1838 lines
71 KiB
Rust
1838 lines
71 KiB
Rust
//! Type checking expressions.
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//!
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//! See `mod.rs` for more context on type checking in general.
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use crate::astconv::AstConv as _;
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use crate::check::cast;
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use crate::check::coercion::CoerceMany;
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use crate::check::fatally_break_rust;
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use crate::check::method::{probe, MethodError, SelfSource};
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use crate::check::report_unexpected_variant_res;
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use crate::check::BreakableCtxt;
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use crate::check::Diverges;
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use crate::check::Expectation::{self, ExpectCastableToType, ExpectHasType, NoExpectation};
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use crate::check::FnCtxt;
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use crate::check::Needs;
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use crate::check::TupleArgumentsFlag::DontTupleArguments;
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use crate::type_error_struct;
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use crate::util::common::ErrorReported;
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use errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder, DiagnosticId};
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use rustc::infer;
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use rustc::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
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use rustc::middle::lang_items;
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use rustc::traits::{self, ObligationCauseCode};
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use rustc::ty;
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use rustc::ty::adjustment::{Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability};
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use rustc::ty::Ty;
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use rustc::ty::TypeFoldable;
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use rustc::ty::{AdtKind, Visibility};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_hir as hir;
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use rustc_hir::def::{CtorKind, DefKind, Res};
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use rustc_hir::def_id::DefId;
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use rustc_hir::{ExprKind, QPath};
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use rustc_span::hygiene::DesugaringKind;
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use rustc_span::source_map::Span;
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use rustc_span::symbol::{kw, sym, Symbol};
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use syntax::ast;
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use syntax::util::lev_distance::find_best_match_for_name;
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use rustc_error_codes::*;
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use std::fmt::Display;
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impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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fn check_expr_eq_type(&self, expr: &'tcx hir::Expr<'tcx>, expected: Ty<'tcx>) {
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let ty = self.check_expr_with_hint(expr, expected);
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self.demand_eqtype(expr.span, expected, ty);
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}
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pub fn check_expr_has_type_or_error(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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expected: Ty<'tcx>,
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extend_err: impl Fn(&mut DiagnosticBuilder<'_>),
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) -> Ty<'tcx> {
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self.check_expr_meets_expectation_or_error(expr, ExpectHasType(expected), extend_err)
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}
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fn check_expr_meets_expectation_or_error(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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expected: Expectation<'tcx>,
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extend_err: impl Fn(&mut DiagnosticBuilder<'_>),
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) -> Ty<'tcx> {
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let expected_ty = expected.to_option(&self).unwrap_or(self.tcx.types.bool);
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let mut ty = self.check_expr_with_expectation(expr, expected);
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// While we don't allow *arbitrary* coercions here, we *do* allow
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// coercions from ! to `expected`.
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if ty.is_never() {
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assert!(
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!self.tables.borrow().adjustments().contains_key(expr.hir_id),
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"expression with never type wound up being adjusted"
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);
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let adj_ty = self.next_diverging_ty_var(TypeVariableOrigin {
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kind: TypeVariableOriginKind::AdjustmentType,
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span: expr.span,
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});
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self.apply_adjustments(
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expr,
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vec![Adjustment { kind: Adjust::NeverToAny, target: adj_ty }],
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);
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ty = adj_ty;
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}
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if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) {
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let expr = expr.peel_drop_temps();
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self.suggest_ref_or_into(&mut err, expr, expected_ty, ty);
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extend_err(&mut err);
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// Error possibly reported in `check_assign` so avoid emitting error again.
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err.emit_unless(self.is_assign_to_bool(expr, expected_ty));
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}
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ty
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}
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pub(super) fn check_expr_coercable_to_type(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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expected: Ty<'tcx>,
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) -> Ty<'tcx> {
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let ty = self.check_expr_with_hint(expr, expected);
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// checks don't need two phase
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self.demand_coerce(expr, ty, expected, AllowTwoPhase::No)
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}
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pub(super) fn check_expr_with_hint(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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expected: Ty<'tcx>,
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) -> Ty<'tcx> {
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self.check_expr_with_expectation(expr, ExpectHasType(expected))
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}
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pub(super) fn check_expr_with_expectation(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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expected: Expectation<'tcx>,
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) -> Ty<'tcx> {
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self.check_expr_with_expectation_and_needs(expr, expected, Needs::None)
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}
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pub(super) fn check_expr(&self, expr: &'tcx hir::Expr<'tcx>) -> Ty<'tcx> {
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self.check_expr_with_expectation(expr, NoExpectation)
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}
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pub(super) fn check_expr_with_needs(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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needs: Needs,
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) -> Ty<'tcx> {
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self.check_expr_with_expectation_and_needs(expr, NoExpectation, needs)
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}
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/// Invariant:
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/// If an expression has any sub-expressions that result in a type error,
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/// inspecting that expression's type with `ty.references_error()` will return
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/// true. Likewise, if an expression is known to diverge, inspecting its
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/// type with `ty::type_is_bot` will return true (n.b.: since Rust is
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/// strict, _|_ can appear in the type of an expression that does not,
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/// itself, diverge: for example, fn() -> _|_.)
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/// Note that inspecting a type's structure *directly* may expose the fact
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/// that there are actually multiple representations for `Error`, so avoid
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/// that when err needs to be handled differently.
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fn check_expr_with_expectation_and_needs(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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expected: Expectation<'tcx>,
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needs: Needs,
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) -> Ty<'tcx> {
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debug!(">> type-checking: expr={:?} expected={:?}", expr, expected);
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// True if `expr` is a `Try::from_ok(())` that is a result of desugaring a try block
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// without the final expr (e.g. `try { return; }`). We don't want to generate an
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// unreachable_code lint for it since warnings for autogenerated code are confusing.
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let is_try_block_generated_unit_expr = match expr.kind {
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ExprKind::Call(_, ref args) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {
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args.len() == 1 && args[0].span.is_desugaring(DesugaringKind::TryBlock)
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}
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_ => false,
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};
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// Warn for expressions after diverging siblings.
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if !is_try_block_generated_unit_expr {
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self.warn_if_unreachable(expr.hir_id, expr.span, "expression");
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}
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// Hide the outer diverging and has_errors flags.
