1 //! Type checking expressions.
3 //! See `mod.rs` for more context on type checking in general.
5 use crate::astconv::AstConv as _;
6 use crate::check::cast;
7 use crate::check::coercion::CoerceMany;
8 use crate::check::fatally_break_rust;
9 use crate::check::method::SelfSource;
10 use crate::check::report_unexpected_variant_res;
11 use crate::check::BreakableCtxt;
12 use crate::check::Diverges;
13 use crate::check::DynamicCoerceMany;
14 use crate::check::Expectation::{self, ExpectCastableToType, ExpectHasType, NoExpectation};
15 use crate::check::FnCtxt;
16 use crate::check::Needs;
17 use crate::check::TupleArgumentsFlag::DontTupleArguments;
19 FieldMultiplySpecifiedInInitializer, FunctionalRecordUpdateOnNonStruct,
20 YieldExprOutsideOfGenerator,
22 use crate::type_error_struct;
24 use crate::errors::{AddressOfTemporaryTaken, ReturnStmtOutsideOfFnBody, StructExprNonExhaustive};
26 use rustc_data_structures::fx::FxHashMap;
27 use rustc_data_structures::stack::ensure_sufficient_stack;
28 use rustc_errors::ErrorReported;
29 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder, DiagnosticId};
31 use rustc_hir::def::{CtorKind, DefKind, Res};
32 use rustc_hir::def_id::DefId;
33 use rustc_hir::intravisit::Visitor;
34 use rustc_hir::{ExprKind, HirId, QPath};
35 use rustc_infer::infer;
36 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
37 use rustc_infer::infer::InferOk;
38 use rustc_middle::middle::stability;
39 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AllowTwoPhase};
40 use rustc_middle::ty::error::ExpectedFound;
41 use rustc_middle::ty::error::TypeError::{FieldMisMatch, Sorts};
42 use rustc_middle::ty::subst::SubstsRef;
43 use rustc_middle::ty::{self, AdtKind, Ty, TypeFoldable};
44 use rustc_session::parse::feature_err;
45 use rustc_span::edition::LATEST_STABLE_EDITION;
46 use rustc_span::hygiene::DesugaringKind;
47 use rustc_span::lev_distance::find_best_match_for_name;
48 use rustc_span::source_map::Span;
49 use rustc_span::symbol::{kw, sym, Ident, Symbol};
50 use rustc_span::{BytePos, Pos};
51 use rustc_trait_selection::traits::{self, ObligationCauseCode};
53 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
54 fn check_expr_eq_type(&self, expr: &'tcx hir::Expr<'tcx>, expected: Ty<'tcx>) {
55 let ty = self.check_expr_with_hint(expr, expected);
56 self.demand_eqtype(expr.span, expected, ty);
59 pub fn check_expr_has_type_or_error(
61 expr: &'tcx hir::Expr<'tcx>,
63 extend_err: impl Fn(&mut DiagnosticBuilder<'_>),
65 self.check_expr_meets_expectation_or_error(expr, ExpectHasType(expected), extend_err)
68 fn check_expr_meets_expectation_or_error(
70 expr: &'tcx hir::Expr<'tcx>,
71 expected: Expectation<'tcx>,
72 extend_err: impl Fn(&mut DiagnosticBuilder<'_>),
74 let expected_ty = expected.to_option(&self).unwrap_or(self.tcx.types.bool);
75 let mut ty = self.check_expr_with_expectation(expr, expected);
77 // While we don't allow *arbitrary* coercions here, we *do* allow
78 // coercions from ! to `expected`.
81 !self.typeck_results.borrow().adjustments().contains_key(expr.hir_id),
82 "expression with never type wound up being adjusted"
84 let adj_ty = self.next_ty_var(TypeVariableOrigin {
85 kind: TypeVariableOriginKind::AdjustmentType,
88 self.apply_adjustments(
90 vec![Adjustment { kind: Adjust::NeverToAny, target: adj_ty }],
95 if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) {
96 let expr = expr.peel_drop_temps();
97 self.suggest_deref_ref_or_into(&mut err, expr, expected_ty, ty, None);
104 pub(super) fn check_expr_coercable_to_type(
106 expr: &'tcx hir::Expr<'tcx>,
108 expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
110 let ty = self.check_expr_with_hint(expr, expected);
111 // checks don't need two phase
112 self.demand_coerce(expr, ty, expected, expected_ty_expr, AllowTwoPhase::No)
115 pub(super) fn check_expr_with_hint(
117 expr: &'tcx hir::Expr<'tcx>,
120 self.check_expr_with_expectation(expr, ExpectHasType(expected))
123 fn check_expr_with_expectation_and_needs(
125 expr: &'tcx hir::Expr<'tcx>,
126 expected: Expectation<'tcx>,
129 let ty = self.check_expr_with_expectation(expr, expected);
131 // If the expression is used in a place whether mutable place is required
132 // e.g. LHS of assignment, perform the conversion.
133 if let Needs::MutPlace = needs {
134 self.convert_place_derefs_to_mutable(expr);
140 pub(super) fn check_expr(&self, expr: &'tcx hir::Expr<'tcx>) -> Ty<'tcx> {
141 self.check_expr_with_expectation(expr, NoExpectation)
144 pub(super) fn check_expr_with_needs(
146 expr: &'tcx hir::Expr<'tcx>,
149 self.check_expr_with_expectation_and_needs(expr, NoExpectation, needs)
153 /// If an expression has any sub-expressions that result in a type error,
154 /// inspecting that expression's type with `ty.references_error()` will return
155 /// true. Likewise, if an expression is known to diverge, inspecting its
156 /// type with `ty::type_is_bot` will return true (n.b.: since Rust is
157 /// strict, _|_ can appear in the type of an expression that does not,
158 /// itself, diverge: for example, fn() -> _|_.)
159 /// Note that inspecting a type's structure *directly* may expose the fact
160 /// that there are actually multiple representations for `Error`, so avoid
161 /// that when err needs to be handled differently.
162 #[instrument(skip(self, expr), level = "debug")]
163 pub(super) fn check_expr_with_expectation(
165 expr: &'tcx hir::Expr<'tcx>,
166 expected: Expectation<'tcx>,
168 self.check_expr_with_expectation_and_args(expr, expected, &[])
171 /// Same as `check_expr_with_expectation`, but allows us to pass in the arguments of a
172 /// `ExprKind::Call` when evaluating its callee when it is an `ExprKind::Path`.
173 pub(super) fn check_expr_with_expectation_and_args(
175 expr: &'tcx hir::Expr<'tcx>,
176 expected: Expectation<'tcx>,
177 args: &'tcx [hir::Expr<'tcx>],
179 if self.tcx().sess.verbose() {
180 // make this code only run with -Zverbose because it is probably slow
181 if let Ok(lint_str) = self.tcx.sess.source_map().span_to_snippet(expr.span) {
182 if !lint_str.contains('\n') {
183 debug!("expr text: {}", lint_str);
185 let mut lines = lint_str.lines();
186 if let Some(line0) = lines.next() {
187 let remaining_lines = lines.count();
188 debug!("expr text: {}", line0);
189 debug!("expr text: ...(and {} more lines)", remaining_lines);
195 // True if `expr` is a `Try::from_ok(())` that is a result of desugaring a try block
196 // without the final expr (e.g. `try { return; }`). We don't want to generate an
197 // unreachable_code lint for it since warnings for autogenerated code are confusing.
198 let is_try_block_generated_unit_expr = match expr.kind {
199 ExprKind::Call(_, args) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {
200 args.len() == 1 && args[0].span.is_desugaring(DesugaringKind::TryBlock)
206 // Warn for expressions after diverging siblings.
207 if !is_try_block_generated_unit_expr {
208 self.warn_if_unreachable(expr.hir_id, expr.span, "expression");
211 // Hide the outer diverging and has_errors flags.
212 let old_diverges = self.diverges.replace(Diverges::Maybe);
213 let old_has_errors = self.has_errors.replace(false);
215 let ty = ensure_sufficient_stack(|| match &expr.kind {
217 qpath @ hir::QPath::Resolved(..) | qpath @ hir::QPath::TypeRelative(..),
218 ) => self.check_expr_path(qpath, expr, args),
219 _ => self.check_expr_kind(expr, expected),
222 // Warn for non-block expressions with diverging children.
228 | ExprKind::Match(..) => {}
229 // If `expr` is a result of desugaring the try block and is an ok-wrapped
230 // diverging expression (e.g. it arose from desugaring of `try { return }`),
231 // we skip issuing a warning because it is autogenerated code.
232 ExprKind::Call(..) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {}
233 ExprKind::Call(callee, _) => self.warn_if_unreachable(expr.hir_id, callee.span, "call"),
234 ExprKind::MethodCall(segment, ..) => {
235 self.warn_if_unreachable(expr.hir_id, segment.ident.span, "call")
237 _ => self.warn_if_unreachable(expr.hir_id, expr.span, "expression"),
240 // Any expression that produces a value of type `!` must have diverged
242 self.diverges.set(self.diverges.get() | Diverges::always(expr.span));
245 // Record the type, which applies it effects.
246 // We need to do this after the warning above, so that
247 // we don't warn for the diverging expression itself.
248 self.write_ty(expr.hir_id, ty);
250 // Combine the diverging and has_error flags.
