--- /dev/null
+//! Type checking expressions.
+//!
+//! See `mod.rs` for more context on type checking in general.
+
+use crate::cast;
+use crate::coercion::CoerceMany;
+use crate::coercion::DynamicCoerceMany;
+use crate::errors::{AddressOfTemporaryTaken, ReturnStmtOutsideOfFnBody, StructExprNonExhaustive};
+use crate::errors::{
+ FieldMultiplySpecifiedInInitializer, FunctionalRecordUpdateOnNonStruct,
+ YieldExprOutsideOfGenerator,
+};
+use crate::fatally_break_rust;
+use crate::method::SelfSource;
+use crate::type_error_struct;
+use crate::Expectation::{self, ExpectCastableToType, ExpectHasType, NoExpectation};
+use crate::{
+ report_unexpected_variant_res, BreakableCtxt, Diverges, FnCtxt, Needs,
+ TupleArgumentsFlag::DontTupleArguments,
+};
+use rustc_ast as ast;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stack::ensure_sufficient_stack;
+use rustc_errors::{
+ pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, DiagnosticId,
+ ErrorGuaranteed, StashKey,
+};
+use rustc_hir as hir;
+use rustc_hir::def::{CtorKind, DefKind, Res};
+use rustc_hir::def_id::DefId;
+use rustc_hir::intravisit::Visitor;
+use rustc_hir::lang_items::LangItem;
+use rustc_hir::{Closure, ExprKind, HirId, QPath};
+use rustc_hir_analysis::astconv::AstConv as _;
+use rustc_hir_analysis::check::ty_kind_suggestion;
+use rustc_infer::infer;
+use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
+use rustc_infer::infer::InferOk;
+use rustc_infer::traits::ObligationCause;
+use rustc_middle::middle::stability;
+use rustc_middle::ty::adjustment::{Adjust, Adjustment, AllowTwoPhase};
+use rustc_middle::ty::error::TypeError::FieldMisMatch;
+use rustc_middle::ty::subst::SubstsRef;
+use rustc_middle::ty::{self, AdtKind, Ty, TypeVisitable};
+use rustc_session::errors::ExprParenthesesNeeded;
+use rustc_session::parse::feature_err;
+use rustc_span::hygiene::DesugaringKind;
+use rustc_span::lev_distance::find_best_match_for_name;
+use rustc_span::source_map::{Span, Spanned};
+use rustc_span::symbol::{kw, sym, Ident, Symbol};
+use rustc_target::spec::abi::Abi::RustIntrinsic;
+use rustc_trait_selection::infer::InferCtxtExt;
+use rustc_trait_selection::traits::{self, ObligationCauseCode};
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+ fn check_expr_eq_type(&self, expr: &'tcx hir::Expr<'tcx>, expected: Ty<'tcx>) {
+ let ty = self.check_expr_with_hint(expr, expected);
+ self.demand_eqtype(expr.span, expected, ty);
+ }
+
+ pub fn check_expr_has_type_or_error(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Ty<'tcx>,
+ extend_err: impl FnMut(&mut Diagnostic),
+ ) -> Ty<'tcx> {
+ self.check_expr_meets_expectation_or_error(expr, ExpectHasType(expected), extend_err)
+ }
+
+ fn check_expr_meets_expectation_or_error(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ mut extend_err: impl FnMut(&mut Diagnostic),
+ ) -> Ty<'tcx> {
+ let expected_ty = expected.to_option(&self).unwrap_or(self.tcx.types.bool);
+ let mut ty = self.check_expr_with_expectation(expr, expected);
+
+ // While we don't allow *arbitrary* coercions here, we *do* allow
+ // coercions from ! to `expected`.
+ if ty.is_never() {
+ if let Some(adjustments) = self.typeck_results.borrow().adjustments().get(expr.hir_id) {
+ self.tcx().sess.delay_span_bug(
+ expr.span,
+ "expression with never type wound up being adjusted",
+ );
+ return if let [Adjustment { kind: Adjust::NeverToAny, target }] = &adjustments[..] {
+ target.to_owned()
+ } else {
+ self.tcx().ty_error()
+ };
+ }
+
+ let adj_ty = self.next_ty_var(TypeVariableOrigin {
+ kind: TypeVariableOriginKind::AdjustmentType,
+ span: expr.span,
+ });
+ self.apply_adjustments(
+ expr,
+ vec![Adjustment { kind: Adjust::NeverToAny, target: adj_ty }],
+ );
+ ty = adj_ty;
+ }
+
+ if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) {
+ let expr = expr.peel_drop_temps();
+ self.suggest_deref_ref_or_into(&mut err, expr, expected_ty, ty, None);
+ extend_err(&mut err);
+ err.emit();
+ }
+ ty
+ }
+
+ pub(super) fn check_expr_coercable_to_type(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Ty<'tcx>,
+ expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
+ ) -> Ty<'tcx> {
+ let ty = self.check_expr_with_hint(expr, expected);
+ // checks don't need two phase
+ self.demand_coerce(expr, ty, expected, expected_ty_expr, AllowTwoPhase::No)
+ }
+
+ pub(super) fn check_expr_with_hint(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Ty<'tcx>,
+ ) -> Ty<'tcx> {
+ self.check_expr_with_expectation(expr, ExpectHasType(expected))
+ }
+
+ fn check_expr_with_expectation_and_needs(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ needs: Needs,
+ ) -> Ty<'tcx> {
+ let ty = self.check_expr_with_expectation(expr, expected);
+
+ // If the expression is used in a place whether mutable place is required
+ // e.g. LHS of assignment, perform the conversion.
+ if let Needs::MutPlace = needs {
+ self.convert_place_derefs_to_mutable(expr);
+ }
+
+ ty
+ }
+
+ pub(super) fn check_expr(&self, expr: &'tcx hir::Expr<'tcx>) -> Ty<'tcx> {
+ self.check_expr_with_expectation(expr, NoExpectation)
+ }
+
+ pub(super) fn check_expr_with_needs(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ needs: Needs,
+ ) -> Ty<'tcx> {
+ self.check_expr_with_expectation_and_needs(expr, NoExpectation, needs)
+ }
+
+ /// Invariant:
+ /// If an expression has any sub-expressions that result in a type error,
+ /// inspecting that expression's type with `ty.references_error()` will return
+ /// true. Likewise, if an expression is known to diverge, inspecting its
+ /// type with `ty::type_is_bot` will return true (n.b.: since Rust is
+ /// strict, _|_ can appear in the type of an expression that does not,
+ /// itself, diverge: for example, fn() -> _|_.)
+ /// Note that inspecting a type's structure *directly* may expose the fact
+ /// that there are actually multiple representations for `Error`, so avoid
+ /// that when err needs to be handled differently.
+ #[instrument(skip(self, expr), level = "debug")]
+ pub(super) fn check_expr_with_expectation(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ self.check_expr_with_expectation_and_args(expr, expected, &[])
+ }
+
+ /// Same as `check_expr_with_expectation`, but allows us to pass in the arguments of a
+ /// `ExprKind::Call` when evaluating its callee when it is an `ExprKind::Path`.
+ pub(super) fn check_expr_with_expectation_and_args(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ args: &'tcx [hir::Expr<'tcx>],
+ ) -> Ty<'tcx> {
+ if self.tcx().sess.verbose() {
+ // make this code only run with -Zverbose because it is probably slow
+ if let Ok(lint_str) = self.tcx.sess.source_map().span_to_snippet(expr.span) {
+ if !lint_str.contains('\n') {
+ debug!("expr text: {lint_str}");
+ } else {
+ let mut lines = lint_str.lines();
+ if let Some(line0) = lines.next() {
+ let remaining_lines = lines.count();
+ debug!("expr text: {line0}");
+ debug!("expr text: ...(and {remaining_lines} more lines)");
+ }
+ }
+ }
+ }
+
+ // True if `expr` is a `Try::from_ok(())` that is a result of desugaring a try block
+ // without the final expr (e.g. `try { return; }`). We don't want to generate an
+ // unreachable_code lint for it since warnings for autogenerated code are confusing.
+ let is_try_block_generated_unit_expr = match expr.kind {
+ ExprKind::Call(_, args) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {
+ args.len() == 1 && args[0].span.is_desugaring(DesugaringKind::TryBlock)
+ }
+
+ _ => false,
+ };
+
+ // Warn for expressions after diverging siblings.
+ if !is_try_block_generated_unit_expr {
+ self.warn_if_unreachable(expr.hir_id, expr.span, "expression");
+ }
+
+ // Hide the outer diverging and has_errors flags.
+ let old_diverges = self.diverges.replace(Diverges::Maybe);
+ let old_has_errors = self.has_errors.replace(false);
+
+ let ty = ensure_sufficient_stack(|| match &expr.kind {
+ hir::ExprKind::Path(
+ qpath @ hir::QPath::Resolved(..) | qpath @ hir::QPath::TypeRelative(..),
+ ) => self.check_expr_path(qpath, expr, args),
+ _ => self.check_expr_kind(expr, expected),
+ });
+
+ // Warn for non-block expressions with diverging children.
+ match expr.kind {
+ ExprKind::Block(..)
+ | ExprKind::If(..)
+ | ExprKind::Let(..)
+ | ExprKind::Loop(..)
+ | ExprKind::Match(..) => {}
+ // If `expr` is a result of desugaring the try block and is an ok-wrapped
+ // diverging expression (e.g. it arose from desugaring of `try { return }`),
+ // we skip issuing a warning because it is autogenerated code.
+ ExprKind::Call(..) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {}
+ ExprKind::Call(callee, _) => self.warn_if_unreachable(expr.hir_id, callee.span, "call"),
+ ExprKind::MethodCall(segment, ..) => {
+ self.warn_if_unreachable(expr.hir_id, segment.ident.span, "call")
+ }
+ _ => self.warn_if_unreachable(expr.hir_id, expr.span, "expression"),
+ }
+
+ // Any expression that produces a value of type `!` must have diverged
+ if ty.is_never() {
+ self.diverges.set(self.diverges.get() | Diverges::always(expr.span));
+ }
+
+ // Record the type, which applies it effects.
+ // We need to do this after the warning above, so that
+ // we don't warn for the diverging expression itself.
+ self.write_ty(expr.hir_id, ty);
+
+ // Combine the diverging and has_error flags.
+ self.diverges.set(self.diverges.get() | old_diverges);
+ self.has_errors.set(self.has_errors.get() | old_has_errors);
+
+ debug!("type of {} is...", self.tcx.hir().node_to_string(expr.hir_id));
+ debug!("... {:?}, expected is {:?}", ty, expected);
+
+ ty
+ }
+
+ #[instrument(skip(self, expr), level = "debug")]
+ fn check_expr_kind(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ trace!("expr={:#?}", expr);
+
+ let tcx = self.tcx;
+ match expr.kind {
+ ExprKind::Box(subexpr) => self.check_expr_box(subexpr, expected),
+ ExprKind::Lit(ref lit) => self.check_lit(&lit, expected),
+ ExprKind::Binary(op, lhs, rhs) => self.check_binop(expr, op, lhs, rhs, expected),
+ ExprKind::Assign(lhs, rhs, span) => {
+ self.check_expr_assign(expr, expected, lhs, rhs, span)
+ }
+ ExprKind::AssignOp(op, lhs, rhs) => {
+ self.check_binop_assign(expr, op, lhs, rhs, expected)
+ }
+ ExprKind::Unary(unop, oprnd) => self.check_expr_unary(unop, oprnd, expected, expr),
+ ExprKind::AddrOf(kind, mutbl, oprnd) => {
+ self.check_expr_addr_of(kind, mutbl, oprnd, expected, expr)
+ }
+ ExprKind::Path(QPath::LangItem(lang_item, _, hir_id)) => {
+ self.check_lang_item_path(lang_item, expr, hir_id)
+ }
+ ExprKind::Path(ref qpath) => self.check_expr_path(qpath, expr, &[]),
+ ExprKind::InlineAsm(asm) => {
+ // We defer some asm checks as we may not have resolved the input and output types yet (they may still be infer vars).
+ self.deferred_asm_checks.borrow_mut().push((asm, expr.hir_id));
+ self.check_expr_asm(asm)
+ }
+ ExprKind::Break(destination, ref expr_opt) => {
+ self.check_expr_break(destination, expr_opt.as_deref(), expr)
+ }
+ ExprKind::Continue(destination) => {
+ if destination.target_id.is_ok() {
+ tcx.types.never
+ } else {
+ // There was an error; make type-check fail.
