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 if $typ.references_error() {
143 $session.diagnostic().struct_dummy()
145 rustc_errors::struct_span_err!($session, $span, $code, $($message)*)
150 /// The type of a local binding, including the revealed type for anon types.
151 #[derive(Copy, Clone, Debug)]
152 pub struct LocalTy<'tcx> {
154 revealed_ty: Ty<'tcx>,
157 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
164 fn maybe_mut_place(m: hir::Mutability) -> Self {
166 hir::Mutability::Mut => Needs::MutPlace,
167 hir::Mutability::Not => Needs::None,
172 #[derive(Copy, Clone)]
173 pub struct UnsafetyState {
175 pub unsafety: hir::Unsafety,
180 pub fn function(unsafety: hir::Unsafety, def: hir::HirId) -> UnsafetyState {
181 UnsafetyState { def, unsafety, from_fn: true }
184 pub fn recurse(self, blk: &hir::Block<'_>) -> UnsafetyState {
185 use hir::BlockCheckMode;
186 match self.unsafety {
187 // If this unsafe, then if the outer function was already marked as
188 // unsafe we shouldn't attribute the unsafe'ness to the block. This
189 // way the block can be warned about instead of ignoring this
190 // extraneous block (functions are never warned about).
191 hir::Unsafety::Unsafe if self.from_fn => self,
194 let (unsafety, def) = match blk.rules {
195 BlockCheckMode::UnsafeBlock(..) => (hir::Unsafety::Unsafe, blk.hir_id),
196 BlockCheckMode::DefaultBlock => (unsafety, self.def),
198 UnsafetyState { def, unsafety, from_fn: false }
204 #[derive(Debug, Copy, Clone)]
210 pub struct BreakableCtxt<'tcx> {
213 // this is `null` for loops where break with a value is illegal,
214 // such as `while`, `for`, and `while let`
215 coerce: Option<DynamicCoerceMany<'tcx>>,
218 pub struct EnclosingBreakables<'tcx> {
219 stack: Vec<BreakableCtxt<'tcx>>,
220 by_id: HirIdMap<usize>,
223 impl<'tcx> EnclosingBreakables<'tcx> {
224 fn find_breakable(&mut self, target_id: hir::HirId) -> &mut BreakableCtxt<'tcx> {
225 self.opt_find_breakable(target_id).unwrap_or_else(|| {
226 bug!("could not find enclosing breakable with id {}", target_id);
230 fn opt_find_breakable(&mut self, target_id: hir::HirId) -> Option<&mut BreakableCtxt<'tcx>> {
231 match self.by_id.get(&target_id) {
232 Some(ix) => Some(&mut self.stack[*ix]),
238 pub fn provide(providers: &mut Providers) {
239 method::provide(providers);
240 *providers = Providers {
244 diagnostic_only_typeck,
248 check_item_well_formed,
249 check_trait_item_well_formed,
250 check_impl_item_well_formed,
251 check_mod_item_types,
256 fn adt_destructor(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::Destructor> {
257 tcx.calculate_dtor(def_id, dropck::check_drop_impl)
260 /// If this `DefId` is a "primary tables entry", returns
261 /// `Some((body_id, body_ty, fn_sig))`. Otherwise, returns `None`.
263 /// If this function returns `Some`, then `typeck_results(def_id)` will
264 /// succeed; if it returns `None`, then `typeck_results(def_id)` may or
265 /// may not succeed. In some cases where this function returns `None`
266 /// (notably closures), `typeck_results(def_id)` would wind up
267 /// redirecting to the owning function.
271 ) -> Option<(hir::BodyId, Option<&hir::Ty<'_>>, Option<&hir::FnSig<'_>>)> {
272 match tcx.hir().get(id) {
273 Node::Item(item) => match item.kind {
274 hir::ItemKind::Const(ref ty, body) | hir::ItemKind::Static(ref ty, _, body) => {
275 Some((body, Some(ty), None))
277 hir::ItemKind::Fn(ref sig, .., body) => Some((body, None, Some(&sig))),
280 Node::TraitItem(item) => match item.kind {
281 hir::TraitItemKind::Const(ref ty, Some(body)) => Some((body, Some(ty), None)),
282 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
283 Some((body, None, Some(&sig)))
287 Node::ImplItem(item) => match item.kind {
288 hir::ImplItemKind::Const(ref ty, body) => Some((body, Some(ty), None)),
289 hir::ImplItemKind::Fn(ref sig, body) => Some((body, None, Some(&sig))),
292 Node::AnonConst(constant) => Some((constant.body, None, None)),
297 fn has_typeck_results(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
298 // Closures' typeck results come from their outermost function,
299 // as they are part of the same "inference environment".
