tcx>, R) {
- let index;
- {
- let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
- index = enclosing_breakables.stack.len();
- enclosing_breakables.by_id.insert(id, index);
- enclosing_breakables.stack.push(ctxt);
- }
- let result = f();
- let ctxt = {
- let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
- debug_assert!(enclosing_breakables.stack.len() == index + 1);
- enclosing_breakables.by_id.remove(&id).expect("missing breakable context");
- enclosing_breakables.stack.pop().expect("missing breakable context")
- };
- (ctxt, result)
- }
-
- /// Instantiate a QueryResponse in a probe context, without a
- /// good ObligationCause.
- pub(super) fn probe_instantiate_query_response(
- &self,
- span: Span,
- original_values: &OriginalQueryValues<'tcx>,
- query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
- ) -> InferResult<'tcx, Ty<'tcx>> {
- self.instantiate_query_response_and_region_obligations(
- &traits::ObligationCause::misc(span, self.body_id),
- self.param_env,
- original_values,
- query_result,
- )
- }
-
- /// Returns `true` if an expression is contained inside the LHS of an assignment expression.
- pub(super) fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool {
- let mut contained_in_place = false;
-
- while let hir::Node::Expr(parent_expr) =
- self.tcx.hir().get(self.tcx.hir().get_parent_node(expr_id))
- {
- match &parent_expr.kind {
- hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => {
- if lhs.hir_id == expr_id {
- contained_in_place = true;
- break;
- }
- }
- _ => (),
- }
- expr_id = parent_expr.hir_id;
- }
-
- contained_in_place
- }
-}
+++ /dev/null
-use super::FnCtxt;
-use crate::astconv::AstConv;
-
-use rustc_ast::util::parser::ExprPrecedence;
-use rustc_span::{self, Span};
-use rustc_trait_selection::traits;
-
-use rustc_errors::{Applicability, DiagnosticBuilder};
-use rustc_hir as hir;
-use rustc_hir::def::{CtorOf, DefKind};
-use rustc_hir::lang_items::LangItem;
-use rustc_hir::{ExprKind, ItemKind, Node};
-use rustc_infer::infer;
-use rustc_middle::ty::{self, Ty};
-use rustc_span::symbol::kw;
-use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
-
-use std::iter;
-
-impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
- pub(super) fn suggest_semicolon_at_end(&self, span: Span, err: &mut DiagnosticBuilder<'_>) {
- err.span_suggestion_short(
- span.shrink_to_hi(),
- "consider using a semicolon here",
- ";".to_string(),
- Applicability::MachineApplicable,
- );
- }
-
- /// On implicit return expressions with mismatched types, provides the following suggestions:
- ///
- /// - Points out the method's return type as the reason for the expected type.
- /// - Possible missing semicolon.
- /// - Possible missing return type if the return type is the default, and not `fn main()`.
- pub fn suggest_mismatched_types_on_tail(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &'tcx hir::Expr<'tcx>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- cause_span: Span,
- blk_id: hir::HirId,
- ) -> bool {
- let expr = expr.peel_drop_temps();
- self.suggest_missing_semicolon(err, expr, expected, cause_span);
- let mut pointing_at_return_type = false;
- if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) {
- pointing_at_return_type =
- self.suggest_missing_return_type(err, &fn_decl, expected, found, can_suggest);
- }
- pointing_at_return_type
- }
-
- /// When encountering an fn-like ctor that needs to unify with a value, check whether calling
- /// the ctor would successfully solve the type mismatch and if so, suggest it:
- /// ```
- /// fn foo(x: usize) -> usize { x }
- /// let x: usize = foo; // suggest calling the `foo` function: `foo(42)`
- /// ```
- fn suggest_fn_call(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) -> bool {
- let hir = self.tcx.hir();
- let (def_id, sig) = match *found.kind() {
- ty::FnDef(def_id, _) => (def_id, found.fn_sig(self.tcx)),
- ty::Closure(def_id, substs) => (def_id, substs.as_closure().sig()),
- _ => return false,
- };
-
- let sig = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, &sig).0;
- let sig = self.normalize_associated_types_in(expr.span, &sig);
- if self.can_coerce(sig.output(), expected) {
- let (mut sugg_call, applicability) = if sig.inputs().is_empty() {
- (String::new(), Applicability::MachineApplicable)
- } else {
- ("...".to_string(), Applicability::HasPlaceholders)
- };
- let mut msg = "call this function";
- match hir.get_if_local(def_id) {
- Some(
- Node::Item(hir::Item { kind: ItemKind::Fn(.., body_id), .. })
- | Node::ImplItem(hir::ImplItem {
- kind: hir::ImplItemKind::Fn(_, body_id), ..