+ tcx.ty_error()
+ }
+ }
+ ExprKind::Ret(ref expr_opt) => self.check_expr_return(expr_opt.as_deref(), expr),
+ ExprKind::Let(let_expr) => self.check_expr_let(let_expr),
+ ExprKind::Loop(body, _, source, _) => {
+ self.check_expr_loop(body, source, expected, expr)
+ }
+ ExprKind::Match(discrim, arms, match_src) => {
+ self.check_match(expr, &discrim, arms, expected, match_src)
+ }
+ ExprKind::Closure(&Closure { capture_clause, fn_decl, body, movability, .. }) => {
+ self.check_expr_closure(expr, capture_clause, &fn_decl, body, movability, expected)
+ }
+ ExprKind::Block(body, _) => self.check_block_with_expected(&body, expected),
+ ExprKind::Call(callee, args) => self.check_call(expr, &callee, args, expected),
+ ExprKind::MethodCall(segment, receiver, args, _) => {
+ self.check_method_call(expr, segment, receiver, args, expected)
+ }
+ ExprKind::Cast(e, t) => self.check_expr_cast(e, t, expr),
+ ExprKind::Type(e, t) => {
+ let ty = self.to_ty_saving_user_provided_ty(&t);
+ self.check_expr_eq_type(&e, ty);
+ ty
+ }
+ ExprKind::If(cond, then_expr, opt_else_expr) => {
+ self.check_then_else(cond, then_expr, opt_else_expr, expr.span, expected)
+ }
+ ExprKind::DropTemps(e) => self.check_expr_with_expectation(e, expected),
+ ExprKind::Array(args) => self.check_expr_array(args, expected, expr),
+ ExprKind::ConstBlock(ref anon_const) => {
+ self.check_expr_const_block(anon_const, expected, expr)
+ }
+ ExprKind::Repeat(element, ref count) => {
+ self.check_expr_repeat(element, count, expected, expr)
+ }
+ ExprKind::Tup(elts) => self.check_expr_tuple(elts, expected, expr),
+ ExprKind::Struct(qpath, fields, ref base_expr) => {
+ self.check_expr_struct(expr, expected, qpath, fields, base_expr)
+ }
+ ExprKind::Field(base, field) => self.check_field(expr, &base, field),
+ ExprKind::Index(base, idx) => self.check_expr_index(base, idx, expr),
+ ExprKind::Yield(value, ref src) => self.check_expr_yield(value, expr, src),
+ hir::ExprKind::Err => tcx.ty_error(),
+ }
+ }
+
+ fn check_expr_box(&self, expr: &'tcx hir::Expr<'tcx>, expected: Expectation<'tcx>) -> Ty<'tcx> {
+ let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| match ty.kind() {
+ ty::Adt(def, _) if def.is_box() => Expectation::rvalue_hint(self, ty.boxed_ty()),
+ _ => NoExpectation,
+ });
+ let referent_ty = self.check_expr_with_expectation(expr, expected_inner);
+ self.require_type_is_sized(referent_ty, expr.span, traits::SizedBoxType);
+ self.tcx.mk_box(referent_ty)
+ }
+
+ fn check_expr_unary(
+ &self,
+ unop: hir::UnOp,
+ oprnd: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let tcx = self.tcx;
+ let expected_inner = match unop {
+ hir::UnOp::Not | hir::UnOp::Neg => expected,
+ hir::UnOp::Deref => NoExpectation,
+ };
+ let mut oprnd_t = self.check_expr_with_expectation(&oprnd, expected_inner);
+
+ if !oprnd_t.references_error() {
+ oprnd_t = self.structurally_resolved_type(expr.span, oprnd_t);
+ match unop {
+ hir::UnOp::Deref => {
+ if let Some(ty) = self.lookup_derefing(expr, oprnd, oprnd_t) {
+ oprnd_t = ty;
+ } else {
+ let mut err = type_error_struct!(
+ tcx.sess,
+ expr.span,
+ oprnd_t,
+ E0614,
+ "type `{oprnd_t}` cannot be dereferenced",
+ );
+ let sp = tcx.sess.source_map().start_point(expr.span);
+ if let Some(sp) =
+ tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp)
+ {
+ err.subdiagnostic(ExprParenthesesNeeded::surrounding(*sp));
+ }
+ err.emit();
+ oprnd_t = tcx.ty_error();
+ }
+ }
+ hir::UnOp::Not => {
+ let result = self.check_user_unop(expr, oprnd_t, unop, expected_inner);
+ // If it's builtin, we can reuse the type, this helps inference.
+ if !(oprnd_t.is_integral() || *oprnd_t.kind() == ty::Bool) {
+ oprnd_t = result;
+ }
+ }
+ hir::UnOp::Neg => {
+ let result = self.check_user_unop(expr, oprnd_t, unop, expected_inner);
+ // If it's builtin, we can reuse the type, this helps inference.
+ if !oprnd_t.is_numeric() {
+ oprnd_t = result;
+ }
+ }
+ }
+ }
+ oprnd_t
+ }
+
+ fn check_expr_addr_of(
+ &self,
+ kind: hir::BorrowKind,
+ mutbl: hir::Mutability,
+ oprnd: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let hint = expected.only_has_type(self).map_or(NoExpectation, |ty| {
+ match ty.kind() {
+ ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
+ if oprnd.is_syntactic_place_expr() {
+ // Places may legitimately have unsized types.
+ // For example, dereferences of a fat pointer and
+ // the last field of a struct can be unsized.
+ ExpectHasType(*ty)
+ } else {
+ Expectation::rvalue_hint(self, *ty)
+ }
+ }
+ _ => NoExpectation,
+ }
+ });
+ let ty =
+ self.check_expr_with_expectation_and_needs(&oprnd, hint, Needs::maybe_mut_place(mutbl));
+
+ let tm = ty::TypeAndMut { ty, mutbl };
+ match kind {
+ _ if tm.ty.references_error() => self.tcx.ty_error(),
+ hir::BorrowKind::Raw => {
+ self.check_named_place_expr(oprnd);
+ self.tcx.mk_ptr(tm)
+ }
+ hir::BorrowKind::Ref => {
+ // Note: at this point, we cannot say what the best lifetime
+ // is to use for resulting pointer. We want to use the
+ // shortest lifetime possible so as to avoid spurious borrowck
+ // errors. Moreover, the longest lifetime will depend on the
+ // precise details of the value whose address is being taken
+ // (and how long it is valid), which we don't know yet until
+ // type inference is complete.
+ //
+ // Therefore, here we simply generate a region variable. The
+ // region inferencer will then select a suitable value.
+ // Finally, borrowck will infer the value of the region again,
+ // this time with enough precision to check that the value
+ // whose address was taken can actually be made to live as long
+ // as it needs to live.
+ let region = self.next_region_var(infer::AddrOfRegion(expr.span));
+ self.tcx.mk_ref(region, tm)
+ }
+ }
+ }
+
+ /// Does this expression refer to a place that either:
+ /// * Is based on a local or static.
+ /// * Contains a dereference
+ /// Note that the adjustments for the children of `expr` should already
+ /// have been resolved.
+ fn check_named_place_expr(&self, oprnd: &'tcx hir::Expr<'tcx>) {
+ let is_named = oprnd.is_place_expr(|base| {
+ // Allow raw borrows if there are any deref adjustments.
+ //
+ // const VAL: (i32,) = (0,);
+ // const REF: &(i32,) = &(0,);
+ //
+ // &raw const VAL.0; // ERROR
+ // &raw const REF.0; // OK, same as &raw const (*REF).0;
+ //
+ // This is maybe too permissive, since it allows
+ // `let u = &raw const Box::new((1,)).0`, which creates an
+ // immediately dangling raw pointer.
+ self.typeck_results
+ .borrow()
+ .adjustments()
+ .get(base.hir_id)
+ .map_or(false, |x| x.iter().any(|adj| matches!(adj.kind, Adjust::Deref(_))))
+ });
+ if !is_named {
+ self.tcx.sess.emit_err(AddressOfTemporaryTaken { span: oprnd.span });
+ }
+ }
+
+ fn check_lang_item_path(
+ &self,
+ lang_item: hir::LangItem,
+ expr: &'tcx hir::Expr<'tcx>,
+ hir_id: Option<hir::HirId>,
+ ) -> Ty<'tcx> {
+ self.resolve_lang_item_path(lang_item, expr.span, expr.hir_id, hir_id).1
+ }
+
+ pub(crate) fn check_expr_path(
+ &self,
+ qpath: &'tcx hir::QPath<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ args: &'tcx [hir::Expr<'tcx>],
+ ) -> Ty<'tcx> {
+ let tcx = self.tcx;
+ let (res, opt_ty, segs) =
+ self.resolve_ty_and_res_fully_qualified_call(qpath, expr.hir_id, expr.span);
+ let ty = match res {
+ Res::Err => {
+ self.set_tainted_by_errors();
+ tcx.ty_error()
+ }
+ Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _) => {
+ report_unexpected_variant_res(tcx, res, qpath, expr.span);
+ tcx.ty_error()
+ }
+ _ => self.instantiate_value_path(segs, opt_ty, res, expr.span, expr.hir_id).0,
+ };
+
+ if let ty::FnDef(did, ..) = *ty.kind() {
+ let fn_sig = ty.fn_sig(tcx);
+ if tcx.fn_sig(did).abi() == RustIntrinsic && tcx.item_name(did) == sym::transmute {
+ let from = fn_sig.inputs().skip_binder()[0];
+ let to = fn_sig.output().skip_binder();
+ // We defer the transmute to the end of typeck, once all inference vars have
+ // been resolved or we errored. This is important as we can only check transmute
+ // on concrete types, but the output type may not be known yet (it would only
+ // be known if explicitly specified via turbofish).
+ self.deferred_transmute_checks.borrow_mut().push((from, to, expr.hir_id));
+ }
+ if !tcx.features().unsized_fn_params {
+ // We want to remove some Sized bounds from std functions,
+ // but don't want to expose the removal to stable Rust.
+ // i.e., we don't want to allow
+ //
+ // ```rust
+ // drop as fn(str);
+ // ```
+ //
+ // to work in stable even if the Sized bound on `drop` is relaxed.
+ for i in 0..fn_sig.inputs().skip_binder().len() {
+ // We just want to check sizedness, so instead of introducing
+ // placeholder lifetimes with probing, we just replace higher lifetimes
+ // with fresh vars.
+ let span = args.get(i).map(|a| a.span).unwrap_or(expr.span);
+ let input = self.replace_bound_vars_with_fresh_vars(
+ span,
+ infer::LateBoundRegionConversionTime::FnCall,
+ fn_sig.input(i),
+ );
+ self.require_type_is_sized_deferred(
+ input,
+ span,
+ traits::SizedArgumentType(None),
+ );
+ }
+ }
+ // Here we want to prevent struct constructors from returning unsized types.
+ // There were two cases this happened: fn pointer coercion in stable
+ // and usual function call in presence of unsized_locals.
+ // Also, as we just want to check sizedness, instead of introducing
+ // placeholder lifetimes with probing, we just replace higher lifetimes
+ // with fresh vars.
+ let output = self.replace_bound_vars_with_fresh_vars(
+ expr.span,
+ infer::LateBoundRegionConversionTime::FnCall,
+ fn_sig.output(),
+ );
+ self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType);
+ }
+
+ // We always require that the type provided as the value for
+ // a type parameter outlives the moment of instantiation.
+ let substs = self.typeck_results.borrow().node_substs(expr.hir_id);
+ self.add_wf_bounds(substs, expr);
+
+ ty
+ }
+
+ fn check_expr_break(
+ &self,
+ destination: hir::Destination,
+ expr_opt: Option<&'tcx hir::Expr<'tcx>>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let tcx = self.tcx;
+ if let Ok(target_id) = destination.target_id {
+ let (e_ty, cause);
+ if let Some(e) = expr_opt {
+ // If this is a break with a value, we need to type-check
+ // the expression. Get an expected type from the loop context.
+ let opt_coerce_to = {
+ // We should release `enclosing_breakables` before the `check_expr_with_hint`
+ // below, so can't move this block of code to the enclosing scope and share
+ // `ctxt` with the second `enclosing_breakables` borrow below.
+ let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
+ match enclosing_breakables.opt_find_breakable(target_id) {
+ Some(ctxt) => ctxt.coerce.as_ref().map(|coerce| coerce.expected_ty()),
+ None => {
+ // Avoid ICE when `break` is inside a closure (#65383).
+ return tcx.ty_error_with_message(
+ expr.span,
+ "break was outside loop, but no error was emitted",
+ );
+ }
+ }
+ };
+
+ // If the loop context is not a `loop { }`, then break with
+ // a value is illegal, and `opt_coerce_to` will be `None`.
+ // Just set expectation to error in that case.
+ let coerce_to = opt_coerce_to.unwrap_or_else(|| tcx.ty_error());
+
+ // Recurse without `enclosing_breakables` borrowed.
+ e_ty = self.check_expr_with_hint(e, coerce_to);
+ cause = self.misc(e.span);
+ } else {
+ // Otherwise, this is a break *without* a value. That's
+ // always legal, and is equivalent to `break ()`.
+ e_ty = tcx.mk_unit();
+ cause = self.misc(expr.span);
+ }
+
+ // Now that we have type-checked `expr_opt`, borrow
+ // the `enclosing_loops` field and let's coerce the
+ // type of `expr_opt` into what is expected.
+ let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
+ let Some(ctxt) = enclosing_breakables.opt_find_breakable(target_id) else {
+ // Avoid ICE when `break` is inside a closure (#65383).
