+++ /dev/null
-use crate::astconv::{
- AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch,
- GenericArgCountResult, IsMethodCall, PathSeg,
-};
-use crate::check::callee::{self, DeferredCallResolution};
-use crate::check::method::{self, MethodCallee, SelfSource};
-use crate::check::rvalue_scopes;
-use crate::check::{BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy};
-
-use rustc_data_structures::captures::Captures;
-use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed, MultiSpan};
-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::visit::TypeVisitable;
-use rustc_middle::ty::{
- self, AdtKind, CanonicalUserType, DefIdTree, EarlyBinder, GenericParamDefKind, ToPolyTraitRef,
- ToPredicate, Ty, UserType,
-};
-use rustc_middle::ty::{GenericArgKind, InternalSubsts, SubstsRef, UserSelfTy, UserSubsts};
-use rustc_session::lint;
-use rustc_span::def_id::LocalDefId;
-use rustc_span::hygiene::DesugaringKind;
-use rustc_span::symbol::{kw, sym, Ident};
-use rustc_span::{Span, DUMMY_SP};
-use rustc_trait_selection::infer::InferCtxtExt as _;
-use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
-use rustc_trait_selection::traits::{
- self, ObligationCause, 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, ty: Ty<'tcx>) -> Ty<'tcx> {
- self.resolve_vars_with_obligations_and_mutate_fulfillment(ty, |_| {})
- }
-
- #[instrument(skip(self, mutate_fulfillment_errors), level = "debug", ret)]
- pub(in super::super) fn resolve_vars_with_obligations_and_mutate_fulfillment(
- &self,
- mut ty: Ty<'tcx>,
- mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
- ) -> Ty<'tcx> {
- // No Infer()? Nothing needs doing.
- if !ty.has_infer_types_or_consts() {
- debug!("no inference var, nothing needs doing");
- 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!(?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, mutate_fulfillment_errors);
- self.resolve_vars_if_possible(ty)
- }
-
- pub(in super::super) fn record_deferred_call_resolution(
- &self,
- closure_def_id: LocalDefId,
- 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: LocalDefId,
- ) -> Vec<DeferredCallResolution<'tcx>> {
- let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
- deferred_call_resolutions.remove(&closure_def_id).unwrap_or_default()
- }
-
- 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);
- }
-
- #[instrument(level = "debug", skip(self))]
- pub(in super::super) fn write_resolution(
- &self,
- hir_id: hir::HirId,
- r: Result<(DefKind, DefId), ErrorGuaranteed>,
- ) {
- self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r);
- }
-
- #[instrument(level = "debug", skip(self))]
- pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) {
- 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_empty() {
- let method_generics = self.tcx.generics_of(method.def_id);
- if !method_generics.params.is_empty() {
- let user_type_annotation = self.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.var_for_def(DUMMY_SP, param)
- } else {
- method.substs[i]
- }
- }),
- user_self_ty: None, // not relevant here
- };
-
- self.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_empty() {
- 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.
- #[instrument(skip(self), level = "debug")]
- 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!("fcx {}", self.tag());
-
- if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) {
- let canonicalized = self.canonicalize_user_type_annotation(UserType::TypeOf(
- def_id,
- UserSubsts { substs, user_self_ty },
- ));
- debug!(?canonicalized);
- self.write_user_type_annotation(hir_id, canonicalized);
- }
- }
-
- #[instrument(skip(self), level = "debug")]
- pub fn write_user_type_annotation(
- &self,
- hir_id: hir::HirId,
- canonical_user_type_annotation: CanonicalUserType<'tcx>,
- ) {
- debug!("fcx {}", 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!("skipping identity substs");
- }
- }
-
- #[instrument(skip(self, expr), level = "debug")]
- pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) {
- debug!("expr = {:#?}", expr);
-
- if adj.is_empty() {
- return;
- }
-
- for a in &adj {
- if let Adjust::NeverToAny = a.kind {
- if a.target.is_ty_var() {
- self.diverging_type_vars.borrow_mut().insert(a.target);
- debug!("apply_adjustments: adding `{:?}` as diverging type var", a.target);
- }
- }
- }
-
- 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.
