mirror of https://github.com/rust-lang/rust
2556 lines
101 KiB
Rust
2556 lines
101 KiB
Rust
use crate::gather_locals::DeclOrigin;
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use crate::{errors, FnCtxt, LoweredTy};
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use rustc_ast as ast;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_errors::{
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codes::*, pluralize, struct_span_code_err, Applicability, Diag, ErrorGuaranteed, MultiSpan,
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};
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use rustc_hir::def::{CtorKind, DefKind, Res};
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use rustc_hir::pat_util::EnumerateAndAdjustIterator;
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use rustc_hir::{self as hir, BindingMode, ByRef, HirId, Mutability, Pat, PatKind};
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use rustc_infer::infer;
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use rustc_middle::mir::interpret::ErrorHandled;
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use rustc_middle::ty::{self, Ty, TypeVisitableExt};
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use rustc_middle::{bug, span_bug};
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use rustc_session::{lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS, parse::feature_err};
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use rustc_span::edit_distance::find_best_match_for_name;
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use rustc_span::hygiene::DesugaringKind;
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use rustc_span::source_map::Spanned;
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use rustc_span::symbol::{kw, sym, Ident};
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use rustc_span::{BytePos, Span, DUMMY_SP};
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use rustc_target::abi::FieldIdx;
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use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode};
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use ty::VariantDef;
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use std::cmp;
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use std::collections::hash_map::Entry::{Occupied, Vacant};
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use super::report_unexpected_variant_res;
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const CANNOT_IMPLICITLY_DEREF_POINTER_TRAIT_OBJ: &str = "\
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This error indicates that a pointer to a trait type cannot be implicitly dereferenced by a \
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pattern. Every trait defines a type, but because the size of trait implementors isn't fixed, \
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this type has no compile-time size. Therefore, all accesses to trait types must be through \
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pointers. If you encounter this error you should try to avoid dereferencing the pointer.
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You can read more about trait objects in the Trait Objects section of the Reference: \
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https://doc.rust-lang.org/reference/types.html#trait-objects";
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fn is_number(text: &str) -> bool {
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text.chars().all(|c: char| c.is_digit(10))
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}
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/// Information about the expected type at the top level of type checking a pattern.
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///
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/// **NOTE:** This is only for use by diagnostics. Do NOT use for type checking logic!
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#[derive(Copy, Clone)]
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struct TopInfo<'tcx> {
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/// The `expected` type at the top level of type checking a pattern.
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expected: Ty<'tcx>,
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/// Was the origin of the `span` from a scrutinee expression?
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///
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/// Otherwise there is no scrutinee and it could be e.g. from the type of a formal parameter.
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origin_expr: Option<&'tcx hir::Expr<'tcx>>,
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/// The span giving rise to the `expected` type, if one could be provided.
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///
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/// If `origin_expr` is `true`, then this is the span of the scrutinee as in:
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///
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/// - `match scrutinee { ... }`
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/// - `let _ = scrutinee;`
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///
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/// This is used to point to add context in type errors.
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/// In the following example, `span` corresponds to the `a + b` expression:
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///
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/// ```text
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/// error[E0308]: mismatched types
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/// --> src/main.rs:L:C
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/// |
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/// L | let temp: usize = match a + b {
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/// | ----- this expression has type `usize`
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/// L | Ok(num) => num,
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/// | ^^^^^^^ expected `usize`, found enum `std::result::Result`
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/// |
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/// = note: expected type `usize`
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/// found type `std::result::Result<_, _>`
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/// ```
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span: Option<Span>,
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/// The [`HirId`] of the top-level pattern.
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hir_id: HirId,
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}
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#[derive(Copy, Clone)]
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struct PatInfo<'tcx, 'a> {
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binding_mode: ByRef,
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max_ref_mutbl: MutblCap,
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top_info: &'a TopInfo<'tcx>,
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decl_origin: Option<DeclOrigin<'tcx>>,
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/// The depth of current pattern
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current_depth: u32,
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}
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impl<'tcx> FnCtxt<'_, 'tcx> {
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fn pattern_cause(&self, ti: &TopInfo<'tcx>, cause_span: Span) -> ObligationCause<'tcx> {
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let code = ObligationCauseCode::Pattern {
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span: ti.span,
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root_ty: ti.expected,
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origin_expr: ti.origin_expr.is_some(),
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};
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self.cause(cause_span, code)
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}
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fn demand_eqtype_pat_diag(
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&self,
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cause_span: Span,
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expected: Ty<'tcx>,
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actual: Ty<'tcx>,
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ti: &TopInfo<'tcx>,
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) -> Option<Diag<'tcx>> {
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let mut diag =
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self.demand_eqtype_with_origin(&self.pattern_cause(ti, cause_span), expected, actual)?;
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if let Some(expr) = ti.origin_expr {
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self.suggest_fn_call(&mut diag, expr, expected, |output| {
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self.can_eq(self.param_env, output, actual)
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});
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}
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Some(diag)
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}
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fn demand_eqtype_pat(
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&self,
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cause_span: Span,
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expected: Ty<'tcx>,
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actual: Ty<'tcx>,
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ti: &TopInfo<'tcx>,
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) {
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if let Some(err) = self.demand_eqtype_pat_diag(cause_span, expected, actual, ti) {
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err.emit();
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}
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}
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}
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/// Mode for adjusting the expected type and binding mode.
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]
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enum AdjustMode {
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/// Peel off all immediate reference types.
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Peel,
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/// Reset binding mode to the initial mode.
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/// Used for destructuring assignment, where we don't want any match ergonomics.
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Reset,
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/// Pass on the input binding mode and expected type.
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Pass,
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}
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/// `ref mut` patterns (explicit or match-ergonomics)
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/// are not allowed behind an `&` reference.
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///
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/// This includes explicit `ref mut` behind `&` patterns
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/// that match against `&mut` references,
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/// where the code would have compiled
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/// had the pattern been written as `&mut`.
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/// However, the borrow checker will not catch
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/// this last case, so we need to throw an error ourselves.
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]
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enum MutblCap {
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/// Mutability restricted to immutable.
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Not,
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/// Mutability restricted to immutable, but only because of the pattern
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/// (not the scrutinee type).
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///
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/// The contained span, if present, points to an `&` pattern
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/// that is the reason for the restriction,
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/// and which will be reported in a diagnostic.
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WeaklyNot(Option<Span>),
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/// No restriction on mutability
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Mut,
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}
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impl MutblCap {
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#[must_use]
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fn cap_to_weakly_not(self, span: Option<Span>) -> Self {
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match self {
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MutblCap::Not => MutblCap::Not,
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_ => MutblCap::WeaklyNot(span),
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}
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}
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#[must_use]
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fn as_mutbl(self) -> Mutability {
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match self {
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MutblCap::Not | MutblCap::WeaklyNot(_) => Mutability::Not,
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MutblCap::Mut => Mutability::Mut,
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}
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}
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}
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impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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/// Type check the given top level pattern against the `expected` type.
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///
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/// If a `Some(span)` is provided and `origin_expr` holds,
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/// then the `span` represents the scrutinee's span.
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/// The scrutinee is found in e.g. `match scrutinee { ... }` and `let pat = scrutinee;`.
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///
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/// Otherwise, `Some(span)` represents the span of a type expression
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/// which originated the `expected` type.
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pub(crate) fn check_pat_top(
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&self,
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pat: &'tcx Pat<'tcx>,
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expected: Ty<'tcx>,
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span: Option<Span>,
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origin_expr: Option<&'tcx hir::Expr<'tcx>>,
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decl_origin: Option<DeclOrigin<'tcx>>,
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) {
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let info = TopInfo { expected, origin_expr, span, hir_id: pat.hir_id };
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let pat_info = PatInfo {
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binding_mode: ByRef::No,
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max_ref_mutbl: MutblCap::Mut,
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top_info: &info,
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decl_origin,
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current_depth: 0,
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};
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self.check_pat(pat, expected, pat_info);
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}
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/// Type check the given `pat` against the `expected` type
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/// with the provided `binding_mode` (default binding mode).
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///
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/// Outside of this module, `check_pat_top` should always be used.
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/// Conversely, inside this module, `check_pat_top` should never be used.
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#[instrument(level = "debug", skip(self, pat_info))]
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fn check_pat(&self, pat: &'tcx Pat<'tcx>, expected: Ty<'tcx>, pat_info: PatInfo<'tcx, '_>) {
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let PatInfo { binding_mode, max_ref_mutbl, top_info: ti, current_depth, .. } = pat_info;
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let path_res = match &pat.kind {
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PatKind::Path(qpath) => {
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Some(self.resolve_ty_and_res_fully_qualified_call(qpath, pat.hir_id, pat.span))
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}
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_ => None,
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};
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let adjust_mode = self.calc_adjust_mode(pat, path_res.map(|(res, ..)| res));
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let (expected, binding_mode, max_ref_mutbl) =
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self.calc_default_binding_mode(pat, expected, binding_mode, adjust_mode, max_ref_mutbl);
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let pat_info = PatInfo {
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binding_mode,
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max_ref_mutbl,
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top_info: ti,
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decl_origin: pat_info.decl_origin,
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current_depth: current_depth + 1,
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};
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let ty = match pat.kind {
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PatKind::Wild | PatKind::Err(_) => expected,
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// We allow any type here; we ensure that the type is uninhabited during match checking.
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PatKind::Never => expected,
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PatKind::Lit(lt) => self.check_pat_lit(pat.span, lt, expected, ti),
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PatKind::Range(lhs, rhs, _) => self.check_pat_range(pat.span, lhs, rhs, expected, ti),
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PatKind::Binding(ba, var_id, ident, sub) => {
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self.check_pat_ident(pat, ba, var_id, ident, sub, expected, pat_info)
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}
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PatKind::TupleStruct(ref qpath, subpats, ddpos) => {
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self.check_pat_tuple_struct(pat, qpath, subpats, ddpos, expected, pat_info)
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}
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PatKind::Path(ref qpath) => {
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self.check_pat_path(pat, qpath, path_res.unwrap(), expected, ti)
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}
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PatKind::Struct(ref qpath, fields, has_rest_pat) => {
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self.check_pat_struct(pat, qpath, fields, has_rest_pat, expected, pat_info)
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}
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PatKind::Or(pats) => {
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for pat in pats {
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self.check_pat(pat, expected, pat_info);
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}
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expected
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}
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PatKind::Tuple(elements, ddpos) => {
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self.check_pat_tuple(pat.span, elements, ddpos, expected, pat_info)
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}
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PatKind::Box(inner) => self.check_pat_box(pat.span, inner, expected, pat_info),
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PatKind::Deref(inner) => self.check_pat_deref(pat.span, inner, expected, pat_info),
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PatKind::Ref(inner, mutbl) => self.check_pat_ref(pat, inner, mutbl, expected, pat_info),
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PatKind::Slice(before, slice, after) => {
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self.check_pat_slice(pat.span, before, slice, after, expected, pat_info)
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}
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};
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self.write_ty(pat.hir_id, ty);
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// (note_1): In most of the cases where (note_1) is referenced
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// (literals and constants being the exception), we relate types
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// using strict equality, even though subtyping would be sufficient.