+ return tcx.ty_error_with_message(
+ expr.span,
+ "break was outside loop, but no error was emitted",
+ );
+ };
+
+ if let Some(ref mut coerce) = ctxt.coerce {
+ if let Some(ref e) = expr_opt {
+ coerce.coerce(self, &cause, e, e_ty);
+ } else {
+ assert!(e_ty.is_unit());
+ let ty = coerce.expected_ty();
+ coerce.coerce_forced_unit(
+ self,
+ &cause,
+ &mut |mut err| {
+ self.suggest_mismatched_types_on_tail(
+ &mut err, expr, ty, e_ty, target_id,
+ );
+ if let Some(val) = ty_kind_suggestion(ty) {
+ let label = destination
+ .label
+ .map(|l| format!(" {}", l.ident))
+ .unwrap_or_else(String::new);
+ err.span_suggestion(
+ expr.span,
+ "give it a value of the expected type",
+ format!("break{label} {val}"),
+ Applicability::HasPlaceholders,
+ );
+ }
+ },
+ false,
+ );
+ }
+ } else {
+ // If `ctxt.coerce` is `None`, we can just ignore
+ // the type of the expression. This is because
+ // either this was a break *without* a value, in
+ // which case it is always a legal type (`()`), or
+ // else an error would have been flagged by the
+ // `loops` pass for using break with an expression
+ // where you are not supposed to.
+ assert!(expr_opt.is_none() || self.tcx.sess.has_errors().is_some());
+ }
+
+ // If we encountered a `break`, then (no surprise) it may be possible to break from the
+ // loop... unless the value being returned from the loop diverges itself, e.g.
+ // `break return 5` or `break loop {}`.
+ ctxt.may_break |= !self.diverges.get().is_always();
+
+ // the type of a `break` is always `!`, since it diverges
+ tcx.types.never
+ } else {
+ // Otherwise, we failed to find the enclosing loop;
+ // this can only happen if the `break` was not
+ // inside a loop at all, which is caught by the
+ // loop-checking pass.
+ let err = self.tcx.ty_error_with_message(
+ expr.span,
+ "break was outside loop, but no error was emitted",
+ );
+
+ // We still need to assign a type to the inner expression to
+ // prevent the ICE in #43162.
+ if let Some(e) = expr_opt {
+ self.check_expr_with_hint(e, err);
+
+ // ... except when we try to 'break rust;'.
+ // ICE this expression in particular (see #43162).
+ if let ExprKind::Path(QPath::Resolved(_, path)) = e.kind {
+ if path.segments.len() == 1 && path.segments[0].ident.name == sym::rust {
+ fatally_break_rust(self.tcx.sess);
+ }
+ }
+ }
+
+ // There was an error; make type-check fail.
+ err
+ }
+ }
+
+ fn check_expr_return(
+ &self,
+ expr_opt: Option<&'tcx hir::Expr<'tcx>>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ if self.ret_coercion.is_none() {
+ let mut err = ReturnStmtOutsideOfFnBody {
+ span: expr.span,
+ encl_body_span: None,
+ encl_fn_span: None,
+ };
+
+ let encl_item_id = self.tcx.hir().get_parent_item(expr.hir_id);
+
+ if let Some(hir::Node::Item(hir::Item {
+ kind: hir::ItemKind::Fn(..),
+ span: encl_fn_span,
+ ..
+ }))
+ | Some(hir::Node::TraitItem(hir::TraitItem {
+ kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)),
+ span: encl_fn_span,
+ ..
+ }))
+ | Some(hir::Node::ImplItem(hir::ImplItem {
+ kind: hir::ImplItemKind::Fn(..),
+ span: encl_fn_span,
+ ..
+ })) = self.tcx.hir().find_by_def_id(encl_item_id.def_id)
+ {
+ // We are inside a function body, so reporting "return statement
+ // outside of function body" needs an explanation.
+
+ let encl_body_owner_id = self.tcx.hir().enclosing_body_owner(expr.hir_id);
+
+ // If this didn't hold, we would not have to report an error in
+ // the first place.
+ assert_ne!(encl_item_id.def_id, encl_body_owner_id);
+
+ let encl_body_id = self.tcx.hir().body_owned_by(encl_body_owner_id);
+ let encl_body = self.tcx.hir().body(encl_body_id);
+
+ err.encl_body_span = Some(encl_body.value.span);
+ err.encl_fn_span = Some(*encl_fn_span);
+ }
+
+ self.tcx.sess.emit_err(err);
+
+ if let Some(e) = expr_opt {
+ // We still have to type-check `e` (issue #86188), but calling
+ // `check_return_expr` only works inside fn bodies.
+ self.check_expr(e);
+ }
+ } else if let Some(e) = expr_opt {
+ if self.ret_coercion_span.get().is_none() {
+ self.ret_coercion_span.set(Some(e.span));
+ }
+ self.check_return_expr(e, true);
+ } else {
+ let mut coercion = self.ret_coercion.as_ref().unwrap().borrow_mut();
+ if self.ret_coercion_span.get().is_none() {
+ self.ret_coercion_span.set(Some(expr.span));
+ }
+ let cause = self.cause(expr.span, ObligationCauseCode::ReturnNoExpression);
+ if let Some((fn_decl, _)) = self.get_fn_decl(expr.hir_id) {
+ coercion.coerce_forced_unit(
+ self,
+ &cause,
+ &mut |db| {
+ let span = fn_decl.output.span();
+ if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
+ db.span_label(
+ span,
+ format!("expected `{snippet}` because of this return type"),
+ );
+ }
+ },
+ true,
+ );
+ } else {
+ coercion.coerce_forced_unit(self, &cause, &mut |_| (), true);
+ }
+ }
+ self.tcx.types.never
+ }
+
+ /// `explicit_return` is `true` if we're checking an explicit `return expr`,
+ /// and `false` if we're checking a trailing expression.
+ pub(super) fn check_return_expr(
+ &self,
+ return_expr: &'tcx hir::Expr<'tcx>,
+ explicit_return: bool,
+ ) {
+ let ret_coercion = self.ret_coercion.as_ref().unwrap_or_else(|| {
+ span_bug!(return_expr.span, "check_return_expr called outside fn body")
+ });
+
+ let ret_ty = ret_coercion.borrow().expected_ty();
+ let return_expr_ty = self.check_expr_with_hint(return_expr, ret_ty);
+ let mut span = return_expr.span;
+ // Use the span of the trailing expression for our cause,
+ // not the span of the entire function
+ if !explicit_return {
+ if let ExprKind::Block(body, _) = return_expr.kind && let Some(last_expr) = body.expr {
+ span = last_expr.span;
+ }
+ }
+ ret_coercion.borrow_mut().coerce(
+ self,
+ &self.cause(span, ObligationCauseCode::ReturnValue(return_expr.hir_id)),
+ return_expr,
+ return_expr_ty,
+ );
+
+ if self.return_type_has_opaque {
+ // Point any obligations that were registered due to opaque type
+ // inference at the return expression.
+ self.select_obligations_where_possible(false, |errors| {
+ self.point_at_return_for_opaque_ty_error(errors, span, return_expr_ty);
+ });
+ }
+ }
+
+ fn point_at_return_for_opaque_ty_error(
+ &self,
+ errors: &mut Vec<traits::FulfillmentError<'tcx>>,
+ span: Span,
+ return_expr_ty: Ty<'tcx>,
+ ) {
+ // Don't point at the whole block if it's empty
+ if span == self.tcx.hir().span(self.body_id) {
+ return;
+ }
+ for err in errors {
+ let cause = &mut err.obligation.cause;
+ if let ObligationCauseCode::OpaqueReturnType(None) = cause.code() {
+ let new_cause = ObligationCause::new(
+ cause.span,
+ cause.body_id,
+ ObligationCauseCode::OpaqueReturnType(Some((return_expr_ty, span))),
+ );
+ *cause = new_cause;
+ }
+ }
+ }
+
+ pub(crate) fn check_lhs_assignable(
+ &self,
+ lhs: &'tcx hir::Expr<'tcx>,
+ err_code: &'static str,
+ op_span: Span,
+ adjust_err: impl FnOnce(&mut Diagnostic),
+ ) {
+ if lhs.is_syntactic_place_expr() {
+ return;
+ }
+
+ // FIXME: Make this use Diagnostic once error codes can be dynamically set.
+ let mut err = self.tcx.sess.struct_span_err_with_code(
+ op_span,
+ "invalid left-hand side of assignment",
+ DiagnosticId::Error(err_code.into()),
+ );
+ err.span_label(lhs.span, "cannot assign to this expression");
+
+ self.comes_from_while_condition(lhs.hir_id, |expr| {
+ err.span_suggestion_verbose(
+ expr.span.shrink_to_lo(),
+ "you might have meant to use pattern destructuring",
+ "let ",
+ Applicability::MachineApplicable,
+ );
+ });
+
+ adjust_err(&mut err);
+
+ err.emit();
+ }
+
+ // Check if an expression `original_expr_id` comes from the condition of a while loop,
+ // as opposed from the body of a while loop, which we can naively check by iterating
+ // parents until we find a loop...
+ pub(super) fn comes_from_while_condition(
+ &self,
+ original_expr_id: HirId,
+ then: impl FnOnce(&hir::Expr<'_>),
+ ) {
+ let mut parent = self.tcx.hir().get_parent_node(original_expr_id);
+ while let Some(node) = self.tcx.hir().find(parent) {
+ match node {
+ hir::Node::Expr(hir::Expr {
+ kind:
+ hir::ExprKind::Loop(
+ hir::Block {
+ expr:
+ Some(hir::Expr {
+ kind:
+ hir::ExprKind::Match(expr, ..) | hir::ExprKind::If(expr, ..),
+ ..
+ }),
+ ..
+ },
+ _,
+ hir::LoopSource::While,
+ _,
+ ),
+ ..
+ }) => {
+ // Check if our original expression is a child of the condition of a while loop
+ let expr_is_ancestor = std::iter::successors(Some(original_expr_id), |id| {
+ self.tcx.hir().find_parent_node(*id)
+ })
+ .take_while(|id| *id != parent)
+ .any(|id| id == expr.hir_id);
+ // if it is, then we have a situation like `while Some(0) = value.get(0) {`,
+ // where `while let` was more likely intended.
+ if expr_is_ancestor {
+ then(expr);
+ }
+ break;
+ }
+ hir::Node::Item(_)
+ | hir::Node::ImplItem(_)
+ | hir::Node::TraitItem(_)
+ | hir::Node::Crate(_) => break,
+ _ => {
+ parent = self.tcx.hir().get_parent_node(parent);
+ }
+ }
+ }
+ }
+
+ // A generic function for checking the 'then' and 'else' clauses in an 'if'
+ // or 'if-else' expression.
+ fn check_then_else(
+ &self,
+ cond_expr: &'tcx hir::Expr<'tcx>,
+ then_expr: &'tcx hir::Expr<'tcx>,
+ opt_else_expr: Option<&'tcx hir::Expr<'tcx>>,
+ sp: Span,
+ orig_expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ let cond_ty = self.check_expr_has_type_or_error(cond_expr, self.tcx.types.bool, |_| {});
+
+ self.warn_if_unreachable(
+ cond_expr.hir_id,
+ then_expr.span,
+ "block in `if` or `while` expression",
+ );
+
+ let cond_diverges = self.diverges.get();
+ self.diverges.set(Diverges::Maybe);
+
+ let expected = orig_expected.adjust_for_branches(self);
+ let then_ty = self.check_expr_with_expectation(then_expr, expected);
+ let then_diverges = self.diverges.get();
+ self.diverges.set(Diverges::Maybe);
+
+ // We've already taken the expected type's preferences
+ // into account when typing the `then` branch. To figure
+ // out the initial shot at a LUB, we thus only consider
+ // `expected` if it represents a *hard* constraint
+ // (`only_has_type`); otherwise, we just go with a
+ // fresh type variable.
+ let coerce_to_ty = expected.coercion_target_type(self, sp);
+ let mut coerce: DynamicCoerceMany<'_> = CoerceMany::new(coerce_to_ty);
+
+ coerce.coerce(self, &self.misc(sp), then_expr, then_ty);
+
+ if let Some(else_expr) = opt_else_expr {
+ let else_ty = self.check_expr_with_expectation(else_expr, expected);
+ let else_diverges = self.diverges.get();
+
+ let opt_suggest_box_span = self.opt_suggest_box_span(then_ty, else_ty, orig_expected);
+ let if_cause = self.if_cause(
+ sp,
+ cond_expr.span,
+ then_expr,
+ else_expr,
+ then_ty,
+ else_ty,
+ opt_suggest_box_span,
+ );
+
+ coerce.coerce(self, &if_cause, else_expr, else_ty);
+
+ // We won't diverge unless both branches do (or the condition does).
+ self.diverges.set(cond_diverges | then_diverges & else_diverges);
+ } else {
+ self.if_fallback_coercion(sp, then_expr, &mut coerce);
+
+ // If the condition is false we can't diverge.