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let old_diverges = self.diverges.get();
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let old_has_errors = self.has_errors.get();
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self.diverges.set(Diverges::Maybe);
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self.has_errors.set(false);
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let ty = self.check_expr_kind(expr, expected, needs);
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// Warn for non-block expressions with diverging children.
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match expr.kind {
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ExprKind::Block(..) | ExprKind::Loop(..) | ExprKind::Match(..) => {}
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// If `expr` is a result of desugaring the try block and is an ok-wrapped
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// diverging expression (e.g. it arose from desugaring of `try { return }`),
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// we skip issuing a warning because it is autogenerated code.
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ExprKind::Call(..) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {}
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ExprKind::Call(ref callee, _) => {
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self.warn_if_unreachable(expr.hir_id, callee.span, "call")
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}
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ExprKind::MethodCall(_, ref span, _) => {
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self.warn_if_unreachable(expr.hir_id, *span, "call")
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}
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_ => self.warn_if_unreachable(expr.hir_id, expr.span, "expression"),
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}
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// Any expression that produces a value of type `!` must have diverged
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if ty.is_never() {
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self.diverges.set(self.diverges.get() | Diverges::always(expr.span));
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}
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// Record the type, which applies it effects.
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// We need to do this after the warning above, so that
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// we don't warn for the diverging expression itself.
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self.write_ty(expr.hir_id, ty);
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// Combine the diverging and has_error flags.
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self.diverges.set(self.diverges.get() | old_diverges);
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self.has_errors.set(self.has_errors.get() | old_has_errors);
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debug!("type of {} is...", self.tcx.hir().node_to_string(expr.hir_id));
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debug!("... {:?}, expected is {:?}", ty, expected);
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ty
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}
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fn check_expr_kind(
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&self,
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expr: &'tcx hir::Expr<'tcx>,
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expected: Expectation<'tcx>,
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needs: Needs,
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) -> Ty<'tcx> {
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debug!("check_expr_kind(expr={:?}, expected={:?}, needs={:?})", expr, expected, needs,);
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let tcx = self.tcx;
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match expr.kind {
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ExprKind::Box(ref subexpr) => self.check_expr_box(subexpr, expected),
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ExprKind::Lit(ref lit) => self.check_lit(&lit, expected),
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ExprKind::Binary(op, ref lhs, ref rhs) => self.check_binop(expr, op, lhs, rhs),
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ExprKind::Assign(ref lhs, ref rhs, ref span) => {
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self.check_expr_assign(expr, expected, lhs, rhs, span)
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}
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ExprKind::AssignOp(op, ref lhs, ref rhs) => self.check_binop_assign(expr, op, lhs, rhs),
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ExprKind::Unary(unop, ref oprnd) => {
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self.check_expr_unary(unop, oprnd, expected, needs, expr)
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}
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ExprKind::AddrOf(kind, mutbl, ref oprnd) => {
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self.check_expr_addr_of(kind, mutbl, oprnd, expected, expr)
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}
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ExprKind::Path(ref qpath) => self.check_expr_path(qpath, expr),
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ExprKind::InlineAsm(ref asm) => {
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for expr in asm.outputs_exprs.iter().chain(asm.inputs_exprs.iter()) {
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self.check_expr(expr);
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}
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tcx.mk_unit()
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}
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ExprKind::Break(destination, ref expr_opt) => {
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self.check_expr_break(destination, expr_opt.as_deref(), expr)
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}
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ExprKind::Continue(destination) => {
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if destination.target_id.is_ok() {
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tcx.types.never
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} else {
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// There was an error; make type-check fail.
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tcx.types.err
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}
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}
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ExprKind::Ret(ref expr_opt) => self.check_expr_return(expr_opt.as_deref(), expr),
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ExprKind::Loop(ref body, _, source) => {
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self.check_expr_loop(body, source, expected, expr)
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}
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ExprKind::Match(ref discrim, ref arms, match_src) => {
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self.check_match(expr, &discrim, arms, expected, match_src)
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}
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ExprKind::Closure(capture, ref decl, body_id, _, gen) => {
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self.check_expr_closure(expr, capture, &decl, body_id, gen, expected)
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}
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ExprKind::Block(ref body, _) => self.check_block_with_expected(&body, expected),
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ExprKind::Call(ref callee, ref args) => self.check_call(expr, &callee, args, expected),
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ExprKind::MethodCall(ref segment, span, ref args) => {
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self.check_method_call(expr, segment, span, args, expected, needs)
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}
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ExprKind::Cast(ref e, ref t) => self.check_expr_cast(e, t, expr),
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ExprKind::Type(ref e, ref t) => {
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let ty = self.to_ty_saving_user_provided_ty(&t);
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self.check_expr_eq_type(&e, ty);
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ty
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}
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ExprKind::DropTemps(ref e) => self.check_expr_with_expectation(e, expected),
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ExprKind::Array(ref args) => self.check_expr_array(args, expected, expr),
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ExprKind::Repeat(ref element, ref count) => {
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self.check_expr_repeat(element, count, expected, expr)
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}
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ExprKind::Tup(ref elts) => self.check_expr_tuple(elts, expected, expr),
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ExprKind::Struct(ref qpath, fields, ref base_expr) => {
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self.check_expr_struct(expr, expected, qpath, fields, base_expr)
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}
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ExprKind::Field(ref base, field) => self.check_field(expr, needs, &base, field),
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ExprKind::Index(ref base, ref idx) => self.check_expr_index(base, idx, needs, expr),
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ExprKind::Yield(ref value, ref src) => self.check_expr_yield(value, expr, src),
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hir::ExprKind::Err => tcx.types.err,
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}
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}
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fn check_expr_box(&self, expr: &'tcx hir::Expr<'tcx>, expected: Expectation<'tcx>) -> Ty<'tcx> {
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let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| match ty.kind {
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ty::Adt(def, _) if def.is_box() => Expectation::rvalue_hint(self, ty.boxed_ty()),
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_ => NoExpectation,
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});
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let referent_ty = self.check_expr_with_expectation(expr, expected_inner);
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self.tcx.mk_box(referent_ty)
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}
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fn check_expr_unary(
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&self,
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unop: hir::UnOp,
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oprnd: &'tcx hir::Expr<'tcx>,
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expected: Expectation<'tcx>,
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needs: Needs,
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expr: &'tcx hir::Expr<'tcx>,
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) -> Ty<'tcx> {
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let tcx = self.tcx;
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let expected_inner = match unop {
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hir::UnOp::UnNot | hir::UnOp::UnNeg => expected,
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hir::UnOp::UnDeref => NoExpectation,
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};
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let needs = match unop {
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hir::UnOp::UnDeref => needs,
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_ => Needs::None,
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};
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let mut oprnd_t = self.check_expr_with_expectation_and_needs(&oprnd, expected_inner, needs);
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if !oprnd_t.references_error() {
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oprnd_t = self.structurally_resolved_type(expr.span, oprnd_t);
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match unop {
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hir::UnOp::UnDeref => {
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if let Some(mt) = oprnd_t.builtin_deref(true) {
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oprnd_t = mt.ty;
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} else if let Some(ok) = self.try_overloaded_deref(expr.span, oprnd_t, needs) {
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let method = self.register_infer_ok_obligations(ok);
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if let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].kind {
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let mutbl = match mutbl {
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hir::Mutability::Not => AutoBorrowMutability::Not,
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hir::Mutability::Mut => AutoBorrowMutability::Mut {
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// (It shouldn't actually matter for unary ops whether
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// we enable two-phase borrows or not, since a unary
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// op has no additional operands.)