- _ => {
- self.tcx.sess.delay_span_bug(
- expr.span,
- &format!(
- "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>,
- {
- debug!("instantiate_type_scheme(value={:?}, substs={:?})", value, substs);
- let value = EarlyBinder(value).subst(self.tcx, substs);
- let result = self.normalize_associated_types_in(span, value);
- debug!("instantiate_type_scheme = {:?}", 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)
- }
-
- 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(
- ObligationCause::misc(span, self.body_id),
- self.param_env,
- value,
- )
- }
-
- pub(in super::super) fn normalize_op_associated_types_in_as_infer_ok<T>(
- &self,
- span: Span,
- value: T,
- opt_input_expr: Option<&hir::Expr<'_>>,
- ) -> InferOk<'tcx, T>
- where
- T: TypeFoldable<'tcx>,
- {
- self.inh.partially_normalize_associated_types_in(
- ObligationCause::new(
- span,
- self.body_id,
- traits::BinOp {
- rhs_span: opt_input_expr.map(|expr| expr.span),
- is_lit: opt_input_expr
- .map_or(false, |expr| matches!(expr.kind, ExprKind::Lit(_))),
- output_ty: None,
- },
- ),
- 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 = <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_t);
- self.register_wf_obligation(t.into(), ast_t.span, traits::WellFormed(None));
- 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.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 array_length_to_const(&self, length: &hir::ArrayLen) -> ty::Const<'tcx> {
- match length {
- &hir::ArrayLen::Infer(_, span) => self.ct_infer(self.tcx.types.usize, None, span),
- hir::ArrayLen::Body(anon_const) => {
- let const_def_id = self.tcx.hir().local_def_id(anon_const.hir_id);
- let span = self.tcx.hir().span(anon_const.hir_id);
- let c = ty::Const::from_anon_const(self.tcx, const_def_id);
- self.register_wf_obligation(c.into(), span, ObligationCauseCode::WellFormed(None));
- self.normalize_associated_types_in(span, c)
- }
- }
- }
-
- pub fn const_arg_to_const(
- &self,
- ast_c: &hir::AnonConst,
- param_def_id: DefId,
- ) -> 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::WellFormed(None),
- );
- 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: TypeVisitable<'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()
- );
- }
- }
- }
-
- pub fn node_ty_opt(&self, id: hir::HirId) -> Option<Ty<'tcx>> {
- match self.typeck_results.borrow().node_types().get(id) {
- Some(&t) => Some(t),
- None if self.is_tainted_by_errors() => Some(self.tcx.ty_error()),
- None => None,
- }
- }
-
- /// Registers an obligation for checking later, during regionck, that `arg` is well-formed.
- pub fn register_wf_obligation(
- &self,
- arg: ty::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::Binder::dummy(ty::PredicateKind::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::WellFormed(None));
- }
- }
-
- // 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_rvalue_scopes(&self, def_id: DefId) {
- let scope_tree = self.tcx.region_scope_tree(def_id);
- let rvalue_scopes = { rvalue_scopes::resolve_rvalue_scopes(self, &scope_tree, def_id) };
- let mut typeck_results = self.inh.typeck_results.borrow_mut();
- typeck_results.rvalue_scopes = rvalue_scopes;
- }
-
- 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,
- );
- }
- }
-
- #[instrument(skip(self), level = "debug")]
- pub(in super::super) fn select_all_obligations_or_error(&self) {
- let mut errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self);
-
- if !errors.is_empty() {
- self.adjust_fulfillment_errors_for_expr_obligation(&mut errors);
- 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_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
- ) {
- let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self);
- if !result.is_empty() {
- mutate_fulfillment_errors(&mut result);
- self.adjust_fulfillment_errors_for_expr_obligation(&mut result);
- self.report_fulfillment_errors(&result, 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()
- }
-
- #[instrument(skip(self), level = "debug")]
- 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_ty);
-
- 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,
- }
- }
-
- #[instrument(skip(self), level = "debug")]
- 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);
- trace!("pending_obligations = {:#?}", self.fulfillment_cx.borrow().pending_obligations());
-
- self.fulfillment_cx
- .borrow()
- .pending_obligations()
- .into_iter()
- .filter_map(move |obligation| {
- let bound_predicate = obligation.predicate.kind();
- match bound_predicate.skip_binder() {
- ty::PredicateKind::Projection(data) => Some((
- bound_predicate.rebind(data).required_poly_trait_ref(self.tcx),
- obligation,
- )),
- ty::PredicateKind::Trait(data) => {
- Some((bound_predicate.rebind(data).to_poly_trait_ref(), obligation))
- }
- ty::PredicateKind::Subtype(..) => None,
- ty::PredicateKind::Coerce(..) => None,
- ty::PredicateKind::RegionOutlives(..) => None,
- ty::PredicateKind::TypeOutlives(..) => None,
- ty::PredicateKind::WellFormed(..) => None,
- ty::PredicateKind::ObjectSafe(..) => None,
- ty::PredicateKind::ConstEvaluatable(..) => None,
- ty::PredicateKind::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 an unresolved
- // inference variable.