+ self.diverges.set(cond_diverges);
+ }
+
+ let result_ty = coerce.complete(self);
+ if cond_ty.references_error() { self.tcx.ty_error() } else { result_ty }
+ }
+
+ /// Type check assignment expression `expr` of form `lhs = rhs`.
+ /// The expected type is `()` and is passed to the function for the purposes of diagnostics.
+ fn check_expr_assign(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ lhs: &'tcx hir::Expr<'tcx>,
+ rhs: &'tcx hir::Expr<'tcx>,
+ span: Span,
+ ) -> Ty<'tcx> {
+ let expected_ty = expected.coercion_target_type(self, expr.span);
+ if expected_ty == self.tcx.types.bool {
+ // The expected type is `bool` but this will result in `()` so we can reasonably
+ // say that the user intended to write `lhs == rhs` instead of `lhs = rhs`.
+ // The likely cause of this is `if foo = bar { .. }`.
+ let actual_ty = self.tcx.mk_unit();
+ let mut err = self.demand_suptype_diag(expr.span, expected_ty, actual_ty).unwrap();
+ let lhs_ty = self.check_expr(&lhs);
+ let rhs_ty = self.check_expr(&rhs);
+ let (applicability, eq) = if self.can_coerce(rhs_ty, lhs_ty) {
+ (Applicability::MachineApplicable, true)
+ } else if let ExprKind::Binary(
+ Spanned { node: hir::BinOpKind::And | hir::BinOpKind::Or, .. },
+ _,
+ rhs_expr,
+ ) = lhs.kind
+ {
+ // if x == 1 && y == 2 { .. }
+ // +
+ let actual_lhs_ty = self.check_expr(&rhs_expr);
+ (Applicability::MaybeIncorrect, self.can_coerce(rhs_ty, actual_lhs_ty))
+ } else if let ExprKind::Binary(
+ Spanned { node: hir::BinOpKind::And | hir::BinOpKind::Or, .. },
+ lhs_expr,
+ _,
+ ) = rhs.kind
+ {
+ // if x == 1 && y == 2 { .. }
+ // +
+ let actual_rhs_ty = self.check_expr(&lhs_expr);
+ (Applicability::MaybeIncorrect, self.can_coerce(actual_rhs_ty, lhs_ty))
+ } else {
+ (Applicability::MaybeIncorrect, false)
+ };
+ if !lhs.is_syntactic_place_expr()
+ && lhs.is_approximately_pattern()
+ && !matches!(lhs.kind, hir::ExprKind::Lit(_))
+ {
+ // Do not suggest `if let x = y` as `==` is way more likely to be the intention.
+ let hir = self.tcx.hir();
+ if let hir::Node::Expr(hir::Expr { kind: ExprKind::If { .. }, .. }) =
+ hir.get(hir.get_parent_node(hir.get_parent_node(expr.hir_id)))
+ {
+ err.span_suggestion_verbose(
+ expr.span.shrink_to_lo(),
+ "you might have meant to use pattern matching",
+ "let ",
+ applicability,
+ );
+ };
+ }
+ if eq {
+ err.span_suggestion_verbose(
+ span.shrink_to_hi(),
+ "you might have meant to compare for equality",
+ '=',
+ applicability,
+ );
+ }
+
+ // If the assignment expression itself is ill-formed, don't
+ // bother emitting another error
+ if lhs_ty.references_error() || rhs_ty.references_error() {
+ err.delay_as_bug()
+ } else {
+ err.emit();
+ }
+ return self.tcx.ty_error();
+ }
+
+ let lhs_ty = self.check_expr_with_needs(&lhs, Needs::MutPlace);
+
+ let suggest_deref_binop = |err: &mut Diagnostic, rhs_ty: Ty<'tcx>| {
+ if let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) {
+ // Can only assign if the type is sized, so if `DerefMut` yields a type that is
+ // unsized, do not suggest dereferencing it.
+ let lhs_deref_ty_is_sized = self
+ .infcx
+ .type_implements_trait(
+ self.tcx.lang_items().sized_trait().unwrap(),
+ lhs_deref_ty,
+ ty::List::empty(),
+ self.param_env,
+ )
+ .may_apply();
+ if lhs_deref_ty_is_sized && self.can_coerce(rhs_ty, lhs_deref_ty) {
+ err.span_suggestion_verbose(
+ lhs.span.shrink_to_lo(),
+ "consider dereferencing here to assign to the mutably borrowed value",
+ "*",
+ Applicability::MachineApplicable,
+ );
+ }
+ }
+ };
+
+ // This is (basically) inlined `check_expr_coercable_to_type`, but we want
+ // to suggest an additional fixup here in `suggest_deref_binop`.
+ let rhs_ty = self.check_expr_with_hint(&rhs, lhs_ty);
+ if let (_, Some(mut diag)) =
+ self.demand_coerce_diag(rhs, rhs_ty, lhs_ty, Some(lhs), AllowTwoPhase::No)
+ {
+ suggest_deref_binop(&mut diag, rhs_ty);
+ diag.emit();
+ }
+
+ self.check_lhs_assignable(lhs, "E0070", span, |err| {
+ if let Some(rhs_ty) = self.typeck_results.borrow().expr_ty_opt(rhs) {
+ suggest_deref_binop(err, rhs_ty);
+ }
+ });
+
+ self.require_type_is_sized(lhs_ty, lhs.span, traits::AssignmentLhsSized);
+
+ if lhs_ty.references_error() || rhs_ty.references_error() {
+ self.tcx.ty_error()
+ } else {
+ self.tcx.mk_unit()
+ }
+ }
+
+ pub(super) fn check_expr_let(&self, let_expr: &'tcx hir::Let<'tcx>) -> Ty<'tcx> {
+ // for let statements, this is done in check_stmt
+ let init = let_expr.init;
+ self.warn_if_unreachable(init.hir_id, init.span, "block in `let` expression");
+ // otherwise check exactly as a let statement
+ self.check_decl(let_expr.into());
+ // but return a bool, for this is a boolean expression
+ self.tcx.types.bool
+ }
+
+ fn check_expr_loop(
+ &self,
+ body: &'tcx hir::Block<'tcx>,
+ source: hir::LoopSource,
+ expected: Expectation<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let coerce = match source {
+ // you can only use break with a value from a normal `loop { }`
+ hir::LoopSource::Loop => {
+ let coerce_to = expected.coercion_target_type(self, body.span);
+ Some(CoerceMany::new(coerce_to))
+ }
+
+ hir::LoopSource::While | hir::LoopSource::ForLoop => None,
+ };
+
+ let ctxt = BreakableCtxt {
+ coerce,
+ may_break: false, // Will get updated if/when we find a `break`.
+ };
+
+ let (ctxt, ()) = self.with_breakable_ctxt(expr.hir_id, ctxt, || {
+ self.check_block_no_value(&body);
+ });
+
+ if ctxt.may_break {
+ // No way to know whether it's diverging because
+ // of a `break` or an outer `break` or `return`.
+ self.diverges.set(Diverges::Maybe);
+ }
+
+ // If we permit break with a value, then result type is
+ // the LUB of the breaks (possibly ! if none); else, it
+ // is nil. This makes sense because infinite loops
+ // (which would have type !) are only possible iff we
+ // permit break with a value [1].
+ if ctxt.coerce.is_none() && !ctxt.may_break {
+ // [1]
+ self.tcx.sess.delay_span_bug(body.span, "no coercion, but loop may not break");
+ }
+ ctxt.coerce.map(|c| c.complete(self)).unwrap_or_else(|| self.tcx.mk_unit())
+ }
+
+ /// Checks a method call.
+ fn check_method_call(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ segment: &hir::PathSegment<'_>,
+ rcvr: &'tcx hir::Expr<'tcx>,
+ args: &'tcx [hir::Expr<'tcx>],
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ let rcvr_t = self.check_expr(&rcvr);
+ // no need to check for bot/err -- callee does that
+ let rcvr_t = self.structurally_resolved_type(rcvr.span, rcvr_t);
+ let span = segment.ident.span;
+
+ let method = match self.lookup_method(rcvr_t, segment, span, expr, rcvr, args) {
+ Ok(method) => {
+ // We could add a "consider `foo::<params>`" suggestion here, but I wasn't able to
+ // trigger this codepath causing `structurally_resolved_type` to emit an error.
+
+ self.write_method_call(expr.hir_id, method);
+ Ok(method)
+ }
+ Err(error) => {
+ if segment.ident.name != kw::Empty {
+ if let Some(mut err) = self.report_method_error(
+ span,
+ rcvr_t,
+ segment.ident,
+ SelfSource::MethodCall(rcvr),
+ error,
+ Some((rcvr, args)),
+ ) {
+ err.emit();
+ }
+ }
+ Err(())
+ }
+ };
+
+ // Call the generic checker.
+ self.check_method_argument_types(span, expr, method, &args, DontTupleArguments, expected)
+ }
+
+ fn check_expr_cast(
+ &self,
+ e: &'tcx hir::Expr<'tcx>,
+ t: &'tcx hir::Ty<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ // Find the type of `e`. Supply hints based on the type we are casting to,
+ // if appropriate.
+ let t_cast = self.to_ty_saving_user_provided_ty(t);
+ let t_cast = self.resolve_vars_if_possible(t_cast);
+ let t_expr = self.check_expr_with_expectation(e, ExpectCastableToType(t_cast));
+ let t_expr = self.resolve_vars_if_possible(t_expr);
+
+ // Eagerly check for some obvious errors.
+ if t_expr.references_error() || t_cast.references_error() {
+ self.tcx.ty_error()
+ } else {
+ // Defer other checks until we're done type checking.
+ let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
+ match cast::CastCheck::new(
+ self,
+ e,
+ t_expr,
+ t_cast,
+ t.span,
+ expr.span,
+ self.param_env.constness(),
+ ) {
+ Ok(cast_check) => {
+ debug!(
+ "check_expr_cast: deferring cast from {:?} to {:?}: {:?}",
+ t_cast, t_expr, cast_check,
+ );
+ deferred_cast_checks.push(cast_check);
+ t_cast
+ }
+ Err(_) => self.tcx.ty_error(),
+ }
+ }
+ }
+
+ fn check_expr_array(
+ &self,
+ args: &'tcx [hir::Expr<'tcx>],
+ expected: Expectation<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let element_ty = if !args.is_empty() {
+ let coerce_to = expected
+ .to_option(self)
+ .and_then(|uty| match *uty.kind() {
+ ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
+ _ => None,
+ })
+ .unwrap_or_else(|| {
+ self.next_ty_var(TypeVariableOrigin {
+ kind: TypeVariableOriginKind::TypeInference,
+ span: expr.span,
+ })
+ });
+ let mut coerce = CoerceMany::with_coercion_sites(coerce_to, args);
+ assert_eq!(self.diverges.get(), Diverges::Maybe);
+ for e in args {
+ let e_ty = self.check_expr_with_hint(e, coerce_to);
+ let cause = self.misc(e.span);
+ coerce.coerce(self, &cause, e, e_ty);
+ }
+ coerce.complete(self)
+ } else {
+ self.next_ty_var(TypeVariableOrigin {
+ kind: TypeVariableOriginKind::TypeInference,
+ span: expr.span,
+ })
+ };
+ let array_len = args.len() as u64;
+ self.suggest_array_len(expr, array_len);
+ self.tcx.mk_array(element_ty, array_len)
+ }
+
+ fn suggest_array_len(&self, expr: &'tcx hir::Expr<'tcx>, array_len: u64) {
+ let parent_node = self.tcx.hir().parent_iter(expr.hir_id).find(|(_, node)| {
+ !matches!(node, hir::Node::Expr(hir::Expr { kind: hir::ExprKind::AddrOf(..), .. }))
+ });
+ let Some((_,
+ hir::Node::Local(hir::Local { ty: Some(ty), .. })
+ | hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, _), .. }))
+ ) = parent_node else {
+ return
+ };
+ if let hir::TyKind::Array(_, length) = ty.peel_refs().kind
+ && let hir::ArrayLen::Body(hir::AnonConst { hir_id, .. }) = length
+ && let Some(span) = self.tcx.hir().opt_span(hir_id)
+ {
+ match self.tcx.sess.diagnostic().steal_diagnostic(span, StashKey::UnderscoreForArrayLengths) {
+ Some(mut err) => {
+ err.span_suggestion(
+ span,
+ "consider specifying the array length",
+ array_len,
+ Applicability::MaybeIncorrect,
+ );
+ err.emit();
+ }
+ None => ()
+ }
+ }
+ }
+
+ fn check_expr_const_block(
+ &self,
+ anon_const: &'tcx hir::AnonConst,
+ expected: Expectation<'tcx>,
+ _expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let body = self.tcx.hir().body(anon_const.body);
+
+ // Create a new function context.