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allow_two_phase_borrow: AllowTwoPhase::No,
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},
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};
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self.apply_adjustments(
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oprnd,
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vec![Adjustment {
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kind: Adjust::Borrow(AutoBorrow::Ref(region, mutbl)),
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target: method.sig.inputs()[0],
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}],
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);
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}
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oprnd_t = self.make_overloaded_place_return_type(method).ty;
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self.write_method_call(expr.hir_id, method);
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} else {
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let mut err = type_error_struct!(
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tcx.sess,
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expr.span,
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oprnd_t,
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E0614,
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"type `{}` cannot be dereferenced",
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oprnd_t,
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);
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let sp = tcx.sess.source_map().start_point(expr.span);
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if let Some(sp) =
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tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp)
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{
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tcx.sess.parse_sess.expr_parentheses_needed(&mut err, *sp, None);
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}
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err.emit();
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oprnd_t = tcx.types.err;
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}
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}
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hir::UnOp::UnNot => {
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let result = self.check_user_unop(expr, oprnd_t, unop);
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// If it's builtin, we can reuse the type, this helps inference.
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if !(oprnd_t.is_integral() || oprnd_t.kind == ty::Bool) {
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oprnd_t = result;
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}
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}
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hir::UnOp::UnNeg => {
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let result = self.check_user_unop(expr, oprnd_t, unop);
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// If it's builtin, we can reuse the type, this helps inference.
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if !oprnd_t.is_numeric() {
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oprnd_t = result;
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}
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}
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}
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}
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oprnd_t
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}
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|
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fn check_expr_addr_of(
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&self,
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kind: hir::BorrowKind,
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mutbl: hir::Mutability,
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oprnd: &'tcx hir::Expr<'tcx>,
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expected: Expectation<'tcx>,
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expr: &'tcx hir::Expr<'tcx>,
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) -> Ty<'tcx> {
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let hint = expected.only_has_type(self).map_or(NoExpectation, |ty| {
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match ty.kind {
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ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
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if oprnd.is_syntactic_place_expr() {
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// Places may legitimately have unsized types.
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// For example, dereferences of a fat pointer and
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// the last field of a struct can be unsized.
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ExpectHasType(ty)
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} else {
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Expectation::rvalue_hint(self, ty)
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}
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}
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_ => NoExpectation,
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}
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});
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let needs = Needs::maybe_mut_place(mutbl);
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let ty = self.check_expr_with_expectation_and_needs(&oprnd, hint, needs);
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let tm = ty::TypeAndMut { ty: ty, mutbl: mutbl };
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match kind {
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_ if tm.ty.references_error() => self.tcx.types.err,
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hir::BorrowKind::Raw => {
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self.check_named_place_expr(oprnd);
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self.tcx.mk_ptr(tm)
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}
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hir::BorrowKind::Ref => {
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// Note: at this point, we cannot say what the best lifetime
|
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// is to use for resulting pointer. We want to use the
|
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// shortest lifetime possible so as to avoid spurious borrowck
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// errors. Moreover, the longest lifetime will depend on the
|
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// precise details of the value whose address is being taken
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// (and how long it is valid), which we don't know yet until
|
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// type inference is complete.
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//
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// 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.tables.borrow().adjustments().get(base.hir_id).map_or(false, |x| {
|
|
x.iter().any(|adj| if let Adjust::Deref(_) = adj.kind { true } else { false })
|
|
})
|
|
});
|
|
if !is_named {
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
oprnd.span,
|
|
E0745,
|
|
"cannot take address of a temporary"
|
|
)
|
|
.span_label(oprnd.span, "temporary value")
|
|
.emit();
|
|
}
|
|
}
|
|
|
|
fn check_expr_path(&self, qpath: &hir::QPath<'_>, expr: &'tcx hir::Expr<'tcx>) -> Ty<'tcx> {
|
|
let tcx = self.tcx;
|
|
let (res, opt_ty, segs) = self.resolve_ty_and_res_ufcs(qpath, expr.hir_id, expr.span);
|
|
let ty = match res {
|
|
Res::Err => {
|
|
self.set_tainted_by_errors();
|
|
tcx.types.err
|
|
}
|
|
Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _) => {
|
|
report_unexpected_variant_res(tcx, res, expr.span, qpath);
|
|
tcx.types.err
|
|
}
|
|
_ => self.instantiate_value_path(segs, opt_ty, res, expr.span, expr.hir_id).0,
|
|
};
|
|
|
|
if let ty::FnDef(..) = ty.kind {
|
|
let fn_sig = ty.fn_sig(tcx);
|
|
if !tcx.features().unsized_locals {
|
|
// 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 input = self
|
|
.replace_bound_vars_with_fresh_vars(
|
|
expr.span,
|
|
infer::LateBoundRegionConversionTime::FnCall,
|
|
&fn_sig.input(i),
|
|
)
|
|
.0;
|
|
self.require_type_is_sized_deferred(
|
|
input,
|
|
expr.span,
|
|
traits::SizedArgumentType,
|
|
);
|
|
}
|
|
}
|
|
// 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(),
|
|
)
|
|
.0;
|
|
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.tables.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(ref 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 `encloding_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).
