5 Within the check phase of type check, we check each item one at a time
6 (bodies of function expressions are checked as part of the containing
7 function). Inference is used to supply types wherever they are unknown.
9 By far the most complex case is checking the body of a function. This
10 can be broken down into several distinct phases:
12 - gather: creates type variables to represent the type of each local
13 variable and pattern binding.
15 - main: the main pass does the lion's share of the work: it
16 determines the types of all expressions, resolves
17 methods, checks for most invalid conditions, and so forth. In
18 some cases, where a type is unknown, it may create a type or region
19 variable and use that as the type of an expression.
21 In the process of checking, various constraints will be placed on
22 these type variables through the subtyping relationships requested
23 through the `demand` module. The `infer` module is in charge
24 of resolving those constraints.
26 - regionck: after main is complete, the regionck pass goes over all
27 types looking for regions and making sure that they did not escape
28 into places they are not in scope. This may also influence the
29 final assignments of the various region variables if there is some
32 - writeback: writes the final types within a function body, replacing
33 type variables with their final inferred types. These final types
34 are written into the `tcx.node_types` table, which should *never* contain
35 any reference to a type variable.
39 While type checking a function, the intermediate types for the
40 expressions, blocks, and so forth contained within the function are
41 stored in `fcx.node_types` and `fcx.node_substs`. These types
42 may contain unresolved type variables. After type checking is
43 complete, the functions in the writeback module are used to take the
44 types from this table, resolve them, and then write them into their
45 permanent home in the type context `tcx`.
47 This means that during inferencing you should use `fcx.write_ty()`
48 and `fcx.expr_ty()` / `fcx.node_ty()` to write/obtain the types of
49 nodes within the function.
51 The types of top-level items, which never contain unbound type
52 variables, are stored directly into the `tcx` typeck_results.
54 N.B., a type variable is not the same thing as a type parameter. A
55 type variable is an instance of a type parameter. That is,
56 given a generic function `fn foo<T>(t: T)`, while checking the
57 function `foo`, the type `ty_param(0)` refers to the type `T`, which
58 is treated in abstract. However, when `foo()` is called, `T` will be
59 substituted for a fresh type variable `N`. This variable will
60 eventually be resolved to some concrete type (which might itself be
81 mod generator_interior;
94 check_abi, check_fn, check_impl_item_well_formed, check_item_well_formed, check_mod_item_types,
95 check_trait_item_well_formed,
97 pub use check::{check_item_type, check_wf_new};
98 pub use diverges::Diverges;
99 pub use expectation::Expectation;
101 pub use inherited::{Inherited, InheritedBuilder};
103 use crate::astconv::AstConv;
104 use crate::check::gather_locals::GatherLocalsVisitor;
105 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
106 use rustc_errors::{pluralize, struct_span_err, Applicability};
107 use rustc_hir as hir;
108 use rustc_hir::def::Res;
109 use rustc_hir::def_id::{DefId, LocalDefId};
110 use rustc_hir::intravisit::Visitor;
111 use rustc_hir::itemlikevisit::ItemLikeVisitor;
112 use rustc_hir::{HirIdMap, ImplicitSelfKind, Node};
113 use rustc_index::bit_set::BitSet;
114 use rustc_index::vec::Idx;
115 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
116 use rustc_middle::ty::query::Providers;
117 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
118 use rustc_middle::ty::{self, Ty, TyCtxt, UserType};
119 use rustc_session::config;
120 use rustc_session::parse::feature_err;
121 use rustc_session::Session;
122 use rustc_span::source_map::DUMMY_SP;
123 use rustc_span::symbol::{kw, Ident};
124 use rustc_span::{self, BytePos, MultiSpan, Span};
125 use rustc_target::abi::VariantIdx;
126 use rustc_target::spec::abi::Abi;
127 use rustc_trait_selection::traits;
128 use rustc_trait_selection::traits::error_reporting::recursive_type_with_infinite_size_error;
129 use rustc_trait_selection::traits::error_reporting::suggestions::ReturnsVisitor;
131 use std::cell::{Ref, RefCell, RefMut};
133 use crate::require_c_abi_if_c_variadic;
134 use crate::util::common::indenter;
136 use self::coercion::DynamicCoerceMany;
137 pub use self::Expectation::*;
140 macro_rules! type_error_struct {
141 ($session:expr, $span:expr, $typ:expr, $code:ident, $($message:tt)*) => ({
142 let mut err = rustc_errors::struct_span_err!($session, $span, $code, $($message)*);
144 if $typ.references_error() {
145 err.downgrade_to_delayed_bug();
152 /// The type of a local binding, including the revealed type for anon types.