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// There are a few reasons for this, some of which are fairly subtle
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// and which cost me (nmatsakis) an hour or two debugging to remember,
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// so I thought I'd write them down this time.
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//
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// 1. There is no loss of expressiveness here, though it does
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// cause some inconvenience. What we are saying is that the type
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// of `x` becomes *exactly* what is expected. This can cause unnecessary
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// errors in some cases, such as this one:
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//
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// ```
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// fn foo<'x>(x: &'x i32) {
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// let a = 1;
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// let mut z = x;
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// z = &a;
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// }
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// ```
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//
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// The reason we might get an error is that `z` might be
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// assigned a type like `&'x i32`, and then we would have
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// a problem when we try to assign `&a` to `z`, because
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// the lifetime of `&a` (i.e., the enclosing block) is
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// shorter than `'x`.
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//
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// HOWEVER, this code works fine. The reason is that the
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// expected type here is whatever type the user wrote, not
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// the initializer's type. In this case the user wrote
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// nothing, so we are going to create a type variable `Z`.
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// Then we will assign the type of the initializer (`&'x i32`)
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// as a subtype of `Z`: `&'x i32 <: Z`. And hence we
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// will instantiate `Z` as a type `&'0 i32` where `'0` is
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// a fresh region variable, with the constraint that `'x : '0`.
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// So basically we're all set.
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//
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// Note that there are two tests to check that this remains true
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// (`regions-reassign-{match,let}-bound-pointer.rs`).
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//
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// 2. An outdated issue related to the old HIR borrowck. See the test
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// `regions-relate-bound-regions-on-closures-to-inference-variables.rs`,
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}
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/// Compute the new expected type and default binding mode from the old ones
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/// as well as the pattern form we are currently checking.
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fn calc_default_binding_mode(
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&self,
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pat: &'tcx Pat<'tcx>,
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expected: Ty<'tcx>,
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def_br: ByRef,
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adjust_mode: AdjustMode,
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max_ref_mutbl: MutblCap,
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) -> (Ty<'tcx>, ByRef, MutblCap) {
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if let ByRef::Yes(Mutability::Mut) = def_br {
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debug_assert!(max_ref_mutbl == MutblCap::Mut);
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}
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match adjust_mode {
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AdjustMode::Pass => (expected, def_br, max_ref_mutbl),
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AdjustMode::Reset => (expected, ByRef::No, MutblCap::Mut),
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AdjustMode::Peel => self.peel_off_references(pat, expected, def_br, max_ref_mutbl),
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}
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}
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/// How should the binding mode and expected type be adjusted?
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///
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/// When the pattern is a path pattern, `opt_path_res` must be `Some(res)`.
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fn calc_adjust_mode(&self, pat: &'tcx Pat<'tcx>, opt_path_res: Option<Res>) -> AdjustMode {
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// When we perform destructuring assignment, we disable default match bindings, which are
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// unintuitive in this context.
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if !pat.default_binding_modes {
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return AdjustMode::Reset;
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}
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match &pat.kind {
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// Type checking these product-like types successfully always require
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// that the expected type be of those types and not reference types.
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PatKind::Struct(..)
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| PatKind::TupleStruct(..)
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| PatKind::Tuple(..)
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| PatKind::Box(_)
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| PatKind::Deref(_)
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| PatKind::Range(..)
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| PatKind::Slice(..) => AdjustMode::Peel,
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// A never pattern behaves somewhat like a literal or unit variant.
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PatKind::Never => AdjustMode::Peel,
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// String and byte-string literals result in types `&str` and `&[u8]` respectively.
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// All other literals result in non-reference types.
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// As a result, we allow `if let 0 = &&0 {}` but not `if let "foo" = &&"foo" {}`.
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//
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// Call `resolve_vars_if_possible` here for inline const blocks.
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PatKind::Lit(lt) => match self.resolve_vars_if_possible(self.check_expr(lt)).kind() {
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ty::Ref(..) => AdjustMode::Pass,
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_ => AdjustMode::Peel,
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},
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PatKind::Path(_) => match opt_path_res.unwrap() {
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// These constants can be of a reference type, e.g. `const X: &u8 = &0;`.
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// Peeling the reference types too early will cause type checking failures.
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// Although it would be possible to *also* peel the types of the constants too.
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Res::Def(DefKind::Const | DefKind::AssocConst, _) => AdjustMode::Pass,
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// In the `ValueNS`, we have `SelfCtor(..) | Ctor(_, Const), _)` remaining which
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// could successfully compile. The former being `Self` requires a unit struct.
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// In either case, and unlike constants, the pattern itself cannot be
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// a reference type wherefore peeling doesn't give up any expressiveness.
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_ => AdjustMode::Peel,
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},
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// Ref patterns are complicated, we handle them in `check_pat_ref`.
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PatKind::Ref(..) => AdjustMode::Pass,
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// A `_` pattern works with any expected type, so there's no need to do anything.
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PatKind::Wild
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// A malformed pattern doesn't have an expected type, so let's just accept any type.
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| PatKind::Err(_)
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// Bindings also work with whatever the expected type is,
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// and moreover if we peel references off, that will give us the wrong binding type.
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// Also, we can have a subpattern `binding @ pat`.
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// Each side of the `@` should be treated independently (like with OR-patterns).
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| PatKind::Binding(..)
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// An OR-pattern just propagates to each individual alternative.
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// This is maximally flexible, allowing e.g., `Some(mut x) | &Some(mut x)`.
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// In that example, `Some(mut x)` results in `Peel` whereas `&Some(mut x)` in `Reset`.
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| PatKind::Or(_) => AdjustMode::Pass,
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}
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}
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/// Peel off as many immediately nested `& mut?` from the expected type as possible
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/// and return the new expected type and binding default binding mode.
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|
/// The adjustments vector, if non-empty is stored in a table.
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fn peel_off_references(
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&self,
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pat: &'tcx Pat<'tcx>,
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expected: Ty<'tcx>,
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mut def_br: ByRef,
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mut max_ref_mutbl: MutblCap,
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) -> (Ty<'tcx>, ByRef, MutblCap) {
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let mut expected = self.try_structurally_resolve_type(pat.span, expected);
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// Peel off as many `&` or `&mut` from the scrutinee type as possible. For example,
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// for `match &&&mut Some(5)` the loop runs three times, aborting when it reaches
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// the `Some(5)` which is not of type Ref.
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//
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|
// For each ampersand peeled off, update the binding mode and push the original
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// type into the adjustments vector.
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//
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|
// See the examples in `ui/match-defbm*.rs`.
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|
let mut pat_adjustments = vec![];
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|
while let ty::Ref(_, inner_ty, inner_mutability) = *expected.kind() {
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debug!("inspecting {:?}", expected);
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|
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debug!("current discriminant is Ref, inserting implicit deref");
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|
// Preserve the reference type. We'll need it later during THIR lowering.
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|
pat_adjustments.push(expected);
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expected = self.try_structurally_resolve_type(pat.span, inner_ty);
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|
def_br = ByRef::Yes(match def_br {
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|
// If default binding mode is by value, make it `ref` or `ref mut`
|
|
// (depending on whether we observe `&` or `&mut`).
|
|
ByRef::No |
|
|
// When `ref mut`, stay a `ref mut` (on `&mut`) or downgrade to `ref` (on `&`).
|
|
ByRef::Yes(Mutability::Mut) => inner_mutability,
|
|
// Once a `ref`, always a `ref`.
|
|
// This is because a `& &mut` cannot mutate the underlying value.
|
|
ByRef::Yes(Mutability::Not) => Mutability::Not,
|
|
});
|
|
}
|
|
|
|
if self.tcx.features().ref_pat_eat_one_layer_2024 {
|
|
def_br = def_br.cap_ref_mutability(max_ref_mutbl.as_mutbl());
|
|
if def_br == ByRef::Yes(Mutability::Not) {
|
|
max_ref_mutbl = MutblCap::Not;
|
|
}
|
|
}
|
|
|
|
if !pat_adjustments.is_empty() {
|
|
debug!("default binding mode is now {:?}", def_br);
|
|
self.typeck_results
|
|
.borrow_mut()
|
|
.pat_adjustments_mut()
|
|
.insert(pat.hir_id, pat_adjustments);
|
|
}
|
|
|
|
(expected, def_br, max_ref_mutbl)
|
|
}
|
|
|
|
fn check_pat_lit(
|
|
&self,
|
|
span: Span,
|
|
lt: &hir::Expr<'tcx>,
|
|
expected: Ty<'tcx>,
|
|
ti: &TopInfo<'tcx>,
|
|
) -> Ty<'tcx> {
|
|
// We've already computed the type above (when checking for a non-ref pat),
|
|
// so avoid computing it again.
|
|
let ty = self.node_ty(lt.hir_id);
|
|
|
|
// Byte string patterns behave the same way as array patterns
|
|
// They can denote both statically and dynamically-sized byte arrays.
|
|
let mut pat_ty = ty;
|
|
if let hir::ExprKind::Lit(Spanned { node: ast::LitKind::ByteStr(..), .. }) = lt.kind {
|
|
let expected = self.structurally_resolve_type(span, expected);
|
|
if let ty::Ref(_, inner_ty, _) = *expected.kind()
|
|
&& self.try_structurally_resolve_type(span, inner_ty).is_slice()
|
|
{
|
|
let tcx = self.tcx;
|
|
trace!(?lt.hir_id.local_id, "polymorphic byte string lit");
|
|
self.typeck_results
|
|
.borrow_mut()
|
|
.treat_byte_string_as_slice
|
|
.insert(lt.hir_id.local_id);
|
|
pat_ty =
|
|
Ty::new_imm_ref(tcx, tcx.lifetimes.re_static, Ty::new_slice(tcx, tcx.types.u8));
|
|
}
|
|
}
|
|
|
|
if self.tcx.features().string_deref_patterns
|
|
&& let hir::ExprKind::Lit(Spanned { node: ast::LitKind::Str(..), .. }) = lt.kind
|
|
{
|
|
let tcx = self.tcx;
|
|
let expected = self.resolve_vars_if_possible(expected);
|
|
pat_ty = match expected.kind() {
|
|
ty::Adt(def, _) if Some(def.did()) == tcx.lang_items().string() => expected,
|
|
ty::Str => Ty::new_static_str(tcx),
|
|
_ => pat_ty,
|
|
};
|
|
}
|
|
|
|
// Somewhat surprising: in this case, the subtyping relation goes the
|
|
// opposite way as the other cases. Actually what we really want is not
|
|
// a subtyping relation at all but rather that there exists a LUB
|
|
// (so that they can be compared). However, in practice, constants are
|
|
// always scalars or strings. For scalars subtyping is irrelevant,
|
|
// and for strings `ty` is type is `&'static str`, so if we say that
|
|
//
|
|
// &'static str <: expected
|
|
//
|
|
// then that's equivalent to there existing a LUB.