300 let outer_def_id = tcx.closure_base_def_id(def_id);
301 if outer_def_id != def_id {
302 return tcx.has_typeck_results(outer_def_id);
305 if let Some(def_id) = def_id.as_local() {
306 let id = tcx.hir().local_def_id_to_hir_id(def_id);
307 primary_body_of(tcx, id).is_some()
313 fn used_trait_imports(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &FxHashSet<LocalDefId> {
314 &*tcx.typeck(def_id).used_trait_imports
317 fn typeck_const_arg<'tcx>(
319 (did, param_did): (LocalDefId, DefId),
320 ) -> &ty::TypeckResults<'tcx> {
321 let fallback = move || tcx.type_of(param_did);
322 typeck_with_fallback(tcx, did, fallback)
325 fn typeck<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &ty::TypeckResults<'tcx> {
326 if let Some(param_did) = tcx.opt_const_param_of(def_id) {
327 tcx.typeck_const_arg((def_id, param_did))
329 let fallback = move || tcx.type_of(def_id.to_def_id());
330 typeck_with_fallback(tcx, def_id, fallback)
334 /// Used only to get `TypeckResults` for type inference during error recovery.
335 /// Currently only used for type inference of `static`s and `const`s to avoid type cycle errors.
336 fn diagnostic_only_typeck<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &ty::TypeckResults<'tcx> {
337 let fallback = move || {
338 let span = tcx.hir().span(tcx.hir().local_def_id_to_hir_id(def_id));
339 tcx.ty_error_with_message(span, "diagnostic only typeck table used")
341 typeck_with_fallback(tcx, def_id, fallback)
344 fn typeck_with_fallback<'tcx>(
347 fallback: impl Fn() -> Ty<'tcx> + 'tcx,
348 ) -> &'tcx ty::TypeckResults<'tcx> {
349 // Closures' typeck results come from their outermost function,
350 // as they are part of the same "inference environment".
351 let outer_def_id = tcx.closure_base_def_id(def_id.to_def_id()).expect_local();
352 if outer_def_id != def_id {
353 return tcx.typeck(outer_def_id);
356 let id = tcx.hir().local_def_id_to_hir_id(def_id);
357 let span = tcx.hir().span(id);
359 // Figure out what primary body this item has.
360 let (body_id, body_ty, fn_sig) = primary_body_of(tcx, id).unwrap_or_else(|| {
361 span_bug!(span, "can't type-check body of {:?}", def_id);
363 let body = tcx.hir().body(body_id);
365 let typeck_results = Inherited::build(tcx, def_id).enter(|inh| {
366 let param_env = tcx.param_env(def_id);
367 let fcx = if let Some(hir::FnSig { header, decl, .. }) = fn_sig {
368 let fn_sig = if crate::collect::get_infer_ret_ty(&decl.output).is_some() {
369 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
370 <dyn AstConv<'_>>::ty_of_fn(
376 &hir::Generics::empty(),
384 check_abi(tcx, id, span, fn_sig.abi());
386 // Compute the fty from point of view of inside the fn.
387 let fn_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), fn_sig);
388 let fn_sig = inh.normalize_associated_types_in(
395 let fcx = check_fn(&inh, param_env, fn_sig, decl, id, body, None).0;
398 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
399 let expected_type = body_ty
400 .and_then(|ty| match ty.kind {
401 hir::TyKind::Infer => Some(<dyn AstConv<'_>>::ast_ty_to_ty(&fcx, ty)),
404 .unwrap_or_else(|| match tcx.hir().get(id) {
405 Node::AnonConst(_) => match tcx.hir().get(tcx.hir().get_parent_node(id)) {
406 Node::Expr(&hir::Expr {
407 kind: hir::ExprKind::ConstBlock(ref anon_const),
409 }) if anon_const.hir_id == id => fcx.next_ty_var(TypeVariableOrigin {
410 kind: TypeVariableOriginKind::TypeInference,
414 kind: hir::TyKind::Typeof(ref anon_const), ..