- })
- | Node::TraitItem(hir::TraitItem {
- kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Provided(body_id)),
- ..
- }),
- ) => {
- let body = hir.body(*body_id);
- sugg_call = body
- .params
- .iter()
- .map(|param| match ¶m.pat.kind {
- hir::PatKind::Binding(_, _, ident, None)
- if ident.name != kw::SelfLower =>
- {
- ident.to_string()
- }
- _ => "_".to_string(),
- })
- .collect::<Vec<_>>()
- .join(", ");
- }
- Some(Node::Expr(hir::Expr {
- kind: ExprKind::Closure(_, _, body_id, _, _),
- span: full_closure_span,
- ..
- })) => {
- if *full_closure_span == expr.span {
- return false;
- }
- msg = "call this closure";
- let body = hir.body(*body_id);
- sugg_call = body
- .params
- .iter()
- .map(|param| match ¶m.pat.kind {
- hir::PatKind::Binding(_, _, ident, None)
- if ident.name != kw::SelfLower =>
- {
- ident.to_string()
- }
- _ => "_".to_string(),
- })
- .collect::<Vec<_>>()
- .join(", ");
- }
- Some(Node::Ctor(hir::VariantData::Tuple(fields, _))) => {
- sugg_call = fields.iter().map(|_| "_").collect::<Vec<_>>().join(", ");
- match def_id.as_local().map(|def_id| hir.def_kind(def_id)) {
- Some(DefKind::Ctor(hir::def::CtorOf::Variant, _)) => {
- msg = "instantiate this tuple variant";
- }
- Some(DefKind::Ctor(CtorOf::Struct, _)) => {
- msg = "instantiate this tuple struct";
- }
- _ => {}
- }
- }
- Some(Node::ForeignItem(hir::ForeignItem {
- kind: hir::ForeignItemKind::Fn(_, idents, _),
- ..
- })) => {
- sugg_call = idents
- .iter()
- .map(|ident| {
- if ident.name != kw::SelfLower {
- ident.to_string()
- } else {
- "_".to_string()
- }
- })
- .collect::<Vec<_>>()
- .join(", ")
- }
- Some(Node::TraitItem(hir::TraitItem {
- kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Required(idents)),
- ..
- })) => {
- sugg_call = idents
- .iter()
- .map(|ident| {
- if ident.name != kw::SelfLower {
- ident.to_string()
- } else {
- "_".to_string()
- }
- })
- .collect::<Vec<_>>()
- .join(", ")
- }
- _ => {}
- }
- err.span_suggestion_verbose(
- expr.span.shrink_to_hi(),
- &format!("use parentheses to {}", msg),
- format!("({})", sugg_call),
- applicability,
- );
- return true;
- }
- false
- }
-
- pub fn suggest_deref_ref_or_into(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
- ) {
- if let Some((sp, msg, suggestion, applicability)) = self.check_ref(expr, found, expected) {
- err.span_suggestion(sp, msg, suggestion, applicability);
- } else if let (ty::FnDef(def_id, ..), true) =
- (&found.kind(), self.suggest_fn_call(err, expr, expected, found))
- {
- if let Some(sp) = self.tcx.hir().span_if_local(*def_id) {
- let sp = self.sess().source_map().guess_head_span(sp);
- err.span_label(sp, &format!("{} defined here", found));
- }
- } else if !self.check_for_cast(err, expr, found, expected, expected_ty_expr) {
- let is_struct_pat_shorthand_field =
- self.is_hir_id_from_struct_pattern_shorthand_field(expr.hir_id, expr.span);
- let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id);
- if let Ok(expr_text) = self.sess().source_map().span_to_snippet(expr.span) {
- let mut suggestions = iter::repeat(&expr_text)
- .zip(methods.iter())
- .filter_map(|(receiver, method)| {
- let method_call = format!(".{}()", method.ident);
- if receiver.ends_with(&method_call) {
- None // do not suggest code that is already there (#53348)
- } else {
- let method_call_list = [".to_vec()", ".to_string()"];
- let sugg = if receiver.ends_with(".clone()")
- && method_call_list.contains(&method_call.as_str())
- {
- let max_len = receiver.rfind('.').unwrap();
- format!("{}{}", &receiver[..max_len], method_call)
- } else {
- if expr.precedence().order() < ExprPrecedence::MethodCall.order() {
- format!("({}){}", receiver, method_call)
- } else {
- format!("{}{}", receiver, method_call)
- }
- };
- Some(if is_struct_pat_shorthand_field {
- format!("{}: {}", receiver, sugg)
- } else {
- sugg
- })
- }
- })
- .peekable();
- if suggestions.peek().is_some() {
- err.span_suggestions(
- expr.span,
- "try using a conversion method",
- suggestions,
- Applicability::MaybeIncorrect,
- );
- }
- }
- }
- }
-
- /// When encountering the expected boxed value allocated in the stack, suggest allocating it
- /// in the heap by calling `Box::new()`.