|
|
let cause = self.pattern_cause(ti, span);
|
|
if let Some(err) = self.demand_suptype_with_origin(&cause, expected, pat_ty) {
|
|
err.emit_unless(
|
|
ti.span
|
|
.filter(|&s| {
|
|
// In the case of `if`- and `while`-expressions we've already checked
|
|
// that `scrutinee: bool`. We know that the pattern is `true`,
|
|
// so an error here would be a duplicate and from the wrong POV.
|
|
s.is_desugaring(DesugaringKind::CondTemporary)
|
|
})
|
|
.is_some(),
|
|
);
|
|
}
|
|
|
|
pat_ty
|
|
}
|
|
|
|
fn check_pat_range(
|
|
&self,
|
|
span: Span,
|
|
lhs: Option<&'tcx hir::Expr<'tcx>>,
|
|
rhs: Option<&'tcx hir::Expr<'tcx>>,
|
|
expected: Ty<'tcx>,
|
|
ti: &TopInfo<'tcx>,
|
|
) -> Ty<'tcx> {
|
|
let calc_side = |opt_expr: Option<&'tcx hir::Expr<'tcx>>| match opt_expr {
|
|
None => None,
|
|
Some(expr) => {
|
|
let ty = self.check_expr(expr);
|
|
// Check that the end-point is possibly of numeric or char type.
|
|
// The early check here is not for correctness, but rather better
|
|
// diagnostics (e.g. when `&str` is being matched, `expected` will
|
|
// be peeled to `str` while ty here is still `&str`, if we don't
|
|
// err early here, a rather confusing unification error will be
|
|
// emitted instead).
|
|
let fail =
|
|
!(ty.is_numeric() || ty.is_char() || ty.is_ty_var() || ty.references_error());
|
|
Some((fail, ty, expr.span))
|
|
}
|
|
};
|
|
let mut lhs = calc_side(lhs);
|
|
let mut rhs = calc_side(rhs);
|
|
|
|
if let (Some((true, ..)), _) | (_, Some((true, ..))) = (lhs, rhs) {
|
|
// There exists a side that didn't meet our criteria that the end-point
|
|
// be of a numeric or char type, as checked in `calc_side` above.
|
|
let guar = self.emit_err_pat_range(span, lhs, rhs);
|
|
return Ty::new_error(self.tcx, guar);
|
|
}
|
|
|
|
// Unify each side with `expected`.
|
|
// Subtyping doesn't matter here, as the value is some kind of scalar.
|
|
let demand_eqtype = |x: &mut _, y| {
|
|
if let Some((ref mut fail, x_ty, x_span)) = *x
|
|
&& let Some(mut err) = self.demand_eqtype_pat_diag(x_span, expected, x_ty, ti)
|
|
{
|
|
if let Some((_, y_ty, y_span)) = y {
|
|
self.endpoint_has_type(&mut err, y_span, y_ty);
|
|
}
|
|
err.emit();
|
|
*fail = true;
|
|
}
|
|
};
|
|
demand_eqtype(&mut lhs, rhs);
|
|
demand_eqtype(&mut rhs, lhs);
|
|
|
|
if let (Some((true, ..)), _) | (_, Some((true, ..))) = (lhs, rhs) {
|
|
return Ty::new_misc_error(self.tcx);
|
|
}
|
|
|
|
// Find the unified type and check if it's of numeric or char type again.
|
|
// This check is needed if both sides are inference variables.
|
|
// We require types to be resolved here so that we emit inference failure
|
|
// rather than "_ is not a char or numeric".
|
|
let ty = self.structurally_resolve_type(span, expected);
|
|
if !(ty.is_numeric() || ty.is_char() || ty.references_error()) {
|
|
if let Some((ref mut fail, _, _)) = lhs {
|
|
*fail = true;
|
|
}
|
|
if let Some((ref mut fail, _, _)) = rhs {
|
|
*fail = true;
|
|
}
|
|
let guar = self.emit_err_pat_range(span, lhs, rhs);
|
|
return Ty::new_error(self.tcx, guar);
|
|
}
|
|
ty
|
|
}
|
|
|
|
fn endpoint_has_type(&self, err: &mut Diag<'_>, span: Span, ty: Ty<'_>) {
|
|
if !ty.references_error() {
|
|
err.span_label(span, format!("this is of type `{ty}`"));
|
|
}
|
|
}
|
|
|
|
fn emit_err_pat_range(
|
|
&self,
|
|
span: Span,
|
|
lhs: Option<(bool, Ty<'tcx>, Span)>,
|
|
rhs: Option<(bool, Ty<'tcx>, Span)>,
|
|
) -> ErrorGuaranteed {
|
|
let span = match (lhs, rhs) {
|
|
(Some((true, ..)), Some((true, ..))) => span,
|
|
(Some((true, _, sp)), _) => sp,
|
|
(_, Some((true, _, sp))) => sp,
|
|
_ => span_bug!(span, "emit_err_pat_range: no side failed or exists but still error?"),
|
|
};
|
|
let mut err = struct_span_code_err!(
|
|
self.dcx(),
|
|
span,
|
|
E0029,
|
|
"only `char` and numeric types are allowed in range patterns"
|
|
);
|
|
let msg = |ty| {
|
|
let ty = self.resolve_vars_if_possible(ty);
|
|
format!("this is of type `{ty}` but it should be `char` or numeric")
|
|
};
|
|
let mut one_side_err = |first_span, first_ty, second: Option<(bool, Ty<'tcx>, Span)>| {
|
|
err.span_label(first_span, msg(first_ty));
|
|
if let Some((_, ty, sp)) = second {
|
|
let ty = self.resolve_vars_if_possible(ty);
|
|
self.endpoint_has_type(&mut err, sp, ty);
|
|
}
|
|
};
|
|
match (lhs, rhs) {
|
|
(Some((true, lhs_ty, lhs_sp)), Some((true, rhs_ty, rhs_sp))) => {
|
|
err.span_label(lhs_sp, msg(lhs_ty));
|
|
err.span_label(rhs_sp, msg(rhs_ty));
|
|
}
|
|
(Some((true, lhs_ty, lhs_sp)), rhs) => one_side_err(lhs_sp, lhs_ty, rhs),
|
|
(lhs, Some((true, rhs_ty, rhs_sp))) => one_side_err(rhs_sp, rhs_ty, lhs),
|
|
_ => span_bug!(span, "Impossible, verified above."),
|
|
}
|
|
if (lhs, rhs).references_error() {
|
|
err.downgrade_to_delayed_bug();
|
|
}
|
|
if self.tcx.sess.teach(err.code.unwrap()) {
|
|
err.note(
|
|
"In a match expression, only numbers and characters can be matched \
|
|
against a range. This is because the compiler checks that the range \
|
|
is non-empty at compile-time, and is unable to evaluate arbitrary \
|
|
comparison functions. If you want to capture values of an orderable \
|
|
type between two end-points, you can use a guard.",
|
|
);
|
|
}
|
|
err.emit()
|
|
}
|
|
|
|
fn check_pat_ident(
|
|
&self,
|
|
pat: &'tcx Pat<'tcx>,
|
|
user_bind_annot: BindingMode,
|
|
var_id: HirId,
|
|
ident: Ident,
|
|
sub: Option<&'tcx Pat<'tcx>>,
|
|
expected: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
let PatInfo { binding_mode: def_br, top_info: ti, .. } = pat_info;
|
|
|
|
// Determine the binding mode...
|
|
let bm = match user_bind_annot {
|
|
BindingMode(ByRef::No, Mutability::Mut) if matches!(def_br, ByRef::Yes(_)) => {
|
|
if pat.span.at_least_rust_2024() && self.tcx.features().ref_pat_eat_one_layer_2024 {
|
|
if !self.tcx.features().mut_ref {
|
|
feature_err(
|
|
&self.tcx.sess,
|
|
sym::mut_ref,
|
|
pat.span.until(ident.span),
|
|
"binding cannot be both mutable and by-reference",
|
|
)
|
|
.emit();
|
|
}
|
|
|
|
BindingMode(def_br, Mutability::Mut)
|
|
} else {
|
|
// `mut` resets binding mode on edition <= 2021
|
|
self.typeck_results
|
|
.borrow_mut()
|
|
.rust_2024_migration_desugared_pats_mut()
|
|
.insert(pat_info.top_info.hir_id);
|
|
BindingMode(ByRef::No, Mutability::Mut)
|
|
}
|
|
}
|
|
BindingMode(ByRef::No, mutbl) => BindingMode(def_br, mutbl),
|
|
BindingMode(ByRef::Yes(_), _) => user_bind_annot,
|
|
};
|
|
|
|
if bm.0 == ByRef::Yes(Mutability::Mut)
|
|
&& let MutblCap::WeaklyNot(and_pat_span) = pat_info.max_ref_mutbl
|
|
{
|
|
let mut err = struct_span_code_err!(
|
|
self.tcx.dcx(),
|
|
ident.span,
|
|
E0596,
|
|
"cannot borrow as mutable inside an `&` pattern"
|
|
);
|
|
|
|
if let Some(span) = and_pat_span {
|
|
err.span_suggestion(
|
|
span,
|
|
"replace this `&` with `&mut`",
|
|
"&mut ",
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
err.emit();
|
|
}
|
|
|
|
// ...and store it in a side table:
|
|
self.typeck_results.borrow_mut().pat_binding_modes_mut().insert(pat.hir_id, bm);
|
|
|
|
debug!("check_pat_ident: pat.hir_id={:?} bm={:?}", pat.hir_id, bm);
|
|
|
|
let local_ty = self.local_ty(pat.span, pat.hir_id);
|
|
let eq_ty = match bm.0 {
|
|
ByRef::Yes(mutbl) => {
|
|
// If the binding is like `ref x | ref mut x`,
|
|
// then `x` is assigned a value of type `&M T` where M is the
|
|
// mutability and T is the expected type.
|
|
//
|
|
// `x` is assigned a value of type `&M T`, hence `&M T <: typeof(x)`
|
|
// is required. However, we use equality, which is stronger.
|
|
// See (note_1) for an explanation.
|
|
self.new_ref_ty(pat.span, mutbl, expected)
|
|
}
|
|
// Otherwise, the type of x is the expected type `T`.
|
|
ByRef::No => expected, // As above, `T <: typeof(x)` is required, but we use equality, see (note_1).