415 }) if anon_const.hir_id == id => fcx.next_ty_var(TypeVariableOrigin {
416 kind: TypeVariableOriginKind::TypeInference,
419 Node::Expr(&hir::Expr { kind: hir::ExprKind::InlineAsm(asm), .. })
420 | Node::Item(&hir::Item { kind: hir::ItemKind::GlobalAsm(asm), .. })
421 if asm.operands.iter().any(|(op, _op_sp)| match op {
422 hir::InlineAsmOperand::Const { anon_const } => {
423 anon_const.hir_id == id
428 // Inline assembly constants must be integers.
436 let expected_type = fcx.normalize_associated_types_in(body.value.span, expected_type);
437 fcx.require_type_is_sized(expected_type, body.value.span, traits::ConstSized);
439 // Gather locals in statics (because of block expressions).
440 GatherLocalsVisitor::new(&fcx).visit_body(body);
442 fcx.check_expr_coercable_to_type(&body.value, expected_type, None);
444 fcx.write_ty(id, expected_type);
449 fcx.type_inference_fallback();
451 // Even though coercion casts provide type hints, we check casts after fallback for
452 // backwards compatibility. This makes fallback a stronger type hint than a cast coercion.
455 // Closure and generator analysis may run after fallback
456 // because they don't constrain other type variables.
457 fcx.closure_analyze(body);
458 assert!(fcx.deferred_call_resolutions.borrow().is_empty());
459 fcx.resolve_generator_interiors(def_id.to_def_id());
461 for (ty, span, code) in fcx.deferred_sized_obligations.borrow_mut().drain(..) {
462 let ty = fcx.normalize_ty(span, ty);
463 fcx.require_type_is_sized(ty, span, code);
466 fcx.select_all_obligations_or_error();
468 if fn_sig.is_some() {
469 fcx.regionck_fn(id, body);
471 fcx.regionck_expr(body);
474 fcx.resolve_type_vars_in_body(body)
477 // Consistency check our TypeckResults instance can hold all ItemLocalIds
478 // it will need to hold.
479 assert_eq!(typeck_results.hir_owner, id.owner);
484 /// When `check_fn` is invoked on a generator (i.e., a body that
485 /// includes yield), it returns back some information about the yield
487 struct GeneratorTypes<'tcx> {
488 /// Type of generator argument / values returned by `yield`.
491 /// Type of value that is yielded.
494 /// Types that are captured (see `GeneratorInterior` for more).
497 /// Indicates if the generator is movable or static (immovable).
498 movability: hir::Movability,
501 /// Given a `DefId` for an opaque type in return position, find its parent item's return
503 fn get_owner_return_paths(
506 ) -> Option<(hir::HirId, ReturnsVisitor<'tcx>)> {
507 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
508 let id = tcx.hir().get_parent_item(hir_id);
512 .and_then(|(hir_id, node)| node.body_id().map(|b| (hir_id, b)))
513 .map(|(hir_id, body_id)| {
514 let body = tcx.hir().body(body_id);
515 let mut visitor = ReturnsVisitor::default();
516 visitor.visit_body(body);
521 // Forbid defining intrinsics in Rust code,
522 // as they must always be defined by the compiler.
523 fn fn_maybe_err(tcx: TyCtxt<'_>, sp: Span, abi: Abi) {
524 if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
525 tcx.sess.span_err(sp, "intrinsic must be in `extern \"rust-intrinsic\" { ... }` block");
529 fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId, span: Span) {
530 // Only restricted on wasm32 target for now
531 if !tcx.sess.opts.target_triple.triple().starts_with("wasm32") {
535 // If `#[link_section]` is missing, then nothing to verify
536 let attrs = tcx.codegen_fn_attrs(id);
537 if attrs.link_section.is_none() {
541 // For the wasm32 target statics with `#[link_section]` are placed into custom
542 // sections of the final output file, but this isn't link custom sections of
543 // other executable formats. Namely we can only embed a list of bytes,
544 // nothing with pointers to anything else or relocations. If any relocation
545 // show up, reject them here.