251 self.diverges.set(self.diverges.get() | old_diverges);
252 self.has_errors.set(self.has_errors.get() | old_has_errors);
254 debug!("type of {} is...", self.tcx.hir().node_to_string(expr.hir_id));
255 debug!("... {:?}, expected is {:?}", ty, expected);
260 #[instrument(skip(self, expr), level = "debug")]
263 expr: &'tcx hir::Expr<'tcx>,
264 expected: Expectation<'tcx>,
266 trace!("expr={:#?}", expr);
270 ExprKind::Box(subexpr) => self.check_expr_box(subexpr, expected),
271 ExprKind::Lit(ref lit) => self.check_lit(&lit, expected),
272 ExprKind::Binary(op, lhs, rhs) => self.check_binop(expr, op, lhs, rhs),
273 ExprKind::Assign(lhs, rhs, ref span) => {
274 self.check_expr_assign(expr, expected, lhs, rhs, span)
276 ExprKind::AssignOp(op, lhs, rhs) => self.check_binop_assign(expr, op, lhs, rhs),
277 ExprKind::Unary(unop, oprnd) => self.check_expr_unary(unop, oprnd, expected, expr),
278 ExprKind::AddrOf(kind, mutbl, oprnd) => {
279 self.check_expr_addr_of(kind, mutbl, oprnd, expected, expr)
281 ExprKind::Path(QPath::LangItem(lang_item, _, hir_id)) => {
282 self.check_lang_item_path(lang_item, expr, hir_id)
284 ExprKind::Path(ref qpath) => self.check_expr_path(qpath, expr, &[]),
285 ExprKind::InlineAsm(asm) => self.check_expr_asm(asm),
286 ExprKind::Break(destination, ref expr_opt) => {
287 self.check_expr_break(destination, expr_opt.as_deref(), expr)
289 ExprKind::Continue(destination) => {
290 if destination.target_id.is_ok() {
293 // There was an error; make type-check fail.
297 ExprKind::Ret(ref expr_opt) => self.check_expr_return(expr_opt.as_deref(), expr),
298 ExprKind::Let(let_expr) => self.check_expr_let(let_expr),
299 ExprKind::Loop(body, _, source, _) => {
300 self.check_expr_loop(body, source, expected, expr)
302 ExprKind::Match(discrim, arms, match_src) => {
303 self.check_match(expr, &discrim, arms, expected, match_src)
305 ExprKind::Closure(capture, decl, body_id, _, gen) => {
306 self.check_expr_closure(expr, capture, &decl, body_id, gen, expected)
308 ExprKind::Block(body, _) => self.check_block_with_expected(&body, expected),
309 ExprKind::Call(callee, args) => self.check_call(expr, &callee, args, expected),
310 ExprKind::MethodCall(segment, args, _) => {
311 self.check_method_call(expr, segment, args, expected)
313 ExprKind::Cast(e, t) => self.check_expr_cast(e, t, expr),
314 ExprKind::Type(e, t) => {
315 let ty = self.to_ty_saving_user_provided_ty(&t);
316 self.check_expr_eq_type(&e, ty);
319 ExprKind::If(cond, then_expr, opt_else_expr) => {
320 self.check_then_else(cond, then_expr, opt_else_expr, expr.span, expected)
322 ExprKind::DropTemps(e) => self.check_expr_with_expectation(e, expected),
323 ExprKind::Array(args) => self.check_expr_array(args, expected, expr),
324 ExprKind::ConstBlock(ref anon_const) => {
325 self.check_expr_const_block(anon_const, expected, expr)
327 ExprKind::Repeat(element, ref count) => {
328 self.check_expr_repeat(element, count, expected, expr)
330 ExprKind::Tup(elts) => self.check_expr_tuple(elts, expected, expr),
331 ExprKind::Struct(qpath, fields, ref base_expr) => {
332 self.check_expr_struct(expr, expected, qpath, fields, base_expr)
334 ExprKind::Field(base, field) => self.check_field(expr, &base, field),
335 ExprKind::Index(base, idx) => self.check_expr_index(base, idx, expr),
336 ExprKind::Yield(value, ref src) => self.check_expr_yield(value, expr, src),
337 hir::ExprKind::Err => tcx.ty_error(),
341 fn check_expr_box(&self, expr: &'tcx hir::Expr<'tcx>, expected: Expectation<'tcx>) -> Ty<'tcx> {
342 let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| match ty.kind() {
343 ty::Adt(def, _) if def.is_box() => Expectation::rvalue_hint(self, ty.boxed_ty()),
346 let referent_ty = self.check_expr_with_expectation(expr, expected_inner);
347 self.require_type_is_sized(referent_ty, expr.span, traits::SizedBoxType);
348 self.tcx.mk_box(referent_ty)
354 oprnd: &'tcx hir::Expr<'tcx>,
355 expected: Expectation<'tcx>,
356 expr: &'tcx hir::Expr<'tcx>,
359 let expected_inner = match unop {
360 hir::UnOp::Not | hir::UnOp::Neg => expected,
361 hir::UnOp::Deref => NoExpectation,
363 let mut oprnd_t = self.check_expr_with_expectation(&oprnd, expected_inner);
365 if !oprnd_t.references_error() {
366 oprnd_t = self.structurally_resolved_type(expr.span, oprnd_t);
368 hir::UnOp::Deref => {
369 if let Some(ty) = self.lookup_derefing(expr, oprnd, oprnd_t) {
372 let mut err = type_error_struct!(
377 "type `{}` cannot be dereferenced",
380 let sp = tcx.sess.source_map().start_point(expr.span);
382 tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp)
384 tcx.sess.parse_sess.expr_parentheses_needed(&mut err, *sp);
387 oprnd_t = tcx.ty_error();
391 let result = self.check_user_unop(expr, oprnd_t, unop);
392 // If it's builtin, we can reuse the type, this helps inference.
393 if !(oprnd_t.is_integral() || *oprnd_t.kind() == ty::Bool) {
398 let result = self.check_user_unop(expr, oprnd_t, unop);
399 // If it's builtin, we can reuse the type, this helps inference.
400 if !oprnd_t.is_numeric() {
409 fn check_expr_addr_of(
411 kind: hir::BorrowKind,
412 mutbl: hir::Mutability,
413 oprnd: &'tcx hir::Expr<'tcx>,
414 expected: Expectation<'tcx>,
415 expr: &'tcx hir::Expr<'tcx>,
417 let hint = expected.only_has_type(self).map_or(NoExpectation, |ty| {
419 ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
420 if oprnd.is_syntactic_place_expr() {
421 // Places may legitimately have unsized types.
422 // For example, dereferences of a fat pointer and
423 // the last field of a struct can be unsized.
426 Expectation::rvalue_hint(self, ty)
433 self.check_expr_with_expectation_and_needs(&oprnd, hint, Needs::maybe_mut_place(mutbl));
435 let tm = ty::TypeAndMut { ty, mutbl };
437 _ if tm.ty.references_error() => self.tcx.ty_error(),
438 hir::BorrowKind::Raw => {
439 self.check_named_place_expr(oprnd);
442 hir::BorrowKind::Ref => {
443 // Note: at this point, we cannot say what the best lifetime
444 // is to use for resulting pointer. We want to use the
445 // shortest lifetime possible so as to avoid spurious borrowck
446 // errors. Moreover, the longest lifetime will depend on the
447 // precise details of the value whose address is being taken
448 // (and how long it is valid), which we don't know yet until
449 // type inference is complete.
451 // Therefore, here we simply generate a region variable. The
452 // region inferencer will then select a suitable value.
453 // Finally, borrowck will infer the value of the region again,
454 // this time with enough precision to check that the value
455 // whose address was taken can actually be made to live as long
456 // as it needs to live.
457 let region = self.next_region_var(infer::AddrOfRegion(expr.span));
458 self.tcx.mk_ref(region, tm)
463 /// Does this expression refer to a place that either:
464 /// * Is based on a local or static.
465 /// * Contains a dereference
466 /// Note that the adjustments for the children of `expr` should already
467 /// have been resolved.
468 fn check_named_place_expr(&self, oprnd: &'tcx hir::Expr<'tcx>) {
469 let is_named = oprnd.is_place_expr(|base| {
470 // Allow raw borrows if there are any deref adjustments.
472 // const VAL: (i32,) = (0,);
473 // const REF: &(i32,) = &(0,);
475 // &raw const VAL.0; // ERROR
476 // &raw const REF.0; // OK, same as &raw const (*REF).0;
478 // This is maybe too permissive, since it allows
479 // `let u = &raw const Box::new((1,)).0`, which creates an
480 // immediately dangling raw pointer.
485 .map_or(false, |x| x.iter().any(|adj| matches!(adj.kind, Adjust::Deref(_))))
488 self.tcx.sess.emit_err(AddressOfTemporaryTaken { span: oprnd.span })
492 fn check_lang_item_path(
494 lang_item: hir::LangItem,
495 expr: &'tcx hir::Expr<'tcx>,
496 hir_id: Option<hir::HirId>,
498 self.resolve_lang_item_path(lang_item, expr.span, expr.hir_id, hir_id).1
501 pub(crate) fn check_expr_path(
503 qpath: &'tcx hir::QPath<'tcx>,
504 expr: &'tcx hir::Expr<'tcx>,
505 args: &'tcx [hir::Expr<'tcx>],
508 let (res, opt_ty, segs) =
509 self.resolve_ty_and_res_fully_qualified_call(qpath, expr.hir_id, expr.span);
512 self.set_tainted_by_errors();
515 Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _) => {
516 report_unexpected_variant_res(tcx, res, expr.span);
519 _ => self.instantiate_value_path(segs, opt_ty, res, expr.span, expr.hir_id).0,
522 if let ty::FnDef(..) = ty.kind() {
523 let fn_sig = ty.fn_sig(tcx);
524 if !tcx.features().unsized_fn_params {
525 // We want to remove some Sized bounds from std functions,
526 // but don't want to expose the removal to stable Rust.