153 #[derive(Copy, Clone, Debug)]
154 pub struct LocalTy<'tcx> {
156 revealed_ty: Ty<'tcx>,
159 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
166 fn maybe_mut_place(m: hir::Mutability) -> Self {
168 hir::Mutability::Mut => Needs::MutPlace,
169 hir::Mutability::Not => Needs::None,
174 #[derive(Copy, Clone)]
175 pub struct UnsafetyState {
177 pub unsafety: hir::Unsafety,
182 pub fn function(unsafety: hir::Unsafety, def: hir::HirId) -> UnsafetyState {
183 UnsafetyState { def, unsafety, from_fn: true }
186 pub fn recurse(self, blk: &hir::Block<'_>) -> UnsafetyState {
187 use hir::BlockCheckMode;
188 match self.unsafety {
189 // If this unsafe, then if the outer function was already marked as
190 // unsafe we shouldn't attribute the unsafe'ness to the block. This
191 // way the block can be warned about instead of ignoring this
192 // extraneous block (functions are never warned about).
193 hir::Unsafety::Unsafe if self.from_fn => self,
196 let (unsafety, def) = match blk.rules {
197 BlockCheckMode::UnsafeBlock(..) => (hir::Unsafety::Unsafe, blk.hir_id),
198 BlockCheckMode::DefaultBlock => (unsafety, self.def),
200 UnsafetyState { def, unsafety, from_fn: false }
206 #[derive(Debug, Copy, Clone)]
212 pub struct BreakableCtxt<'tcx> {
215 // this is `null` for loops where break with a value is illegal,
216 // such as `while`, `for`, and `while let`
217 coerce: Option<DynamicCoerceMany<'tcx>>,
220 pub struct EnclosingBreakables<'tcx> {
221 stack: Vec<BreakableCtxt<'tcx>>,
222 by_id: HirIdMap<usize>,
225 impl<'tcx> EnclosingBreakables<'tcx> {
226 fn find_breakable(&mut self, target_id: hir::HirId) -> &mut BreakableCtxt<'tcx> {
227 self.opt_find_breakable(target_id).unwrap_or_else(|| {
228 bug!("could not find enclosing breakable with id {}", target_id);
232 fn opt_find_breakable(&mut self, target_id: hir::HirId) -> Option<&mut BreakableCtxt<'tcx>> {
233 match self.by_id.get(&target_id) {
234 Some(ix) => Some(&mut self.stack[*ix]),
240 pub fn provide(providers: &mut Providers) {
241 method::provide(providers);
242 *providers = Providers {
246 diagnostic_only_typeck,
250 check_item_well_formed,
251 check_trait_item_well_formed,
252 check_impl_item_well_formed,
253 check_mod_item_types,
258 fn adt_destructor(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::Destructor> {
259 tcx.calculate_dtor(def_id, dropck::check_drop_impl)
262 /// If this `DefId` is a "primary tables entry", returns
263 /// `Some((body_id, body_ty, fn_sig))`. Otherwise, returns `None`.
265 /// If this function returns `Some`, then `typeck_results(def_id)` will
266 /// succeed; if it returns `None`, then `typeck_results(def_id)` may or
267 /// may not succeed. In some cases where this function returns `None`
268 /// (notably closures), `typeck_results(def_id)` would wind up
269 /// redirecting to the owning function.
273 ) -> Option<(hir::BodyId, Option<&hir::Ty<'_>>, Option<&hir::FnSig<'_>>)> {
274 match tcx.hir().get(id) {
275 Node::Item(item) => match item.kind {
276 hir::ItemKind::Const(ty, body) | hir::ItemKind::Static(ty, _, body) => {
277 Some((body, Some(ty), None))
279 hir::ItemKind::Fn(ref sig, .., body) => Some((body, None, Some(sig))),
282 Node::TraitItem(item) => match item.kind {
283 hir::TraitItemKind::Const(ty, Some(body)) => Some((body, Some(ty), None)),
284 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
285 Some((body, None, Some(sig)))
289 Node::ImplItem(item) => match item.kind {
290 hir::ImplItemKind::Const(ty, body) => Some((body, Some(ty), None)),
291 hir::ImplItemKind::Fn(ref sig, body) => Some((body, None, Some(sig))),
294 Node::AnonConst(constant) => Some((constant.body, None, None)),
299 fn has_typeck_results(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
300 // Closures' typeck results come from their outermost function,
301 // as they are part of the same "inference environment".