|
|
self.tcx.sess.delay_span_bug(
|
|
expr.span,
|
|
"break was outside loop, but no error was emitted",
|
|
);
|
|
return tcx.types.err;
|
|
}
|
|
}
|
|
};
|
|
|
|
// 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(tcx.types.err);
|
|
|
|
// 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 ctxt = match enclosing_breakables.opt_find_breakable(target_id) {
|
|
Some(ctxt) => ctxt,
|
|
None => {
|
|
// Avoid ICE when `break` is inside a closure (#65383).
|
|
self.tcx.sess.delay_span_bug(
|
|
expr.span,
|
|
"break was outside loop, but no error was emitted",
|
|
);
|
|
return tcx.types.err;
|
|
}
|
|
};
|
|
|
|
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, cause.span, 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());
|
|
}
|
|
|
|
ctxt.may_break = true;
|
|
|
|
// 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.
|
|
self.tcx
|
|
.sess
|
|
.delay_span_bug(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(ref e) = expr_opt {
|
|
self.check_expr_with_hint(e, tcx.types.err);
|
|
|
|
// ... except when we try to 'break rust;'.
|
|
// ICE this expression in particular (see #43162).
|
|
if let ExprKind::Path(QPath::Resolved(_, ref 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.
|
|
tcx.types.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() {
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
expr.span,
|
|
E0572,
|
|
"return statement outside of function body",
|
|
)
|
|
.emit();
|
|
} else if let Some(ref e) = expr_opt {
|
|
if self.ret_coercion_span.borrow().is_none() {
|
|
*self.ret_coercion_span.borrow_mut() = Some(e.span);
|
|
}
|
|
self.check_return_expr(e);
|
|
} else {
|
|
let mut coercion = self.ret_coercion.as_ref().unwrap().borrow_mut();
|
|
if self.ret_coercion_span.borrow().is_none() {
|
|
*self.ret_coercion_span.borrow_mut() = 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| {
|
|
db.span_label(
|
|
fn_decl.output.span(),
|
|
format!("expected `{}` because of this return type", fn_decl.output,),
|
|
);
|
|
},
|
|
true,
|
|
);
|
|
} else {
|
|
coercion.coerce_forced_unit(self, &cause, &mut |_| (), true);
|
|
}
|
|
}
|
|
self.tcx.types.never
|
|
}
|
|
|
|
pub(super) fn check_return_expr(&self, return_expr: &'tcx hir::Expr<'tcx>) {
|
|
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.clone());
|
|
ret_coercion.borrow_mut().coerce(
|
|
self,
|
|
&self.cause(return_expr.span, ObligationCauseCode::ReturnValue(return_expr.hir_id)),
|
|
return_expr,
|
|
return_expr_ty,
|
|
);
|
|
}
|
|
|
|
fn is_destructuring_place_expr(&self, expr: &'tcx hir::Expr<'tcx>) -> bool {
|
|
match &expr.kind {
|
|
ExprKind::Array(comps) | ExprKind::Tup(comps) => {
|
|
comps.iter().all(|e| self.is_destructuring_place_expr(e))
|
|
}
|
|
ExprKind::Struct(_path, fields, rest) => {
|
|
rest.as_ref().map(|e| self.is_destructuring_place_expr(e)).unwrap_or(true)
|
|
&& fields.iter().all(|f| self.is_destructuring_place_expr(&f.expr))
|
|
}
|
|
_ => expr.is_syntactic_place_expr(),
|
|
}
|
|
}
|
|
|
|
pub(crate) fn check_lhs_assignable(
|
|
&self,
|
|
lhs: &'tcx hir::Expr<'tcx>,
|
|
err_code: &'static str,
|
|
expr_span: &Span,
|
|
) {
|
|
if !lhs.is_syntactic_place_expr() {
|
|
let mut err = self.tcx.sess.struct_span_err_with_code(
|
|
*expr_span,
|
|
"invalid left-hand side of assignment",
|
|
DiagnosticId::Error(err_code.into()),
|
|
);
|
|
err.span_label(lhs.span, "cannot assign to this expression");
|
|
if self.is_destructuring_place_expr(lhs) {
|
|
err.note("destructuring assignments are not currently supported");
|
|
err.note("for more information, see https://github.com/rust-lang/rfcs/issues/372");
|
|
}
|
|
err.emit();
|
|
}
|
|
}
|
|
|
|
/// Type check assignment expression `expr` of form `lhs = rhs`.
|
|
/// The expected type is `()` and is passsed 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 lhs_ty = self.check_expr_with_needs(&lhs, Needs::MutPlace);
|
|
let rhs_ty = self.check_expr_coercable_to_type(&rhs, lhs_ty);
|
|
|
|
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 msg = "try comparing for equality";
|
|
let left = self.tcx.sess.source_map().span_to_snippet(lhs.span);
|
|
let right = self.tcx.sess.source_map().span_to_snippet(rhs.span);
|
|
if let (Ok(left), Ok(right)) = (left, right) {
|
|
let help = format!("{} == {}", left, right);
|
|
err.span_suggestion(expr.span, msg, help, Applicability::MaybeIncorrect);
|
|
} else {
|
|
err.help(msg);
|
|
}
|
|
err.emit();
|
|
} else {
|
|
self.check_lhs_assignable(lhs, "E0070", span);
|
|
}
|
|
|
|
self.require_type_is_sized(lhs_ty, lhs.span, traits::AssignmentLhsSized);
|
|
|
|
if lhs_ty.references_error() || rhs_ty.references_error() {
|
|
self.tcx.types.err
|
|
} else {
|
|
self.tcx.mk_unit()
|
|
}
|
|
}
|
|
|
|
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::WhileLet | 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<'_>,
|
|
span: Span,
|
|
args: &'tcx [hir::Expr<'tcx>],
|
|
expected: Expectation<'tcx>,
|
|
needs: Needs,
|
|
) -> Ty<'tcx> {
|
|
let rcvr = &args[0];
|
|
let rcvr_t = self.check_expr_with_needs(&rcvr, needs);
|
|
// no need to check for bot/err -- callee does that
|
|
let rcvr_t = self.structurally_resolved_type(args[0].span, rcvr_t);
|
|
|
|
let method = match self.lookup_method(rcvr_t, segment, span, expr, rcvr) {
|
|
Ok(method) => {
|
|
// We could add a "consider `foo::<params>`" suggestion here, but I wasn't able to
|
|
// trigger this codepath causing `structuraly_resolved_type` to emit an error.