|
|
};
|
|
self.demand_eqtype_pat(pat.span, eq_ty, local_ty, ti);
|
|
|
|
// If there are multiple arms, make sure they all agree on
|
|
// what the type of the binding `x` ought to be.
|
|
if var_id != pat.hir_id {
|
|
self.check_binding_alt_eq_ty(user_bind_annot, pat.span, var_id, local_ty, ti);
|
|
}
|
|
|
|
if let Some(p) = sub {
|
|
self.check_pat(p, expected, pat_info);
|
|
}
|
|
|
|
local_ty
|
|
}
|
|
|
|
/// When a variable is bound several times in a `PatKind::Or`, it'll resolve all of the
|
|
/// subsequent bindings of the same name to the first usage. Verify that all of these
|
|
/// bindings have the same type by comparing them all against the type of that first pat.
|
|
fn check_binding_alt_eq_ty(
|
|
&self,
|
|
ba: BindingMode,
|
|
span: Span,
|
|
var_id: HirId,
|
|
ty: Ty<'tcx>,
|
|
ti: &TopInfo<'tcx>,
|
|
) {
|
|
let var_ty = self.local_ty(span, var_id);
|
|
if let Some(mut err) = self.demand_eqtype_pat_diag(span, var_ty, ty, ti) {
|
|
let hir = self.tcx.hir();
|
|
let var_ty = self.resolve_vars_if_possible(var_ty);
|
|
let msg = format!("first introduced with type `{var_ty}` here");
|
|
err.span_label(hir.span(var_id), msg);
|
|
let in_match = hir.parent_iter(var_id).any(|(_, n)| {
|
|
matches!(
|
|
n,
|
|
hir::Node::Expr(hir::Expr {
|
|
kind: hir::ExprKind::Match(.., hir::MatchSource::Normal),
|
|
..
|
|
})
|
|
)
|
|
});
|
|
let pre = if in_match { "in the same arm, " } else { "" };
|
|
err.note(format!("{pre}a binding must have the same type in all alternatives"));
|
|
self.suggest_adding_missing_ref_or_removing_ref(
|
|
&mut err,
|
|
span,
|
|
var_ty,
|
|
self.resolve_vars_if_possible(ty),
|
|
ba,
|
|
);
|
|
err.emit();
|
|
}
|
|
}
|
|
|
|
fn suggest_adding_missing_ref_or_removing_ref(
|
|
&self,
|
|
err: &mut Diag<'_>,
|
|
span: Span,
|
|
expected: Ty<'tcx>,
|
|
actual: Ty<'tcx>,
|
|
ba: BindingMode,
|
|
) {
|
|
match (expected.kind(), actual.kind(), ba) {
|
|
(ty::Ref(_, inner_ty, _), _, BindingMode::NONE)
|
|
if self.can_eq(self.param_env, *inner_ty, actual) =>
|
|
{
|
|
err.span_suggestion_verbose(
|
|
span.shrink_to_lo(),
|
|
"consider adding `ref`",
|
|
"ref ",
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
(_, ty::Ref(_, inner_ty, _), BindingMode::REF)
|
|
if self.can_eq(self.param_env, expected, *inner_ty) =>
|
|
{
|
|
err.span_suggestion_verbose(
|
|
span.with_hi(span.lo() + BytePos(4)),
|
|
"consider removing `ref`",
|
|
"",
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
/// Precondition: pat is a `Ref(_)` pattern
|
|
fn borrow_pat_suggestion(&self, err: &mut Diag<'_>, pat: &Pat<'_>) {
|
|
let tcx = self.tcx;
|
|
if let PatKind::Ref(inner, mutbl) = pat.kind
|
|
&& let PatKind::Binding(_, _, binding, ..) = inner.kind
|
|
{
|
|
let binding_parent = tcx.parent_hir_node(pat.hir_id);
|
|
debug!(?inner, ?pat, ?binding_parent);
|
|
|
|
let mutability = match mutbl {
|
|
ast::Mutability::Mut => "mut",
|
|
ast::Mutability::Not => "",
|
|
};
|
|
|
|
let mut_var_suggestion = 'block: {
|
|
if mutbl.is_not() {
|
|
break 'block None;
|
|
}
|
|
|
|
let ident_kind = match binding_parent {
|
|
hir::Node::Param(_) => "parameter",
|
|
hir::Node::LetStmt(_) => "variable",
|
|
hir::Node::Arm(_) => "binding",
|
|
|
|
// Provide diagnostics only if the parent pattern is struct-like,
|
|
// i.e. where `mut binding` makes sense
|
|
hir::Node::Pat(Pat { kind, .. }) => match kind {
|
|
PatKind::Struct(..)
|
|
| PatKind::TupleStruct(..)
|
|
| PatKind::Or(..)
|
|
| PatKind::Tuple(..)
|
|
| PatKind::Slice(..) => "binding",
|
|
|
|
PatKind::Wild
|
|
| PatKind::Never
|
|
| PatKind::Binding(..)
|
|
| PatKind::Path(..)
|
|
| PatKind::Box(..)
|
|
| PatKind::Deref(_)
|
|
| PatKind::Ref(..)
|
|
| PatKind::Lit(..)
|
|
| PatKind::Range(..)
|
|
| PatKind::Err(_) => break 'block None,
|
|
},
|
|
|
|
// Don't provide suggestions in other cases
|
|
_ => break 'block None,
|
|
};
|
|
|
|
Some((
|
|
pat.span,
|
|
format!("to declare a mutable {ident_kind} use"),
|
|
format!("mut {binding}"),
|
|
))
|
|
};
|
|
|
|
match binding_parent {
|
|
// Check that there is explicit type (ie this is not a closure param with inferred type)
|
|
// so we don't suggest moving something to the type that does not exist
|
|
hir::Node::Param(hir::Param { ty_span, pat, .. }) if pat.span != *ty_span => {
|
|
err.multipart_suggestion_verbose(
|
|
format!("to take parameter `{binding}` by reference, move `&{mutability}` to the type"),
|
|
vec![
|
|
(pat.span.until(inner.span), "".to_owned()),
|
|
(ty_span.shrink_to_lo(), mutbl.ref_prefix_str().to_owned()),
|
|
],
|
|
Applicability::MachineApplicable
|
|
);
|
|
|
|
if let Some((sp, msg, sugg)) = mut_var_suggestion {
|
|
err.span_note(sp, format!("{msg}: `{sugg}`"));
|
|
}
|
|
}
|
|
hir::Node::Pat(pt) if let PatKind::TupleStruct(_, pat_arr, _) = pt.kind => {
|
|
for i in pat_arr.iter() {
|
|
if let PatKind::Ref(the_ref, _) = i.kind
|
|
&& let PatKind::Binding(mt, _, ident, _) = the_ref.kind
|
|
{
|
|
let BindingMode(_, mtblty) = mt;
|
|
err.span_suggestion_verbose(
|
|
i.span,
|
|
format!("consider removing `&{mutability}` from the pattern"),
|
|
mtblty.prefix_str().to_string() + &ident.name.to_string(),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
}
|
|
if let Some((sp, msg, sugg)) = mut_var_suggestion {
|
|
err.span_note(sp, format!("{msg}: `{sugg}`"));
|
|
}
|
|
}
|
|
hir::Node::Param(_) | hir::Node::Arm(_) | hir::Node::Pat(_) => {
|
|
// rely on match ergonomics or it might be nested `&&pat`
|
|
err.span_suggestion_verbose(
|
|
pat.span.until(inner.span),
|
|
format!("consider removing `&{mutability}` from the pattern"),
|
|
"",
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
|
|
if let Some((sp, msg, sugg)) = mut_var_suggestion {
|
|
err.span_note(sp, format!("{msg}: `{sugg}`"));
|
|
}
|
|
}
|
|
_ if let Some((sp, msg, sugg)) = mut_var_suggestion => {
|
|
err.span_suggestion(sp, msg, sugg, Applicability::MachineApplicable);
|
|
}
|
|
_ => {} // don't provide suggestions in other cases #55175
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn check_dereferenceable(
|
|
&self,
|
|
span: Span,
|
|
expected: Ty<'tcx>,
|
|
inner: &Pat<'_>,
|
|
) -> Result<(), ErrorGuaranteed> {
|
|
if let PatKind::Binding(..) = inner.kind
|
|
&& let Some(pointee_ty) = self.shallow_resolve(expected).builtin_deref(true)
|
|
&& let ty::Dynamic(..) = pointee_ty.kind()
|
|
{
|
|
// This is "x = dyn SomeTrait" being reduced from
|
|
// "let &x = &dyn SomeTrait" or "let box x = Box<dyn SomeTrait>", an error.
|
|
let type_str = self.ty_to_string(expected);
|
|
let mut err = struct_span_code_err!(
|
|
self.dcx(),
|
|
span,
|
|
E0033,
|
|
"type `{}` cannot be dereferenced",
|
|
type_str
|
|
);
|
|
err.span_label(span, format!("type `{type_str}` cannot be dereferenced"));
|
|
if self.tcx.sess.teach(err.code.unwrap()) {
|
|
err.note(CANNOT_IMPLICITLY_DEREF_POINTER_TRAIT_OBJ);
|
|
}
|
|
return Err(err.emit());
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn check_pat_struct(
|
|
&self,
|
|
pat: &'tcx Pat<'tcx>,
|
|
qpath: &hir::QPath<'tcx>,
|
|
fields: &'tcx [hir::PatField<'tcx>],
|
|
has_rest_pat: bool,
|
|
expected: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
// Resolve the path and check the definition for errors.
|
|
let (variant, pat_ty) = match self.check_struct_path(qpath, pat.hir_id) {
|
|
Ok(data) => data,
|
|
Err(guar) => {
|
|
let err = Ty::new_error(self.tcx, guar);
|
|
for field in fields {
|
|
self.check_pat(field.pat, err, pat_info);
|
|
}
|
|
return err;
|
|
}
|
|
};
|
|
|
|
// Type-check the path.
|
|
self.demand_eqtype_pat(pat.span, expected, pat_ty, pat_info.top_info);
|
|
|
|
// Type-check subpatterns.
|
|
if self.check_struct_pat_fields(pat_ty, pat, variant, fields, has_rest_pat, pat_info) {
|
|
pat_ty
|
|
} else {
|
|
Ty::new_misc_error(self.tcx)
|
|
}
|
|
}
|
|
|
|
fn check_pat_path(
|
|
&self,
|
|
pat: &Pat<'tcx>,
|
|
qpath: &hir::QPath<'_>,
|
|
path_resolution: (Res, Option<LoweredTy<'tcx>>, &'tcx [hir::PathSegment<'tcx>]),
|
|
expected: Ty<'tcx>,
|
|
ti: &TopInfo<'tcx>,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx;
|
|
|
|
// We have already resolved the path.