302 let typeck_root_def_id = tcx.typeck_root_def_id(def_id);
303 if typeck_root_def_id != def_id {
304 return tcx.has_typeck_results(typeck_root_def_id);
307 if let Some(def_id) = def_id.as_local() {
308 let id = tcx.hir().local_def_id_to_hir_id(def_id);
309 primary_body_of(tcx, id).is_some()
315 fn used_trait_imports(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &FxHashSet<LocalDefId> {
316 &*tcx.typeck(def_id).used_trait_imports
319 fn typeck_const_arg<'tcx>(
321 (did, param_did): (LocalDefId, DefId),
322 ) -> &ty::TypeckResults<'tcx> {
323 let fallback = move || tcx.type_of(param_did);
324 typeck_with_fallback(tcx, did, fallback)
327 fn typeck<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &ty::TypeckResults<'tcx> {
328 if let Some(param_did) = tcx.opt_const_param_of(def_id) {
329 tcx.typeck_const_arg((def_id, param_did))
331 let fallback = move || tcx.type_of(def_id.to_def_id());
332 typeck_with_fallback(tcx, def_id, fallback)
336 /// Used only to get `TypeckResults` for type inference during error recovery.
337 /// Currently only used for type inference of `static`s and `const`s to avoid type cycle errors.
338 fn diagnostic_only_typeck<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &ty::TypeckResults<'tcx> {
339 let fallback = move || {
340 let span = tcx.hir().span(tcx.hir().local_def_id_to_hir_id(def_id));
341 tcx.ty_error_with_message(span, "diagnostic only typeck table used")
343 typeck_with_fallback(tcx, def_id, fallback)
346 fn typeck_with_fallback<'tcx>(
349 fallback: impl Fn() -> Ty<'tcx> + 'tcx,
350 ) -> &'tcx ty::TypeckResults<'tcx> {
351 // Closures' typeck results come from their outermost function,
352 // as they are part of the same "inference environment".
353 let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id()).expect_local();
354 if typeck_root_def_id != def_id {
355 return tcx.typeck(typeck_root_def_id);
358 let id = tcx.hir().local_def_id_to_hir_id(def_id);
359 let span = tcx.hir().span(id);
361 // Figure out what primary body this item has.
362 let (body_id, body_ty, fn_sig) = primary_body_of(tcx, id).unwrap_or_else(|| {
363 span_bug!(span, "can't type-check body of {:?}", def_id);
365 let body = tcx.hir().body(body_id);
367 let typeck_results = Inherited::build(tcx, def_id).enter(|inh| {
368 let param_env = tcx.param_env(def_id);
369 let (fcx, wf_tys) = if let Some(hir::FnSig { header, decl, .. }) = fn_sig {
370 let fn_sig = if crate::collect::get_infer_ret_ty(&decl.output).is_some() {
371 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
372 <dyn AstConv<'_>>::ty_of_fn(
378 &hir::Generics::empty(),
386 check_abi(tcx, id, span, fn_sig.abi());
388 // When normalizing the function signature, we assume all types are
389 // well-formed. So, we don't need to worry about the obligations
390 // from normalization. We could just discard these, but to align with
391 // compare_method and elsewhere, we just add implied bounds for
393 let mut wf_tys = FxHashSet::default();
394 // Compute the fty from point of view of inside the fn.
395 let fn_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), fn_sig);
396 let fn_sig = inh.normalize_associated_types_in(
402 wf_tys.extend(fn_sig.inputs_and_output.iter());
404 let fcx = check_fn(&inh, param_env, fn_sig, decl, id, body, None, true).0;
407 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
408 let expected_type = body_ty
409 .and_then(|ty| match ty.kind {
410 hir::TyKind::Infer => Some(<dyn AstConv<'_>>::ast_ty_to_ty(&fcx, ty)),
413 .unwrap_or_else(|| match tcx.hir().get(id) {
414 Node::AnonConst(_) => match tcx.hir().get(tcx.hir().get_parent_node(id)) {
415 Node::Expr(&hir::Expr {
416 kind: hir::ExprKind::ConstBlock(ref anon_const),
418 }) if anon_const.hir_id == id => fcx.next_ty_var(TypeVariableOrigin {
419 kind: TypeVariableOriginKind::TypeInference,
423 kind: hir::TyKind::Typeof(ref anon_const), ..