+ let fcx = FnCtxt::new(self, self.param_env.with_const(), body.value.hir_id);
+ crate::GatherLocalsVisitor::new(&fcx).visit_body(body);
+
+ let ty = fcx.check_expr_with_expectation(&body.value, expected);
+ fcx.require_type_is_sized(ty, body.value.span, traits::ConstSized);
+ fcx.write_ty(anon_const.hir_id, ty);
+ ty
+ }
+
+ fn check_expr_repeat(
+ &self,
+ element: &'tcx hir::Expr<'tcx>,
+ count: &'tcx hir::ArrayLen,
+ expected: Expectation<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let tcx = self.tcx;
+ let count = self.array_length_to_const(count);
+ if let Some(count) = count.try_eval_usize(tcx, self.param_env) {
+ self.suggest_array_len(expr, count);
+ }
+
+ let uty = match expected {
+ ExpectHasType(uty) => match *uty.kind() {
+ ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
+ _ => None,
+ },
+ _ => None,
+ };
+
+ let (element_ty, t) = match uty {
+ Some(uty) => {
+ self.check_expr_coercable_to_type(&element, uty, None);
+ (uty, uty)
+ }
+ None => {
+ let ty = self.next_ty_var(TypeVariableOrigin {
+ kind: TypeVariableOriginKind::MiscVariable,
+ span: element.span,
+ });
+ let element_ty = self.check_expr_has_type_or_error(&element, ty, |_| {});
+ (element_ty, ty)
+ }
+ };
+
+ if element_ty.references_error() {
+ return tcx.ty_error();
+ }
+
+ self.check_repeat_element_needs_copy_bound(element, count, element_ty);
+
+ tcx.mk_ty(ty::Array(t, count))
+ }
+
+ fn check_repeat_element_needs_copy_bound(
+ &self,
+ element: &hir::Expr<'_>,
+ count: ty::Const<'tcx>,
+ element_ty: Ty<'tcx>,
+ ) {
+ let tcx = self.tcx;
+ // Actual constants as the repeat element get inserted repeatedly instead of getting copied via Copy.
+ match &element.kind {
+ hir::ExprKind::ConstBlock(..) => return,
+ hir::ExprKind::Path(qpath) => {
+ let res = self.typeck_results.borrow().qpath_res(qpath, element.hir_id);
+ if let Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::AnonConst, _) = res
+ {
+ return;
+ }
+ }
+ _ => {}
+ }
+ // If someone calls a const fn, they can extract that call out into a separate constant (or a const
+ // block in the future), so we check that to tell them that in the diagnostic. Does not affect typeck.
+ let is_const_fn = match element.kind {
+ hir::ExprKind::Call(func, _args) => match *self.node_ty(func.hir_id).kind() {
+ ty::FnDef(def_id, _) => tcx.is_const_fn(def_id),
+ _ => false,
+ },
+ _ => false,
+ };
+
+ // If the length is 0, we don't create any elements, so we don't copy any. If the length is 1, we
+ // don't copy that one element, we move it. Only check for Copy if the length is larger.
+ if count.try_eval_usize(tcx, self.param_env).map_or(true, |len| len > 1) {
+ let lang_item = self.tcx.require_lang_item(LangItem::Copy, None);
+ let code = traits::ObligationCauseCode::RepeatElementCopy { is_const_fn };
+ self.require_type_meets(element_ty, element.span, code, lang_item);
+ }
+ }
+
+ fn check_expr_tuple(
+ &self,
+ elts: &'tcx [hir::Expr<'tcx>],
+ expected: Expectation<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let flds = expected.only_has_type(self).and_then(|ty| {
+ let ty = self.resolve_vars_with_obligations(ty);
+ match ty.kind() {
+ ty::Tuple(flds) => Some(&flds[..]),
+ _ => None,
+ }
+ });
+
+ let elt_ts_iter = elts.iter().enumerate().map(|(i, e)| match flds {
+ Some(fs) if i < fs.len() => {
+ let ety = fs[i];
+ self.check_expr_coercable_to_type(&e, ety, None);
+ ety
+ }
+ _ => self.check_expr_with_expectation(&e, NoExpectation),
+ });
+ let tuple = self.tcx.mk_tup(elt_ts_iter);
+ if tuple.references_error() {
+ self.tcx.ty_error()
+ } else {
+ self.require_type_is_sized(tuple, expr.span, traits::TupleInitializerSized);
+ tuple
+ }
+ }
+
+ fn check_expr_struct(
+ &self,
+ expr: &hir::Expr<'_>,
+ expected: Expectation<'tcx>,
+ qpath: &QPath<'_>,
+ fields: &'tcx [hir::ExprField<'tcx>],
+ base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
+ ) -> Ty<'tcx> {
+ // Find the relevant variant
+ let Some((variant, adt_ty)) = self.check_struct_path(qpath, expr.hir_id) else {
+ self.check_struct_fields_on_error(fields, base_expr);
+ return self.tcx.ty_error();
+ };
+
+ // Prohibit struct expressions when non-exhaustive flag is set.
+ let adt = adt_ty.ty_adt_def().expect("`check_struct_path` returned non-ADT type");
+ if !adt.did().is_local() && variant.is_field_list_non_exhaustive() {
+ self.tcx
+ .sess
+ .emit_err(StructExprNonExhaustive { span: expr.span, what: adt.variant_descr() });
+ }
+
+ self.check_expr_struct_fields(
+ adt_ty,
+ expected,
+ expr.hir_id,
+ qpath.span(),
+ variant,
+ fields,
+ base_expr,
+ expr.span,
+ );
+
+ self.require_type_is_sized(adt_ty, expr.span, traits::StructInitializerSized);
+ adt_ty
+ }
+
+ fn check_expr_struct_fields(
+ &self,
+ adt_ty: Ty<'tcx>,
+ expected: Expectation<'tcx>,
+ expr_id: hir::HirId,
+ span: Span,
+ variant: &'tcx ty::VariantDef,
+ ast_fields: &'tcx [hir::ExprField<'tcx>],
+ base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
+ expr_span: Span,
+ ) {
+ let tcx = self.tcx;
+
+ let expected_inputs =
+ self.expected_inputs_for_expected_output(span, expected, adt_ty, &[adt_ty]);
+ let adt_ty_hint = if let Some(expected_inputs) = expected_inputs {
+ expected_inputs.get(0).cloned().unwrap_or(adt_ty)
+ } else {
+ adt_ty
+ };
+ // re-link the regions that EIfEO can erase.
+ self.demand_eqtype(span, adt_ty_hint, adt_ty);
+
+ let ty::Adt(adt, substs) = adt_ty.kind() else {
+ span_bug!(span, "non-ADT passed to check_expr_struct_fields");
+ };
+ let adt_kind = adt.adt_kind();
+
+ let mut remaining_fields = variant
+ .fields
+ .iter()
+ .enumerate()
+ .map(|(i, field)| (field.ident(tcx).normalize_to_macros_2_0(), (i, field)))
+ .collect::<FxHashMap<_, _>>();
+
+ let mut seen_fields = FxHashMap::default();
+
+ let mut error_happened = false;
+
+ // Type-check each field.
+ for (idx, field) in ast_fields.iter().enumerate() {
+ let ident = tcx.adjust_ident(field.ident, variant.def_id);
+ let field_type = if let Some((i, v_field)) = remaining_fields.remove(&ident) {
+ seen_fields.insert(ident, field.span);
+ self.write_field_index(field.hir_id, i);
+
+ // We don't look at stability attributes on
+ // struct-like enums (yet...), but it's definitely not
+ // a bug to have constructed one.
+ if adt_kind != AdtKind::Enum {
+ tcx.check_stability(v_field.did, Some(expr_id), field.span, None);
+ }
+
+ self.field_ty(field.span, v_field, substs)
+ } else {
+ error_happened = true;
+ if let Some(prev_span) = seen_fields.get(&ident) {
+ tcx.sess.emit_err(FieldMultiplySpecifiedInInitializer {
+ span: field.ident.span,
+ prev_span: *prev_span,
+ ident,
+ });
+ } else {
+ self.report_unknown_field(
+ adt_ty,
+ variant,
+ field,
+ ast_fields,
+ adt.variant_descr(),
+ expr_span,
+ );
+ }
+
+ tcx.ty_error()
+ };
+
+ // Make sure to give a type to the field even if there's
+ // an error, so we can continue type-checking.
+ let ty = self.check_expr_with_hint(&field.expr, field_type);
+ let (_, diag) =
+ self.demand_coerce_diag(&field.expr, ty, field_type, None, AllowTwoPhase::No);
+
+ if let Some(mut diag) = diag {
+ if idx == ast_fields.len() - 1 && remaining_fields.is_empty() {
+ self.suggest_fru_from_range(field, variant, substs, &mut diag);
+ }
+ diag.emit();
+ }
+ }
+
+ // Make sure the programmer specified correct number of fields.
+ if adt_kind == AdtKind::Union {
+ if ast_fields.len() != 1 {
+ struct_span_err!(
+ tcx.sess,
+ span,
+ E0784,
+ "union expressions should have exactly one field",
+ )
+ .emit();
+ }
+ }
+
+ // If check_expr_struct_fields hit an error, do not attempt to populate
+ // the fields with the base_expr. This could cause us to hit errors later
+ // when certain fields are assumed to exist that in fact do not.
+ if error_happened {
+ return;
+ }
+
+ if let Some(base_expr) = base_expr {
+ // FIXME: We are currently creating two branches here in order to maintain
+ // consistency. But they should be merged as much as possible.
+ let fru_tys = if self.tcx.features().type_changing_struct_update {
+ if adt.is_struct() {
+ // Make some fresh substitutions for our ADT type.
+ let fresh_substs = self.fresh_substs_for_item(base_expr.span, adt.did());
+ // We do subtyping on the FRU fields first, so we can
+ // learn exactly what types we expect the base expr
+ // needs constrained to be compatible with the struct
+ // type we expect from the expectation value.
+ let fru_tys = variant
+ .fields
+ .iter()
+ .map(|f| {
+ let fru_ty = self.normalize_associated_types_in(
+ expr_span,
+ self.field_ty(base_expr.span, f, fresh_substs),
+ );
+ let ident = self.tcx.adjust_ident(f.ident(self.tcx), variant.def_id);
+ if let Some(_) = remaining_fields.remove(&ident) {
+ let target_ty = self.field_ty(base_expr.span, f, substs);
+ let cause = self.misc(base_expr.span);
+ match self.at(&cause, self.param_env).sup(target_ty, fru_ty) {
+ Ok(InferOk { obligations, value: () }) => {
+ self.register_predicates(obligations)
+ }
+ Err(_) => {
+ // This should never happen, since we're just subtyping the
+ // remaining_fields, but it's fine to emit this, I guess.
+ self.err_ctxt()
+ .report_mismatched_types(
+ &cause,
+ target_ty,
+ fru_ty,
+ FieldMisMatch(variant.name, ident.name),
+ )
+ .emit();
+ }
+ }
+ }
+ self.resolve_vars_if_possible(fru_ty)
+ })
+ .collect();
+ // The use of fresh substs that we have subtyped against
+ // our base ADT type's fields allows us to guide inference
+ // along so that, e.g.
+ // ```
+ // MyStruct<'a, F1, F2, const C: usize> {
+ // f: F1,
+ // // Other fields that reference `'a`, `F2`, and `C`
+ // }
+ //
+ // let x = MyStruct {
+ // f: 1usize,
+ // ..other_struct
+ // };
+ // ```
+ // will have the `other_struct` expression constrained to
+ // `MyStruct<'a, _, F2, C>`, as opposed to just `_`...
+ // This is important to allow coercions to happen in
+ // `other_struct` itself. See `coerce-in-base-expr.rs`.
+ let fresh_base_ty = self.tcx.mk_adt(*adt, fresh_substs);
+ self.check_expr_has_type_or_error(
+ base_expr,
+ self.resolve_vars_if_possible(fresh_base_ty),
+ |_| {},
+ );
+ fru_tys
+ } else {
+ // Check the base_expr, regardless of a bad expected adt_ty, so we can get
+ // type errors on that expression, too.