|
|
let (res, opt_ty, segments) = path_resolution;
|
|
match res {
|
|
Res::Err => {
|
|
let e = tcx.dcx().span_delayed_bug(qpath.span(), "`Res::Err` but no error emitted");
|
|
self.set_tainted_by_errors(e);
|
|
return Ty::new_error(tcx, e);
|
|
}
|
|
Res::Def(DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn) | DefKind::Variant, _) => {
|
|
let expected = "unit struct, unit variant or constant";
|
|
let e = report_unexpected_variant_res(tcx, res, qpath, pat.span, E0533, expected);
|
|
return Ty::new_error(tcx, e);
|
|
}
|
|
Res::SelfCtor(def_id) => {
|
|
if let ty::Adt(adt_def, _) = *tcx.type_of(def_id).skip_binder().kind()
|
|
&& adt_def.is_struct()
|
|
&& let Some((CtorKind::Const, _)) = adt_def.non_enum_variant().ctor
|
|
{
|
|
// Ok, we allow unit struct ctors in patterns only.
|
|
} else {
|
|
let e = report_unexpected_variant_res(
|
|
tcx,
|
|
res,
|
|
qpath,
|
|
pat.span,
|
|
E0533,
|
|
"unit struct",
|
|
);
|
|
return Ty::new_error(tcx, e);
|
|
}
|
|
}
|
|
Res::Def(
|
|
DefKind::Ctor(_, CtorKind::Const)
|
|
| DefKind::Const
|
|
| DefKind::AssocConst
|
|
| DefKind::ConstParam,
|
|
_,
|
|
) => {} // OK
|
|
_ => bug!("unexpected pattern resolution: {:?}", res),
|
|
}
|
|
|
|
// Type-check the path.
|
|
let (pat_ty, pat_res) =
|
|
self.instantiate_value_path(segments, opt_ty, res, pat.span, pat.span, pat.hir_id);
|
|
if let Some(err) =
|
|
self.demand_suptype_with_origin(&self.pattern_cause(ti, pat.span), expected, pat_ty)
|
|
{
|
|
self.emit_bad_pat_path(err, pat, res, pat_res, pat_ty, segments);
|
|
}
|
|
pat_ty
|
|
}
|
|
|
|
fn maybe_suggest_range_literal(
|
|
&self,
|
|
e: &mut Diag<'_>,
|
|
opt_def_id: Option<hir::def_id::DefId>,
|
|
ident: Ident,
|
|
) -> bool {
|
|
match opt_def_id {
|
|
Some(def_id) => match self.tcx.hir().get_if_local(def_id) {
|
|
Some(hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Const(_, _, body_id),
|
|
..
|
|
})) => match self.tcx.hir_node(body_id.hir_id) {
|
|
hir::Node::Expr(expr) => {
|
|
if hir::is_range_literal(expr) {
|
|
let span = self.tcx.hir().span(body_id.hir_id);
|
|
if let Ok(snip) = self.tcx.sess.source_map().span_to_snippet(span) {
|
|
e.span_suggestion_verbose(
|
|
ident.span,
|
|
"you may want to move the range into the match block",
|
|
snip,
|
|
Applicability::MachineApplicable,
|
|
);
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
_ => (),
|
|
},
|
|
_ => (),
|
|
},
|
|
_ => (),
|
|
}
|
|
false
|
|
}
|
|
|
|
fn emit_bad_pat_path(
|
|
&self,
|
|
mut e: Diag<'_>,
|
|
pat: &hir::Pat<'tcx>,
|
|
res: Res,
|
|
pat_res: Res,
|
|
pat_ty: Ty<'tcx>,
|
|
segments: &'tcx [hir::PathSegment<'tcx>],
|
|
) {
|
|
let pat_span = pat.span;
|
|
if let Some(span) = self.tcx.hir().res_span(pat_res) {
|
|
e.span_label(span, format!("{} defined here", res.descr()));
|
|
if let [hir::PathSegment { ident, .. }] = &*segments {
|
|
e.span_label(
|
|
pat_span,
|
|
format!(
|
|
"`{}` is interpreted as {} {}, not a new binding",
|
|
ident,
|
|
res.article(),
|
|
res.descr(),
|
|
),
|
|
);
|
|
match self.tcx.parent_hir_node(pat.hir_id) {
|
|
hir::Node::PatField(..) => {
|
|
e.span_suggestion_verbose(
|
|
ident.span.shrink_to_hi(),
|
|
"bind the struct field to a different name instead",
|
|
format!(": other_{}", ident.as_str().to_lowercase()),
|
|
Applicability::HasPlaceholders,
|
|
);
|
|
}
|
|
_ => {
|
|
let (type_def_id, item_def_id) = match pat_ty.kind() {
|
|
ty::Adt(def, _) => match res {
|
|
Res::Def(DefKind::Const, def_id) => (Some(def.did()), Some(def_id)),
|
|
_ => (None, None),
|
|
},
|
|
_ => (None, None),
|
|
};
|
|
|
|
let ranges = &[
|
|
self.tcx.lang_items().range_struct(),
|
|
self.tcx.lang_items().range_from_struct(),
|
|
self.tcx.lang_items().range_to_struct(),
|
|
self.tcx.lang_items().range_full_struct(),
|
|
self.tcx.lang_items().range_inclusive_struct(),
|
|
self.tcx.lang_items().range_to_inclusive_struct(),
|
|
];
|
|
if type_def_id != None && ranges.contains(&type_def_id) {
|
|
if !self.maybe_suggest_range_literal(&mut e, item_def_id, *ident) {
|
|
let msg = "constants only support matching by type, \
|
|
if you meant to match against a range of values, \
|
|
consider using a range pattern like `min ..= max` in the match block";
|
|
e.note(msg);
|
|
}
|
|
} else {
|
|
let msg = "introduce a new binding instead";
|
|
let sugg = format!("other_{}", ident.as_str().to_lowercase());
|
|
e.span_suggestion(
|
|
ident.span,
|
|
msg,
|
|
sugg,
|
|
Applicability::HasPlaceholders,
|
|
);
|
|
}
|
|
}
|
|
};
|
|
}
|
|
}
|
|
e.emit();
|
|
}
|
|
|
|
fn check_pat_tuple_struct(
|
|
&self,
|
|
pat: &'tcx Pat<'tcx>,
|
|
qpath: &'tcx hir::QPath<'tcx>,
|
|
subpats: &'tcx [Pat<'tcx>],
|
|
ddpos: hir::DotDotPos,
|
|
expected: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx;
|
|
let on_error = |e| {
|
|
for pat in subpats {
|
|
self.check_pat(pat, Ty::new_error(tcx, e), pat_info);
|
|
}
|
|
};
|
|
let report_unexpected_res = |res: Res| {
|
|
let expected = "tuple struct or tuple variant";
|
|
let e = report_unexpected_variant_res(tcx, res, qpath, pat.span, E0164, expected);
|
|
on_error(e);
|
|
e
|
|
};
|
|
|
|
// Resolve the path and check the definition for errors.
|
|
let (res, opt_ty, segments) =
|
|
self.resolve_ty_and_res_fully_qualified_call(qpath, pat.hir_id, pat.span);
|
|
if res == Res::Err {
|
|
let e = tcx.dcx().span_delayed_bug(pat.span, "`Res::Err` but no error emitted");
|
|
self.set_tainted_by_errors(e);
|
|
on_error(e);
|
|
return Ty::new_error(tcx, e);
|
|
}
|
|
|
|
// Type-check the path.
|
|
let (pat_ty, res) =
|
|
self.instantiate_value_path(segments, opt_ty, res, pat.span, pat.span, pat.hir_id);
|
|
if !pat_ty.is_fn() {
|
|
let e = report_unexpected_res(res);
|
|
return Ty::new_error(tcx, e);
|
|
}
|
|
|
|
let variant = match res {
|
|
Res::Err => {
|
|
tcx.dcx().span_bug(pat.span, "`Res::Err` but no error emitted");
|
|
}
|
|
Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) => {
|
|
let e = report_unexpected_res(res);
|
|
return Ty::new_error(tcx, e);
|
|
}
|
|
Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) => tcx.expect_variant_res(res),
|
|
_ => bug!("unexpected pattern resolution: {:?}", res),
|
|
};
|
|
|
|
// Replace constructor type with constructed type for tuple struct patterns.
|
|
let pat_ty = pat_ty.fn_sig(tcx).output();
|
|
let pat_ty = pat_ty.no_bound_vars().expect("expected fn type");
|
|
|
|
// Type-check the tuple struct pattern against the expected type.
|
|
let diag = self.demand_eqtype_pat_diag(pat.span, expected, pat_ty, pat_info.top_info);
|
|
let had_err = if let Some(err) = diag {
|
|
err.emit();
|
|
true
|
|
} else {
|
|
false
|
|
};
|
|
|
|
// Type-check subpatterns.
|
|
if subpats.len() == variant.fields.len()
|
|
|| subpats.len() < variant.fields.len() && ddpos.as_opt_usize().is_some()
|
|
{
|
|
let ty::Adt(_, args) = pat_ty.kind() else {
|
|
bug!("unexpected pattern type {:?}", pat_ty);
|
|
};
|
|
for (i, subpat) in subpats.iter().enumerate_and_adjust(variant.fields.len(), ddpos) {
|
|
let field = &variant.fields[FieldIdx::from_usize(i)];
|
|
let field_ty = self.field_ty(subpat.span, field, args);
|
|
self.check_pat(subpat, field_ty, pat_info);
|
|
|
|
self.tcx.check_stability(
|
|
variant.fields[FieldIdx::from_usize(i)].did,
|
|
Some(pat.hir_id),
|
|
subpat.span,
|
|
None,
|
|
);
|
|
}
|
|
} else {
|
|
let e = self.emit_err_pat_wrong_number_of_fields(
|
|
pat.span,
|
|
res,
|
|
qpath,
|
|
subpats,
|
|
&variant.fields.raw,
|
|
expected,
|
|
had_err,
|
|
);
|
|
on_error(e);
|
|
return Ty::new_error(tcx, e);
|
|
}
|
|
pat_ty
|
|
}
|
|
|
|
fn emit_err_pat_wrong_number_of_fields(
|
|
&self,
|
|
pat_span: Span,
|
|
res: Res,
|
|
qpath: &hir::QPath<'_>,
|
|
subpats: &'tcx [Pat<'tcx>],
|
|
fields: &'tcx [ty::FieldDef],
|
|
expected: Ty<'tcx>,
|
|
had_err: bool,
|
|
) -> ErrorGuaranteed {
|
|
let subpats_ending = pluralize!(subpats.len());
|
|
let fields_ending = pluralize!(fields.len());
|
|
|
|
let subpat_spans = if subpats.is_empty() {
|
|
vec![pat_span]
|
|
} else {
|
|
subpats.iter().map(|p| p.span).collect()
|
|
};
|
|
let last_subpat_span = *subpat_spans.last().unwrap();
|
|
let res_span = self.tcx.def_span(res.def_id());
|
|
let def_ident_span = self.tcx.def_ident_span(res.def_id()).unwrap_or(res_span);
|
|
let field_def_spans = if fields.is_empty() {
|
|
vec![res_span]
|
|
} else {
|
|
fields.iter().map(|f| f.ident(self.tcx).span).collect()
|
|
};
|
|
let last_field_def_span = *field_def_spans.last().unwrap();
|
|
|
|
let mut err = struct_span_code_err!(
|
|
self.dcx(),
|
|
MultiSpan::from_spans(subpat_spans),
|
|
E0023,
|
|
"this pattern has {} field{}, but the corresponding {} has {} field{}",
|
|
subpats.len(),
|
|
subpats_ending,
|
|
res.descr(),
|
|
fields.len(),
|
|
fields_ending,
|
|
);
|
|
err.span_label(
|
|
last_subpat_span,
|
|
format!("expected {} field{}, found {}", fields.len(), fields_ending, subpats.len()),
|
|
);
|
|
if self.tcx.sess.source_map().is_multiline(qpath.span().between(last_subpat_span)) {
|
|
err.span_label(qpath.span(), "");
|
|
}
|
|
if self.tcx.sess.source_map().is_multiline(def_ident_span.between(last_field_def_span)) {
|
|
err.span_label(def_ident_span, format!("{} defined here", res.descr()));
|
|
}
|
|
for span in &field_def_spans[..field_def_spans.len() - 1] {
|
|
err.span_label(*span, "");
|
|
}
|
|
err.span_label(
|
|
last_field_def_span,
|
|
format!("{} has {} field{}", res.descr(), fields.len(), fields_ending),
|
|
);
|
|
|
|
// Identify the case `Some(x, y)` where the expected type is e.g. `Option<(T, U)>`.
