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(ty, body) | hir::ItemKind::Static(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(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(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 typeck_root_def_id = tcx.typeck_root_def_id(def_id);
301 if typeck_root_def_id != def_id {
302 return tcx.has_typeck_results(typeck_root_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 typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id()).expect_local();
352 if typeck_root_def_id != def_id {
353 return tcx.typeck(typeck_root_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, wf_tys) = 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 // When normalizing the function signature, we assume all types are
387 // well-formed. So, we don't need to worry about the obligations
388 // from normalization. We could just discard these, but to align with
389 // compare_method and elsewhere, we just add implied bounds for
391 let mut wf_tys = FxHashSet::default();
392 // Compute the fty from point of view of inside the fn.
393 let fn_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), fn_sig);
394 wf_tys.extend(fn_sig.inputs_and_output.iter());
395 let fn_sig = inh.normalize_associated_types_in(
401 wf_tys.extend(fn_sig.inputs_and_output.iter());
403 let fcx = check_fn(&inh, param_env, fn_sig, decl, id, body, None, true).0;
406 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
407 let expected_type = body_ty
408 .and_then(|ty| match ty.kind {
409 hir::TyKind::Infer => Some(<dyn AstConv<'_>>::ast_ty_to_ty(&fcx, ty)),
412 .unwrap_or_else(|| match tcx.hir().get(id) {
413 Node::AnonConst(_) => match tcx.hir().get(tcx.hir().get_parent_node(id)) {
414 Node::Expr(&hir::Expr {
415 kind: hir::ExprKind::ConstBlock(ref anon_const),
417 }) if anon_const.hir_id == id => fcx.next_ty_var(TypeVariableOrigin {
418 kind: TypeVariableOriginKind::TypeInference,
422 kind: hir::TyKind::Typeof(ref anon_const), ..
423 }) if anon_const.hir_id == id => fcx.next_ty_var(TypeVariableOrigin {
424 kind: TypeVariableOriginKind::TypeInference,
427 Node::Expr(&hir::Expr { kind: hir::ExprKind::InlineAsm(asm), .. })
428 | Node::Item(&hir::Item { kind: hir::ItemKind::GlobalAsm(asm), .. })
429 if asm.operands.iter().any(|(op, _op_sp)| match op {
430 hir::InlineAsmOperand::Const { anon_const } => {
431 anon_const.hir_id == id
436 // Inline assembly constants must be integers.
444 let expected_type = fcx.normalize_associated_types_in(body.value.span, expected_type);
445 fcx.require_type_is_sized(expected_type, body.value.span, traits::ConstSized);
447 // Gather locals in statics (because of block expressions).
448 GatherLocalsVisitor::new(&fcx).visit_body(body);
450 fcx.check_expr_coercable_to_type(&body.value, expected_type, None);
452 fcx.write_ty(id, expected_type);
454 (fcx, FxHashSet::default())
457 let fallback_has_occurred = fcx.type_inference_fallback();
459 // Even though coercion casts provide type hints, we check casts after fallback for
460 // backwards compatibility. This makes fallback a stronger type hint than a cast coercion.
462 fcx.select_obligations_where_possible(fallback_has_occurred, |_| {});
464 // Closure and generator analysis may run after fallback
465 // because they don't constrain other type variables.
466 fcx.closure_analyze(body);
467 assert!(fcx.deferred_call_resolutions.borrow().is_empty());
468 fcx.resolve_generator_interiors(def_id.to_def_id());
470 for (ty, span, code) in fcx.deferred_sized_obligations.borrow_mut().drain(..) {
471 let ty = fcx.normalize_ty(span, ty);
472 fcx.require_type_is_sized(ty, span, code);
475 fcx.select_all_obligations_or_error();
477 if fn_sig.is_some() {
478 fcx.regionck_fn(id, body, span, wf_tys);
480 fcx.regionck_expr(body);
483 fcx.resolve_type_vars_in_body(body)
486 // Consistency check our TypeckResults instance can hold all ItemLocalIds
487 // it will need to hold.
488 assert_eq!(typeck_results.hir_owner, id.owner);
493 /// When `check_fn` is invoked on a generator (i.e., a body that
494 /// includes yield), it returns back some information about the yield
496 struct GeneratorTypes<'tcx> {
497 /// Type of generator argument / values returned by `yield`.
500 /// Type of value that is yielded.
503 /// Types that are captured (see `GeneratorInterior` for more).
506 /// Indicates if the generator is movable or static (immovable).