+ self.check_expr(base_expr);
+ self.tcx
+ .sess
+ .emit_err(FunctionalRecordUpdateOnNonStruct { span: base_expr.span });
+ return;
+ }
+ } else {
+ self.check_expr_has_type_or_error(base_expr, adt_ty, |_| {
+ let base_ty = self.typeck_results.borrow().expr_ty(*base_expr);
+ let same_adt = match (adt_ty.kind(), base_ty.kind()) {
+ (ty::Adt(adt, _), ty::Adt(base_adt, _)) if adt == base_adt => true,
+ _ => false,
+ };
+ if self.tcx.sess.is_nightly_build() && same_adt {
+ feature_err(
+ &self.tcx.sess.parse_sess,
+ sym::type_changing_struct_update,
+ base_expr.span,
+ "type changing struct updating is experimental",
+ )
+ .emit();
+ }
+ });
+ match adt_ty.kind() {
+ ty::Adt(adt, substs) if adt.is_struct() => variant
+ .fields
+ .iter()
+ .map(|f| {
+ self.normalize_associated_types_in(expr_span, f.ty(self.tcx, substs))
+ })
+ .collect(),
+ _ => {
+ self.tcx
+ .sess
+ .emit_err(FunctionalRecordUpdateOnNonStruct { span: base_expr.span });
+ return;
+ }
+ }
+ };
+ self.typeck_results.borrow_mut().fru_field_types_mut().insert(expr_id, fru_tys);
+ } else if adt_kind != AdtKind::Union && !remaining_fields.is_empty() {
+ debug!(?remaining_fields);
+ let private_fields: Vec<&ty::FieldDef> = variant
+ .fields
+ .iter()
+ .filter(|field| !field.vis.is_accessible_from(tcx.parent_module(expr_id), tcx))
+ .collect();
+
+ if !private_fields.is_empty() {
+ self.report_private_fields(adt_ty, span, private_fields, ast_fields);
+ } else {
+ self.report_missing_fields(
+ adt_ty,
+ span,
+ remaining_fields,
+ variant,
+ ast_fields,
+ substs,
+ );
+ }
+ }
+ }
+
+ fn check_struct_fields_on_error(
+ &self,
+ fields: &'tcx [hir::ExprField<'tcx>],
+ base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
+ ) {
+ for field in fields {
+ self.check_expr(&field.expr);
+ }
+ if let Some(base) = *base_expr {
+ self.check_expr(&base);
+ }
+ }
+
+ /// Report an error for a struct field expression when there are fields which aren't provided.
+ ///
+ /// ```text
+ /// error: missing field `you_can_use_this_field` in initializer of `foo::Foo`
+ /// --> src/main.rs:8:5
+ /// |
+ /// 8 | foo::Foo {};
+ /// | ^^^^^^^^ missing `you_can_use_this_field`
+ ///
+ /// error: aborting due to previous error
+ /// ```
+ fn report_missing_fields(
+ &self,
+ adt_ty: Ty<'tcx>,
+ span: Span,
+ remaining_fields: FxHashMap<Ident, (usize, &ty::FieldDef)>,
+ variant: &'tcx ty::VariantDef,
+ ast_fields: &'tcx [hir::ExprField<'tcx>],
+ substs: SubstsRef<'tcx>,
+ ) {
+ let len = remaining_fields.len();
+
+ let mut displayable_field_names: Vec<&str> =
+ remaining_fields.keys().map(|ident| ident.as_str()).collect();
+ // sorting &str primitives here, sort_unstable is ok
+ displayable_field_names.sort_unstable();
+
+ let mut truncated_fields_error = String::new();
+ let remaining_fields_names = match &displayable_field_names[..] {
+ [field1] => format!("`{}`", field1),
+ [field1, field2] => format!("`{field1}` and `{field2}`"),
+ [field1, field2, field3] => format!("`{field1}`, `{field2}` and `{field3}`"),
+ _ => {
+ truncated_fields_error =
+ format!(" and {} other field{}", len - 3, pluralize!(len - 3));
+ displayable_field_names
+ .iter()
+ .take(3)
+ .map(|n| format!("`{n}`"))
+ .collect::<Vec<_>>()
+ .join(", ")
+ }
+ };
+
+ let mut err = struct_span_err!(
+ self.tcx.sess,
+ span,
+ E0063,
+ "missing field{} {}{} in initializer of `{}`",
+ pluralize!(len),
+ remaining_fields_names,
+ truncated_fields_error,
+ adt_ty
+ );
+ err.span_label(span, format!("missing {remaining_fields_names}{truncated_fields_error}"));
+
+ if let Some(last) = ast_fields.last() {
+ self.suggest_fru_from_range(last, variant, substs, &mut err);
+ }
+
+ err.emit();
+ }
+
+ /// If the last field is a range literal, but it isn't supposed to be, then they probably
+ /// meant to use functional update syntax.
+ fn suggest_fru_from_range(
+ &self,
+ last_expr_field: &hir::ExprField<'tcx>,
+ variant: &ty::VariantDef,
+ substs: SubstsRef<'tcx>,
+ err: &mut Diagnostic,
+ ) {
+ // I don't use 'is_range_literal' because only double-sided, half-open ranges count.
+ if let ExprKind::Struct(
+ QPath::LangItem(LangItem::Range, ..),
+ &[ref range_start, ref range_end],
+ _,
+ ) = last_expr_field.expr.kind
+ && let variant_field =
+ variant.fields.iter().find(|field| field.ident(self.tcx) == last_expr_field.ident)
+ && let range_def_id = self.tcx.lang_items().range_struct()
+ && variant_field
+ .and_then(|field| field.ty(self.tcx, substs).ty_adt_def())
+ .map(|adt| adt.did())
+ != range_def_id
+ {
+ let instead = self
+ .tcx
+ .sess
+ .source_map()
+ .span_to_snippet(range_end.expr.span)
+ .map(|s| format!(" from `{s}`"))
+ .unwrap_or_default();
+ err.span_suggestion(
+ range_start.span.shrink_to_hi(),
+ &format!("to set the remaining fields{instead}, separate the last named field with a comma"),
+ ",",
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+
+ /// Report an error for a struct field expression when there are invisible fields.
+ ///
+ /// ```text
+ /// error: cannot construct `Foo` with struct literal syntax due to private fields
+ /// --> src/main.rs:8:5
+ /// |
+ /// 8 | foo::Foo {};
+ /// | ^^^^^^^^
+ ///
+ /// error: aborting due to previous error
+ /// ```
+ fn report_private_fields(
+ &self,
+ adt_ty: Ty<'tcx>,
+ span: Span,
+ private_fields: Vec<&ty::FieldDef>,
+ used_fields: &'tcx [hir::ExprField<'tcx>],
+ ) {
+ let mut err = self.tcx.sess.struct_span_err(
+ span,
+ &format!(
+ "cannot construct `{adt_ty}` with struct literal syntax due to private fields",
+ ),
+ );
+ let (used_private_fields, remaining_private_fields): (
+ Vec<(Symbol, Span, bool)>,
+ Vec<(Symbol, Span, bool)>,
+ ) = private_fields
+ .iter()
+ .map(|field| {
+ match used_fields.iter().find(|used_field| field.name == used_field.ident.name) {
+ Some(used_field) => (field.name, used_field.span, true),
+ None => (field.name, self.tcx.def_span(field.did), false),
+ }
+ })
+ .partition(|field| field.2);
+ err.span_labels(used_private_fields.iter().map(|(_, span, _)| *span), "private field");
+ if !remaining_private_fields.is_empty() {
+ let remaining_private_fields_len = remaining_private_fields.len();
+ let names = match &remaining_private_fields
+ .iter()
+ .map(|(name, _, _)| name)
+ .collect::<Vec<_>>()[..]
+ {
+ _ if remaining_private_fields_len > 6 => String::new(),
+ [name] => format!("`{name}` "),
+ [names @ .., last] => {
+ let names = names.iter().map(|name| format!("`{name}`")).collect::<Vec<_>>();
+ format!("{} and `{last}` ", names.join(", "))
+ }
+ [] => unreachable!(),
+ };
+ err.note(format!(
+ "... and other private field{s} {names}that {were} not provided",
+ s = pluralize!(remaining_private_fields_len),
+ were = pluralize!("was", remaining_private_fields_len),
+ ));
+ }
+ err.emit();
+ }
+
+ fn report_unknown_field(
+ &self,
+ ty: Ty<'tcx>,
+ variant: &'tcx ty::VariantDef,
+ field: &hir::ExprField<'_>,
+ skip_fields: &[hir::ExprField<'_>],
+ kind_name: &str,
+ expr_span: Span,
+ ) {
+ if variant.is_recovered() {
+ self.set_tainted_by_errors();
+ return;
+ }
+ let mut err = self.err_ctxt().type_error_struct_with_diag(
+ field.ident.span,
+ |actual| match ty.kind() {
+ ty::Adt(adt, ..) if adt.is_enum() => struct_span_err!(
+ self.tcx.sess,
+ field.ident.span,
+ E0559,
+ "{} `{}::{}` has no field named `{}`",
+ kind_name,
+ actual,
+ variant.name,
+ field.ident
+ ),
+ _ => struct_span_err!(
+ self.tcx.sess,
+ field.ident.span,
+ E0560,
+ "{} `{}` has no field named `{}`",
+ kind_name,
+ actual,
+ field.ident
+ ),
+ },
+ ty,
+ );
+
+ let variant_ident_span = self.tcx.def_ident_span(variant.def_id).unwrap();
+ match variant.ctor_kind {
+ CtorKind::Fn => match ty.kind() {
+ ty::Adt(adt, ..) if adt.is_enum() => {
+ err.span_label(
+ variant_ident_span,
+ format!(
+ "`{adt}::{variant}` defined here",
+ adt = ty,
+ variant = variant.name,
+ ),
+ );
+ err.span_label(field.ident.span, "field does not exist");
+ err.span_suggestion_verbose(
+ expr_span,
+ &format!(
+ "`{adt}::{variant}` is a tuple {kind_name}, use the appropriate syntax",
+ adt = ty,
+ variant = variant.name,
+ ),
+ format!(
+ "{adt}::{variant}(/* fields */)",
+ adt = ty,
+ variant = variant.name,
+ ),
+ Applicability::HasPlaceholders,
+ );
+ }
+ _ => {
+ err.span_label(variant_ident_span, format!("`{adt}` defined here", adt = ty));
+ err.span_label(field.ident.span, "field does not exist");
+ err.span_suggestion_verbose(
+ expr_span,
+ &format!(
+ "`{adt}` is a tuple {kind_name}, use the appropriate syntax",
+ adt = ty,
+ kind_name = kind_name,
+ ),
+ format!("{adt}(/* fields */)", adt = ty),
+ Applicability::HasPlaceholders,
+ );
+ }
+ },
+ _ => {
+ // prevent all specified fields from being suggested
+ let skip_fields = skip_fields.iter().map(|x| x.ident.name);
+ if let Some(field_name) = self.suggest_field_name(
+ variant,
+ field.ident.name,
+ skip_fields.collect(),
+ expr_span,
+ ) {
+ err.span_suggestion(
+ field.ident.span,
+ "a field with a similar name exists",
+ field_name,
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ match ty.kind() {
+ ty::Adt(adt, ..) => {
+ if adt.is_enum() {
+ err.span_label(
+ field.ident.span,
+ format!("`{}::{}` does not have this field", ty, variant.name),
+ );
+ } else {
+ err.span_label(
+ field.ident.span,
+ format!("`{ty}` does not have this field"),
+ );
+ }
+ let available_field_names =
+ self.available_field_names(variant, expr_span);
+ if !available_field_names.is_empty() {
+ err.note(&format!(
+ "available fields are: {}",
+ self.name_series_display(available_field_names)
+ ));
+ }
+ }
+ _ => bug!("non-ADT passed to report_unknown_field"),
+ }
+ };
+ }
+ }
+ err.emit();
+ }
+
+ // Return a hint about the closest match in field names
+ fn suggest_field_name(
+ &self,
+ variant: &'tcx ty::VariantDef,
+ field: Symbol,
+ skip: Vec<Symbol>,
+ // The span where stability will be checked
+ span: Span,
+ ) -> Option<Symbol> {
+ let names = variant
+ .fields
+ .iter()
+ .filter_map(|field| {
+ // ignore already set fields and private fields from non-local crates
+ // and unstable fields.
+ if skip.iter().any(|&x| x == field.name)
+ || (!variant.def_id.is_local() && !field.vis.is_public())
+ || matches!(
+ self.tcx.eval_stability(field.did, None, span, None),
+ stability::EvalResult::Deny { .. }
+ )
+ {
+ None
+ } else {
+ Some(field.name)
+ }
+ })
+ .collect::<Vec<Symbol>>();
+
+ find_best_match_for_name(&names, field, None)
+ }
+
+ fn available_field_names(
+ &self,
+ variant: &'tcx ty::VariantDef,
+ access_span: Span,
+ ) -> Vec<Symbol> {
+ variant
+ .fields
+ .iter()
+ .filter(|field| {
+ let def_scope = self
+ .tcx
+ .adjust_ident_and_get_scope(field.ident(self.tcx), variant.def_id, self.body_id)
+ .1;
+ field.vis.is_accessible_from(def_scope, self.tcx)
+ && !matches!(
+ self.tcx.eval_stability(field.did, None, access_span, None),
+ stability::EvalResult::Deny { .. }
+ )
+ })
+ .filter(|field| !self.tcx.is_doc_hidden(field.did))
+ .map(|field| field.name)
+ .collect()
+ }
+
+ fn name_series_display(&self, names: Vec<Symbol>) -> String {
+ // dynamic limit, to never omit just one field
+ let limit = if names.len() == 6 { 6 } else { 5 };
+ let mut display =
+ names.iter().take(limit).map(|n| format!("`{}`", n)).collect::<Vec<_>>().join(", ");
+ if names.len() > limit {
+ display = format!("{} ... and {} others", display, names.len() - limit);
+ }
+ display
+ }
+
+ // Check field access expressions
+ fn check_field(
+ &self,
+ expr: &'tcx hir::Expr<'tcx>,
+ base: &'tcx hir::Expr<'tcx>,
+ field: Ident,
+ ) -> Ty<'tcx> {
+ debug!("check_field(expr: {:?}, base: {:?}, field: {:?})", expr, base, field);
+ let base_ty = self.check_expr(base);
+ let base_ty = self.structurally_resolved_type(base.span, base_ty);
+ let mut private_candidate = None;
+ let mut autoderef = self.autoderef(expr.span, base_ty);
+ while let Some((deref_base_ty, _)) = autoderef.next() {
+ debug!("deref_base_ty: {:?}", deref_base_ty);
+ match deref_base_ty.kind() {
+ ty::Adt(base_def, substs) if !base_def.is_enum() => {
+ debug!("struct named {:?}", deref_base_ty);
+ let (ident, def_scope) =
+ self.tcx.adjust_ident_and_get_scope(field, base_def.did(), self.body_id);
+ let fields = &base_def.non_enum_variant().fields;
+ if let Some(index) = fields
+ .iter()
+ .position(|f| f.ident(self.tcx).normalize_to_macros_2_0() == ident)
+ {
+ let field = &fields[index];
+ let field_ty = self.field_ty(expr.span, field, substs);
+ // Save the index of all fields regardless of their visibility in case
+ // of error recovery.