527 // i.e., we don't want to allow
533 // to work in stable even if the Sized bound on `drop` is relaxed.
534 for i in 0..fn_sig.inputs().skip_binder().len() {
535 // We just want to check sizedness, so instead of introducing
536 // placeholder lifetimes with probing, we just replace higher lifetimes
538 let span = args.get(i).map(|a| a.span).unwrap_or(expr.span);
540 .replace_bound_vars_with_fresh_vars(
542 infer::LateBoundRegionConversionTime::FnCall,
546 self.require_type_is_sized_deferred(
549 traits::SizedArgumentType(None),
553 // Here we want to prevent struct constructors from returning unsized types.
554 // There were two cases this happened: fn pointer coercion in stable
555 // and usual function call in presence of unsized_locals.
556 // Also, as we just want to check sizedness, instead of introducing
557 // placeholder lifetimes with probing, we just replace higher lifetimes
560 .replace_bound_vars_with_fresh_vars(
562 infer::LateBoundRegionConversionTime::FnCall,
566 self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType);
569 // We always require that the type provided as the value for
570 // a type parameter outlives the moment of instantiation.
571 let substs = self.typeck_results.borrow().node_substs(expr.hir_id);
572 self.add_wf_bounds(substs, expr);
579 destination: hir::Destination,
580 expr_opt: Option<&'tcx hir::Expr<'tcx>>,
581 expr: &'tcx hir::Expr<'tcx>,
584 if let Ok(target_id) = destination.target_id {
586 if let Some(e) = expr_opt {
587 // If this is a break with a value, we need to type-check
588 // the expression. Get an expected type from the loop context.
589 let opt_coerce_to = {
590 // We should release `enclosing_breakables` before the `check_expr_with_hint`
591 // below, so can't move this block of code to the enclosing scope and share
592 // `ctxt` with the second `encloding_breakables` borrow below.
593 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
594 match enclosing_breakables.opt_find_breakable(target_id) {
595 Some(ctxt) => ctxt.coerce.as_ref().map(|coerce| coerce.expected_ty()),
597 // Avoid ICE when `break` is inside a closure (#65383).
598 return tcx.ty_error_with_message(
600 "break was outside loop, but no error was emitted",
606 // If the loop context is not a `loop { }`, then break with
607 // a value is illegal, and `opt_coerce_to` will be `None`.
608 // Just set expectation to error in that case.
609 let coerce_to = opt_coerce_to.unwrap_or_else(|| tcx.ty_error());
611 // Recurse without `enclosing_breakables` borrowed.
612 e_ty = self.check_expr_with_hint(e, coerce_to);
613 cause = self.misc(e.span);
615 // Otherwise, this is a break *without* a value. That's
616 // always legal, and is equivalent to `break ()`.
617 e_ty = tcx.mk_unit();
618 cause = self.misc(expr.span);
621 // Now that we have type-checked `expr_opt`, borrow
622 // the `enclosing_loops` field and let's coerce the
623 // type of `expr_opt` into what is expected.
624 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
625 let ctxt = match enclosing_breakables.opt_find_breakable(target_id) {
628 // Avoid ICE when `break` is inside a closure (#65383).
629 return tcx.ty_error_with_message(
631 "break was outside loop, but no error was emitted",
636 if let Some(ref mut coerce) = ctxt.coerce {
637 if let Some(ref e) = expr_opt {
638 coerce.coerce(self, &cause, e, e_ty);
640 assert!(e_ty.is_unit());
641 let ty = coerce.expected_ty();
642 coerce.coerce_forced_unit(
646 self.suggest_mismatched_types_on_tail(
647 &mut err, expr, ty, e_ty, target_id,
649 if let Some(val) = ty_kind_suggestion(ty) {
650 let label = destination
652 .map(|l| format!(" {}", l.ident))
653 .unwrap_or_else(String::new);
656 "give it a value of the expected type",
657 format!("break{} {}", label, val),
658 Applicability::HasPlaceholders,
666 // If `ctxt.coerce` is `None`, we can just ignore
667 // the type of the expression. This is because
668 // either this was a break *without* a value, in
669 // which case it is always a legal type (`()`), or
670 // else an error would have been flagged by the
671 // `loops` pass for using break with an expression
672 // where you are not supposed to.
673 assert!(expr_opt.is_none() || self.tcx.sess.has_errors());
676 // If we encountered a `break`, then (no surprise) it may be possible to break from the
677 // loop... unless the value being returned from the loop diverges itself, e.g.
678 // `break return 5` or `break loop {}`.
679 ctxt.may_break |= !self.diverges.get().is_always();
681 // the type of a `break` is always `!`, since it diverges
684 // Otherwise, we failed to find the enclosing loop;
685 // this can only happen if the `break` was not
686 // inside a loop at all, which is caught by the
687 // loop-checking pass.
688 let err = self.tcx.ty_error_with_message(
690 "break was outside loop, but no error was emitted",
693 // We still need to assign a type to the inner expression to
694 // prevent the ICE in #43162.
695 if let Some(e) = expr_opt {
696 self.check_expr_with_hint(e, err);
698 // ... except when we try to 'break rust;'.
699 // ICE this expression in particular (see #43162).
700 if let ExprKind::Path(QPath::Resolved(_, path)) = e.kind {
701 if path.segments.len() == 1 && path.segments[0].ident.name == sym::rust {
702 fatally_break_rust(self.tcx.sess);
707 // There was an error; make type-check fail.
712 fn check_expr_return(
714 expr_opt: Option<&'tcx hir::Expr<'tcx>>,
715 expr: &'tcx hir::Expr<'tcx>,
717 if self.ret_coercion.is_none() {
718 let mut err = ReturnStmtOutsideOfFnBody {
720 encl_body_span: None,
724 let encl_item_id = self.tcx.hir().get_parent_item(expr.hir_id);
726 if let Some(hir::Node::Item(hir::Item {
727 kind: hir::ItemKind::Fn(..),
731 | Some(hir::Node::TraitItem(hir::TraitItem {
732 kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)),
736 | Some(hir::Node::ImplItem(hir::ImplItem {
737 kind: hir::ImplItemKind::Fn(..),
740 })) = self.tcx.hir().find_by_def_id(encl_item_id)
742 // We are inside a function body, so reporting "return statement
743 // outside of function body" needs an explanation.
745 let encl_body_owner_id = self.tcx.hir().enclosing_body_owner(expr.hir_id);
747 // If this didn't hold, we would not have to report an error in
749 assert_ne!(hir::HirId::make_owner(encl_item_id), encl_body_owner_id);
751 let encl_body_id = self.tcx.hir().body_owned_by(encl_body_owner_id);
752 let encl_body = self.tcx.hir().body(encl_body_id);
754 err.encl_body_span = Some(encl_body.value.span);
755 err.encl_fn_span = Some(*encl_fn_span);
758 self.tcx.sess.emit_err(err);
760 if let Some(e) = expr_opt {
761 // We still have to type-check `e` (issue #86188), but calling
762 // `check_return_expr` only works inside fn bodies.
765 } else if let Some(e) = expr_opt {
766 if self.ret_coercion_span.get().is_none() {
767 self.ret_coercion_span.set(Some(e.span));
769 self.check_return_expr(e, true);
771 let mut coercion = self.ret_coercion.as_ref().unwrap().borrow_mut();
772 if self.ret_coercion_span.get().is_none() {
773 self.ret_coercion_span.set(Some(expr.span));
775 let cause = self.cause(expr.span, ObligationCauseCode::ReturnNoExpression);
776 if let Some((fn_decl, _)) = self.get_fn_decl(expr.hir_id) {
777 coercion.coerce_forced_unit(
781 let span = fn_decl.output.span();
782 if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
785 format!("expected `{}` because of this return type", snippet),
792 coercion.coerce_forced_unit(self, &cause, &mut |_| (), true);
798 /// `explicit_return` is `true` if we're checkng an explicit `return expr`,
799 /// and `false` if we're checking a trailing expression.
800 pub(super) fn check_return_expr(
802 return_expr: &'tcx hir::Expr<'tcx>,
803 explicit_return: bool,
805 let ret_coercion = self.ret_coercion.as_ref().unwrap_or_else(|| {
806 span_bug!(return_expr.span, "check_return_expr called outside fn body")
809 let ret_ty = ret_coercion.borrow().expected_ty();
810 let return_expr_ty = self.check_expr_with_hint(return_expr, ret_ty);
811 let mut span = return_expr.span;
812 // Use the span of the trailing expression for our cause,
813 // not the span of the entire function
814 if !explicit_return {
815 if let ExprKind::Block(body, _) = return_expr.kind {
816 if let Some(last_expr) = body.expr {
817 span = last_expr.span;
821 ret_coercion.borrow_mut().coerce(
823 &self.cause(span, ObligationCauseCode::ReturnValue(return_expr.hir_id)),
829 pub(crate) fn check_lhs_assignable(
831 lhs: &'tcx hir::Expr<'tcx>,
832 err_code: &'static str,
835 if lhs.is_syntactic_place_expr() {
839 // FIXME: Make this use SessionDiagnostic once error codes can be dynamically set.