424 }) if anon_const.hir_id == id => fcx.next_ty_var(TypeVariableOrigin {
425 kind: TypeVariableOriginKind::TypeInference,
428 Node::Expr(&hir::Expr { kind: hir::ExprKind::InlineAsm(asm), .. })
429 | Node::Item(&hir::Item { kind: hir::ItemKind::GlobalAsm(asm), .. })
430 if asm.operands.iter().any(|(op, _op_sp)| match op {
431 hir::InlineAsmOperand::Const { anon_const } => {
432 anon_const.hir_id == id
437 // Inline assembly constants must be integers.
445 let expected_type = fcx.normalize_associated_types_in(body.value.span, expected_type);
446 fcx.require_type_is_sized(expected_type, body.value.span, traits::ConstSized);
448 // Gather locals in statics (because of block expressions).
449 GatherLocalsVisitor::new(&fcx).visit_body(body);
451 fcx.check_expr_coercable_to_type(&body.value, expected_type, None);
453 fcx.write_ty(id, expected_type);
455 (fcx, FxHashSet::default())
458 let fallback_has_occurred = fcx.type_inference_fallback();
460 // Even though coercion casts provide type hints, we check casts after fallback for
461 // backwards compatibility. This makes fallback a stronger type hint than a cast coercion.
463 fcx.select_obligations_where_possible(fallback_has_occurred, |_| {});
465 // Closure and generator analysis may run after fallback
466 // because they don't constrain other type variables.
467 fcx.closure_analyze(body);
468 assert!(fcx.deferred_call_resolutions.borrow().is_empty());
469 fcx.resolve_generator_interiors(def_id.to_def_id());
471 for (ty, span, code) in fcx.deferred_sized_obligations.borrow_mut().drain(..) {
472 let ty = fcx.normalize_ty(span, ty);
473 fcx.require_type_is_sized(ty, span, code);
476 fcx.select_all_obligations_or_error();
478 if fn_sig.is_some() {
479 fcx.regionck_fn(id, body, span, wf_tys);
481 fcx.regionck_expr(body);
484 fcx.resolve_type_vars_in_body(body)
487 // Consistency check our TypeckResults instance can hold all ItemLocalIds
488 // it will need to hold.
489 assert_eq!(typeck_results.hir_owner, id.owner);
494 /// When `check_fn` is invoked on a generator (i.e., a body that
495 /// includes yield), it returns back some information about the yield
497 struct GeneratorTypes<'tcx> {
498 /// Type of generator argument / values returned by `yield`.
501 /// Type of value that is yielded.
504 /// Types that are captured (see `GeneratorInterior` for more).
507 /// Indicates if the generator is movable or static (immovable).
508 movability: hir::Movability,
511 /// Given a `DefId` for an opaque type in return position, find its parent item's return
513 fn get_owner_return_paths<'tcx>(
516 ) -> Option<(LocalDefId, ReturnsVisitor<'tcx>)> {
517 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
518 let parent_id = tcx.hir().get_parent_item(hir_id);
519 tcx.hir().find_by_def_id(parent_id).and_then(|node| node.body_id()).map(|body_id| {
520 let body = tcx.hir().body(body_id);
521 let mut visitor = ReturnsVisitor::default();
522 visitor.visit_body(body);
527 // Forbid defining intrinsics in Rust code,
528 // as they must always be defined by the compiler.
529 fn fn_maybe_err(tcx: TyCtxt<'_>, sp: Span, abi: Abi) {
530 if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
531 tcx.sess.span_err(sp, "intrinsic must be in `extern \"rust-intrinsic\" { ... }` block");
535 fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId, span: Span) {
536 // Only restricted on wasm target for now
537 if !tcx.sess.target.is_like_wasm {
541 // If `#[link_section]` is missing, then nothing to verify
542 let attrs = tcx.codegen_fn_attrs(id);
543 if attrs.link_section.is_none() {
547 // For the wasm32 target statics with `#[link_section]` are placed into custom
548 // sections of the final output file, but this isn't link custom sections of
549 // other executable formats. Namely we can only embed a list of bytes,
550 // nothing with pointers to anything else or relocations. If any relocation
551 // show up, reject them here.