507 movability: hir::Movability,
510 /// Given a `DefId` for an opaque type in return position, find its parent item's return
512 fn get_owner_return_paths(
515 ) -> Option<(hir::HirId, ReturnsVisitor<'tcx>)> {
516 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
517 let id = tcx.hir().get_parent_item(hir_id);
521 .and_then(|(hir_id, node)| node.body_id().map(|b| (hir_id, b)))
522 .map(|(hir_id, body_id)| {
523 let body = tcx.hir().body(body_id);
524 let mut visitor = ReturnsVisitor::default();
525 visitor.visit_body(body);
530 // Forbid defining intrinsics in Rust code,
531 // as they must always be defined by the compiler.
532 fn fn_maybe_err(tcx: TyCtxt<'_>, sp: Span, abi: Abi) {
533 if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
534 tcx.sess.span_err(sp, "intrinsic must be in `extern \"rust-intrinsic\" { ... }` block");
538 fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId, span: Span) {
539 // Only restricted on wasm32 target for now
540 if !tcx.sess.opts.target_triple.triple().starts_with("wasm32") {
544 // If `#[link_section]` is missing, then nothing to verify
545 let attrs = tcx.codegen_fn_attrs(id);
546 if attrs.link_section.is_none() {
550 // For the wasm32 target statics with `#[link_section]` are placed into custom
551 // sections of the final output file, but this isn't link custom sections of
552 // other executable formats. Namely we can only embed a list of bytes,
553 // nothing with pointers to anything else or relocations. If any relocation
554 // show up, reject them here.
555 // `#[link_section]` may contain arbitrary, or even undefined bytes, but it is
556 // the consumer's responsibility to ensure all bytes that have been read
557 // have defined values.
558 if let Ok(alloc) = tcx.eval_static_initializer(id.to_def_id()) {
559 if alloc.relocations().len() != 0 {
560 let msg = "statics with a custom `#[link_section]` must be a \
561 simple list of bytes on the wasm target with no \
562 extra levels of indirection such as references";
563 tcx.sess.span_err(span, msg);
568 fn report_forbidden_specialization(
570 impl_item: &hir::ImplItem<'_>,
573 let mut err = struct_span_err!(
577 "`{}` specializes an item from a parent `impl`, but \
578 that item is not marked `default`",
581 err.span_label(impl_item.span, format!("cannot specialize default item `{}`", impl_item.ident));
583 match tcx.span_of_impl(parent_impl) {
585 err.span_label(span, "parent `impl` is here");
587 "to specialize, `{}` in the parent `impl` must be marked `default`",
592 err.note(&format!("parent implementation is in crate `{}`", cname));
599 fn missing_items_err(
602 missing_items: &[ty::AssocItem],
603 full_impl_span: Span,
605 let missing_items_msg = missing_items
607 .map(|trait_item| trait_item.ident.to_string())
611 let mut err = struct_span_err!(
615 "not all trait items implemented, missing: `{}`",
618 err.span_label(impl_span, format!("missing `{}` in implementation", missing_items_msg));
620 // `Span` before impl block closing brace.
621 let hi = full_impl_span.hi() - BytePos(1);
622 // Point at the place right before the closing brace of the relevant `impl` to suggest
623 // adding the associated item at the end of its body.
624 let sugg_sp = full_impl_span.with_lo(hi).with_hi(hi);
625 // Obtain the level of indentation ending in `sugg_sp`.
626 let indentation = tcx.sess.source_map().span_to_margin(sugg_sp).unwrap_or(0);
627 // Make the whitespace that will make the suggestion have the right indentation.
628 let padding: String = " ".repeat(indentation);
630 for trait_item in missing_items {
631 let snippet = suggestion_signature(trait_item, tcx);
632 let code = format!("{}{}\n{}", padding, snippet, padding);
633 let msg = format!("implement the missing item: `{}`", snippet);
634 let appl = Applicability::HasPlaceholders;
635 if let Some(span) = tcx.hir().span_if_local(trait_item.def_id) {
636 err.span_label(span, format!("`{}` from trait", trait_item.ident));
637 err.tool_only_span_suggestion(sugg_sp, &msg, code, appl);
639 err.span_suggestion_hidden(sugg_sp, &msg, code, appl);
645 /// Resugar `ty::GenericPredicates` in a way suitable to be used in structured suggestions.
646 fn bounds_from_generic_predicates<'tcx>(
648 predicates: ty::GenericPredicates<'tcx>,
649 ) -> (String, String) {
650 let mut types: FxHashMap<Ty<'tcx>, Vec<DefId>> = FxHashMap::default();
651 let mut projections = vec![];
652 for (predicate, _) in predicates.predicates {
653 debug!("predicate {:?}", predicate);
654 let bound_predicate = predicate.kind();
655 match bound_predicate.skip_binder() {
656 ty::PredicateKind::Trait(trait_predicate) => {
657 let entry = types.entry(trait_predicate.self_ty()).or_default();
658 let def_id = trait_predicate.def_id();
659 if Some(def_id) != tcx.lang_items().sized_trait() {
660 // Type params are `Sized` by default, do not add that restriction to the list
661 // if it is a positive requirement.