+ self.write_field_index(expr.hir_id, index);
+ let adjustments = self.adjust_steps(&autoderef);
+ if field.vis.is_accessible_from(def_scope, self.tcx) {
+ self.apply_adjustments(base, adjustments);
+ self.register_predicates(autoderef.into_obligations());
+
+ self.tcx.check_stability(field.did, Some(expr.hir_id), expr.span, None);
+ return field_ty;
+ }
+ private_candidate = Some((adjustments, base_def.did(), field_ty));
+ }
+ }
+ ty::Tuple(tys) => {
+ let fstr = field.as_str();
+ if let Ok(index) = fstr.parse::<usize>() {
+ if fstr == index.to_string() {
+ if let Some(&field_ty) = tys.get(index) {
+ let adjustments = self.adjust_steps(&autoderef);
+ self.apply_adjustments(base, adjustments);
+ self.register_predicates(autoderef.into_obligations());
+
+ self.write_field_index(expr.hir_id, index);
+ return field_ty;
+ }
+ }
+ }
+ }
+ _ => {}
+ }
+ }
+ self.structurally_resolved_type(autoderef.span(), autoderef.final_ty(false));
+
+ if let Some((adjustments, did, field_ty)) = private_candidate {
+ // (#90483) apply adjustments to avoid ExprUseVisitor from
+ // creating erroneous projection.
+ self.apply_adjustments(base, adjustments);
+ self.ban_private_field_access(expr, base_ty, field, did);
+ return field_ty;
+ }
+
+ if field.name == kw::Empty {
+ } else if self.method_exists(field, base_ty, expr.hir_id, true) {
+ self.ban_take_value_of_method(expr, base_ty, field);
+ } else if !base_ty.is_primitive_ty() {
+ self.ban_nonexisting_field(field, base, expr, base_ty);
+ } else {
+ let field_name = field.to_string();
+ let mut err = type_error_struct!(
+ self.tcx().sess,
+ field.span,
+ base_ty,
+ E0610,
+ "`{base_ty}` is a primitive type and therefore doesn't have fields",
+ );
+ let is_valid_suffix = |field: &str| {
+ if field == "f32" || field == "f64" {
+ return true;
+ }
+ let mut chars = field.chars().peekable();
+ match chars.peek() {
+ Some('e') | Some('E') => {
+ chars.next();
+ if let Some(c) = chars.peek()
+ && !c.is_numeric() && *c != '-' && *c != '+'
+ {
+ return false;
+ }
+ while let Some(c) = chars.peek() {
+ if !c.is_numeric() {
+ break;
+ }
+ chars.next();
+ }
+ }
+ _ => (),
+ }
+ let suffix = chars.collect::<String>();
+ suffix.is_empty() || suffix == "f32" || suffix == "f64"
+ };
+ let maybe_partial_suffix = |field: &str| -> Option<&str> {
+ let first_chars = ['f', 'l'];
+ if field.len() >= 1
+ && field.to_lowercase().starts_with(first_chars)
+ && field[1..].chars().all(|c| c.is_ascii_digit())
+ {
+ if field.to_lowercase().starts_with(['f']) { Some("f32") } else { Some("f64") }
+ } else {
+ None
+ }
+ };
+ if let ty::Infer(ty::IntVar(_)) = base_ty.kind()
+ && let ExprKind::Lit(Spanned {
+ node: ast::LitKind::Int(_, ast::LitIntType::Unsuffixed),
+ ..
+ }) = base.kind
+ && !base.span.from_expansion()
+ {
+ if is_valid_suffix(&field_name) {
+ err.span_suggestion_verbose(
+ field.span.shrink_to_lo(),
+ "if intended to be a floating point literal, consider adding a `0` after the period",
+ '0',
+ Applicability::MaybeIncorrect,
+ );
+ } else if let Some(correct_suffix) = maybe_partial_suffix(&field_name) {
+ err.span_suggestion_verbose(
+ field.span,
+ format!("if intended to be a floating point literal, consider adding a `0` after the period and a `{correct_suffix}` suffix"),
+ format!("0{correct_suffix}"),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+ err.emit();
+ }
+
+ self.tcx().ty_error()
+ }
+
+ fn suggest_await_on_field_access(
+ &self,
+ err: &mut Diagnostic,
+ field_ident: Ident,
+ base: &'tcx hir::Expr<'tcx>,
+ ty: Ty<'tcx>,
+ ) {
+ let output_ty = match self.get_impl_future_output_ty(ty) {
+ Some(output_ty) => self.resolve_vars_if_possible(output_ty),
+ _ => return,
+ };
+ let mut add_label = true;
+ if let ty::Adt(def, _) = output_ty.skip_binder().kind() {
+ // no field access on enum type
+ if !def.is_enum() {
+ if def
+ .non_enum_variant()
+ .fields
+ .iter()
+ .any(|field| field.ident(self.tcx) == field_ident)
+ {
+ add_label = false;
+ err.span_label(
+ field_ident.span,
+ "field not available in `impl Future`, but it is available in its `Output`",
+ );
+ err.span_suggestion_verbose(
+ base.span.shrink_to_hi(),
+ "consider `await`ing on the `Future` and access the field of its `Output`",
+ ".await",
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+ }
+ if add_label {
+ err.span_label(field_ident.span, &format!("field not found in `{ty}`"));
+ }
+ }
+
+ fn ban_nonexisting_field(
+ &self,
+ ident: Ident,
+ base: &'tcx hir::Expr<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ base_ty: Ty<'tcx>,
+ ) {
+ debug!(
+ "ban_nonexisting_field: field={:?}, base={:?}, expr={:?}, base_ty={:?}",
+ ident, base, expr, base_ty
+ );
+ let mut err = self.no_such_field_err(ident, base_ty, base.hir_id);
+
+ match *base_ty.peel_refs().kind() {
+ ty::Array(_, len) => {
+ self.maybe_suggest_array_indexing(&mut err, expr, base, ident, len);
+ }
+ ty::RawPtr(..) => {
+ self.suggest_first_deref_field(&mut err, expr, base, ident);
+ }
+ ty::Adt(def, _) if !def.is_enum() => {
+ self.suggest_fields_on_recordish(&mut err, def, ident, expr.span);
+ }
+ ty::Param(param_ty) => {
+ self.point_at_param_definition(&mut err, param_ty);
+ }
+ ty::Opaque(_, _) => {
+ self.suggest_await_on_field_access(&mut err, ident, base, base_ty.peel_refs());
+ }
+ _ => {}
+ }
+
+ self.suggest_fn_call(&mut err, base, base_ty, |output_ty| {
+ if let ty::Adt(def, _) = output_ty.kind() && !def.is_enum() {
+ def.non_enum_variant().fields.iter().any(|field| {
+ field.ident(self.tcx) == ident
+ && field.vis.is_accessible_from(expr.hir_id.owner.def_id, self.tcx)
+ })
+ } else if let ty::Tuple(tys) = output_ty.kind()
+ && let Ok(idx) = ident.as_str().parse::<usize>()
+ {
+ idx < tys.len()
+ } else {
+ false
+ }
+ });
+
+ if ident.name == kw::Await {
+ // We know by construction that `<expr>.await` is either on Rust 2015
+ // or results in `ExprKind::Await`. Suggest switching the edition to 2018.
+ err.note("to `.await` a `Future`, switch to Rust 2018 or later");
+ err.help_use_latest_edition();
+ }
+
+ err.emit();
+ }
+
+ fn ban_private_field_access(
+ &self,
+ expr: &hir::Expr<'_>,
+ expr_t: Ty<'tcx>,
+ field: Ident,
+ base_did: DefId,
+ ) {
+ let struct_path = self.tcx().def_path_str(base_did);
+ let kind_name = self.tcx().def_kind(base_did).descr(base_did);
+ let mut err = struct_span_err!(
+ self.tcx().sess,
+ field.span,
+ E0616,
+ "field `{field}` of {kind_name} `{struct_path}` is private",
+ );
+ err.span_label(field.span, "private field");
+ // Also check if an accessible method exists, which is often what is meant.
+ if self.method_exists(field, expr_t, expr.hir_id, false) && !self.expr_in_place(expr.hir_id)
+ {
+ self.suggest_method_call(
+ &mut err,
+ &format!("a method `{field}` also exists, call it with parentheses"),
+ field,
+ expr_t,
+ expr,
+ None,
+ );
+ }
+ err.emit();
+ }
+
+ fn ban_take_value_of_method(&self, expr: &hir::Expr<'_>, expr_t: Ty<'tcx>, field: Ident) {
+ let mut err = type_error_struct!(
+ self.tcx().sess,
+ field.span,
+ expr_t,
+ E0615,
+ "attempted to take value of method `{field}` on type `{expr_t}`",
+ );
+ err.span_label(field.span, "method, not a field");
+ let expr_is_call =
+ if let hir::Node::Expr(hir::Expr { kind: ExprKind::Call(callee, _args), .. }) =
+ self.tcx.hir().get(self.tcx.hir().get_parent_node(expr.hir_id))
+ {
+ expr.hir_id == callee.hir_id
+ } else {
+ false
+ };
+ let expr_snippet =
+ self.tcx.sess.source_map().span_to_snippet(expr.span).unwrap_or_default();
+ let is_wrapped = expr_snippet.starts_with('(') && expr_snippet.ends_with(')');
+ let after_open = expr.span.lo() + rustc_span::BytePos(1);
+ let before_close = expr.span.hi() - rustc_span::BytePos(1);
+
+ if expr_is_call && is_wrapped {
+ err.multipart_suggestion(
+ "remove wrapping parentheses to call the method",
+ vec![
+ (expr.span.with_hi(after_open), String::new()),
+ (expr.span.with_lo(before_close), String::new()),
+ ],
+ Applicability::MachineApplicable,
+ );
+ } else if !self.expr_in_place(expr.hir_id) {
+ // Suggest call parentheses inside the wrapping parentheses
+ let span = if is_wrapped {
+ expr.span.with_lo(after_open).with_hi(before_close)
+ } else {
+ expr.span
+ };
+ self.suggest_method_call(
+ &mut err,
+ "use parentheses to call the method",
+ field,
+ expr_t,
+ expr,
+ Some(span),
+ );
+ } else if let ty::RawPtr(ty_and_mut) = expr_t.kind()
+ && let ty::Adt(adt_def, _) = ty_and_mut.ty.kind()
+ && let ExprKind::Field(base_expr, _) = expr.kind
+ && adt_def.variants().len() == 1
+ && adt_def
+ .variants()
+ .iter()
+ .next()
+ .unwrap()
+ .fields
+ .iter()
+ .any(|f| f.ident(self.tcx) == field)
+ {
+ err.multipart_suggestion(
+ "to access the field, dereference first",
+ vec![
+ (base_expr.span.shrink_to_lo(), "(*".to_string()),
+ (base_expr.span.shrink_to_hi(), ")".to_string()),
+ ],
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ err.help("methods are immutable and cannot be assigned to");
+ }
+
+ err.emit();
+ }
+
+ fn point_at_param_definition(&self, err: &mut Diagnostic, param: ty::ParamTy) {
+ let generics = self.tcx.generics_of(self.body_id.owner.to_def_id());
+ let generic_param = generics.type_param(¶m, self.tcx);
+ if let ty::GenericParamDefKind::Type { synthetic: true, .. } = generic_param.kind {
+ return;
+ }
+ let param_def_id = generic_param.def_id;
+ let param_hir_id = match param_def_id.as_local() {
+ Some(x) => self.tcx.hir().local_def_id_to_hir_id(x),
+ None => return,
+ };
+ let param_span = self.tcx.hir().span(param_hir_id);
+ let param_name = self.tcx.hir().ty_param_name(param_def_id.expect_local());
+
+ err.span_label(param_span, &format!("type parameter '{param_name}' declared here"));
+ }
+
+ fn suggest_fields_on_recordish(
+ &self,
+ err: &mut Diagnostic,
+ def: ty::AdtDef<'tcx>,
+ field: Ident,
+ access_span: Span,
+ ) {
+ if let Some(suggested_field_name) =
+ self.suggest_field_name(def.non_enum_variant(), field.name, vec![], access_span)
+ {
+ err.span_suggestion(
+ field.span,
+ "a field with a similar name exists",
+ suggested_field_name,
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ err.span_label(field.span, "unknown field");
+ let struct_variant_def = def.non_enum_variant();
+ let field_names = self.available_field_names(struct_variant_def, access_span);
+ if !field_names.is_empty() {
+ err.note(&format!(
+ "available fields are: {}",
+ self.name_series_display(field_names),
+ ));
+ }
+ }
+ }
+
+ fn maybe_suggest_array_indexing(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ base: &hir::Expr<'_>,
+ field: Ident,
+ len: ty::Const<'tcx>,
+ ) {
+ if let (Some(len), Ok(user_index)) =
+ (len.try_eval_usize(self.tcx, self.param_env), field.as_str().parse::<u64>())
+ && let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span)
+ {
+ let help = "instead of using tuple indexing, use array indexing";
+ let suggestion = format!("{base}[{field}]");
+ let applicability = if len < user_index {
+ Applicability::MachineApplicable
+ } else {
+ Applicability::MaybeIncorrect
+ };
+ err.span_suggestion(expr.span, help, suggestion, applicability);
+ }
+ }
+
+ fn suggest_first_deref_field(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ base: &hir::Expr<'_>,
+ field: Ident,
+ ) {
+ if let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span) {
+ let msg = format!("`{base}` is a raw pointer; try dereferencing it");
+ let suggestion = format!("(*{base}).{field}");
+ err.span_suggestion(expr.span, &msg, suggestion, Applicability::MaybeIncorrect);
+ }
+ }
+
+ fn no_such_field_err(
+ &self,
+ field: Ident,
+ expr_t: Ty<'tcx>,
+ id: HirId,
+ ) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
+ let span = field.span;
+ debug!("no_such_field_err(span: {:?}, field: {:?}, expr_t: {:?})", span, field, expr_t);
+
+ let mut err = type_error_struct!(
+ self.tcx().sess,
+ field.span,
+ expr_t,
+ E0609,
+ "no field `{field}` on type `{expr_t}`",
+ );
+
+ // try to add a suggestion in case the field is a nested field of a field of the Adt
+ let mod_id = self.tcx.parent_module(id).to_def_id();
+ if let Some((fields, substs)) =
+ self.get_field_candidates_considering_privacy(span, expr_t, mod_id)
+ {
+ let candidate_fields: Vec<_> = fields
+ .filter_map(|candidate_field| {
+ self.check_for_nested_field_satisfying(
+ span,
+ &|candidate_field, _| candidate_field.ident(self.tcx()) == field,
+ candidate_field,
+ substs,
+ vec![],
+ mod_id,
+ )
+ })
+ .map(|mut field_path| {
+ field_path.pop();
+ field_path
+ .iter()
+ .map(|id| id.name.to_ident_string())
+ .collect::<Vec<String>>()
+ .join(".")