840 let mut err = self.tcx.sess.struct_span_err_with_code(
842 "invalid left-hand side of assignment",
843 DiagnosticId::Error(err_code.into()),
845 err.span_label(lhs.span, "cannot assign to this expression");
847 let mut parent = self.tcx.hir().get_parent_node(lhs.hir_id);
848 while let Some(node) = self.tcx.hir().find(parent) {
850 hir::Node::Expr(hir::Expr {
857 hir::ExprKind::Match(expr, ..) | hir::ExprKind::If(expr, ..),
863 hir::LoopSource::While,
868 // Check if our lhs is a child of the condition of a while loop
869 let expr_is_ancestor = std::iter::successors(Some(lhs.hir_id), |id| {
870 self.tcx.hir().find_parent_node(*id)
872 .take_while(|id| *id != parent)
873 .any(|id| id == expr.hir_id);
874 // if it is, then we have a situation like `while Some(0) = value.get(0) {`,
875 // where `while let` was more likely intended.
876 if expr_is_ancestor {
877 err.span_suggestion_verbose(
878 expr.span.shrink_to_lo(),
879 "you might have meant to use pattern destructuring",
881 Applicability::MachineApplicable,
887 | hir::Node::ImplItem(_)
888 | hir::Node::TraitItem(_)
889 | hir::Node::Crate(_) => break,
891 parent = self.tcx.hir().get_parent_node(parent);
899 // A generic function for checking the 'then' and 'else' clauses in an 'if'
900 // or 'if-else' expression.
903 cond_expr: &'tcx hir::Expr<'tcx>,
904 then_expr: &'tcx hir::Expr<'tcx>,
905 opt_else_expr: Option<&'tcx hir::Expr<'tcx>>,
907 orig_expected: Expectation<'tcx>,
909 let cond_ty = self.check_expr_has_type_or_error(cond_expr, self.tcx.types.bool, |_| {});
911 self.warn_if_unreachable(
914 "block in `if` or `while` expression",
917 let cond_diverges = self.diverges.get();
918 self.diverges.set(Diverges::Maybe);
920 let expected = orig_expected.adjust_for_branches(self);
921 let then_ty = self.check_expr_with_expectation(then_expr, expected);
922 let then_diverges = self.diverges.get();
923 self.diverges.set(Diverges::Maybe);
925 // We've already taken the expected type's preferences
926 // into account when typing the `then` branch. To figure
927 // out the initial shot at a LUB, we thus only consider
928 // `expected` if it represents a *hard* constraint
929 // (`only_has_type`); otherwise, we just go with a
930 // fresh type variable.
931 let coerce_to_ty = expected.coercion_target_type(self, sp);
932 let mut coerce: DynamicCoerceMany<'_> = CoerceMany::new(coerce_to_ty);
934 coerce.coerce(self, &self.misc(sp), then_expr, then_ty);
936 if let Some(else_expr) = opt_else_expr {
937 let else_ty = if sp.desugaring_kind() == Some(DesugaringKind::LetElse) {
938 // todo introduce `check_expr_with_expectation(.., Expectation::LetElse)`
939 // for errors that point to the offending expression rather than the entire block.
940 // We could use `check_expr_eq_type(.., tcx.types.never)`, but then there is no
941 // way to detect that the expected type originated from let-else and provide
942 // a customized error.
943 let else_ty = self.check_expr(else_expr);
944 let cause = self.cause(else_expr.span, ObligationCauseCode::LetElse);
946 if let Some(mut err) =
947 self.demand_eqtype_with_origin(&cause, self.tcx.types.never, else_ty)
955 self.check_expr_with_expectation(else_expr, expected)
957 let else_diverges = self.diverges.get();
959 let opt_suggest_box_span =
960 self.opt_suggest_box_span(else_expr.span, else_ty, orig_expected);
962 self.if_cause(sp, then_expr, else_expr, then_ty, else_ty, opt_suggest_box_span);
964 coerce.coerce(self, &if_cause, else_expr, else_ty);
966 // We won't diverge unless both branches do (or the condition does).
967 self.diverges.set(cond_diverges | then_diverges & else_diverges);
969 self.if_fallback_coercion(sp, then_expr, &mut coerce);
971 // If the condition is false we can't diverge.
972 self.diverges.set(cond_diverges);
975 let result_ty = coerce.complete(self);
976 if cond_ty.references_error() { self.tcx.ty_error() } else { result_ty }
979 /// Type check assignment expression `expr` of form `lhs = rhs`.
980 /// The expected type is `()` and is passed to the function for the purposes of diagnostics.
981 fn check_expr_assign(
983 expr: &'tcx hir::Expr<'tcx>,
984 expected: Expectation<'tcx>,
985 lhs: &'tcx hir::Expr<'tcx>,
986 rhs: &'tcx hir::Expr<'tcx>,
989 let expected_ty = expected.coercion_target_type(self, expr.span);
990 if expected_ty == self.tcx.types.bool {
991 // The expected type is `bool` but this will result in `()` so we can reasonably
992 // say that the user intended to write `lhs == rhs` instead of `lhs = rhs`.
993 // The likely cause of this is `if foo = bar { .. }`.
994 let actual_ty = self.tcx.mk_unit();
995 let mut err = self.demand_suptype_diag(expr.span, expected_ty, actual_ty).unwrap();
996 let lhs_ty = self.check_expr(&lhs);
997 let rhs_ty = self.check_expr(&rhs);
998 let (applicability, eq) = if self.can_coerce(rhs_ty, lhs_ty) {
999 (Applicability::MachineApplicable, true)
1001 (Applicability::MaybeIncorrect, false)
1003 if !lhs.is_syntactic_place_expr() && !matches!(lhs.kind, hir::ExprKind::Lit(_)) {
1004 // Do not suggest `if let x = y` as `==` is way more likely to be the intention.
1005 let hir = self.tcx.hir();
1006 if let hir::Node::Expr(hir::Expr { kind: ExprKind::If { .. }, .. }) =
1007 hir.get(hir.get_parent_node(hir.get_parent_node(expr.hir_id)))
1009 err.span_suggestion_verbose(
1010 expr.span.shrink_to_lo(),
1011 "you might have meant to use pattern matching",
1018 err.span_suggestion_verbose(
1020 "you might have meant to compare for equality",
1026 // If the assignment expression itself is ill-formed, don't
1027 // bother emitting another error
1028 if lhs_ty.references_error() || rhs_ty.references_error() {
1033 return self.tcx.ty_error();
1036 self.check_lhs_assignable(lhs, "E0070", *span);
1038 let lhs_ty = self.check_expr_with_needs(&lhs, Needs::MutPlace);
1039 let rhs_ty = self.check_expr_coercable_to_type(&rhs, lhs_ty, Some(lhs));
1041 self.require_type_is_sized(lhs_ty, lhs.span, traits::AssignmentLhsSized);
1043 if lhs_ty.references_error() || rhs_ty.references_error() {
1050 fn check_expr_let(&self, let_expr: &'tcx hir::Let<'tcx>) -> Ty<'tcx> {
1051 // for let statements, this is done in check_stmt
1052 let init = let_expr.init;
1053 self.warn_if_unreachable(init.hir_id, init.span, "block in `let` expression");
1054 // otherwise check exactly as a let statement
1055 self.check_decl(let_expr.into());
1056 // but return a bool, for this is a boolean expression
1062 body: &'tcx hir::Block<'tcx>,
1063 source: hir::LoopSource,
1064 expected: Expectation<'tcx>,
1065 expr: &'tcx hir::Expr<'tcx>,
1067 let coerce = match source {
1068 // you can only use break with a value from a normal `loop { }`
1069 hir::LoopSource::Loop => {
1070 let coerce_to = expected.coercion_target_type(self, body.span);
1071 Some(CoerceMany::new(coerce_to))
1074 hir::LoopSource::While | hir::LoopSource::ForLoop => None,
1077 let ctxt = BreakableCtxt {
1079 may_break: false, // Will get updated if/when we find a `break`.
1082 let (ctxt, ()) = self.with_breakable_ctxt(expr.hir_id, ctxt, || {
1083 self.check_block_no_value(&body);
1087 // No way to know whether it's diverging because
1088 // of a `break` or an outer `break` or `return`.
1089 self.diverges.set(Diverges::Maybe);
1092 // If we permit break with a value, then result type is
1093 // the LUB of the breaks (possibly ! if none); else, it
1094 // is nil. This makes sense because infinite loops
1095 // (which would have type !) are only possible iff we
1096 // permit break with a value [1].
1097 if ctxt.coerce.is_none() && !ctxt.may_break {
1099 self.tcx.sess.delay_span_bug(body.span, "no coercion, but loop may not break");
1101 ctxt.coerce.map(|c| c.complete(self)).unwrap_or_else(|| self.tcx.mk_unit())
1104 /// Checks a method call.
1105 fn check_method_call(
1107 expr: &'tcx hir::Expr<'tcx>,
1108 segment: &hir::PathSegment<'_>,
1109 args: &'tcx [hir::Expr<'tcx>],
1110 expected: Expectation<'tcx>,
1112 let rcvr = &args[0];
1113 let rcvr_t = self.check_expr(&rcvr);
1114 // no need to check for bot/err -- callee does that
1115 let rcvr_t = self.structurally_resolved_type(args[0].span, rcvr_t);
1116 let span = segment.ident.span;
1118 let method = match self.lookup_method(rcvr_t, segment, span, expr, rcvr, args) {
1120 // We could add a "consider `foo::<params>`" suggestion here, but I wasn't able to
1121 // trigger this codepath causing `structuraly_resolved_type` to emit an error.