- ty::PredicateKind::ClosureKind(..) => None,
- ty::PredicateKind::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.
- #[instrument(skip(self, call_span), level = "debug")]
- 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>],
- ) -> Option<Vec<Ty<'tcx>>> {
- let formal_ret = self.resolve_vars_with_obligations(formal_ret);
- let ret_ty = expected_ret.only_has_type(self)?;
-
- // HACK(oli-obk): This is a hack to keep RPIT and TAIT in sync wrt their behaviour.
- // Without it, the inference
- // variable will get instantiated with the opaque type. The inference variable often
- // has various helpful obligations registered for it that help closures figure out their
- // signature. If we infer the inference var to the opaque type, the closure won't be able
- // to find those obligations anymore, and it can't necessarily find them from the opaque
- // type itself. We could be more powerful with inference if we *combined* the obligations
- // so that we got both the obligations from the opaque type and the ones from the inference
- // variable. That will accept more code than we do right now, so we need to carefully consider
- // the implications.
- // Note: this check is pessimistic, as the inference type could be matched with something other
- // than the opaque type, but then we need a new `TypeRelation` just for this specific case and
- // can't re-use `sup` below.
- // See src/test/ui/impl-trait/hidden-type-is-opaque.rs and
- // src/test/ui/impl-trait/hidden-type-is-opaque-2.rs for examples that hit this path.
- if formal_ret.has_infer_types() {
- for ty in ret_ty.walk() {
- if let ty::subst::GenericArgKind::Type(ty) = ty.unpack()
- && let ty::Opaque(def_id, _) = *ty.kind()
- && let Some(def_id) = def_id.as_local()
- && self.opaque_type_origin(def_id, DUMMY_SP).is_some() {
- return None;
- }
- }
- }
-
- 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.
- let errors = self.save_and_restore_in_snapshot_flag(|_| {
- let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx);
- for obligation in ok.obligations {
- fulfill.register_predicate_obligation(self, obligation);
- }
- fulfill.select_where_possible(self)
- });
-
- if !errors.is_empty() {
- return Err(());
- }
- }
- Err(_) => return Err(()),
- }
-
- // Record all the argument types, with the substitutions
- // produced from the above subtyping unification.
- Ok(Some(formal_args.iter().map(|&ty| self.resolve_vars_if_possible(ty)).collect()))
- })
- .unwrap_or_default();
- debug!(?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,
- expr_hir_id: Option<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.bound_type_of(self.tcx.parent(def_id))
- } else {
- self.tcx.bound_type_of(def_id)
- };
- let substs = self.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)));
-
- let code = match lang_item {
- hir::LangItem::IntoFutureIntoFuture => {
- Some(ObligationCauseCode::AwaitableExpr(expr_hir_id))
- }
- hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => {
- Some(ObligationCauseCode::ForLoopIterator)
- }
- hir::LangItem::TryTraitFromOutput
- | hir::LangItem::TryTraitFromResidual
- | hir::LangItem::TryTraitBranch => Some(ObligationCauseCode::QuestionMark),
- _ => None,
- };
- if let Some(code) = code {
- self.add_required_obligations_with_code(span, def_id, substs, move |_, _| code.clone());
- } else {
- self.add_required_obligations_for_hir(span, def_id, substs, hir_id);
- }
-
- (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_fully_qualified_call(
- &self,
- qpath: &'tcx QPath<'tcx>,
- hir_id: hir::HirId,
- span: Span,
- ) -> (Res, Option<Ty<'tcx>>, &'tcx [hir::PathSegment<'tcx>]) {
- debug!(
- "resolve_ty_and_res_fully_qualified_call: 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) => {
- // Don't use `self.to_ty`, since this will register a WF obligation.
- // If we're trying to call a non-existent method on a trait
- // (e.g. `MyTrait::missing_method`), then resolution will
- // give us a `QPath::TypeRelative` with a trait object as
- // `qself`. In that case, we want to avoid registering a WF obligation
- // for `dyn MyTrait`, since we don't actually need the trait
- // to be object-safe.
- // We manually call `register_wf_obligation` in the success path
- // below.