|
|
|
|
self.write_method_call(expr.hir_id, method);
|
|
Ok(method)
|
|
}
|
|
Err(error) => {
|
|
if segment.ident.name != kw::Invalid {
|
|
self.report_extended_method_error(segment, span, args, rcvr_t, error);
|
|
}
|
|
Err(())
|
|
}
|
|
};
|
|
|
|
// Call the generic checker.
|
|
self.check_method_argument_types(
|
|
span,
|
|
expr,
|
|
method,
|
|
&args[1..],
|
|
DontTupleArguments,
|
|
expected,
|
|
)
|
|
}
|
|
|
|
fn report_extended_method_error(
|
|
&self,
|
|
segment: &hir::PathSegment<'_>,
|
|
span: Span,
|
|
args: &'tcx [hir::Expr<'tcx>],
|
|
rcvr_t: Ty<'tcx>,
|
|
error: MethodError<'tcx>,
|
|
) {
|
|
let rcvr = &args[0];
|
|
let try_alt_rcvr = |err: &mut DiagnosticBuilder<'_>, rcvr_t, lang_item| {
|
|
if let Some(new_rcvr_t) = self.tcx.mk_lang_item(rcvr_t, lang_item) {
|
|
if let Ok(pick) = self.lookup_probe(
|
|
span,
|
|
segment.ident,
|
|
new_rcvr_t,
|
|
rcvr,
|
|
probe::ProbeScope::AllTraits,
|
|
) {
|
|
err.span_label(
|
|
pick.item.ident.span,
|
|
&format!("the method is available for `{}` here", new_rcvr_t),
|
|
);
|
|
}
|
|
}
|
|
};
|
|
|
|
if let Some(mut err) = self.report_method_error(
|
|
span,
|
|
rcvr_t,
|
|
segment.ident,
|
|
SelfSource::MethodCall(rcvr),
|
|
error,
|
|
Some(args),
|
|
) {
|
|
if let ty::Adt(..) = rcvr_t.kind {
|
|
// Try alternative arbitrary self types that could fulfill this call.
|
|
// FIXME: probe for all types that *could* be arbitrary self-types, not
|
|
// just this whitelist.
|
|
try_alt_rcvr(&mut err, rcvr_t, lang_items::OwnedBoxLangItem);
|
|
try_alt_rcvr(&mut err, rcvr_t, lang_items::PinTypeLangItem);
|
|
try_alt_rcvr(&mut err, rcvr_t, lang_items::Arc);
|
|
try_alt_rcvr(&mut err, rcvr_t, lang_items::Rc);
|
|
}
|
|
err.emit();
|
|
}
|
|
}
|
|
|
|
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_cast = self.resolve_vars_if_possible(&t_cast);
|
|
|
|
// Eagerly check for some obvious errors.
|
|
if t_expr.references_error() || t_cast.references_error() {
|
|
self.tcx.types.err
|
|
} 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) {
|
|
Ok(cast_check) => {
|
|
deferred_cast_checks.push(cast_check);
|
|
t_cast
|
|
}
|
|
Err(ErrorReported) => self.tcx.types.err,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_expr_array(
|
|
&self,
|
|
args: &'tcx [hir::Expr<'tcx>],
|
|
expected: Expectation<'tcx>,
|
|
expr: &'tcx hir::Expr<'tcx>,
|
|
) -> Ty<'tcx> {
|
|
let uty = expected.to_option(self).and_then(|uty| match uty.kind {
|
|
ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
|
|
_ => None,
|
|
});
|
|
|
|
let element_ty = if !args.is_empty() {
|
|
let coerce_to = uty.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,
|
|
})
|
|
};
|
|
self.tcx.mk_array(element_ty, args.len() as u64)
|
|
}
|
|
|
|
fn check_expr_repeat(
|
|
&self,
|
|
element: &'tcx hir::Expr<'tcx>,
|
|
count: &'tcx hir::AnonConst,
|
|
expected: Expectation<'tcx>,
|
|
_expr: &'tcx hir::Expr<'tcx>,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx;
|
|
let count_def_id = tcx.hir().local_def_id(count.hir_id);
|
|
let count = if self.const_param_def_id(count).is_some() {
|
|
Ok(self.to_const(count, tcx.type_of(count_def_id)))
|
|
} else {
|
|
tcx.const_eval_poly(count_def_id)
|
|
};
|
|
|
|
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);
|
|
(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() {
|
|
tcx.types.err
|
|
} else if let Ok(count) = count {
|
|
tcx.mk_ty(ty::Array(t, count))
|
|
} else {
|
|
tcx.types.err
|
|
}
|
|
}
|
|
|
|
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(ref flds) => Some(&flds[..]),
|
|
_ => None,
|
|
}
|
|
});
|
|
|
|
let elt_ts_iter = elts.iter().enumerate().map(|(i, e)| {
|
|
let t = match flds {
|
|
Some(ref fs) if i < fs.len() => {
|
|
let ety = fs[i].expect_ty();
|
|
self.check_expr_coercable_to_type(&e, ety);
|
|
ety
|
|
}
|
|
_ => self.check_expr_with_expectation(&e, NoExpectation),
|
|
};
|
|
t
|
|
});
|
|
let tuple = self.tcx.mk_tup(elt_ts_iter);
|
|
if tuple.references_error() {
|
|
self.tcx.types.err
|
|
} 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::Field<'tcx>],
|
|
base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
|
|
) -> Ty<'tcx> {
|
|
// Find the relevant variant
|
|
let (variant, adt_ty) = if let Some(variant_ty) = self.check_struct_path(qpath, expr.hir_id)
|
|
{
|
|
variant_ty
|
|
} else {
|
|
self.check_struct_fields_on_error(fields, base_expr);
|
|
return self.tcx.types.err;
|
|
};
|
|
|
|
let path_span = match *qpath {
|
|
QPath::Resolved(_, ref path) => path.span,
|
|
QPath::TypeRelative(ref qself, _) => qself.span,
|
|
};
|
|
|
|
// 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() {
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
expr.span,
|
|
E0639,
|
|
"cannot create non-exhaustive {} using struct expression",
|
|
adt.variant_descr()
|
|
)
|
|
.emit();
|
|
}
|
|
|
|
let error_happened = self.check_expr_struct_fields(
|
|
adt_ty,
|
|
expected,
|
|
expr.hir_id,
|
|
path_span,
|
|
variant,
|
|
fields,
|
|
base_expr.is_none(),
|
|
);
|
|
if let &Some(ref base_expr) = base_expr {
|
|
// 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 {
|
|
self.check_expr_has_type_or_error(base_expr, adt_ty, |_| {});
|
|
match adt_ty.kind {
|
|
ty::Adt(adt, substs) if adt.is_struct() => {
|
|
let fru_field_types = adt
|
|
.non_enum_variant()
|
|
.fields
|
|
.iter()
|
|
.map(|f| {
|
|
self.normalize_associated_types_in(
|
|
expr.span,
|
|
&f.ty(self.tcx, substs),
|
|
)
|
|
})
|
|
.collect();
|
|
|
|
self.tables
|
|
.borrow_mut()
|
|
.fru_field_types_mut()
|
|
.insert(expr.hir_id, fru_field_types);
|
|
}
|
|
_ => {
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
base_expr.span,
|
|
E0436,
|
|
"functional record update syntax requires a struct"
|
|
)
|
|
.emit();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
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::Field<'tcx>],
|
|
check_completeness: bool,
|
|
) -> bool {
|
|
let tcx = self.tcx;
|
|
|
|
let adt_ty_hint = self
|
|
.expected_inputs_for_expected_output(span, expected, adt_ty, &[adt_ty])
|
|
.get(0)
|
|
.cloned()
|
|
.unwrap_or(adt_ty);
|
|
// re-link the regions that EIfEO can erase.