|
|
// More generally, the expected type wants a tuple variant with one field of an
|
|
// N-arity-tuple, e.g., `V_i((p_0, .., p_N))`. Meanwhile, the user supplied a pattern
|
|
// with the subpatterns directly in the tuple variant pattern, e.g., `V_i(p_0, .., p_N)`.
|
|
let missing_parentheses = match (&expected.kind(), fields, had_err) {
|
|
// #67037: only do this if we could successfully type-check the expected type against
|
|
// the tuple struct pattern. Otherwise the args could get out of range on e.g.,
|
|
// `let P() = U;` where `P != U` with `struct P<T>(T);`.
|
|
(ty::Adt(_, args), [field], false) => {
|
|
let field_ty = self.field_ty(pat_span, field, args);
|
|
match field_ty.kind() {
|
|
ty::Tuple(fields) => fields.len() == subpats.len(),
|
|
_ => false,
|
|
}
|
|
}
|
|
_ => false,
|
|
};
|
|
if missing_parentheses {
|
|
let (left, right) = match subpats {
|
|
// This is the zero case; we aim to get the "hi" part of the `QPath`'s
|
|
// span as the "lo" and then the "hi" part of the pattern's span as the "hi".
|
|
// This looks like:
|
|
//
|
|
// help: missing parentheses
|
|
// |
|
|
// L | let A(()) = A(());
|
|
// | ^ ^
|
|
[] => (qpath.span().shrink_to_hi(), pat_span),
|
|
// Easy case. Just take the "lo" of the first sub-pattern and the "hi" of the
|
|
// last sub-pattern. In the case of `A(x)` the first and last may coincide.
|
|
// This looks like:
|
|
//
|
|
// help: missing parentheses
|
|
// |
|
|
// L | let A((x, y)) = A((1, 2));
|
|
// | ^ ^
|
|
[first, ..] => (first.span.shrink_to_lo(), subpats.last().unwrap().span),
|
|
};
|
|
err.multipart_suggestion(
|
|
"missing parentheses",
|
|
vec![(left, "(".to_string()), (right.shrink_to_hi(), ")".to_string())],
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else if fields.len() > subpats.len() && pat_span != DUMMY_SP {
|
|
let after_fields_span = pat_span.with_hi(pat_span.hi() - BytePos(1)).shrink_to_hi();
|
|
let all_fields_span = match subpats {
|
|
[] => after_fields_span,
|
|
[field] => field.span,
|
|
[first, .., last] => first.span.to(last.span),
|
|
};
|
|
|
|
// Check if all the fields in the pattern are wildcards.
|
|
let all_wildcards = subpats.iter().all(|pat| matches!(pat.kind, PatKind::Wild));
|
|
let first_tail_wildcard =
|
|
subpats.iter().enumerate().fold(None, |acc, (pos, pat)| match (acc, &pat.kind) {
|
|
(None, PatKind::Wild) => Some(pos),
|
|
(Some(_), PatKind::Wild) => acc,
|
|
_ => None,
|
|
});
|
|
let tail_span = match first_tail_wildcard {
|
|
None => after_fields_span,
|
|
Some(0) => subpats[0].span.to(after_fields_span),
|
|
Some(pos) => subpats[pos - 1].span.shrink_to_hi().to(after_fields_span),
|
|
};
|
|
|
|
// FIXME: heuristic-based suggestion to check current types for where to add `_`.
|
|
let mut wildcard_sugg = vec!["_"; fields.len() - subpats.len()].join(", ");
|
|
if !subpats.is_empty() {
|
|
wildcard_sugg = String::from(", ") + &wildcard_sugg;
|
|
}
|
|
|
|
err.span_suggestion_verbose(
|
|
after_fields_span,
|
|
"use `_` to explicitly ignore each field",
|
|
wildcard_sugg,
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
|
|
// Only suggest `..` if more than one field is missing
|
|
// or the pattern consists of all wildcards.
|
|
if fields.len() - subpats.len() > 1 || all_wildcards {
|
|
if subpats.is_empty() || all_wildcards {
|
|
err.span_suggestion_verbose(
|
|
all_fields_span,
|
|
"use `..` to ignore all fields",
|
|
"..",
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
} else {
|
|
err.span_suggestion_verbose(
|
|
tail_span,
|
|
"use `..` to ignore the rest of the fields",
|
|
", ..",
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
err.emit()
|
|
}
|
|
|
|
fn check_pat_tuple(
|
|
&self,
|
|
span: Span,
|
|
elements: &'tcx [Pat<'tcx>],
|
|
ddpos: hir::DotDotPos,
|
|
expected: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx;
|
|
let mut expected_len = elements.len();
|
|
if ddpos.as_opt_usize().is_some() {
|
|
// Require known type only when `..` is present.
|
|
if let ty::Tuple(tys) = self.structurally_resolve_type(span, expected).kind() {
|
|
expected_len = tys.len();
|
|
}
|
|
}
|
|
let max_len = cmp::max(expected_len, elements.len());
|
|
|
|
let element_tys_iter = (0..max_len).map(|_| self.next_ty_var(span));
|
|
let element_tys = tcx.mk_type_list_from_iter(element_tys_iter);
|
|
let pat_ty = Ty::new_tup(tcx, element_tys);
|
|
if let Some(err) = self.demand_eqtype_pat_diag(span, expected, pat_ty, pat_info.top_info) {
|
|
let reported = err.emit();
|
|
// Walk subpatterns with an expected type of `err` in this case to silence
|
|
// further errors being emitted when using the bindings. #50333
|
|
let element_tys_iter = (0..max_len).map(|_| Ty::new_error(tcx, reported));
|
|
for (_, elem) in elements.iter().enumerate_and_adjust(max_len, ddpos) {
|
|
self.check_pat(elem, Ty::new_error(tcx, reported), pat_info);
|
|
}
|
|
Ty::new_tup_from_iter(tcx, element_tys_iter)
|
|
} else {
|
|
for (i, elem) in elements.iter().enumerate_and_adjust(max_len, ddpos) {
|
|
self.check_pat(elem, element_tys[i], pat_info);
|
|
}
|
|
pat_ty
|
|
}
|
|
}
|
|
|
|
fn check_struct_pat_fields(
|
|
&self,
|
|
adt_ty: Ty<'tcx>,
|
|
pat: &'tcx Pat<'tcx>,
|
|
variant: &'tcx ty::VariantDef,
|
|
fields: &'tcx [hir::PatField<'tcx>],
|
|
has_rest_pat: bool,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> bool {
|
|
let tcx = self.tcx;
|
|
|
|
let ty::Adt(adt, args) = adt_ty.kind() else {
|
|
span_bug!(pat.span, "struct pattern is not an ADT");
|
|
};
|
|
|
|
// Index the struct fields' types.
|
|
let field_map = variant
|
|
.fields
|
|
.iter_enumerated()
|
|
.map(|(i, field)| (field.ident(self.tcx).normalize_to_macros_2_0(), (i, field)))
|
|
.collect::<FxHashMap<_, _>>();
|
|
|
|
// Keep track of which fields have already appeared in the pattern.
|
|
let mut used_fields = FxHashMap::default();
|
|
let mut no_field_errors = true;
|
|
|
|
let mut inexistent_fields = vec![];
|
|
// Typecheck each field.
|
|
for field in fields {
|
|
let span = field.span;
|
|
let ident = tcx.adjust_ident(field.ident, variant.def_id);
|
|
let field_ty = match used_fields.entry(ident) {
|
|
Occupied(occupied) => {
|
|
no_field_errors = false;
|
|
let guar = self.error_field_already_bound(span, field.ident, *occupied.get());
|
|
Ty::new_error(tcx, guar)
|
|
}
|
|
Vacant(vacant) => {
|
|
vacant.insert(span);
|
|
field_map
|
|
.get(&ident)
|
|
.map(|(i, f)| {
|
|
// FIXME: handle nested fields
|
|
self.write_field_index(field.hir_id, *i, Vec::new());
|
|
self.tcx.check_stability(f.did, Some(pat.hir_id), span, None);
|
|
self.field_ty(span, f, args)
|
|
})
|
|
.unwrap_or_else(|| {
|
|
inexistent_fields.push(field);
|
|
no_field_errors = false;
|
|
Ty::new_misc_error(tcx)
|
|
})
|
|
}
|
|
};
|
|
|
|
self.check_pat(field.pat, field_ty, pat_info);
|
|
}
|
|
|
|
let mut unmentioned_fields = variant
|
|
.fields
|
|
.iter()
|
|
.map(|field| (field, field.ident(self.tcx).normalize_to_macros_2_0()))
|
|
.filter(|(_, ident)| !used_fields.contains_key(ident))
|
|
.collect::<Vec<_>>();
|
|
|
|
let inexistent_fields_err = if !(inexistent_fields.is_empty() || variant.is_recovered())
|
|
&& !inexistent_fields.iter().any(|field| field.ident.name == kw::Underscore)
|
|
{
|
|
Some(self.error_inexistent_fields(
|
|
adt.variant_descr(),
|
|
&inexistent_fields,
|
|
&mut unmentioned_fields,
|
|
pat,
|
|
variant,
|
|
args,
|
|
))
|
|
} else {
|
|
None
|
|
};
|
|
|
|
// Require `..` if struct has non_exhaustive attribute.