1123 self.write_method_call(expr.hir_id, method);
1127 if segment.ident.name != kw::Empty {
1128 if let Some(mut err) = self.report_method_error(
1132 SelfSource::MethodCall(&args[0]),
1143 // Call the generic checker.
1144 self.check_method_argument_types(
1156 e: &'tcx hir::Expr<'tcx>,
1157 t: &'tcx hir::Ty<'tcx>,
1158 expr: &'tcx hir::Expr<'tcx>,
1160 // Find the type of `e`. Supply hints based on the type we are casting to,
1162 let t_cast = self.to_ty_saving_user_provided_ty(t);
1163 let t_cast = self.resolve_vars_if_possible(t_cast);
1164 let t_expr = self.check_expr_with_expectation(e, ExpectCastableToType(t_cast));
1165 let t_expr = self.resolve_vars_if_possible(t_expr);
1167 // Eagerly check for some obvious errors.
1168 if t_expr.references_error() || t_cast.references_error() {
1171 // Defer other checks until we're done type checking.
1172 let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
1173 match cast::CastCheck::new(self, e, t_expr, t_cast, t.span, expr.span) {
1176 "check_expr_cast: deferring cast from {:?} to {:?}: {:?}",
1177 t_cast, t_expr, cast_check,
1179 deferred_cast_checks.push(cast_check);
1182 Err(ErrorReported) => self.tcx.ty_error(),
1187 fn check_expr_array(
1189 args: &'tcx [hir::Expr<'tcx>],
1190 expected: Expectation<'tcx>,
1191 expr: &'tcx hir::Expr<'tcx>,
1193 let element_ty = if !args.is_empty() {
1194 let coerce_to = expected
1196 .and_then(|uty| match *uty.kind() {
1197 ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
1200 .unwrap_or_else(|| {
1201 self.next_ty_var(TypeVariableOrigin {
1202 kind: TypeVariableOriginKind::TypeInference,
1206 let mut coerce = CoerceMany::with_coercion_sites(coerce_to, args);
1207 assert_eq!(self.diverges.get(), Diverges::Maybe);
1209 let e_ty = self.check_expr_with_hint(e, coerce_to);
1210 let cause = self.misc(e.span);
1211 coerce.coerce(self, &cause, e, e_ty);
1213 coerce.complete(self)
1215 self.next_ty_var(TypeVariableOrigin {
1216 kind: TypeVariableOriginKind::TypeInference,
1220 self.tcx.mk_array(element_ty, args.len() as u64)
1223 fn check_expr_const_block(
1225 anon_const: &'tcx hir::AnonConst,
1226 expected: Expectation<'tcx>,
1227 _expr: &'tcx hir::Expr<'tcx>,
1229 let body = self.tcx.hir().body(anon_const.body);
1231 // Create a new function context.
1232 let fcx = FnCtxt::new(self, self.param_env.with_const(), body.value.hir_id);
1233 crate::check::GatherLocalsVisitor::new(&fcx).visit_body(body);
1235 let ty = fcx.check_expr_with_expectation(&body.value, expected);
1236 fcx.require_type_is_sized(ty, body.value.span, traits::ConstSized);
1237 fcx.write_ty(anon_const.hir_id, ty);
1241 fn check_expr_repeat(
1243 element: &'tcx hir::Expr<'tcx>,
1244 count: &'tcx hir::ArrayLen,
1245 expected: Expectation<'tcx>,
1246 _expr: &'tcx hir::Expr<'tcx>,
1249 let count = self.array_length_to_const(count);
1251 let uty = match expected {
1252 ExpectHasType(uty) => match *uty.kind() {
1253 ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
1259 let (element_ty, t) = match uty {
1261 self.check_expr_coercable_to_type(&element, uty, None);
1265 let ty = self.next_ty_var(TypeVariableOrigin {
1266 kind: TypeVariableOriginKind::MiscVariable,
1269 let element_ty = self.check_expr_has_type_or_error(&element, ty, |_| {});
1274 if element_ty.references_error() {
1275 return tcx.ty_error();
1278 tcx.mk_ty(ty::Array(t, count))
1281 fn check_expr_tuple(
1283 elts: &'tcx [hir::Expr<'tcx>],
1284 expected: Expectation<'tcx>,
1285 expr: &'tcx hir::Expr<'tcx>,
1287 let flds = expected.only_has_type(self).and_then(|ty| {
1288 let ty = self.resolve_vars_with_obligations(ty);
1290 ty::Tuple(flds) => Some(&flds[..]),
1295 let elt_ts_iter = elts.iter().enumerate().map(|(i, e)| match flds {
1296 Some(fs) if i < fs.len() => {
1297 let ety = fs[i].expect_ty();
1298 self.check_expr_coercable_to_type(&e, ety, None);
1301 _ => self.check_expr_with_expectation(&e, NoExpectation),
1303 let tuple = self.tcx.mk_tup(elt_ts_iter);
1304 if tuple.references_error() {
1307 self.require_type_is_sized(tuple, expr.span, traits::TupleInitializerSized);
1312 fn check_expr_struct(
1314 expr: &hir::Expr<'_>,
1315 expected: Expectation<'tcx>,
1317 fields: &'tcx [hir::ExprField<'tcx>],
1318 base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
1320 // Find the relevant variant
1321 let (variant, adt_ty) = if let Some(variant_ty) = self.check_struct_path(qpath, expr.hir_id)
1325 self.check_struct_fields_on_error(fields, base_expr);
1326 return self.tcx.ty_error();
1329 // Prohibit struct expressions when non-exhaustive flag is set.
1330 let adt = adt_ty.ty_adt_def().expect("`check_struct_path` returned non-ADT type");
1331 if !adt.did.is_local() && variant.is_field_list_non_exhaustive() {
1334 .emit_err(StructExprNonExhaustive { span: expr.span, what: adt.variant_descr() });
1337 self.check_expr_struct_fields(
1348 self.require_type_is_sized(adt_ty, expr.span, traits::StructInitializerSized);
1352 fn check_expr_struct_fields(
1355 expected: Expectation<'tcx>,
1356 expr_id: hir::HirId,
1358 variant: &'tcx ty::VariantDef,
1359 ast_fields: &'tcx [hir::ExprField<'tcx>],
1360 base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
1365 let adt_ty_hint = self
1366 .expected_inputs_for_expected_output(span, expected, adt_ty, &[adt_ty])
1370 // re-link the regions that EIfEO can erase.
1371 self.demand_eqtype(span, adt_ty_hint, adt_ty);
1373 let (substs, adt_kind, kind_name) = match adt_ty.kind() {
1374 ty::Adt(adt, substs) => (substs, adt.adt_kind(), adt.variant_descr()),
1375 _ => span_bug!(span, "non-ADT passed to check_expr_struct_fields"),
1378 let mut remaining_fields = variant
1382 .map(|(i, field)| (field.ident(tcx).normalize_to_macros_2_0(), (i, field)))
1383 .collect::<FxHashMap<_, _>>();
1385 let mut seen_fields = FxHashMap::default();
1387 let mut error_happened = false;
1389 // Type-check each field.
1390 for field in ast_fields {
1391 let ident = tcx.adjust_ident(field.ident, variant.def_id);
1392 let field_type = if let Some((i, v_field)) = remaining_fields.remove(&ident) {
1393 seen_fields.insert(ident, field.span);
1394 self.write_field_index(field.hir_id, i);
1396 // We don't look at stability attributes on
1397 // struct-like enums (yet...), but it's definitely not
1398 // a bug to have constructed one.
1399 if adt_kind != AdtKind::Enum {
1400 tcx.check_stability(v_field.did, Some(expr_id), field.span, None);
1403 self.field_ty(field.span, v_field, substs)
1405 error_happened = true;
1406 if let Some(prev_span) = seen_fields.get(&ident) {
1407 tcx.sess.emit_err(FieldMultiplySpecifiedInInitializer {
1408 span: field.ident.span,
1409 prev_span: *prev_span,
1413 self.report_unknown_field(
1414 adt_ty, variant, field, ast_fields, kind_name, expr_span,
1421 // Make sure to give a type to the field even if there's
1422 // an error, so we can continue type-checking.
1423 self.check_expr_coercable_to_type(&field.expr, field_type, None);
1426 // Make sure the programmer specified correct number of fields.
1427 if kind_name == "union" {
1428 if ast_fields.len() != 1 {
1433 "union expressions should have exactly one field",
1439 // If check_expr_struct_fields hit an error, do not attempt to populate
1440 // the fields with the base_expr. This could cause us to hit errors later
1441 // when certain fields are assumed to exist that in fact do not.
1446 if let Some(base_expr) = base_expr {
1447 // FIXME: We are currently creating two branches here in order to maintain
1448 // consistency. But they should be merged as much as possible.