- pub(super) fn suggest_boxing_when_appropriate(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) {
- if self.tcx.hir().is_inside_const_context(expr.hir_id) {
- // Do not suggest `Box::new` in const context.
- return;
- }
- if !expected.is_box() || found.is_box() {
- return;
- }
- let boxed_found = self.tcx.mk_box(found);
- if let (true, Ok(snippet)) = (
- self.can_coerce(boxed_found, expected),
- self.sess().source_map().span_to_snippet(expr.span),
- ) {
- err.span_suggestion(
- expr.span,
- "store this in the heap by calling `Box::new`",
- format!("Box::new({})", snippet),
- Applicability::MachineApplicable,
- );
- err.note(
- "for more on the distinction between the stack and the heap, read \
- https://doc.rust-lang.org/book/ch15-01-box.html, \
- https://doc.rust-lang.org/rust-by-example/std/box.html, and \
- https://doc.rust-lang.org/std/boxed/index.html",
- );
- }
- }
-
- /// When encountering an `impl Future` where `BoxFuture` is expected, suggest `Box::pin`.
- pub(super) fn suggest_calling_boxed_future_when_appropriate(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) -> bool {
- // Handle #68197.
-
- if self.tcx.hir().is_inside_const_context(expr.hir_id) {
- // Do not suggest `Box::new` in const context.
- return false;
- }
- let pin_did = self.tcx.lang_items().pin_type();
- match expected.kind() {
- ty::Adt(def, _) if Some(def.did) != pin_did => return false,
- // This guards the `unwrap` and `mk_box` below.
- _ if pin_did.is_none() || self.tcx.lang_items().owned_box().is_none() => return false,
- _ => {}
- }
- let boxed_found = self.tcx.mk_box(found);
- let new_found = self.tcx.mk_lang_item(boxed_found, LangItem::Pin).unwrap();
- if let (true, Ok(snippet)) = (
- self.can_coerce(new_found, expected),
- self.sess().source_map().span_to_snippet(expr.span),
- ) {
- match found.kind() {
- ty::Adt(def, _) if def.is_box() => {
- err.help("use `Box::pin`");
- }
- _ => {
- err.span_suggestion(
- expr.span,
- "you need to pin and box this expression",
- format!("Box::pin({})", snippet),
- Applicability::MachineApplicable,
- );
- }
- }
- true
- } else {
- false
- }
- }
-
- /// A common error is to forget to add a semicolon at the end of a block, e.g.,
- ///
- /// ```
- /// fn foo() {
- /// bar_that_returns_u32()
- /// }
- /// ```
- ///
- /// This routine checks if the return expression in a block would make sense on its own as a
- /// statement and the return type has been left as default or has been specified as `()`. If so,
- /// it suggests adding a semicolon.
- fn suggest_missing_semicolon(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expression: &'tcx hir::Expr<'tcx>,
- expected: Ty<'tcx>,
- cause_span: Span,
- ) {
- if expected.is_unit() {
- // `BlockTailExpression` only relevant if the tail expr would be
- // useful on its own.
- match expression.kind {
- ExprKind::Call(..)
- | ExprKind::MethodCall(..)
- | ExprKind::Loop(..)
- | ExprKind::Match(..)
- | ExprKind::Block(..) => {
- err.span_suggestion(
- cause_span.shrink_to_hi(),
- "try adding a semicolon",
- ";".to_string(),
- Applicability::MachineApplicable,
- );
- }
- _ => (),
- }
- }
- }
-
- /// A possible error is to forget to add a return type that is needed:
- ///
- /// ```
- /// fn foo() {
- /// bar_that_returns_u32()
- /// }
- /// ```
- ///
- /// This routine checks if the return type is left as default, the method is not part of an
- /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return
- /// type.
- pub(super) fn suggest_missing_return_type(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- fn_decl: &hir::FnDecl<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- can_suggest: bool,
- ) -> bool {
- // Only suggest changing the return type for methods that
- // haven't set a return type at all (and aren't `fn main()` or an impl).
- match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) {
- (&hir::FnRetTy::DefaultReturn(span), true, true, true) => {
- err.span_suggestion(
- span,
- "try adding a return type",
- format!("-> {} ", self.resolve_vars_with_obligations(found)),
- Applicability::MachineApplicable,
- );
- true
- }
- (&hir::FnRetTy::DefaultReturn(span), false, true, true) => {
- err.span_label(span, "possibly return type missing here?");
- true
- }
- (&hir::FnRetTy::DefaultReturn(span), _, false, true) => {
- // `fn main()` must return `()`, do not suggest changing return type
- err.span_label(span, "expected `()` because of default return type");
- true
- }
- // expectation was caused by something else, not the default return
- (&hir::FnRetTy::DefaultReturn(_), _, _, false) => false,
- (&hir::FnRetTy::Return(ref ty), _, _, _) => {
- // Only point to return type if the expected type is the return type, as if they
- // are not, the expectation must have been caused by something else.
- debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind);
- let sp = ty.span;
- let ty = AstConv::ast_ty_to_ty(self, ty);
- debug!("suggest_missing_return_type: return type {:?}", ty);
- debug!("suggest_missing_return_type: expected type {:?}", ty);
- if ty.kind() == expected.kind() {
- err.span_label(sp, format!("expected `{}` because of return type", expected));
- return true;
- }
- false
- }
- }
- }
-
- /// A possible error is to forget to add `.await` when using futures:
- ///
- /// ```
- /// async fn make_u32() -> u32 {
- /// 22
- /// }
- ///
- /// fn take_u32(x: u32) {}
- ///
- /// async fn foo() {
- /// let x = make_u32();
- /// take_u32(x);
- /// }
- /// ```
- ///
- /// This routine checks if the found type `T` implements `Future<Output=U>` where `U` is the
- /// expected type. If this is the case, and we are inside of an async body, it suggests adding
- /// `.await` to the tail of the expression.
- pub(super) fn suggest_missing_await(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) {
- debug!("suggest_missing_await: expr={:?} expected={:?}, found={:?}", expr, expected, found);
- // `.await` is not permitted outside of `async` bodies, so don't bother to suggest if the
- // body isn't `async`.
- let item_id = self.tcx().hir().get_parent_node(self.body_id);
- if let Some(body_id) = self.tcx().hir().maybe_body_owned_by(item_id) {
- let body = self.tcx().hir().body(body_id);
- if let Some(hir::GeneratorKind::Async(_)) = body.generator_kind {
- let sp = expr.span;
- // Check for `Future` implementations by constructing a predicate to
- // prove: `<T as Future>::Output == U`
- let future_trait = self.tcx.require_lang_item(LangItem::Future, Some(sp));
- let item_def_id = self
- .tcx
- .associated_items(future_trait)
- .in_definition_order()
- .next()
- .unwrap()
- .def_id;
- // `<T as Future>::Output`
- let projection_ty = ty::ProjectionTy {
- // `T`
- substs: self
- .tcx
- .mk_substs_trait(found, self.fresh_substs_for_item(sp, item_def_id)),
- // `Future::Output`
- item_def_id,
- };
-
- let predicate = ty::PredicateAtom::Projection(ty::ProjectionPredicate {
- projection_ty,
- ty: expected,
- })
- .potentially_quantified(self.tcx, ty::PredicateKind::ForAll);
- let obligation = traits::Obligation::new(self.misc(sp), self.param_env, predicate);
-
- debug!("suggest_missing_await: trying obligation {:?}", obligation);
-
- if self.infcx.predicate_may_hold(&obligation) {
- debug!("suggest_missing_await: obligation held: {:?}", obligation);
- if let Ok(code) = self.sess().source_map().span_to_snippet(sp) {
- err.span_suggestion(
- sp,
- "consider using `.await` here",
- format!("{}.await", code),
- Applicability::MaybeIncorrect,
- );
- } else {
- debug!("suggest_missing_await: no snippet for {:?}", sp);
- }
- } else {
- debug!("suggest_missing_await: obligation did not hold: {:?}", obligation)
- }
- }
- }
- }
-
- pub(super) fn suggest_missing_parentheses(
- &self,
- err: &mut DiagnosticBuilder<'_>,
- expr: &hir::Expr<'_>,
- ) {
- let sp = self.tcx.sess.source_map().start_point(expr.span);
- if let Some(sp) = self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) {
- // `{ 42 } &&x` (#61475) or `{ 42 } && if x { 1 } else { 0 }`
- self.tcx.sess.parse_sess.expr_parentheses_needed(err, *sp, None);
- }
- }
-}
mod expectation;
mod expr;
mod fn_ctxt;
-mod fn_ctxt_checks;
-mod fn_ctxt_impl;
-mod fn_ctxt_suggestions;
mod gather_locals;
mod generator_interior;
mod inherited;
pub use check::{check_item_type, check_wf_new};
pub use diverges::Diverges;
pub use expectation::Expectation;
-pub use fn_ctxt::FnCtxt;
-pub use fn_ctxt_checks::*;
-pub use fn_ctxt_impl::*;
-pub use fn_ctxt_suggestions::*;
+pub use fn_ctxt::*;
pub use inherited::{Inherited, InheritedBuilder};
use crate::astconv::AstConv;
projects / rust.git / commitdiff