552 // `#[link_section]` may contain arbitrary, or even undefined bytes, but it is
553 // the consumer's responsibility to ensure all bytes that have been read
554 // have defined values.
555 if let Ok(alloc) = tcx.eval_static_initializer(id.to_def_id()) {
556 if alloc.inner().relocations().len() != 0 {
557 let msg = "statics with a custom `#[link_section]` must be a \
558 simple list of bytes on the wasm target with no \
559 extra levels of indirection such as references";
560 tcx.sess.span_err(span, msg);
565 fn report_forbidden_specialization(
567 impl_item: &hir::ImplItemRef,
570 let mut err = struct_span_err!(
574 "`{}` specializes an item from a parent `impl`, but \
575 that item is not marked `default`",
578 err.span_label(impl_item.span, format!("cannot specialize default item `{}`", impl_item.ident));
580 match tcx.span_of_impl(parent_impl) {
582 err.span_label(span, "parent `impl` is here");
584 "to specialize, `{}` in the parent `impl` must be marked `default`",
589 err.note(&format!("parent implementation is in crate `{}`", cname));
596 fn missing_items_err(
599 missing_items: &[&ty::AssocItem],
600 full_impl_span: Span,
602 let missing_items_msg = missing_items
604 .map(|trait_item| trait_item.name.to_string())
608 let mut err = struct_span_err!(
612 "not all trait items implemented, missing: `{}`",
615 err.span_label(impl_span, format!("missing `{}` in implementation", missing_items_msg));
617 // `Span` before impl block closing brace.
618 let hi = full_impl_span.hi() - BytePos(1);
619 // Point at the place right before the closing brace of the relevant `impl` to suggest
620 // adding the associated item at the end of its body.
621 let sugg_sp = full_impl_span.with_lo(hi).with_hi(hi);
622 // Obtain the level of indentation ending in `sugg_sp`.
623 let indentation = tcx.sess.source_map().span_to_margin(sugg_sp).unwrap_or(0);
624 // Make the whitespace that will make the suggestion have the right indentation.
625 let padding: String = " ".repeat(indentation);
627 for trait_item in missing_items {
628 let snippet = suggestion_signature(trait_item, tcx);
629 let code = format!("{}{}\n{}", padding, snippet, padding);
630 let msg = format!("implement the missing item: `{}`", snippet);
631 let appl = Applicability::HasPlaceholders;
632 if let Some(span) = tcx.hir().span_if_local(trait_item.def_id) {
633 err.span_label(span, format!("`{}` from trait", trait_item.name));
634 err.tool_only_span_suggestion(sugg_sp, &msg, code, appl);
636 err.span_suggestion_hidden(sugg_sp, &msg, code, appl);
642 fn missing_items_must_implement_one_of_err(
645 missing_items: &[Ident],
646 annotation_span: Option<Span>,
648 let missing_items_msg =
649 missing_items.iter().map(Ident::to_string).collect::<Vec<_>>().join("`, `");
651 let mut err = struct_span_err!(
655 "not all trait items implemented, missing one of: `{}`",
658 err.span_label(impl_span, format!("missing one of `{}` in implementation", missing_items_msg));
660 if let Some(annotation_span) = annotation_span {
661 err.span_note(annotation_span, "required because of this annotation");
667 /// Resugar `ty::GenericPredicates` in a way suitable to be used in structured suggestions.
668 fn bounds_from_generic_predicates<'tcx>(
670 predicates: ty::GenericPredicates<'tcx>,
671 ) -> (String, String) {
672 let mut types: FxHashMap<Ty<'tcx>, Vec<DefId>> = FxHashMap::default();
673 let mut projections = vec![];
674 for (predicate, _) in predicates.predicates {
675 debug!("predicate {:?}", predicate);
676 let bound_predicate = predicate.kind();
677 match bound_predicate.skip_binder() {
678 ty::PredicateKind::Trait(trait_predicate) => {
679 let entry = types.entry(trait_predicate.self_ty()).or_default();
680 let def_id = trait_predicate.def_id();
681 if Some(def_id) != tcx.lang_items().sized_trait() {
682 // Type params are `Sized` by default, do not add that restriction to the list
683 // if it is a positive requirement.