|
|
self.demand_eqtype(span, adt_ty_hint, adt_ty);
|
|
|
|
let (substs, adt_kind, kind_name) = match &adt_ty.kind {
|
|
&ty::Adt(adt, substs) => (substs, adt.adt_kind(), adt.variant_descr()),
|
|
_ => span_bug!(span, "non-ADT passed to check_expr_struct_fields"),
|
|
};
|
|
|
|
let mut remaining_fields = variant
|
|
.fields
|
|
.iter()
|
|
.enumerate()
|
|
.map(|(i, field)| (field.ident.modern(), (i, field)))
|
|
.collect::<FxHashMap<_, _>>();
|
|
|
|
let mut seen_fields = FxHashMap::default();
|
|
|
|
let mut error_happened = false;
|
|
|
|
// Type-check each field.
|
|
for field in ast_fields {
|
|
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);
|
|
}
|
|
|
|
self.field_ty(field.span, v_field, substs)
|
|
} else {
|
|
error_happened = true;
|
|
if let Some(prev_span) = seen_fields.get(&ident) {
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
field.ident.span,
|
|
E0062,
|
|
"field `{}` specified more than once",
|
|
ident
|
|
);
|
|
|
|
err.span_label(field.ident.span, "used more than once");
|
|
err.span_label(*prev_span, format!("first use of `{}`", ident));
|
|
|
|
err.emit();
|
|
} else {
|
|
self.report_unknown_field(adt_ty, variant, field, ast_fields, kind_name, span);
|
|
}
|
|
|
|
tcx.types.err
|
|
};
|
|
|
|
// Make sure to give a type to the field even if there's
|
|
// an error, so we can continue type-checking.
|
|
self.check_expr_coercable_to_type(&field.expr, field_type);
|
|
}
|
|
|
|
// Make sure the programmer specified correct number of fields.
|
|
if kind_name == "union" {
|
|
if ast_fields.len() != 1 {
|
|
tcx.sess.span_err(span, "union expressions should have exactly one field");
|
|
}
|
|
} else if check_completeness && !error_happened && !remaining_fields.is_empty() {
|
|
let len = remaining_fields.len();
|
|
|
|
let mut displayable_field_names =
|
|
remaining_fields.keys().map(|ident| ident.as_str()).collect::<Vec<_>>();
|
|
|
|
displayable_field_names.sort();
|
|
|
|
let truncated_fields_error = if len <= 3 {
|
|
String::new()
|
|
} else {
|
|
format!(" and {} other field{}", (len - 3), if len - 3 == 1 { "" } else { "s" })
|
|
};
|
|
|
|
let remaining_fields_names = displayable_field_names
|
|
.iter()
|
|
.take(3)
|
|
.map(|n| format!("`{}`", n))
|
|
.collect::<Vec<_>>()
|
|
.join(", ");
|
|
|
|
struct_span_err!(
|
|
tcx.sess,
|
|
span,
|
|
E0063,
|
|
"missing field{} {}{} in initializer of `{}`",
|
|
pluralize!(remaining_fields.len()),
|
|
remaining_fields_names,
|
|
truncated_fields_error,
|
|
adt_ty
|
|
)
|
|
.span_label(
|
|
span,
|
|
format!("missing {}{}", remaining_fields_names, truncated_fields_error),
|
|
)
|
|
.emit();
|
|
}
|
|
error_happened
|
|
}
|
|
|
|
fn check_struct_fields_on_error(
|
|
&self,
|
|
fields: &'tcx [hir::Field<'tcx>],
|
|
base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>,
|
|
) {
|
|
for field in fields {
|
|
self.check_expr(&field.expr);
|
|
}
|
|
if let Some(ref base) = *base_expr {
|
|
self.check_expr(&base);
|
|
}
|
|
}
|
|
|
|
fn report_unknown_field(
|
|
&self,
|
|
ty: Ty<'tcx>,
|
|
variant: &'tcx ty::VariantDef,
|
|
field: &hir::Field<'_>,
|
|
skip_fields: &[hir::Field<'_>],
|
|
kind_name: &str,
|
|
ty_span: Span,
|
|
) {
|
|
if variant.recovered {
|
|
return;
|
|
}
|
|
let mut err = self.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.ident,
|
|
field.ident
|
|
),
|
|
_ => struct_span_err!(
|
|
self.tcx.sess,
|
|
field.ident.span,
|
|
E0560,
|
|
"{} `{}` has no field named `{}`",
|
|
kind_name,
|
|
actual,
|
|
field.ident
|
|
),
|
|
},
|
|
ty,
|
|
);
|
|
match variant.ctor_kind {
|
|
CtorKind::Fn => {
|
|
err.span_label(variant.ident.span, format!("`{adt}` defined here", adt = ty));
|
|
err.span_label(field.ident.span, "field does not exist");
|
|
err.span_label(
|
|
ty_span,
|
|
format!(
|
|
"`{adt}` is a tuple {kind_name}, \
|
|
use the appropriate syntax: `{adt}(/* fields */)`",
|
|
adt = ty,
|
|
kind_name = kind_name
|
|
),
|
|
);
|
|
}
|
|
_ => {
|
|
// prevent all specified fields from being suggested
|
|
let skip_fields = skip_fields.iter().map(|ref x| x.ident.name);
|
|
if let Some(field_name) =
|
|
Self::suggest_field_name(variant, &field.ident.as_str(), skip_fields.collect())
|
|
{
|
|
err.span_suggestion(
|
|
field.ident.span,
|
|
"a field with a similar name exists",
|
|
field_name.to_string(),
|
|
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.ident),
|
|
);
|
|
} else {
|
|
err.span_label(
|
|
field.ident.span,
|
|
format!("`{}` does not have this field", ty),
|
|
);
|
|
}
|
|
let available_field_names = self.available_field_names(variant);
|
|