546 // `#[link_section]` may contain arbitrary, or even undefined bytes, but it is
547 // the consumer's responsibility to ensure all bytes that have been read
548 // have defined values.
549 match tcx.eval_static_initializer(id.to_def_id()) {
551 if alloc.relocations().len() != 0 {
552 let msg = "statics with a custom `#[link_section]` must be a \
553 simple list of bytes on the wasm target with no \
554 extra levels of indirection such as references";
555 tcx.sess.span_err(span, msg);
562 fn report_forbidden_specialization(
564 impl_item: &hir::ImplItem<'_>,
567 let mut err = struct_span_err!(
571 "`{}` specializes an item from a parent `impl`, but \
572 that item is not marked `default`",
575 err.span_label(impl_item.span, format!("cannot specialize default item `{}`", impl_item.ident));
577 match tcx.span_of_impl(parent_impl) {
579 err.span_label(span, "parent `impl` is here");
581 "to specialize, `{}` in the parent `impl` must be marked `default`",
586 err.note(&format!("parent implementation is in crate `{}`", cname));
593 fn missing_items_err(
596 missing_items: &[ty::AssocItem],
597 full_impl_span: Span,
599 let missing_items_msg = missing_items
601 .map(|trait_item| trait_item.ident.to_string())
605 let mut err = struct_span_err!(
609 "not all trait items implemented, missing: `{}`",
612 err.span_label(impl_span, format!("missing `{}` in implementation", missing_items_msg));
614 // `Span` before impl block closing brace.
615 let hi = full_impl_span.hi() - BytePos(1);
616 // Point at the place right before the closing brace of the relevant `impl` to suggest
617 // adding the associated item at the end of its body.
618 let sugg_sp = full_impl_span.with_lo(hi).with_hi(hi);
619 // Obtain the level of indentation ending in `sugg_sp`.
620 let indentation = tcx.sess.source_map().span_to_margin(sugg_sp).unwrap_or(0);
621 // Make the whitespace that will make the suggestion have the right indentation.
622 let padding: String = " ".repeat(indentation);
624 for trait_item in missing_items {
625 let snippet = suggestion_signature(&trait_item, tcx);
626 let code = format!("{}{}\n{}", padding, snippet, padding);
627 let msg = format!("implement the missing item: `{}`", snippet);
628 let appl = Applicability::HasPlaceholders;
629 if let Some(span) = tcx.hir().span_if_local(trait_item.def_id) {
630 err.span_label(span, format!("`{}` from trait", trait_item.ident));
631 err.tool_only_span_suggestion(sugg_sp, &msg, code, appl);
633 err.span_suggestion_hidden(sugg_sp, &msg, code, appl);
639 /// Resugar `ty::GenericPredicates` in a way suitable to be used in structured suggestions.
640 fn bounds_from_generic_predicates<'tcx>(
642 predicates: ty::GenericPredicates<'tcx>,
643 ) -> (String, String) {
644 let mut types: FxHashMap<Ty<'tcx>, Vec<DefId>> = FxHashMap::default();
645 let mut projections = vec![];
646 for (predicate, _) in predicates.predicates {
647 debug!("predicate {:?}", predicate);
648 let bound_predicate = predicate.kind();
649 match bound_predicate.skip_binder() {
650 ty::PredicateKind::Trait(trait_predicate) => {
651 let entry = types.entry(trait_predicate.self_ty()).or_default();
652 let def_id = trait_predicate.def_id();
653 if Some(def_id) != tcx.lang_items().sized_trait() {
654 // Type params are `Sized` by default, do not add that restriction to the list
655 // if it is a positive requirement.