684 entry.push(trait_predicate.def_id());
687 ty::PredicateKind::Projection(projection_pred) => {
688 projections.push(bound_predicate.rebind(projection_pred));
693 let generics = if types.is_empty() {
700 .filter_map(|t| match t.kind() {
701 ty::Param(_) => Some(t.to_string()),
702 // Avoid suggesting the following:
703 // fn foo<T, <T as Trait>::Bar>(_: T) where T: Trait, <T as Trait>::Bar: Other {}
710 let mut where_clauses = vec![];
711 for (ty, bounds) in types {
713 .extend(bounds.into_iter().map(|bound| format!("{}: {}", ty, tcx.def_path_str(bound))));
715 for projection in &projections {
716 let p = projection.skip_binder();
717 // FIXME: this is not currently supported syntax, we should be looking at the `types` and
718 // insert the associated types where they correspond, but for now let's be "lazy" and
719 // propose this instead of the following valid resugaring:
720 // `T: Trait, Trait::Assoc = K` → `T: Trait<Assoc = K>`
721 where_clauses.push(format!(
723 tcx.def_path_str(p.projection_ty.item_def_id),
727 let where_clauses = if where_clauses.is_empty() {
730 format!(" where {}", where_clauses.join(", "))
732 (generics, where_clauses)
735 /// Return placeholder code for the given function.
736 fn fn_sig_suggestion<'tcx>(
738 sig: ty::FnSig<'tcx>,
740 predicates: ty::GenericPredicates<'tcx>,
741 assoc: &ty::AssocItem,
748 Some(match ty.kind() {
749 ty::Param(_) if assoc.fn_has_self_parameter && i == 0 => "self".to_string(),
750 ty::Ref(reg, ref_ty, mutability) if i == 0 => {
751 let reg = match &format!("{}", reg)[..] {
752 "'_" | "" => String::new(),
753 reg => format!("{} ", reg),
755 if assoc.fn_has_self_parameter {
756 match ref_ty.kind() {
757 ty::Param(param) if param.name == kw::SelfUpper => {
758 format!("&{}{}self", reg, mutability.prefix_str())
761 _ => format!("self: {}", ty),
768 if assoc.fn_has_self_parameter && i == 0 {
769 format!("self: {}", ty)
776 .chain(std::iter::once(if sig.c_variadic { Some("...".to_string()) } else { None }))
778 .collect::<Vec<String>>()
780 let output = sig.output();
781 let output = if !output.is_unit() { format!(" -> {}", output) } else { String::new() };
783 let unsafety = sig.unsafety.prefix_str();
784 let (generics, where_clauses) = bounds_from_generic_predicates(tcx, predicates);
786 // FIXME: this is not entirely correct, as the lifetimes from borrowed params will
787 // not be present in the `fn` definition, not will we account for renamed
788 // lifetimes between the `impl` and the `trait`, but this should be good enough to
789 // fill in a significant portion of the missing code, and other subsequent
790 // suggestions can help the user fix the code.
792 "{}fn {}{}({}){}{} {{ todo!() }}",
793 unsafety, ident, generics, args, output, where_clauses
797 /// Return placeholder code for the given associated item.
798 /// Similar to `ty::AssocItem::suggestion`, but appropriate for use as the code snippet of a
799 /// structured suggestion.
800 fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String {
802 ty::AssocKind::Fn => {
803 // We skip the binder here because the binder would deanonymize all
804 // late-bound regions, and we don't want method signatures to show up
805 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
806 // regions just fine, showing `fn(&MyType)`.
809 tcx.fn_sig(assoc.def_id).skip_binder(),
811 tcx.predicates_of(assoc.def_id),
815 ty::AssocKind::Type => format!("type {} = Type;", assoc.name),
816 ty::AssocKind::Const => {
817 let ty = tcx.type_of(assoc.def_id);
818 let val = expr::ty_kind_suggestion(ty).unwrap_or("value");
819 format!("const {}: {} = {};", assoc.name, ty, val)
824 /// Emit an error when encountering two or more variants in a transparent enum.