1449 let fru_tys = if self.tcx.features().type_changing_struct_update {
1450 let base_ty = self.check_expr(base_expr);
1451 match adt_ty.kind() {
1452 ty::Adt(adt, substs) if adt.is_struct() => {
1453 match base_ty.kind() {
1454 ty::Adt(base_adt, base_subs) if adt == base_adt => {
1459 let fru_ty = self.normalize_associated_types_in(
1461 self.field_ty(base_expr.span, f, base_subs),
1465 .adjust_ident(f.ident(self.tcx), variant.def_id);
1466 if let Some(_) = remaining_fields.remove(&ident) {
1468 self.field_ty(base_expr.span, f, substs);
1469 let cause = self.misc(base_expr.span);
1471 .at(&cause, self.param_env)
1472 .sup(target_ty, fru_ty)
1474 Ok(InferOk { obligations, value: () }) => {
1475 self.register_predicates(obligations)
1477 // FIXME: Need better diagnostics for `FieldMisMatch` error
1479 .report_mismatched_types(
1483 FieldMisMatch(variant.name, ident.name),
1494 .report_mismatched_types(
1495 &self.misc(base_expr.span),
1498 Sorts(ExpectedFound::new(true, adt_ty, base_ty)),
1508 .emit_err(FunctionalRecordUpdateOnNonStruct { span: base_expr.span });
1512 self.check_expr_has_type_or_error(base_expr, adt_ty, |_| {
1513 let base_ty = self.typeck_results.borrow().node_type(base_expr.hir_id);
1514 let same_adt = match (adt_ty.kind(), base_ty.kind()) {
1515 (ty::Adt(adt, _), ty::Adt(base_adt, _)) if adt == base_adt => true,
1518 if self.tcx.sess.is_nightly_build() && same_adt {
1520 &self.tcx.sess.parse_sess,
1521 sym::type_changing_struct_update,
1523 "type changing struct updating is experimental",
1528 match adt_ty.kind() {
1529 ty::Adt(adt, substs) if adt.is_struct() => variant
1533 self.normalize_associated_types_in(expr_span, f.ty(self.tcx, substs))
1540 .emit_err(FunctionalRecordUpdateOnNonStruct { span: base_expr.span });
1544 self.typeck_results.borrow_mut().fru_field_types_mut().insert(expr_id, fru_tys);
1545 } else if kind_name != "union" && !remaining_fields.is_empty() {
1546 let inaccessible_remaining_fields = remaining_fields.iter().any(|(_, (_, field))| {
1547 !field.vis.is_accessible_from(tcx.parent_module(expr_id).to_def_id(), tcx)
1550 if inaccessible_remaining_fields {
1551 self.report_inaccessible_fields(adt_ty, span);
1553 self.report_missing_fields(adt_ty, span, remaining_fields);
1558 fn check_struct_fields_on_error(
1560 fields: &'tcx [hir::ExprField<'tcx>],
1561 base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
1563 for field in fields {
1564 self.check_expr(&field.expr);
1566 if let Some(base) = *base_expr {
1567 self.check_expr(&base);
1571 /// Report an error for a struct field expression when there are fields which aren't provided.
1574 /// error: missing field `you_can_use_this_field` in initializer of `foo::Foo`
1575 /// --> src/main.rs:8:5
1577 /// 8 | foo::Foo {};
1578 /// | ^^^^^^^^ missing `you_can_use_this_field`
1580 /// error: aborting due to previous error
1582 fn report_missing_fields(
1586 remaining_fields: FxHashMap<Ident, (usize, &ty::FieldDef)>,
1588 let len = remaining_fields.len();
1590 let mut displayable_field_names: Vec<&str> =
1591 remaining_fields.keys().map(|ident| ident.as_str()).collect();
1592 // sorting &str primitives here, sort_unstable is ok
1593 displayable_field_names.sort_unstable();
1595 let mut truncated_fields_error = String::new();
1596 let remaining_fields_names = match &displayable_field_names[..] {
1597 [field1] => format!("`{}`", field1),
1598 [field1, field2] => format!("`{}` and `{}`", field1, field2),
1599 [field1, field2, field3] => format!("`{}`, `{}` and `{}`", field1, field2, field3),
1601 truncated_fields_error =
1602 format!(" and {} other field{}", len - 3, pluralize!(len - 3));
1603 displayable_field_names
1606 .map(|n| format!("`{}`", n))
1607 .collect::<Vec<_>>()
1616 "missing field{} {}{} in initializer of `{}`",
1618 remaining_fields_names,
1619 truncated_fields_error,
1622 .span_label(span, format!("missing {}{}", remaining_fields_names, truncated_fields_error))
1626 /// Report an error for a struct field expression when there are invisible fields.
1629 /// error: cannot construct `Foo` with struct literal syntax due to inaccessible fields
1630 /// --> src/main.rs:8:5
1632 /// 8 | foo::Foo {};
1635 /// error: aborting due to previous error
1637 fn report_inaccessible_fields(&self, adt_ty: Ty<'tcx>, span: Span) {
1638 self.tcx.sess.span_err(
1641 "cannot construct `{}` with struct literal syntax due to inaccessible fields",
1647 fn report_unknown_field(
1650 variant: &'tcx ty::VariantDef,
1651 field: &hir::ExprField<'_>,
1652 skip_fields: &[hir::ExprField<'_>],
1656 if variant.is_recovered() {
1657 self.set_tainted_by_errors();
1660 let mut err = self.type_error_struct_with_diag(
1662 |actual| match ty.kind() {
1663 ty::Adt(adt, ..) if adt.is_enum() => struct_span_err!(
1667 "{} `{}::{}` has no field named `{}`",
1673 _ => struct_span_err!(
1677 "{} `{}` has no field named `{}`",
1686 let variant_ident_span = self.tcx.def_ident_span(variant.def_id).unwrap();
1687 match variant.ctor_kind {
1688 CtorKind::Fn => match ty.kind() {
1689 ty::Adt(adt, ..) if adt.is_enum() => {
1693 "`{adt}::{variant}` defined here",
1695 variant = variant.name,
1698 err.span_label(field.ident.span, "field does not exist");
1699 err.span_suggestion_verbose(
1702 "`{adt}::{variant}` is a tuple {kind_name}, use the appropriate syntax",
1704 variant = variant.name,
1707 "{adt}::{variant}(/* fields */)",
1709 variant = variant.name,
1711 Applicability::HasPlaceholders,
1715 err.span_label(variant_ident_span, format!("`{adt}` defined here", adt = ty));
1716 err.span_label(field.ident.span, "field does not exist");
1717 err.span_suggestion_verbose(
1720 "`{adt}` is a tuple {kind_name}, use the appropriate syntax",
1722 kind_name = kind_name,
1724 format!("{adt}(/* fields */)", adt = ty),
1725 Applicability::HasPlaceholders,
1730 // prevent all specified fields from being suggested
1731 let skip_fields = skip_fields.iter().map(|x| x.ident.name);
1732 if let Some(field_name) = self.suggest_field_name(
1735 skip_fields.collect(),
1738 err.span_suggestion(
1740 "a field with a similar name exists",
1741 field_name.to_string(),
1742 Applicability::MaybeIncorrect,
1746 ty::Adt(adt, ..) => {
1750 format!("`{}::{}` does not have this field", ty, variant.name),
1755 format!("`{}` does not have this field", ty),
1758 let available_field_names =
1759 self.available_field_names(variant, expr_span);
1760 if !available_field_names.is_empty() {
1762 "available fields are: {}",
1763 self.name_series_display(available_field_names)
1767 _ => bug!("non-ADT passed to report_unknown_field"),
1775 // Return a hint about the closest match in field names
1776 fn suggest_field_name(
1778 variant: &'tcx ty::VariantDef,
1781 // The span where stability will be checked
1783 ) -> Option<Symbol> {
1787 .filter_map(|field| {
1788 // ignore already set fields and private fields from non-local crates
1789 // and unstable fields.
1790 if skip.iter().any(|&x| x == field.name)
1791 || (!variant.def_id.is_local() && !field.vis.is_public())
1793 self.tcx.eval_stability(field.did, None, span, None),
1794 stability::EvalResult::Deny { .. }
1802 .collect::<Vec<Symbol>>();
1804 find_best_match_for_name(&names, field, None)
1807 fn available_field_names(
1809 variant: &'tcx ty::VariantDef,
1816 let def_scope = self
1818 .adjust_ident_and_get_scope(field.ident(self.tcx), variant.def_id, self.body_id)
1820 field.vis.is_accessible_from(def_scope, self.tcx)
1822 self.tcx.eval_stability(field.did, None, access_span, None),
1823 stability::EvalResult::Deny { .. }
1826 .filter(|field| !self.tcx.is_doc_hidden(field.did))
1827 .map(|field| field.name)
1831 fn name_series_display(&self, names: Vec<Symbol>) -> String {
1832 // dynamic limit, to never omit just one field
1833 let limit = if names.len() == 6 { 6 } else { 5 };
1835 names.iter().take(limit).map(|n| format!("`{}`", n)).collect::<Vec<_>>().join(", ");
1836 if names.len() > limit {
1837 display = format!("{} ... and {} others", display, names.len() - limit);
1842 // Check field access expressions
1845 expr: &'tcx hir::Expr<'tcx>,
1846 base: &'tcx hir::Expr<'tcx>,
1849 debug!("check_field(expr: {:?}, base: {:?}, field: {:?})", expr, base, field);
1850 let expr_t = self.check_expr(base);
1851 let expr_t = self.structurally_resolved_type(base.span, expr_t);
1852 let mut private_candidate = None;
1853 let mut autoderef = self.autoderef(expr.span, expr_t);
1854 while let Some((base_t, _)) = autoderef.next() {
1855 debug!("base_t: {:?}", base_t);
1856 match base_t.kind() {
1857 ty::Adt(base_def, substs) if !base_def.is_enum() => {
1858 debug!("struct named {:?}", base_t);
1859 let (ident, def_scope) =
1860 self.tcx.adjust_ident_and_get_scope(field, base_def.did, self.body_id);
1861 let fields = &base_def.non_enum_variant().fields;
1862 if let Some(index) = fields
1864 .position(|f| f.ident(self.tcx).normalize_to_macros_2_0() == ident)
1866 let field = &fields[index];
1867 let field_ty = self.field_ty(expr.span, field, substs);
1868 // Save the index of all fields regardless of their visibility in case
1869 // of error recovery.