|
|
let non_exhaustive = variant.is_field_list_non_exhaustive() && !adt.did().is_local();
|
|
if non_exhaustive && !has_rest_pat {
|
|
self.error_foreign_non_exhaustive_spat(pat, adt.variant_descr(), fields.is_empty());
|
|
}
|
|
|
|
let mut unmentioned_err = None;
|
|
// Report an error if an incorrect number of fields was specified.
|
|
if adt.is_union() {
|
|
if fields.len() != 1 {
|
|
tcx.dcx().emit_err(errors::UnionPatMultipleFields { span: pat.span });
|
|
}
|
|
if has_rest_pat {
|
|
tcx.dcx().emit_err(errors::UnionPatDotDot { span: pat.span });
|
|
}
|
|
} else if !unmentioned_fields.is_empty() {
|
|
let accessible_unmentioned_fields: Vec<_> = unmentioned_fields
|
|
.iter()
|
|
.copied()
|
|
.filter(|(field, _)| self.is_field_suggestable(field, pat.hir_id, pat.span))
|
|
.collect();
|
|
|
|
if !has_rest_pat {
|
|
if accessible_unmentioned_fields.is_empty() {
|
|
unmentioned_err = Some(self.error_no_accessible_fields(pat, fields));
|
|
} else {
|
|
unmentioned_err = Some(self.error_unmentioned_fields(
|
|
pat,
|
|
&accessible_unmentioned_fields,
|
|
accessible_unmentioned_fields.len() != unmentioned_fields.len(),
|
|
fields,
|
|
));
|
|
}
|
|
} else if non_exhaustive && !accessible_unmentioned_fields.is_empty() {
|
|
self.lint_non_exhaustive_omitted_patterns(
|
|
pat,
|
|
&accessible_unmentioned_fields,
|
|
adt_ty,
|
|
)
|
|
}
|
|
}
|
|
match (inexistent_fields_err, unmentioned_err) {
|
|
(Some(i), Some(u)) => {
|
|
if let Some(e) = self.error_tuple_variant_as_struct_pat(pat, fields, variant) {
|
|
// We don't want to show the nonexistent fields error when this was
|
|
// `Foo { a, b }` when it should have been `Foo(a, b)`.
|
|
i.delay_as_bug();
|
|
u.delay_as_bug();
|
|
e.emit();
|
|
} else {
|
|
i.emit();
|
|
u.emit();
|
|
}
|
|
}
|
|
(None, Some(u)) => {
|
|
if let Some(e) = self.error_tuple_variant_as_struct_pat(pat, fields, variant) {
|
|
u.delay_as_bug();
|
|
e.emit();
|
|
} else {
|
|
u.emit();
|
|
}
|
|
}
|
|
(Some(err), None) => {
|
|
err.emit();
|
|
}
|
|
(None, None)
|
|
if let Some(err) =
|
|
self.error_tuple_variant_index_shorthand(variant, pat, fields) =>
|
|
{
|
|
err.emit();
|
|
}
|
|
(None, None) => {}
|
|
}
|
|
no_field_errors
|
|
}
|
|
|
|
fn error_tuple_variant_index_shorthand(
|
|
&self,
|
|
variant: &VariantDef,
|
|
pat: &'_ Pat<'_>,
|
|
fields: &[hir::PatField<'_>],
|
|
) -> Option<Diag<'_>> {
|
|
// if this is a tuple struct, then all field names will be numbers
|
|
// so if any fields in a struct pattern use shorthand syntax, they will
|
|
// be invalid identifiers (for example, Foo { 0, 1 }).
|
|
if let (Some(CtorKind::Fn), PatKind::Struct(qpath, field_patterns, ..)) =
|
|
(variant.ctor_kind(), &pat.kind)
|
|
{
|
|
let has_shorthand_field_name = field_patterns.iter().any(|field| field.is_shorthand);
|
|
if has_shorthand_field_name {
|
|
let path = rustc_hir_pretty::qpath_to_string(&self.tcx, qpath);
|
|
let mut err = struct_span_code_err!(
|
|
self.dcx(),
|
|
pat.span,
|
|
E0769,
|
|
"tuple variant `{path}` written as struct variant",
|
|
);
|
|
err.span_suggestion_verbose(
|
|
qpath.span().shrink_to_hi().to(pat.span.shrink_to_hi()),
|
|
"use the tuple variant pattern syntax instead",
|
|
format!("({})", self.get_suggested_tuple_struct_pattern(fields, variant)),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
return Some(err);
|
|
}
|
|
}
|
|
None
|
|
}
|
|
|
|
fn error_foreign_non_exhaustive_spat(&self, pat: &Pat<'_>, descr: &str, no_fields: bool) {
|
|
let sess = self.tcx.sess;
|
|
let sm = sess.source_map();
|
|
let sp_brace = sm.end_point(pat.span);
|
|
let sp_comma = sm.end_point(pat.span.with_hi(sp_brace.hi()));
|
|
let sugg = if no_fields || sp_brace != sp_comma { ".. }" } else { ", .. }" };
|
|
|
|
struct_span_code_err!(
|
|
self.dcx(),
|
|
pat.span,
|
|
E0638,
|
|
"`..` required with {descr} marked as non-exhaustive",
|
|
)
|
|
.with_span_suggestion_verbose(
|
|
sp_comma,
|
|
"add `..` at the end of the field list to ignore all other fields",
|
|
sugg,
|
|
Applicability::MachineApplicable,
|
|
)
|
|
.emit();
|
|
}
|
|
|
|
fn error_field_already_bound(
|
|
&self,
|
|
span: Span,
|
|
ident: Ident,
|
|
other_field: Span,
|
|
) -> ErrorGuaranteed {
|
|
struct_span_code_err!(
|
|
self.dcx(),
|
|
span,
|
|
E0025,
|
|
"field `{}` bound multiple times in the pattern",
|
|
ident
|
|
)
|
|
.with_span_label(span, format!("multiple uses of `{ident}` in pattern"))
|
|
.with_span_label(other_field, format!("first use of `{ident}`"))
|
|
.emit()
|
|
}
|
|
|
|
fn error_inexistent_fields(
|
|
&self,
|
|
kind_name: &str,
|
|
inexistent_fields: &[&hir::PatField<'tcx>],
|
|
unmentioned_fields: &mut Vec<(&'tcx ty::FieldDef, Ident)>,
|
|
pat: &'tcx Pat<'tcx>,
|
|
variant: &ty::VariantDef,
|
|
args: ty::GenericArgsRef<'tcx>,
|
|
) -> Diag<'tcx> {
|
|
let tcx = self.tcx;
|
|
let (field_names, t, plural) = if let [field] = inexistent_fields {
|
|
(format!("a field named `{}`", field.ident), "this", "")
|
|
} else {
|
|
(
|
|
format!(
|
|
"fields named {}",
|
|
inexistent_fields
|
|
.iter()
|
|
.map(|field| format!("`{}`", field.ident))
|
|
.collect::<Vec<String>>()
|
|
.join(", ")
|
|
),
|
|
"these",
|
|
"s",
|
|
)
|
|
};
|
|
let spans = inexistent_fields.iter().map(|field| field.ident.span).collect::<Vec<_>>();
|
|
let mut err = struct_span_code_err!(
|
|
tcx.dcx(),
|
|
spans,
|
|
E0026,
|
|
"{} `{}` does not have {}",
|
|
kind_name,
|
|
tcx.def_path_str(variant.def_id),
|
|
field_names
|
|
);
|
|
if let Some(pat_field) = inexistent_fields.last() {
|
|
err.span_label(
|
|
pat_field.ident.span,
|
|
format!(
|
|
"{} `{}` does not have {} field{}",
|
|
kind_name,
|
|
tcx.def_path_str(variant.def_id),
|
|
t,
|
|
plural
|
|
),
|
|
);
|
|
|
|
if let [(field_def, field)] = unmentioned_fields.as_slice()
|
|
&& self.is_field_suggestable(field_def, pat.hir_id, pat.span)
|
|
{
|
|
let suggested_name =
|
|
find_best_match_for_name(&[field.name], pat_field.ident.name, None);
|
|
if let Some(suggested_name) = suggested_name {
|
|
err.span_suggestion(
|
|
pat_field.ident.span,
|
|
"a field with a similar name exists",
|
|
suggested_name,
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
|
|
// When we have a tuple struct used with struct we don't want to suggest using
|
|
// the (valid) struct syntax with numeric field names. Instead we want to
|
|
// suggest the expected syntax. We infer that this is the case by parsing the
|
|
// `Ident` into an unsized integer. The suggestion will be emitted elsewhere in
|
|
// `smart_resolve_context_dependent_help`.
|
|
if suggested_name.to_ident_string().parse::<usize>().is_err() {
|
|
// We don't want to throw `E0027` in case we have thrown `E0026` for them.