662 entry.push(trait_predicate.def_id());
665 ty::PredicateKind::Projection(projection_pred) => {
666 projections.push(bound_predicate.rebind(projection_pred));
671 let generics = if types.is_empty() {
678 .filter_map(|t| match t.kind() {
679 ty::Param(_) => Some(t.to_string()),
680 // Avoid suggesting the following:
681 // fn foo<T, <T as Trait>::Bar>(_: T) where T: Trait, <T as Trait>::Bar: Other {}
688 let mut where_clauses = vec![];
689 for (ty, bounds) in types {
690 for bound in &bounds {
691 where_clauses.push(format!("{}: {}", ty, tcx.def_path_str(*bound)));
694 for projection in &projections {
695 let p = projection.skip_binder();
696 // FIXME: this is not currently supported syntax, we should be looking at the `types` and
697 // insert the associated types where they correspond, but for now let's be "lazy" and
698 // propose this instead of the following valid resugaring:
699 // `T: Trait, Trait::Assoc = K` → `T: Trait<Assoc = K>`
700 where_clauses.push(format!("{} = {}", tcx.def_path_str(p.projection_ty.item_def_id), p.ty));
702 let where_clauses = if where_clauses.is_empty() {
705 format!(" where {}", where_clauses.join(", "))
707 (generics, where_clauses)
710 /// Return placeholder code for the given function.
711 fn fn_sig_suggestion<'tcx>(
713 sig: ty::FnSig<'tcx>,
715 predicates: ty::GenericPredicates<'tcx>,
716 assoc: &ty::AssocItem,
723 Some(match ty.kind() {
724 ty::Param(_) if assoc.fn_has_self_parameter && i == 0 => "self".to_string(),
725 ty::Ref(reg, ref_ty, mutability) if i == 0 => {
726 let reg = match &format!("{}", reg)[..] {
727 "'_" | "" => String::new(),
728 reg => format!("{} ", reg),
730 if assoc.fn_has_self_parameter {
731 match ref_ty.kind() {
732 ty::Param(param) if param.name == kw::SelfUpper => {
733 format!("&{}{}self", reg, mutability.prefix_str())
736 _ => format!("self: {}", ty),
743 if assoc.fn_has_self_parameter && i == 0 {
744 format!("self: {}", ty)
751 .chain(std::iter::once(if sig.c_variadic { Some("...".to_string()) } else { None }))
753 .collect::<Vec<String>>()
755 let output = sig.output();
756 let output = if !output.is_unit() { format!(" -> {}", output) } else { String::new() };
758 let unsafety = sig.unsafety.prefix_str();
759 let (generics, where_clauses) = bounds_from_generic_predicates(tcx, predicates);
761 // FIXME: this is not entirely correct, as the lifetimes from borrowed params will
762 // not be present in the `fn` definition, not will we account for renamed
763 // lifetimes between the `impl` and the `trait`, but this should be good enough to
764 // fill in a significant portion of the missing code, and other subsequent
765 // suggestions can help the user fix the code.
767 "{}fn {}{}({}){}{} {{ todo!() }}",
768 unsafety, ident, generics, args, output, where_clauses
772 /// Return placeholder code for the given associated item.
773 /// Similar to `ty::AssocItem::suggestion`, but appropriate for use as the code snippet of a
774 /// structured suggestion.
775 fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String {
777 ty::AssocKind::Fn => {
778 // We skip the binder here because the binder would deanonymize all
779 // late-bound regions, and we don't want method signatures to show up
780 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
781 // regions just fine, showing `fn(&MyType)`.
784 tcx.fn_sig(assoc.def_id).skip_binder(),
786 tcx.predicates_of(assoc.def_id),
790 ty::AssocKind::Type => format!("type {} = Type;", assoc.ident),
791 ty::AssocKind::Const => {
792 let ty = tcx.type_of(assoc.def_id);
793 let val = expr::ty_kind_suggestion(ty).unwrap_or("value");
794 format!("const {}: {} = {};", assoc.ident, ty, val)
799 /// Emit an error when encountering two or more variants in a transparent enum.