1870 self.write_field_index(expr.hir_id, index);
1871 let adjustments = self.adjust_steps(&autoderef);
1872 if field.vis.is_accessible_from(def_scope, self.tcx) {
1873 self.apply_adjustments(base, adjustments);
1874 self.register_predicates(autoderef.into_obligations());
1876 self.tcx.check_stability(field.did, Some(expr.hir_id), expr.span, None);
1879 private_candidate = Some((adjustments, base_def.did, field_ty));
1883 let fstr = field.as_str();
1884 if let Ok(index) = fstr.parse::<usize>() {
1885 if fstr == index.to_string() {
1886 if let Some(field_ty) = tys.get(index) {
1887 let adjustments = self.adjust_steps(&autoderef);
1888 self.apply_adjustments(base, adjustments);
1889 self.register_predicates(autoderef.into_obligations());
1891 self.write_field_index(expr.hir_id, index);
1892 return field_ty.expect_ty();
1900 self.structurally_resolved_type(autoderef.span(), autoderef.final_ty(false));
1902 if let Some((adjustments, did, field_ty)) = private_candidate {
1903 // (#90483) apply adjustments to avoid ExprUseVisitor from
1904 // creating erroneous projection.
1905 self.apply_adjustments(base, adjustments);
1906 self.ban_private_field_access(expr, expr_t, field, did);
1910 if field.name == kw::Empty {
1911 } else if self.method_exists(field, expr_t, expr.hir_id, true) {
1912 self.ban_take_value_of_method(expr, expr_t, field);
1913 } else if !expr_t.is_primitive_ty() {
1914 self.ban_nonexisting_field(field, base, expr, expr_t);
1921 "`{}` is a primitive type and therefore doesn't have fields",
1927 self.tcx().ty_error()
1930 fn suggest_await_on_field_access(
1932 err: &mut DiagnosticBuilder<'_>,
1934 base: &'tcx hir::Expr<'tcx>,
1937 let output_ty = match self.infcx.get_impl_future_output_ty(ty) {
1938 Some(output_ty) => self.resolve_vars_if_possible(output_ty),
1941 let mut add_label = true;
1942 if let ty::Adt(def, _) = output_ty.skip_binder().kind() {
1943 // no field access on enum type
1949 .any(|field| field.ident(self.tcx) == field_ident)
1954 "field not available in `impl Future`, but it is available in its `Output`",
1956 err.span_suggestion_verbose(
1957 base.span.shrink_to_hi(),
1958 "consider `await`ing on the `Future` and access the field of its `Output`",
1959 ".await".to_string(),
1960 Applicability::MaybeIncorrect,
1966 err.span_label(field_ident.span, &format!("field not found in `{}`", ty));
1970 fn ban_nonexisting_field(
1973 base: &'tcx hir::Expr<'tcx>,
1974 expr: &'tcx hir::Expr<'tcx>,
1978 "ban_nonexisting_field: field={:?}, base={:?}, expr={:?}, expr_ty={:?}",
1979 field, base, expr, expr_t
1981 let mut err = self.no_such_field_err(field, expr_t, base.hir_id);
1983 match *expr_t.peel_refs().kind() {
1984 ty::Array(_, len) => {
1985 self.maybe_suggest_array_indexing(&mut err, expr, base, field, len);
1988 self.suggest_first_deref_field(&mut err, expr, base, field);
1990 ty::Adt(def, _) if !def.is_enum() => {
1991 self.suggest_fields_on_recordish(&mut err, def, field, expr.span);
1993 ty::Param(param_ty) => {
1994 self.point_at_param_definition(&mut err, param_ty);
1996 ty::Opaque(_, _) => {
1997 self.suggest_await_on_field_access(&mut err, field, base, expr_t.peel_refs());
2002 if field.name == kw::Await {
2003 // We know by construction that `<expr>.await` is either on Rust 2015
2004 // or results in `ExprKind::Await`. Suggest switching the edition to 2018.
2005 err.note("to `.await` a `Future`, switch to Rust 2018 or later");
2006 err.help(&format!("set `edition = \"{}\"` in `Cargo.toml`", LATEST_STABLE_EDITION));
2007 err.note("for more on editions, read https://doc.rust-lang.org/edition-guide");
2013 fn ban_private_field_access(
2015 expr: &hir::Expr<'_>,
2020 let struct_path = self.tcx().def_path_str(base_did);
2021 let kind_name = self.tcx().def_kind(base_did).descr(base_did);
2022 let mut err = struct_span_err!(
2026 "field `{}` of {} `{}` is private",
2031 err.span_label(field.span, "private field");
2032 // Also check if an accessible method exists, which is often what is meant.
2033 if self.method_exists(field, expr_t, expr.hir_id, false) && !self.expr_in_place(expr.hir_id)
2035 self.suggest_method_call(
2037 &format!("a method `{}` also exists, call it with parentheses", field),
2047 fn ban_take_value_of_method(&self, expr: &hir::Expr<'_>, expr_t: Ty<'tcx>, field: Ident) {
2048 let mut err = type_error_struct!(
2053 "attempted to take value of method `{}` on type `{}`",
2057 err.span_label(field.span, "method, not a field");
2059 if let hir::Node::Expr(hir::Expr { kind: ExprKind::Call(callee, _args), .. }) =
2060 self.tcx.hir().get(self.tcx.hir().get_parent_node(expr.hir_id))
2062 expr.hir_id == callee.hir_id
2067 self.tcx.sess.source_map().span_to_snippet(expr.span).unwrap_or(String::new());
2068 let is_wrapped = expr_snippet.starts_with('(') && expr_snippet.ends_with(')');
2069 let after_open = expr.span.lo() + rustc_span::BytePos(1);
2070 let before_close = expr.span.hi() - rustc_span::BytePos(1);
2072 if expr_is_call && is_wrapped {
2073 err.multipart_suggestion(
2074 "remove wrapping parentheses to call the method",
2076 (expr.span.with_hi(after_open), String::new()),
2077 (expr.span.with_lo(before_close), String::new()),
2079 Applicability::MachineApplicable,
2081 } else if !self.expr_in_place(expr.hir_id) {
2082 // Suggest call parentheses inside the wrapping parentheses
2083 let span = if is_wrapped {
2084 expr.span.with_lo(after_open).with_hi(before_close)
2088 self.suggest_method_call(
2090 "use parentheses to call the method",
2097 let mut found = false;
2099 if let ty::RawPtr(ty_and_mut) = expr_t.kind() {
2100 if let ty::Adt(adt_def, _) = ty_and_mut.ty.kind() {
2101 if adt_def.variants.len() == 1
2109 .any(|f| f.ident(self.tcx) == field)
2111 if let Some(dot_loc) = expr_snippet.rfind('.') {
2113 err.span_suggestion(
2114 expr.span.with_hi(expr.span.lo() + BytePos::from_usize(dot_loc)),
2115 "to access the field, dereference first",
2116 format!("(*{})", &expr_snippet[0..dot_loc]),
2117 Applicability::MaybeIncorrect,
2125 err.help("methods are immutable and cannot be assigned to");
2132 fn point_at_param_definition(&self, err: &mut DiagnosticBuilder<'_>, param: ty::ParamTy) {
2133 let generics = self.tcx.generics_of(self.body_id.owner.to_def_id());
2134 let generic_param = generics.type_param(¶m, self.tcx);
2135 if let ty::GenericParamDefKind::Type { synthetic: true, .. } = generic_param.kind {
2138 let param_def_id = generic_param.def_id;
2139 let param_hir_id = match param_def_id.as_local() {
2140 Some(x) => self.tcx.hir().local_def_id_to_hir_id(x),
2143 let param_span = self.tcx.hir().span(param_hir_id);
2144 let param_name = self.tcx.hir().ty_param_name(param_hir_id);
2146 err.span_label(param_span, &format!("type parameter '{}' declared here", param_name));
2149 fn suggest_fields_on_recordish(
2151 err: &mut DiagnosticBuilder<'_>,
2152 def: &'tcx ty::AdtDef,
2156 if let Some(suggested_field_name) =
2157 self.suggest_field_name(def.non_enum_variant(), field.name, vec![], access_span)
2159 err.span_suggestion(
2161 "a field with a similar name exists",
2162 suggested_field_name.to_string(),
2163 Applicability::MaybeIncorrect,
2166 err.span_label(field.span, "unknown field");
2167 let struct_variant_def = def.non_enum_variant();
2168 let field_names = self.available_field_names(struct_variant_def, access_span);
2169 if !field_names.is_empty() {
2171 "available fields are: {}",
2172 self.name_series_display(field_names),
2178 fn maybe_suggest_array_indexing(
2180 err: &mut DiagnosticBuilder<'_>,
2181 expr: &hir::Expr<'_>,
2182 base: &hir::Expr<'_>,
2184 len: &ty::Const<'tcx>,
2186 if let (Some(len), Ok(user_index)) =
2187 (len.try_eval_usize(self.tcx, self.param_env), field.as_str().parse::<u64>())
2189 if let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span) {
2190 let help = "instead of using tuple indexing, use array indexing";
2191 let suggestion = format!("{}[{}]", base, field);