+ })
+ .collect::<Vec<_>>();
+
+ let len = candidate_fields.len();
+ if len > 0 {
+ err.span_suggestions(
+ field.span.shrink_to_lo(),
+ format!(
+ "{} of the expressions' fields {} a field of the same name",
+ if len > 1 { "some" } else { "one" },
+ if len > 1 { "have" } else { "has" },
+ ),
+ candidate_fields.iter().map(|path| format!("{path}.")),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+ err
+ }
+
+ pub(crate) fn get_field_candidates_considering_privacy(
+ &self,
+ span: Span,
+ base_ty: Ty<'tcx>,
+ mod_id: DefId,
+ ) -> Option<(impl Iterator<Item = &'tcx ty::FieldDef> + 'tcx, SubstsRef<'tcx>)> {
+ debug!("get_field_candidates(span: {:?}, base_t: {:?}", span, base_ty);
+
+ for (base_t, _) in self.autoderef(span, base_ty) {
+ match base_t.kind() {
+ ty::Adt(base_def, substs) if !base_def.is_enum() => {
+ let tcx = self.tcx;
+ let fields = &base_def.non_enum_variant().fields;
+ // Some struct, e.g. some that impl `Deref`, have all private fields
+ // because you're expected to deref them to access the _real_ fields.
+ // This, for example, will help us suggest accessing a field through a `Box<T>`.
+ if fields.iter().all(|field| !field.vis.is_accessible_from(mod_id, tcx)) {
+ continue;
+ }
+ return Some((
+ fields
+ .iter()
+ .filter(move |field| field.vis.is_accessible_from(mod_id, tcx))
+ // For compile-time reasons put a limit on number of fields we search
+ .take(100),
+ substs,
+ ));
+ }
+ _ => {}
+ }
+ }
+ None
+ }
+
+ /// This method is called after we have encountered a missing field error to recursively
+ /// search for the field
+ pub(crate) fn check_for_nested_field_satisfying(
+ &self,
+ span: Span,
+ matches: &impl Fn(&ty::FieldDef, Ty<'tcx>) -> bool,
+ candidate_field: &ty::FieldDef,
+ subst: SubstsRef<'tcx>,
+ mut field_path: Vec<Ident>,
+ mod_id: DefId,
+ ) -> Option<Vec<Ident>> {
+ debug!(
+ "check_for_nested_field_satisfying(span: {:?}, candidate_field: {:?}, field_path: {:?}",
+ span, candidate_field, field_path
+ );
+
+ if field_path.len() > 3 {
+ // For compile-time reasons and to avoid infinite recursion we only check for fields
+ // up to a depth of three
+ None
+ } else {
+ field_path.push(candidate_field.ident(self.tcx).normalize_to_macros_2_0());
+ let field_ty = candidate_field.ty(self.tcx, subst);
+ if matches(candidate_field, field_ty) {
+ return Some(field_path);
+ } else if let Some((nested_fields, subst)) =
+ self.get_field_candidates_considering_privacy(span, field_ty, mod_id)
+ {
+ // recursively search fields of `candidate_field` if it's a ty::Adt
+ for field in nested_fields {
+ if let Some(field_path) = self.check_for_nested_field_satisfying(
+ span,
+ matches,
+ field,
+ subst,
+ field_path.clone(),
+ mod_id,
+ ) {
+ return Some(field_path);
+ }
+ }
+ }
+ None
+ }
+ }
+
+ fn check_expr_index(
+ &self,
+ base: &'tcx hir::Expr<'tcx>,
+ idx: &'tcx hir::Expr<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ ) -> Ty<'tcx> {
+ let base_t = self.check_expr(&base);
+ let idx_t = self.check_expr(&idx);
+
+ if base_t.references_error() {
+ base_t
+ } else if idx_t.references_error() {
+ idx_t
+ } else {
+ let base_t = self.structurally_resolved_type(base.span, base_t);
+ match self.lookup_indexing(expr, base, base_t, idx, idx_t) {
+ Some((index_ty, element_ty)) => {
+ // two-phase not needed because index_ty is never mutable
+ self.demand_coerce(idx, idx_t, index_ty, None, AllowTwoPhase::No);
+ self.select_obligations_where_possible(false, |errors| {
+ self.point_at_index_if_possible(errors, idx.span)
+ });
+ element_ty
+ }
+ None => {
+ let mut err = type_error_struct!(
+ self.tcx.sess,
+ expr.span,
+ base_t,
+ E0608,
+ "cannot index into a value of type `{base_t}`",
+ );
+ // Try to give some advice about indexing tuples.
+ if let ty::Tuple(..) = base_t.kind() {
+ let mut needs_note = true;
+ // If the index is an integer, we can show the actual
+ // fixed expression:
+ if let ExprKind::Lit(ref lit) = idx.kind {
+ if let ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) = lit.node {
+ let snip = self.tcx.sess.source_map().span_to_snippet(base.span);
+ if let Ok(snip) = snip {
+ err.span_suggestion(
+ expr.span,
+ "to access tuple elements, use",
+ format!("{snip}.{i}"),
+ Applicability::MachineApplicable,
+ );
+ needs_note = false;
+ }
+ }
+ }
+ if needs_note {
+ err.help(
+ "to access tuple elements, use tuple indexing \
+ syntax (e.g., `tuple.0`)",
+ );
+ }
+ }
+ err.emit();
+ self.tcx.ty_error()
+ }
+ }
+ }
+ }
+
+ fn point_at_index_if_possible(
+ &self,
+ errors: &mut Vec<traits::FulfillmentError<'tcx>>,
+ span: Span,
+ ) {
+ for error in errors {
+ match error.obligation.predicate.kind().skip_binder() {
+ ty::PredicateKind::Trait(predicate)
+ if self.tcx.is_diagnostic_item(sym::SliceIndex, predicate.trait_ref.def_id) => {
+ }
+ _ => continue,
+ }
+ error.obligation.cause.span = span;
+ }
+ }
+
+ fn check_expr_yield(
+ &self,
+ value: &'tcx hir::Expr<'tcx>,
+ expr: &'tcx hir::Expr<'tcx>,
+ src: &'tcx hir::YieldSource,
+ ) -> Ty<'tcx> {
+ match self.resume_yield_tys {
+ Some((resume_ty, yield_ty)) => {
+ self.check_expr_coercable_to_type(&value, yield_ty, None);
+
+ resume_ty
+ }
+ // Given that this `yield` expression was generated as a result of lowering a `.await`,
+ // we know that the yield type must be `()`; however, the context won't contain this
+ // information. Hence, we check the source of the yield expression here and check its
+ // value's type against `()` (this check should always hold).
+ None if src.is_await() => {
+ self.check_expr_coercable_to_type(&value, self.tcx.mk_unit(), None);
+ self.tcx.mk_unit()
+ }
+ _ => {
+ self.tcx.sess.emit_err(YieldExprOutsideOfGenerator { span: expr.span });
+ // Avoid expressions without types during writeback (#78653).
+ self.check_expr(value);
+ self.tcx.mk_unit()
+ }
+ }
+ }
+
+ fn check_expr_asm_operand(&self, expr: &'tcx hir::Expr<'tcx>, is_input: bool) {
+ let needs = if is_input { Needs::None } else { Needs::MutPlace };
+ let ty = self.check_expr_with_needs(expr, needs);
+ self.require_type_is_sized(ty, expr.span, traits::InlineAsmSized);
+
+ if !is_input && !expr.is_syntactic_place_expr() {
+ let mut err = self.tcx.sess.struct_span_err(expr.span, "invalid asm output");
+ err.span_label(expr.span, "cannot assign to this expression");
+ err.emit();
+ }
+
+ // If this is an input value, we require its type to be fully resolved
+ // at this point. This allows us to provide helpful coercions which help
+ // pass the type candidate list in a later pass.
+ //
+ // We don't require output types to be resolved at this point, which
+ // allows them to be inferred based on how they are used later in the
+ // function.
+ if is_input {
+ let ty = self.structurally_resolved_type(expr.span, ty);
+ match *ty.kind() {
+ ty::FnDef(..) => {
+ let fnptr_ty = self.tcx.mk_fn_ptr(ty.fn_sig(self.tcx));
+ self.demand_coerce(expr, ty, fnptr_ty, None, AllowTwoPhase::No);
+ }
+ ty::Ref(_, base_ty, mutbl) => {
+ let ptr_ty = self.tcx.mk_ptr(ty::TypeAndMut { ty: base_ty, mutbl });
+ self.demand_coerce(expr, ty, ptr_ty, None, AllowTwoPhase::No);
+ }
+ _ => {}
+ }
+ }
+ }
+
+ fn check_expr_asm(&self, asm: &'tcx hir::InlineAsm<'tcx>) -> Ty<'tcx> {
+ for (op, _op_sp) in asm.operands {
+ match op {
+ hir::InlineAsmOperand::In { expr, .. } => {
+ self.check_expr_asm_operand(expr, true);
+ }
+ hir::InlineAsmOperand::Out { expr: Some(expr), .. }
+ | hir::InlineAsmOperand::InOut { expr, .. } => {
+ self.check_expr_asm_operand(expr, false);
+ }
+ hir::InlineAsmOperand::Out { expr: None, .. } => {}
+ hir::InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
+ self.check_expr_asm_operand(in_expr, true);
+ if let Some(out_expr) = out_expr {
+ self.check_expr_asm_operand(out_expr, false);
+ }
+ }
+ // `AnonConst`s have their own body and is type-checked separately.
+ // As they don't flow into the type system we don't need them to
+ // be well-formed.
+ hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::SymFn { .. } => {}
+ hir::InlineAsmOperand::SymStatic { .. } => {}
+ }
+ }
+ if asm.options.contains(ast::InlineAsmOptions::NORETURN) {
+ self.tcx.types.never
+ } else {
+ self.tcx.mk_unit()
+ }
+ }
+}
projects / rustc.git / blobdiff