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 an hint about the closest match in field names
|
|
fn suggest_field_name(
|
|
variant: &'tcx ty::VariantDef,
|
|
field: &str,
|
|
skip: Vec<Symbol>,
|
|
) -> Option<Symbol> {
|
|
let names = variant.fields.iter().filter_map(|field| {
|
|
// ignore already set fields and private fields from non-local crates
|
|
if skip.iter().any(|&x| x == field.ident.name)
|
|
|| (!variant.def_id.is_local() && field.vis != Visibility::Public)
|
|
{
|
|
None
|
|
} else {
|
|
Some(&field.ident.name)
|
|
}
|
|
});
|
|
|
|
find_best_match_for_name(names, field, None)
|
|
}
|
|
|
|
fn available_field_names(&self, variant: &'tcx ty::VariantDef) -> Vec<ast::Name> {
|
|
variant
|
|
.fields
|
|
.iter()
|
|
.filter(|field| {
|
|
let def_scope = self
|
|
.tcx
|
|
.adjust_ident_and_get_scope(field.ident, variant.def_id, self.body_id)
|
|
.1;
|
|
field.vis.is_accessible_from(def_scope, self.tcx)
|
|
})
|
|
.map(|field| field.ident.name)
|
|
.collect()
|
|
}
|
|
|
|
fn name_series_display(&self, names: Vec<ast::Name>) -> 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>,
|
|
needs: Needs,
|
|
base: &'tcx hir::Expr<'tcx>,
|
|
field: ast::Ident,
|
|
) -> Ty<'tcx> {
|
|
let expr_t = self.check_expr_with_needs(base, needs);
|
|
let expr_t = self.structurally_resolved_type(base.span, expr_t);
|
|
let mut private_candidate = None;
|
|
let mut autoderef = self.autoderef(expr.span, expr_t);
|
|
while let Some((base_t, _)) = autoderef.next() {
|
|
match base_t.kind {
|
|
ty::Adt(base_def, substs) if !base_def.is_enum() => {
|
|
debug!("struct named {:?}", base_t);
|
|
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.modern() == 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);
|
|
if field.vis.is_accessible_from(def_scope, self.tcx) {
|
|
let adjustments = autoderef.adjust_steps(self, needs);
|
|
self.apply_adjustments(base, adjustments);
|
|
autoderef.finalize(self);
|
|
|
|
self.tcx.check_stability(field.did, Some(expr.hir_id), expr.span);
|
|
return field_ty;
|
|
}
|
|
private_candidate = Some((base_def.did, field_ty));
|
|
}
|
|
}
|
|
ty::Tuple(ref 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 = autoderef.adjust_steps(self, needs);
|
|
self.apply_adjustments(base, adjustments);
|
|
autoderef.finalize(self);
|
|
|
|
self.write_field_index(expr.hir_id, index);
|
|
return field_ty.expect_ty();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
autoderef.unambiguous_final_ty(self);
|
|
|
|
if let Some((did, field_ty)) = private_candidate {
|
|
self.ban_private_field_access(expr, expr_t, field, did);
|
|
return field_ty;
|
|
}
|
|
|
|
if field.name == kw::Invalid {
|
|
} else if self.method_exists(field, expr_t, expr.hir_id, true) {
|
|
self.ban_take_value_of_method(expr, expr_t, field);
|
|
} else if !expr_t.is_primitive_ty() {
|
|
self.ban_nonexisting_field(field, base, expr, expr_t);
|
|
} else {
|
|
type_error_struct!(
|
|
self.tcx().sess,
|
|
field.span,
|
|
expr_t,
|
|
E0610,
|
|
"`{}` is a primitive type and therefore doesn't have fields",
|
|
expr_t
|
|
)
|
|
.emit();
|
|
}
|
|
|
|
self.tcx().types.err
|
|
}
|
|
|
|
fn ban_nonexisting_field(
|
|
&self,
|
|
field: ast::Ident,
|
|
base: &'tcx hir::Expr<'tcx>,
|
|
expr: &'tcx hir::Expr<'tcx>,
|
|
expr_t: Ty<'tcx>,
|
|
) {
|
|
let mut err = self.no_such_field_err(field.span, field, expr_t);
|
|
|
|
match expr_t.peel_refs().kind {
|
|
ty::Array(_, len) => {
|
|
self.maybe_suggest_array_indexing(&mut err, expr, base, field, len);
|
|
}
|
|
ty::RawPtr(..) => {
|
|
self.suggest_first_deref_field(&mut err, expr, base, field);
|
|
}
|
|
ty::Adt(def, _) if !def.is_enum() => {
|
|
self.suggest_fields_on_recordish(&mut err, def, field);
|
|
}
|
|
ty::Param(param_ty) => {
|
|
self.point_at_param_definition(&mut err, param_ty);
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
if field.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");
|
|
err.help("set `edition = \"2018\"` in `Cargo.toml`");
|
|
err.note("for more on editions, read https://doc.rust-lang.org/edition-guide");
|
|
}
|
|
|
|
err.emit();
|
|
}
|
|
|
|
fn ban_private_field_access(
|
|
&self,
|
|
expr: &hir::Expr<'_>,
|
|
expr_t: Ty<'tcx>,
|
|
field: ast::Ident,
|
|
base_did: DefId,
|
|
) {
|
|
let struct_path = self.tcx().def_path_str(base_did);
|
|
let kind_name = match self.tcx().def_kind(base_did) {
|
|
Some(def_kind) => def_kind.descr(base_did),
|
|
_ => " ",
|
|
};
|
|
let mut err = struct_span_err!(
|
|
self.tcx().sess,
|
|
expr.span,
|
|
E0616,
|
|
"field `{}` of {} `{}` is private",
|
|
field,
|
|
kind_name,
|
|
struct_path
|
|
);
|
|