825 fn bad_variant_count<'tcx>(tcx: TyCtxt<'tcx>, adt: &'tcx ty::AdtDef, sp: Span, did: DefId) {
826 let variant_spans: Vec<_> = adt
829 .map(|variant| tcx.hir().span_if_local(variant.def_id).unwrap())
831 let msg = format!("needs exactly one variant, but has {}", adt.variants.len(),);
832 let mut err = struct_span_err!(tcx.sess, sp, E0731, "transparent enum {}", msg);
833 err.span_label(sp, &msg);
834 if let [start @ .., end] = &*variant_spans {
835 for variant_span in start {
836 err.span_label(*variant_span, "");
838 err.span_label(*end, &format!("too many variants in `{}`", tcx.def_path_str(did)));
843 /// Emit an error when encountering two or more non-zero-sized fields in a transparent
845 fn bad_non_zero_sized_fields<'tcx>(
847 adt: &'tcx ty::AdtDef,
849 field_spans: impl Iterator<Item = Span>,
852 let msg = format!("needs at most one non-zero-sized field, but has {}", field_count);
853 let mut err = struct_span_err!(
857 "{}transparent {} {}",
858 if adt.is_enum() { "the variant of a " } else { "" },
862 err.span_label(sp, &msg);
863 for sp in field_spans {
864 err.span_label(sp, "this field is non-zero-sized");
869 fn report_unexpected_variant_res(tcx: TyCtxt<'_>, res: Res, span: Span) {
874 "expected unit struct, unit variant or constant, found {}{}",
878 .span_to_snippet(span)
879 .map_or_else(|_| String::new(), |s| format!(" `{}`", s)),
884 /// Controls whether the arguments are tupled. This is used for the call
887 /// Tupling means that all call-side arguments are packed into a tuple and
888 /// passed as a single parameter. For example, if tupling is enabled, this
891 /// fn f(x: (isize, isize))
893 /// Can be called as:
900 #[derive(Clone, Eq, PartialEq)]
901 enum TupleArgumentsFlag {
906 /// A wrapper for `InferCtxt`'s `in_progress_typeck_results` field.
907 #[derive(Copy, Clone)]
908 struct MaybeInProgressTables<'a, 'tcx> {
909 maybe_typeck_results: Option<&'a RefCell<ty::TypeckResults<'tcx>>>,
912 impl<'a, 'tcx> MaybeInProgressTables<'a, 'tcx> {
913 fn borrow(self) -> Ref<'a, ty::TypeckResults<'tcx>> {
914 match self.maybe_typeck_results {
915 Some(typeck_results) => typeck_results.borrow(),
917 "MaybeInProgressTables: inh/fcx.typeck_results.borrow() with no typeck results"
922 fn borrow_mut(self) -> RefMut<'a, ty::TypeckResults<'tcx>> {
923 match self.maybe_typeck_results {
924 Some(typeck_results) => typeck_results.borrow_mut(),
926 "MaybeInProgressTables: inh/fcx.typeck_results.borrow_mut() with no typeck results"
932 struct CheckItemTypesVisitor<'tcx> {
936 impl<'tcx> ItemLikeVisitor<'tcx> for CheckItemTypesVisitor<'tcx> {
937 fn visit_item(&mut self, i: &'tcx hir::Item<'tcx>) {
938 check_item_type(self.tcx, i);
940 fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem<'tcx>) {}
941 fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem<'tcx>) {}
942 fn visit_foreign_item(&mut self, _: &'tcx hir::ForeignItem<'tcx>) {}
945 fn typeck_item_bodies(tcx: TyCtxt<'_>, (): ()) {
946 tcx.hir().par_body_owners(|body_owner_def_id| tcx.ensure().typeck(body_owner_def_id));
949 fn fatally_break_rust(sess: &Session) {
950 let handler = sess.diagnostic();
951 handler.span_bug_no_panic(
953 "It looks like you're trying to break rust; would you like some ICE?",
955 handler.note_without_error("the compiler expectedly panicked. this is a feature.");
956 handler.note_without_error(
957 "we would appreciate a joke overview: \
958 https://github.com/rust-lang/rust/issues/43162#issuecomment-320764675",
960 handler.note_without_error(&format!(
961 "rustc {} running on {}",
962 option_env!("CFG_VERSION").unwrap_or("unknown_version"),
963 config::host_triple(),
967 fn potentially_plural_count(count: usize, word: &str) -> String {
968 format!("{} {}{}", count, word, pluralize!(count))
971 fn has_expected_num_generic_args<'tcx>(
973 trait_did: Option<DefId>,
976 trait_did.map_or(true, |trait_did| {
977 let generics = tcx.generics_of(trait_did);
978 generics.count() == expected + if generics.has_self { 1 } else { 0 }