656 entry.push(trait_predicate.def_id());
659 ty::PredicateKind::Projection(projection_pred) => {
660 projections.push(bound_predicate.rebind(projection_pred));
665 let generics = if types.is_empty() {
672 .filter_map(|t| match t.kind() {
673 ty::Param(_) => Some(t.to_string()),
674 // Avoid suggesting the following:
675 // fn foo<T, <T as Trait>::Bar>(_: T) where T: Trait, <T as Trait>::Bar: Other {}
682 let mut where_clauses = vec![];
683 for (ty, bounds) in types {
684 for bound in &bounds {
685 where_clauses.push(format!("{}: {}", ty, tcx.def_path_str(*bound)));
688 for projection in &projections {
689 let p = projection.skip_binder();
690 // FIXME: this is not currently supported syntax, we should be looking at the `types` and
691 // insert the associated types where they correspond, but for now let's be "lazy" and
692 // propose this instead of the following valid resugaring:
693 // `T: Trait, Trait::Assoc = K` → `T: Trait<Assoc = K>`
694 where_clauses.push(format!("{} = {}", tcx.def_path_str(p.projection_ty.item_def_id), p.ty));
696 let where_clauses = if where_clauses.is_empty() {
699 format!(" where {}", where_clauses.join(", "))
701 (generics, where_clauses)
704 /// Return placeholder code for the given function.
705 fn fn_sig_suggestion<'tcx>(
707 sig: ty::FnSig<'tcx>,
709 predicates: ty::GenericPredicates<'tcx>,
710 assoc: &ty::AssocItem,
717 Some(match ty.kind() {
718 ty::Param(_) if assoc.fn_has_self_parameter && i == 0 => "self".to_string(),
719 ty::Ref(reg, ref_ty, mutability) if i == 0 => {
720 let reg = match &format!("{}", reg)[..] {
721 "'_" | "" => String::new(),
722 reg => format!("{} ", reg),
724 if assoc.fn_has_self_parameter {
725 match ref_ty.kind() {
726 ty::Param(param) if param.name == kw::SelfUpper => {
727 format!("&{}{}self", reg, mutability.prefix_str())
730 _ => format!("self: {}", ty),
737 if assoc.fn_has_self_parameter && i == 0 {
738 format!("self: {}", ty)
745 .chain(std::iter::once(if sig.c_variadic { Some("...".to_string()) } else { None }))
747 .collect::<Vec<String>>()
749 let output = sig.output();
750 let output = if !output.is_unit() { format!(" -> {}", output) } else { String::new() };
752 let unsafety = sig.unsafety.prefix_str();
753 let (generics, where_clauses) = bounds_from_generic_predicates(tcx, predicates);
755 // FIXME: this is not entirely correct, as the lifetimes from borrowed params will
756 // not be present in the `fn` definition, not will we account for renamed
757 // lifetimes between the `impl` and the `trait`, but this should be good enough to
758 // fill in a significant portion of the missing code, and other subsequent
759 // suggestions can help the user fix the code.
761 "{}fn {}{}({}){}{} {{ todo!() }}",
762 unsafety, ident, generics, args, output, where_clauses
766 /// Return placeholder code for the given associated item.
767 /// Similar to `ty::AssocItem::suggestion`, but appropriate for use as the code snippet of a
768 /// structured suggestion.
769 fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String {
771 ty::AssocKind::Fn => {
772 // We skip the binder here because the binder would deanonymize all
773 // late-bound regions, and we don't want method signatures to show up
774 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
775 // regions just fine, showing `fn(&MyType)`.
778 tcx.fn_sig(assoc.def_id).skip_binder(),
780 tcx.predicates_of(assoc.def_id),
784 ty::AssocKind::Type => format!("type {} = Type;", assoc.ident),
785 ty::AssocKind::Const => {
786 let ty = tcx.type_of(assoc.def_id);
787 let val = expr::ty_kind_suggestion(ty).unwrap_or("value");
788 format!("const {}: {} = {};", assoc.ident, ty, val)
793 /// Emit an error when encountering two or more variants in a transparent enum.