// 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 `{}` also exists, call it with parentheses", field),
|
|
field,
|
|
expr_t,
|
|
expr.hir_id,
|
|
);
|
|
}
|
|
err.emit();
|
|
}
|
|
|
|
fn ban_take_value_of_method(&self, expr: &hir::Expr<'_>, expr_t: Ty<'tcx>, field: ast::Ident) {
|
|
let mut err = type_error_struct!(
|
|
self.tcx().sess,
|
|
field.span,
|
|
expr_t,
|
|
E0615,
|
|
"attempted to take value of method `{}` on type `{}`",
|
|
field,
|
|
expr_t
|
|
);
|
|
|
|
if !self.expr_in_place(expr.hir_id) {
|
|
self.suggest_method_call(
|
|
&mut err,
|
|
"use parentheses to call the method",
|
|
field,
|
|
expr_t,
|
|
expr.hir_id,
|
|
);
|
|
} else {
|
|
err.help("methods are immutable and cannot be assigned to");
|
|
}
|
|
|
|
err.emit();
|
|
}
|
|
|
|
fn point_at_param_definition(&self, err: &mut DiagnosticBuilder<'_>, param: ty::ParamTy) {
|
|
let generics = self.tcx.generics_of(self.body_id.owner_def_id());
|
|
let generic_param = generics.type_param(¶m, self.tcx);
|
|
if let ty::GenericParamDefKind::Type { synthetic: Some(..), .. } = generic_param.kind {
|
|
return;
|
|
}
|
|
let param_def_id = generic_param.def_id;
|
|
let param_hir_id = match self.tcx.hir().as_local_hir_id(param_def_id) {
|
|
Some(x) => x,
|
|
None => return,
|
|
};
|
|
let param_span = self.tcx.hir().span(param_hir_id);
|
|
let param_name = self.tcx.hir().ty_param_name(param_hir_id);
|
|
|
|
err.span_label(param_span, &format!("type parameter '{}' declared here", param_name));
|
|
}
|
|
|
|
fn suggest_fields_on_recordish(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
def: &'tcx ty::AdtDef,
|
|
field: ast::Ident,
|
|
) {
|
|
if let Some(suggested_field_name) =
|
|
Self::suggest_field_name(def.non_enum_variant(), &field.as_str(), vec![])
|
|
{
|
|
err.span_suggestion(
|
|
field.span,
|
|
"a field with a similar name exists",
|
|
suggested_field_name.to_string(),
|
|
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);
|
|
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 DiagnosticBuilder<'_>,
|
|
expr: &hir::Expr<'_>,
|
|
base: &hir::Expr<'_>,
|
|
field: ast::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 base = self
|
|
.tcx
|
|
.sess
|
|
.source_map()
|
|
.span_to_snippet(base.span)
|
|
.unwrap_or_else(|_| self.tcx.hir().hir_to_pretty_string(base.hir_id));
|
|
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 DiagnosticBuilder<'_>,
|
|
expr: &hir::Expr<'_>,
|
|
base: &hir::Expr<'_>,
|
|
field: ast::Ident,
|
|
) {
|
|
let base = self
|
|
.tcx
|
|
.sess
|
|
.source_map()
|
|
.span_to_snippet(base.span)
|
|
.unwrap_or_else(|_| self.tcx.hir().hir_to_pretty_string(base.hir_id));
|
|
let msg = format!("`{}` is a raw pointer; try dereferencing it", base);
|
|
let suggestion = format!("(*{}).{}", base, field);
|
|
err.span_suggestion(expr.span, &msg, suggestion, Applicability::MaybeIncorrect);
|
|
}
|
|
|
|
fn no_such_field_err<T: Display>(
|
|
&self,
|
|
span: Span,
|
|
field: T,
|
|
expr_t: &ty::TyS<'_>,
|
|
) -> DiagnosticBuilder<'_> {
|
|
type_error_struct!(
|
|
self.tcx().sess,
|
|
span,
|
|
expr_t,
|
|
E0609,
|
|
"no field `{}` on type `{}`",
|
|
field,
|
|
expr_t
|
|
)
|
|
}
|
|
|
|
fn check_expr_index(
|
|
&self,
|
|
base: &'tcx hir::Expr<'tcx>,
|
|
idx: &'tcx hir::Expr<'tcx>,
|
|
needs: Needs,
|
|
expr: &'tcx hir::Expr<'tcx>,
|
|
) -> Ty<'tcx> {
|
|
let base_t = self.check_expr_with_needs(&base, needs);
|
|
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_t, needs) {
|
|
Some((index_ty, element_ty)) => {
|
|
// two-phase not needed because index_ty is never mutable
|
|
self.demand_coerce(idx, idx_t, index_ty, AllowTwoPhase::No);
|
|
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.types.err
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_expr_yield(
|
|
&self,
|
|
value: &'tcx hir::Expr<'tcx>,
|
|
expr: &'tcx hir::Expr<'tcx>,
|
|
src: &'tcx hir::YieldSource,
|
|
) -> Ty<'tcx> {
|
|
match self.yield_ty {
|
|
Some(ty) => {
|
|
self.check_expr_coercable_to_type(&value, 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 == &hir::YieldSource::Await => {
|
|
self.check_expr_coercable_to_type(&value, self.tcx.mk_unit());
|
|
}
|
|
_ => {
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
expr.span,
|
|
E0627,
|
|
"yield expression outside of generator literal"
|
|
)
|
|
.emit();
|
|
}
|
|
}
|
|
self.tcx.mk_unit()
|
|
}
|
|
}
|
|
|
|
pub(super) fn ty_kind_suggestion(ty: Ty<'_>) -> Option<&'static str> {
|
|
Some(match ty.kind {
|
|
ty::Bool => "true",
|
|
ty::Char => "'a'",
|
|
ty::Int(_) | ty::Uint(_) => "42",
|
|
ty::Float(_) => "3.14159",
|
|
ty::Error | ty::Never => return None,
|
|
_ => "value",
|
|
})
|
|
}
|