800 fn bad_variant_count<'tcx>(tcx: TyCtxt<'tcx>, adt: &'tcx ty::AdtDef, sp: Span, did: DefId) {
801 let variant_spans: Vec<_> = adt
804 .map(|variant| tcx.hir().span_if_local(variant.def_id).unwrap())
806 let msg = format!("needs exactly one variant, but has {}", adt.variants.len(),);
807 let mut err = struct_span_err!(tcx.sess, sp, E0731, "transparent enum {}", msg);
808 err.span_label(sp, &msg);
809 if let [start @ .., end] = &*variant_spans {
810 for variant_span in start {
811 err.span_label(*variant_span, "");
813 err.span_label(*end, &format!("too many variants in `{}`", tcx.def_path_str(did)));
818 /// Emit an error when encountering two or more non-zero-sized fields in a transparent
820 fn bad_non_zero_sized_fields<'tcx>(
822 adt: &'tcx ty::AdtDef,
824 field_spans: impl Iterator<Item = Span>,
827 let msg = format!("needs at most one non-zero-sized field, but has {}", field_count);
828 let mut err = struct_span_err!(
832 "{}transparent {} {}",
833 if adt.is_enum() { "the variant of a " } else { "" },
837 err.span_label(sp, &msg);
838 for sp in field_spans {
839 err.span_label(sp, "this field is non-zero-sized");
844 fn report_unexpected_variant_res(tcx: TyCtxt<'_>, res: Res, span: Span) {
849 "expected unit struct, unit variant or constant, found {}{}",
853 .span_to_snippet(span)
854 .map_or_else(|_| String::new(), |s| format!(" `{}`", s)),
859 /// Controls whether the arguments are tupled. This is used for the call
862 /// Tupling means that all call-side arguments are packed into a tuple and
863 /// passed as a single parameter. For example, if tupling is enabled, this
866 /// fn f(x: (isize, isize))
868 /// Can be called as:
875 #[derive(Clone, Eq, PartialEq)]
876 enum TupleArgumentsFlag {
881 /// A wrapper for `InferCtxt`'s `in_progress_typeck_results` field.
882 #[derive(Copy, Clone)]
883 struct MaybeInProgressTables<'a, 'tcx> {
884 maybe_typeck_results: Option<&'a RefCell<ty::TypeckResults<'tcx>>>,
887 impl<'a, 'tcx> MaybeInProgressTables<'a, 'tcx> {
888 fn borrow(self) -> Ref<'a, ty::TypeckResults<'tcx>> {
889 match self.maybe_typeck_results {
890 Some(typeck_results) => typeck_results.borrow(),
892 "MaybeInProgressTables: inh/fcx.typeck_results.borrow() with no typeck results"
897 fn borrow_mut(self) -> RefMut<'a, ty::TypeckResults<'tcx>> {
898 match self.maybe_typeck_results {
899 Some(typeck_results) => typeck_results.borrow_mut(),
901 "MaybeInProgressTables: inh/fcx.typeck_results.borrow_mut() with no typeck results"
907 struct CheckItemTypesVisitor<'tcx> {
911 impl ItemLikeVisitor<'tcx> for CheckItemTypesVisitor<'tcx> {
912 fn visit_item(&mut self, i: &'tcx hir::Item<'tcx>) {
913 check_item_type(self.tcx, i);
915 fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem<'tcx>) {}
916 fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem<'tcx>) {}
917 fn visit_foreign_item(&mut self, _: &'tcx hir::ForeignItem<'tcx>) {}
920 fn typeck_item_bodies(tcx: TyCtxt<'_>, (): ()) {
921 tcx.hir().par_body_owners(|body_owner_def_id| tcx.ensure().typeck(body_owner_def_id));
924 fn fatally_break_rust(sess: &Session) {
925 let handler = sess.diagnostic();
926 handler.span_bug_no_panic(
928 "It looks like you're trying to break rust; would you like some ICE?",
930 handler.note_without_error("the compiler expectedly panicked. this is a feature.");
931 handler.note_without_error(
932 "we would appreciate a joke overview: \
933 https://github.com/rust-lang/rust/issues/43162#issuecomment-320764675",
935 handler.note_without_error(&format!(
936 "rustc {} running on {}",
937 option_env!("CFG_VERSION").unwrap_or("unknown_version"),
938 config::host_triple(),
942 fn potentially_plural_count(count: usize, word: &str) -> String {
943 format!("{} {}{}", count, word, pluralize!(count))
946 fn has_expected_num_generic_args<'tcx>(
948 trait_did: Option<DefId>,
951 trait_did.map_or(true, |trait_did| {
952 let generics = tcx.generics_of(trait_did);
953 generics.count() == expected + if generics.has_self { 1 } else { 0 }