2192 let applicability = if len < user_index {
2193 Applicability::MachineApplicable
2195 Applicability::MaybeIncorrect
2197 err.span_suggestion(expr.span, help, suggestion, applicability);
2202 fn suggest_first_deref_field(
2204 err: &mut DiagnosticBuilder<'_>,
2205 expr: &hir::Expr<'_>,
2206 base: &hir::Expr<'_>,
2209 if let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span) {
2210 let msg = format!("`{}` is a raw pointer; try dereferencing it", base);
2211 let suggestion = format!("(*{}).{}", base, field);
2212 err.span_suggestion(expr.span, &msg, suggestion, Applicability::MaybeIncorrect);
2216 fn no_such_field_err(
2219 expr_t: &'tcx ty::TyS<'tcx>,
2221 ) -> DiagnosticBuilder<'_> {
2222 let span = field.span;
2223 debug!("no_such_field_err(span: {:?}, field: {:?}, expr_t: {:?})", span, field, expr_t);
2225 let mut err = type_error_struct!(
2230 "no field `{}` on type `{}`",
2235 // try to add a suggestion in case the field is a nested field of a field of the Adt
2236 if let Some((fields, substs)) = self.get_field_candidates(span, &expr_t) {
2237 for candidate_field in fields.iter() {
2238 if let Some(field_path) = self.check_for_nested_field(
2244 self.tcx.parent_module(id).to_def_id(),
2246 let field_path_str = field_path
2248 .map(|id| id.name.to_ident_string())
2249 .collect::<Vec<String>>()
2251 debug!("field_path_str: {:?}", field_path_str);
2253 err.span_suggestion_verbose(
2254 field.span.shrink_to_lo(),
2255 "one of the expressions' fields has a field of the same name",
2256 format!("{}.", field_path_str),
2257 Applicability::MaybeIncorrect,
2265 fn get_field_candidates(
2269 ) -> Option<(&Vec<ty::FieldDef>, SubstsRef<'tcx>)> {
2270 debug!("get_field_candidates(span: {:?}, base_t: {:?}", span, base_t);
2272 for (base_t, _) in self.autoderef(span, base_t) {
2273 match base_t.kind() {
2274 ty::Adt(base_def, substs) if !base_def.is_enum() => {
2275 let fields = &base_def.non_enum_variant().fields;
2276 // For compile-time reasons put a limit on number of fields we search
2277 if fields.len() > 100 {
2280 return Some((fields, substs));
2288 /// This method is called after we have encountered a missing field error to recursively
2289 /// search for the field
2290 fn check_for_nested_field(
2293 target_field: Ident,
2294 candidate_field: &ty::FieldDef,
2295 subst: SubstsRef<'tcx>,
2296 mut field_path: Vec<Ident>,
2298 ) -> Option<Vec<Ident>> {
2300 "check_for_nested_field(span: {:?}, candidate_field: {:?}, field_path: {:?}",
2301 span, candidate_field, field_path
2304 if candidate_field.ident(self.tcx) == target_field {
2306 } else if field_path.len() > 3 {
2307 // For compile-time reasons and to avoid infinite recursion we only check for fields
2308 // up to a depth of three
2311 // recursively search fields of `candidate_field` if it's a ty::Adt
2313 field_path.push(candidate_field.ident(self.tcx).normalize_to_macros_2_0());
2314 let field_ty = candidate_field.ty(self.tcx, subst);
2315 if let Some((nested_fields, subst)) = self.get_field_candidates(span, &field_ty) {
2316 for field in nested_fields.iter() {
2317 let accessible = field.vis.is_accessible_from(id, self.tcx);
2319 let ident = field.ident(self.tcx).normalize_to_macros_2_0();
2320 if ident == target_field {
2321 return Some(field_path);
2323 let field_path = field_path.clone();
2324 if let Some(path) = self.check_for_nested_field(
2341 fn check_expr_index(
2343 base: &'tcx hir::Expr<'tcx>,
2344 idx: &'tcx hir::Expr<'tcx>,
2345 expr: &'tcx hir::Expr<'tcx>,
2347 let base_t = self.check_expr(&base);
2348 let idx_t = self.check_expr(&idx);
2350 if base_t.references_error() {
2352 } else if idx_t.references_error() {
2355 let base_t = self.structurally_resolved_type(base.span, base_t);
2356 match self.lookup_indexing(expr, base, base_t, idx, idx_t) {
2357 Some((index_ty, element_ty)) => {
2358 // two-phase not needed because index_ty is never mutable
2359 self.demand_coerce(idx, idx_t, index_ty, None, AllowTwoPhase::No);
2363 let mut err = type_error_struct!(
2368 "cannot index into a value of type `{}`",
2371 // Try to give some advice about indexing tuples.
2372 if let ty::Tuple(..) = base_t.kind() {
2373 let mut needs_note = true;
2374 // If the index is an integer, we can show the actual
2375 // fixed expression:
2376 if let ExprKind::Lit(ref lit) = idx.kind {
2377 if let ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) = lit.node {
2378 let snip = self.tcx.sess.source_map().span_to_snippet(base.span);
2379 if let Ok(snip) = snip {
2380 err.span_suggestion(
2382 "to access tuple elements, use",
2383 format!("{}.{}", snip, i),
2384 Applicability::MachineApplicable,
2392 "to access tuple elements, use tuple indexing \
2393 syntax (e.g., `tuple.0`)",
2404 fn check_expr_yield(
2406 value: &'tcx hir::Expr<'tcx>,
2407 expr: &'tcx hir::Expr<'tcx>,
2408 src: &'tcx hir::YieldSource,
2410 match self.resume_yield_tys {
2411 Some((resume_ty, yield_ty)) => {
2412 self.check_expr_coercable_to_type(&value, yield_ty, None);
2416 // Given that this `yield` expression was generated as a result of lowering a `.await`,
2417 // we know that the yield type must be `()`; however, the context won't contain this
2418 // information. Hence, we check the source of the yield expression here and check its
2419 // value's type against `()` (this check should always hold).
2420 None if src.is_await() => {
2421 self.check_expr_coercable_to_type(&value, self.tcx.mk_unit(), None);
2425 self.tcx.sess.emit_err(YieldExprOutsideOfGenerator { span: expr.span });
2426 // Avoid expressions without types during writeback (#78653).
2427 self.check_expr(value);
2433 fn check_expr_asm_operand(&self, expr: &'tcx hir::Expr<'tcx>, is_input: bool) {
2434 let needs = if is_input { Needs::None } else { Needs::MutPlace };
2435 let ty = self.check_expr_with_needs(expr, needs);
2436 self.require_type_is_sized(ty, expr.span, traits::InlineAsmSized);
2438 if !is_input && !expr.is_syntactic_place_expr() {
2439 let mut err = self.tcx.sess.struct_span_err(expr.span, "invalid asm output");
2440 err.span_label(expr.span, "cannot assign to this expression");
2444 // If this is an input value, we require its type to be fully resolved
2445 // at this point. This allows us to provide helpful coercions which help
2446 // pass the type candidate list in a later pass.
2448 // We don't require output types to be resolved at this point, which
2449 // allows them to be inferred based on how they are used later in the
2452 let ty = self.structurally_resolved_type(expr.span, &ty);
2455 let fnptr_ty = self.tcx.mk_fn_ptr(ty.fn_sig(self.tcx));
2456 self.demand_coerce(expr, ty, fnptr_ty, None, AllowTwoPhase::No);
2458 ty::Ref(_, base_ty, mutbl) => {
2459 let ptr_ty = self.tcx.mk_ptr(ty::TypeAndMut { ty: base_ty, mutbl });
2460 self.demand_coerce(expr, ty, ptr_ty, None, AllowTwoPhase::No);
2467 fn check_expr_asm(&self, asm: &'tcx hir::InlineAsm<'tcx>) -> Ty<'tcx> {
2468 for (op, _op_sp) in asm.operands {
2470 hir::InlineAsmOperand::In { expr, .. } => {
2471 self.check_expr_asm_operand(expr, true);
2473 hir::InlineAsmOperand::Out { expr: Some(expr), .. }
2474 | hir::InlineAsmOperand::InOut { expr, .. } => {
2475 self.check_expr_asm_operand(expr, false);
2477 hir::InlineAsmOperand::Out { expr: None, .. } => {}
2478 hir::InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
2479 self.check_expr_asm_operand(in_expr, true);
2480 if let Some(out_expr) = out_expr {
2481 self.check_expr_asm_operand(out_expr, false);
2484 hir::InlineAsmOperand::Const { anon_const } => {
2485 self.to_const(anon_const);
2487 hir::InlineAsmOperand::Sym { expr } => {
2488 self.check_expr(expr);
2492 if asm.options.contains(ast::InlineAsmOptions::NORETURN) {
2493 self.tcx.types.never
2500 pub(super) fn ty_kind_suggestion(ty: Ty<'_>) -> Option<&'static str> {
2501 Some(match ty.kind() {
2504 ty::Int(_) | ty::Uint(_) => "42",
2505 ty::Float(_) => "3.14159",
2506 ty::Error(_) | ty::Never => return None,