- (<dyn AstConv<'_>>::ast_ty_to_ty_in_path(self, qself), qself, segment)
- }
- QPath::LangItem(..) => {
- bug!("`resolve_ty_and_res_fully_qualified_call` called on `LangItem`")
- }
- };
- if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id)
- {
- self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None));
- // 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_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id));
- return (def, Some(ty), slice::from_ref(&**item_segment));
- }
- let item_name = item_segment.ident;
- let result = self
- .resolve_fully_qualified_call(span, item_name, ty, qself.span, hir_id)
- .or_else(|error| {
- let result = match error {
- method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
- _ => Err(ErrorGuaranteed::unchecked_claim_error_was_emitted()),
- };
-
- // If we have a path like `MyTrait::missing_method`, then don't register
- // a WF obligation for `dyn MyTrait` when method lookup fails. Otherwise,
- // register a WF obligation so that we can detect any additional
- // errors in the self type.
- if !(matches!(error, method::MethodError::NoMatch(_)) && ty.is_trait()) {
- self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None));
- }
- if item_name.name != kw::Empty {
- if let Some(mut e) = self.report_method_error(
- span,
- ty,
- item_name,
- SelfSource::QPath(qself),
- error,
- None,
- ) {
- e.emit();
- }
- }
- result
- });
-
- if result.is_ok() {
- self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None));
- }
-
- // Write back the new resolution.
- self.write_resolution(hir_id, result);
- (
- result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
- 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 Diagnostic,
- 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...",
- );
- 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 Diagnostic,
- 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.bound_fn_sig(*did1).subst(self.tcx, substs1);
- let sig2 = self.tcx.bound_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.bound_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
- ));
- }
-
- // Instantiates the given path, which must refer to an item with the given
- // number of type parameters and type.
- #[instrument(skip(self, span), level = "debug")]
- 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) {
- let tcx = self.tcx;
-
- let path_segs = match res {
- Res::Local(_) | Res::SelfCtor(_) => vec![],
- Res::Def(kind, def_id) => <dyn 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 assoc_item = tcx.associated_item(def_id);
- let container = assoc_item.container;
- let container_id = assoc_item.container_id(tcx);
- debug!(?def_id, ?container, ?container_id);
- match container {
- ty::TraitContainer => {
- callee::check_legal_trait_for_method_call(tcx, span, None, span, container_id)
- }
- ty::ImplContainer => {
- 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: container_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 = <dyn 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();
-
- let mut explicit_late_bound = ExplicitLateBound::No;
- 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.
- let arg_count = <dyn AstConv<'_>>::check_generic_arg_count_for_call(
- tcx,
- span,
- def_id,
- &generics,
- seg,
- IsMethodCall::No,
- );
-
- if let ExplicitLateBound::Yes = arg_count.explicit_late_bound {
- explicit_late_bound = ExplicitLateBound::Yes;
- }
-
- if let Err(GenericArgCountMismatch { reported: Some(_), .. }) = arg_count.correct {
- 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",
- "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,
- correct: if infer_args_for_err.is_empty() {
- Ok(())
- } else {
- Err(GenericArgCountMismatch::default())
- },
- };
-
- struct CreateCtorSubstsContext<'a, 'tcx> {
- fcx: &'a FnCtxt<'a, 'tcx>,
- span: Span,
- path_segs: &'a [PathSeg],
- infer_args_for_err: &'a FxHashSet<usize>,
- segments: &'a [hir::PathSegment<'a>],
- }
- impl<'tcx, 'a> CreateSubstsForGenericArgsCtxt<'a, 'tcx> for CreateCtorSubstsContext<'a, 'tcx> {
- fn args_for_def_id(
- &mut self,
- def_id: DefId,
- ) -> (Option<&'a hir::GenericArgs<'a>>, bool) {
- if let Some(&PathSeg(_, index)) =
- self.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 !self.infer_args_for_err.contains(&index) {
- // Check whether the user has provided generic arguments.