794 fn bad_variant_count<'tcx>(tcx: TyCtxt<'tcx>, adt: &'tcx ty::AdtDef, sp: Span, did: DefId) {
795 let variant_spans: Vec<_> = adt
798 .map(|variant| tcx.hir().span_if_local(variant.def_id).unwrap())
800 let msg = format!("needs exactly one variant, but has {}", adt.variants.len(),);
801 let mut err = struct_span_err!(tcx.sess, sp, E0731, "transparent enum {}", msg);
802 err.span_label(sp, &msg);
803 if let [start @ .., end] = &*variant_spans {
804 for variant_span in start {
805 err.span_label(*variant_span, "");
807 err.span_label(*end, &format!("too many variants in `{}`", tcx.def_path_str(did)));
812 /// Emit an error when encountering two or more non-zero-sized fields in a transparent
814 fn bad_non_zero_sized_fields<'tcx>(
816 adt: &'tcx ty::AdtDef,
818 field_spans: impl Iterator<Item = Span>,
821 let msg = format!("needs at most one non-zero-sized field, but has {}", field_count);
822 let mut err = struct_span_err!(
826 "{}transparent {} {}",
827 if adt.is_enum() { "the variant of a " } else { "" },
831 err.span_label(sp, &msg);
832 for sp in field_spans {
833 err.span_label(sp, "this field is non-zero-sized");
838 fn report_unexpected_variant_res(tcx: TyCtxt<'_>, res: Res, span: Span) {
843 "expected unit struct, unit variant or constant, found {}{}",
847 .span_to_snippet(span)
848 .map_or_else(|_| String::new(), |s| format!(" `{}`", s)),
853 /// Controls whether the arguments are tupled. This is used for the call
856 /// Tupling means that all call-side arguments are packed into a tuple and
857 /// passed as a single parameter. For example, if tupling is enabled, this
860 /// fn f(x: (isize, isize))
862 /// Can be called as:
869 #[derive(Clone, Eq, PartialEq)]
870 enum TupleArgumentsFlag {
875 /// A wrapper for `InferCtxt`'s `in_progress_typeck_results` field.
876 #[derive(Copy, Clone)]
877 struct MaybeInProgressTables<'a, 'tcx> {
878 maybe_typeck_results: Option<&'a RefCell<ty::TypeckResults<'tcx>>>,
881 impl<'a, 'tcx> MaybeInProgressTables<'a, 'tcx> {
882 fn borrow(self) -> Ref<'a, ty::TypeckResults<'tcx>> {
883 match self.maybe_typeck_results {
884 Some(typeck_results) => typeck_results.borrow(),
886 "MaybeInProgressTables: inh/fcx.typeck_results.borrow() with no typeck results"
891 fn borrow_mut(self) -> RefMut<'a, ty::TypeckResults<'tcx>> {
892 match self.maybe_typeck_results {
893 Some(typeck_results) => typeck_results.borrow_mut(),
895 "MaybeInProgressTables: inh/fcx.typeck_results.borrow_mut() with no typeck results"
901 struct CheckItemTypesVisitor<'tcx> {
905 impl ItemLikeVisitor<'tcx> for CheckItemTypesVisitor<'tcx> {
906 fn visit_item(&mut self, i: &'tcx hir::Item<'tcx>) {
907 check_item_type(self.tcx, i);
909 fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem<'tcx>) {}
910 fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem<'tcx>) {}
911 fn visit_foreign_item(&mut self, _: &'tcx hir::ForeignItem<'tcx>) {}
914 fn typeck_item_bodies(tcx: TyCtxt<'_>, (): ()) {
915 tcx.par_body_owners(|body_owner_def_id| {
916 tcx.ensure().typeck(body_owner_def_id);
920 fn fatally_break_rust(sess: &Session) {
921 let handler = sess.diagnostic();
922 handler.span_bug_no_panic(
924 "It looks like you're trying to break rust; would you like some ICE?",
926 handler.note_without_error("the compiler expectedly panicked. this is a feature.");
927 handler.note_without_error(
928 "we would appreciate a joke overview: \
929 https://github.com/rust-lang/rust/issues/43162#issuecomment-320764675",
931 handler.note_without_error(&format!(
932 "rustc {} running on {}",
933 option_env!("CFG_VERSION").unwrap_or("unknown_version"),
934 config::host_triple(),
938 fn potentially_plural_count(count: usize, word: &str) -> String {
939 format!("{} {}{}", count, word, pluralize!(count))
942 fn has_expected_num_generic_args<'tcx>(
944 trait_did: Option<DefId>,
947 trait_did.map_or(true, |trait_did| {
948 let generics = tcx.generics_of(trait_did);
949 generics.count() == expected + if generics.has_self { 1 } else { 0 }