- if let Some(ref data) = self.segments[index].args {
- return (Some(data), self.segments[index].infer_args);
- }
- }
- return (None, self.segments[index].infer_args);
- }
-
- (None, true)
- }
-
- fn provided_kind(
- &mut self,
- param: &ty::GenericParamDef,
- arg: &GenericArg<'_>,
- ) -> ty::GenericArg<'tcx> {
- match (¶m.kind, arg) {
- (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
- <dyn AstConv<'_>>::ast_region_to_region(self.fcx, lt, Some(param)).into()
- }
- (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
- self.fcx.to_ty(ty).into()
- }
- (GenericParamDefKind::Const { .. }, GenericArg::Const(ct)) => {
- self.fcx.const_arg_to_const(&ct.value, param.def_id).into()
- }
- (GenericParamDefKind::Type { .. }, GenericArg::Infer(inf)) => {
- self.fcx.ty_infer(Some(param), inf.span).into()
- }
- (GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => {
- let tcx = self.fcx.tcx();
- self.fcx.ct_infer(tcx.type_of(param.def_id), Some(param), inf.span).into()
- }
- _ => unreachable!(),
- }
- }
-
- fn inferred_kind(
- &mut self,
- substs: Option<&[ty::GenericArg<'tcx>]>,
- param: &ty::GenericParamDef,
- infer_args: bool,
- ) -> ty::GenericArg<'tcx> {
- let tcx = self.fcx.tcx();
- match param.kind {
- GenericParamDefKind::Lifetime => {
- self.fcx.re_infer(Some(param), self.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.bound_type_of(param.def_id);
- self.fcx
- .normalize_ty(self.span, default.subst(tcx, substs.unwrap()))
- .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.fcx.var_for_def(self.span, param)
- }
- }
- GenericParamDefKind::Const { has_default } => {
- if !infer_args && has_default {
- tcx.bound_const_param_default(param.def_id)
- .subst(tcx, substs.unwrap())
- .into()
- } else {
- self.fcx.var_for_def(self.span, param)
- }
- }
- }
- }
- }
-
- let substs = self_ctor_substs.unwrap_or_else(|| {
- <dyn AstConv<'_>>::create_substs_for_generic_args(
- tcx,
- def_id,
- &[],
- has_self,
- self_ty,
- &arg_count,
- &mut CreateCtorSubstsContext {
- fcx: self,
- span,
- path_segs: &path_segs,
- infer_args_for_err: &infer_args_for_err,
- segments,
- },
- )
- });
- 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_for_hir(span, def_id, &substs, hir_id);
-
- // 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).eq(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,
- ),
- );
- }
- }
- }
-
- 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.
- pub(crate) fn add_required_obligations_for_hir(
- &self,
- span: Span,
- def_id: DefId,
- substs: SubstsRef<'tcx>,
- hir_id: hir::HirId,
- ) {
- self.add_required_obligations_with_code(span, def_id, substs, |idx, span| {
- if span.is_dummy() {
- ObligationCauseCode::ExprItemObligation(def_id, hir_id, idx)
- } else {
- ObligationCauseCode::ExprBindingObligation(def_id, span, hir_id, idx)
- }
- })
- }
-
- #[instrument(level = "debug", skip(self, code, span, substs))]
- fn add_required_obligations_with_code(
- &self,
- span: Span,
- def_id: DefId,
- substs: SubstsRef<'tcx>,
- code: impl Fn(usize, Span) -> ObligationCauseCode<'tcx>,
- ) {
- let param_env = self.param_env;
-
- let remap = match self.tcx.def_kind(def_id) {
- // Associated consts have `Self: ~const Trait` bounds that should be satisfiable when
- // `Self: Trait` is satisfied because it does not matter whether the impl is `const`.
- // Therefore we have to remap the param env here to be non-const.
- hir::def::DefKind::AssocConst => true,
- hir::def::DefKind::AssocFn
- if self.tcx.def_kind(self.tcx.parent(def_id)) == hir::def::DefKind::Trait =>
- {
- // N.B.: All callsites to this function involve checking a path expression.
- //
- // When instantiating a trait method as a function item, it does not actually matter whether
- // the trait is `const` or not, or whether `where T: ~const Tr` needs to be satisfied as
- // `const`. If we were to introduce instantiating trait methods as `const fn`s, we would
- // check that after this, either via a bound `where F: ~const FnOnce` or when coercing to a
- // `const fn` pointer.
- //
- // FIXME(fee1-dead) FIXME(const_trait_impl): update this doc when trait methods can satisfy
- // `~const FnOnce` or can be coerced to `const fn` pointer.
- true
- }
- _ => false,
- };
- let (bounds, _) = self.instantiate_bounds(span, def_id, &substs);
-
- for mut obligation in traits::predicates_for_generics(
- |idx, predicate_span| {
- traits::ObligationCause::new(span, self.body_id, code(idx, predicate_span))
- },
- param_env,
- bounds,
- ) {
- if remap {
- obligation = obligation.without_const(self.tcx);
- }
- 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, true)
- .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
- }
-}
projects / rust.git / blobdiff