|
|
unmentioned_fields.retain(|&(_, x)| x.name != suggested_name);
|
|
}
|
|
} else if inexistent_fields.len() == 1 {
|
|
match pat_field.pat.kind {
|
|
PatKind::Lit(expr)
|
|
if !self.can_coerce(
|
|
self.typeck_results.borrow().expr_ty(expr),
|
|
self.field_ty(field.span, field_def, args),
|
|
) => {}
|
|
_ => {
|
|
err.span_suggestion_short(
|
|
pat_field.ident.span,
|
|
format!(
|
|
"`{}` has a field named `{}`",
|
|
tcx.def_path_str(variant.def_id),
|
|
field.name,
|
|
),
|
|
field.name,
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if tcx.sess.teach(err.code.unwrap()) {
|
|
err.note(
|
|
"This error indicates that a struct pattern attempted to \
|
|
extract a nonexistent field from a struct. Struct fields \
|
|
are identified by the name used before the colon : so struct \
|
|
patterns should resemble the declaration of the struct type \
|
|
being matched.\n\n\
|
|
If you are using shorthand field patterns but want to refer \
|
|
to the struct field by a different name, you should rename \
|
|
it explicitly.",
|
|
);
|
|
}
|
|
err
|
|
}
|
|
|
|
fn error_tuple_variant_as_struct_pat(
|
|
&self,
|
|
pat: &Pat<'_>,
|
|
fields: &'tcx [hir::PatField<'tcx>],
|
|
variant: &ty::VariantDef,
|
|
) -> Option<Diag<'tcx>> {
|
|
if let (Some(CtorKind::Fn), PatKind::Struct(qpath, pattern_fields, ..)) =
|
|
(variant.ctor_kind(), &pat.kind)
|
|
{
|
|
let is_tuple_struct_match = !pattern_fields.is_empty()
|
|
&& pattern_fields.iter().map(|field| field.ident.name.as_str()).all(is_number);
|
|
if is_tuple_struct_match {
|
|
return None;
|
|
}
|
|
|
|
let path = rustc_hir_pretty::qpath_to_string(&self.tcx, qpath);
|
|
let mut err = struct_span_code_err!(
|
|
self.dcx(),
|
|
pat.span,
|
|
E0769,
|
|
"tuple variant `{}` written as struct variant",
|
|
path
|
|
);
|
|
let (sugg, appl) = if fields.len() == variant.fields.len() {
|
|
(
|
|
self.get_suggested_tuple_struct_pattern(fields, variant),
|
|
Applicability::MachineApplicable,
|
|
)
|
|
} else {
|
|
(
|
|
variant.fields.iter().map(|_| "_").collect::<Vec<&str>>().join(", "),
|
|
Applicability::MaybeIncorrect,
|
|
)
|
|
};
|
|
err.span_suggestion_verbose(
|
|
qpath.span().shrink_to_hi().to(pat.span.shrink_to_hi()),
|
|
"use the tuple variant pattern syntax instead",
|
|
format!("({sugg})"),
|
|
appl,
|
|
);
|
|
return Some(err);
|
|
}
|
|
None
|
|
}
|
|
|
|
fn get_suggested_tuple_struct_pattern(
|
|
&self,
|
|
fields: &[hir::PatField<'_>],
|
|
variant: &VariantDef,
|
|
) -> String {
|
|
let variant_field_idents =
|
|
variant.fields.iter().map(|f| f.ident(self.tcx)).collect::<Vec<Ident>>();
|
|
fields
|
|
.iter()
|
|
.map(|field| {
|
|
match self.tcx.sess.source_map().span_to_snippet(field.pat.span) {
|
|
Ok(f) => {
|
|
// Field names are numbers, but numbers
|
|
// are not valid identifiers
|
|
if variant_field_idents.contains(&field.ident) {
|
|
String::from("_")
|
|
} else {
|
|
f
|
|
}
|
|
}
|
|
Err(_) => rustc_hir_pretty::pat_to_string(&self.tcx, field.pat),
|
|
}
|
|
})
|
|
.collect::<Vec<String>>()
|
|
.join(", ")
|
|
}
|
|
|
|
/// Returns a diagnostic reporting a struct pattern which is missing an `..` due to
|
|
/// inaccessible fields.
|
|
///
|
|
/// ```text
|
|
/// error: pattern requires `..` due to inaccessible fields
|
|
/// --> src/main.rs:10:9
|
|
/// |
|
|
/// LL | let foo::Foo {} = foo::Foo::default();
|
|
/// | ^^^^^^^^^^^
|
|
/// |
|
|
/// help: add a `..`
|
|
/// |
|
|
/// LL | let foo::Foo { .. } = foo::Foo::default();
|
|
/// | ^^^^^^
|
|
/// ```
|
|
fn error_no_accessible_fields(
|
|
&self,
|
|
pat: &Pat<'_>,
|
|
fields: &'tcx [hir::PatField<'tcx>],
|
|
) -> Diag<'tcx> {
|
|
let mut err = self
|
|
.dcx()
|
|
.struct_span_err(pat.span, "pattern requires `..` due to inaccessible fields");
|
|
|
|
if let Some(field) = fields.last() {
|
|
err.span_suggestion_verbose(
|
|
field.span.shrink_to_hi(),
|
|
"ignore the inaccessible and unused fields",
|
|
", ..",
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else {
|
|
let qpath_span = if let PatKind::Struct(qpath, ..) = &pat.kind {
|
|
qpath.span()
|
|
} else {
|
|
bug!("`error_no_accessible_fields` called on non-struct pattern");
|
|
};
|
|
|
|
// Shrink the span to exclude the `foo:Foo` in `foo::Foo { }`.
|
|
let span = pat.span.with_lo(qpath_span.shrink_to_hi().hi());
|
|
err.span_suggestion_verbose(
|
|
span,
|
|
"ignore the inaccessible and unused fields",
|
|
" { .. }",
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
err
|
|
}
|
|
|
|
/// Report that a pattern for a `#[non_exhaustive]` struct marked with `non_exhaustive_omitted_patterns`
|
|
/// is not exhaustive enough.
|
|
///
|
|
/// Nb: the partner lint for enums lives in `compiler/rustc_mir_build/src/thir/pattern/usefulness.rs`.
|
|
fn lint_non_exhaustive_omitted_patterns(
|
|
&self,
|
|
pat: &Pat<'_>,
|
|
unmentioned_fields: &[(&ty::FieldDef, Ident)],
|
|
ty: Ty<'tcx>,
|
|
) {
|
|
fn joined_uncovered_patterns(witnesses: &[&Ident]) -> String {
|
|
const LIMIT: usize = 3;
|
|
match witnesses {
|
|
[] => {
|
|
unreachable!(
|
|
"expected an uncovered pattern, otherwise why are we emitting an error?"
|
|
)
|
|
}
|
|
[witness] => format!("`{witness}`"),
|
|
[head @ .., tail] if head.len() < LIMIT => {
|
|
let head: Vec<_> = head.iter().map(<_>::to_string).collect();
|
|
format!("`{}` and `{}`", head.join("`, `"), tail)
|
|
}
|
|
_ => {
|
|
let (head, tail) = witnesses.split_at(LIMIT);
|
|
let head: Vec<_> = head.iter().map(<_>::to_string).collect();
|
|
format!("`{}` and {} more", head.join("`, `"), tail.len())
|
|
}
|
|
}
|
|
}
|
|
let joined_patterns = joined_uncovered_patterns(
|
|
&unmentioned_fields.iter().map(|(_, i)| i).collect::<Vec<_>>(),
|
|
);
|
|
|
|
self.tcx.node_span_lint(NON_EXHAUSTIVE_OMITTED_PATTERNS, pat.hir_id, pat.span, |lint| {
|
|
lint.primary_message("some fields are not explicitly listed");
|
|
lint.span_label(pat.span, format!("field{} {} not listed", rustc_errors::pluralize!(unmentioned_fields.len()), joined_patterns));
|
|
lint.help(
|
|
"ensure that all fields are mentioned explicitly by adding the suggested fields",
|
|
);
|
|
lint.note(format!(
|
|
"the pattern is of type `{ty}` and the `non_exhaustive_omitted_patterns` attribute was found",
|
|
));
|
|
});
|
|
}
|
|
|
|
/// Returns a diagnostic reporting a struct pattern which does not mention some fields.
|
|
///
|
|
/// ```text
|
|
/// error[E0027]: pattern does not mention field `bar`
|
|
/// --> src/main.rs:15:9
|
|
/// |
|
|
/// LL | let foo::Foo {} = foo::Foo::new();
|
|
/// | ^^^^^^^^^^^ missing field `bar`
|
|
/// ```
|
|
fn error_unmentioned_fields(
|
|
&self,
|
|
pat: &Pat<'_>,
|
|
unmentioned_fields: &[(&ty::FieldDef, Ident)],
|
|
have_inaccessible_fields: bool,
|
|
fields: &'tcx [hir::PatField<'tcx>],
|
|
) -> Diag<'tcx> {
|
|
let inaccessible = if have_inaccessible_fields { " and inaccessible fields" } else { "" };
|
|
let field_names = if let [(_, field)] = unmentioned_fields {
|
|
format!("field `{field}`{inaccessible}")
|
|
} else {
|
|
let fields = unmentioned_fields
|
|
.iter()
|
|
.map(|(_, name)| format!("`{name}`"))
|
|
.collect::<Vec<String>>()
|
|
.join(", ");
|
|
format!("fields {fields}{inaccessible}")
|
|
};
|
|
let mut err = struct_span_code_err!(
|
|
self.dcx(),
|
|
pat.span,
|
|
E0027,
|
|
"pattern does not mention {}",
|
|
field_names
|
|
);
|
|
err.span_label(pat.span, format!("missing {field_names}"));
|
|
let len = unmentioned_fields.len();
|
|
let (prefix, postfix, sp) = match fields {
|
|
[] => match &pat.kind {
|
|
PatKind::Struct(path, [], false) => {
|
|
(" { ", " }", path.span().shrink_to_hi().until(pat.span.shrink_to_hi()))
|
|
}
|
|
_ => return err,
|
|
},
|
|
[.., field] => {
|
|
// Account for last field having a trailing comma or parse recovery at the tail of
|
|
// the pattern to avoid invalid suggestion (#78511).
|
|
let tail = field.span.shrink_to_hi().with_hi(pat.span.hi());
|
|
match &pat.kind {
|
|
PatKind::Struct(..) => (", ", " }", tail),
|
|
_ => return err,
|
|
}
|
|
}
|
|
};
|
|
err.span_suggestion(
|
|
sp,
|
|
format!(
|
|
"include the missing field{} in the pattern{}",
|
|
pluralize!(len),
|
|
if have_inaccessible_fields { " and ignore the inaccessible fields" } else { "" }
|
|
),
|
|
format!(
|
|
"{}{}{}{}",
|
|
prefix,
|
|
unmentioned_fields
|
|
.iter()
|
|
.map(|(_, name)| {
|
|
let field_name = name.to_string();
|
|
if is_number(&field_name) { format!("{field_name}: _") } else { field_name }
|
|
})
|
|
.collect::<Vec<_>>()
|
|
.join(", "),
|
|
if have_inaccessible_fields { ", .." } else { "" },
|
|
postfix,
|
|
),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
err.span_suggestion(
|
|
sp,
|
|
format!(
|
|
"if you don't care about {these} missing field{s}, you can explicitly ignore {them}",
|
|
these = pluralize!("this", len),
|
|
s = pluralize!(len),
|
|
them = if len == 1 { "it" } else { "them" },
|
|
),
|
|
format!("{prefix}..{postfix}"),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
err
|
|
}
|
|
|
|
fn check_pat_box(
|
|
&self,
|
|
span: Span,
|
|
inner: &'tcx Pat<'tcx>,
|
|
expected: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx;
|
|
let (box_ty, inner_ty) = match self.check_dereferenceable(span, expected, inner) {
|
|
Ok(()) => {
|
|
// Here, `demand::subtype` is good enough, but I don't
|
|
// think any errors can be introduced by using `demand::eqtype`.
|
|
let inner_ty = self.next_ty_var(inner.span);
|
|
let box_ty = Ty::new_box(tcx, inner_ty);
|
|
self.demand_eqtype_pat(span, expected, box_ty, pat_info.top_info);
|
|
(box_ty, inner_ty)
|
|
}
|
|
Err(guar) => {
|
|
let err = Ty::new_error(tcx, guar);
|
|
(err, err)
|
|
}
|
|
};
|
|
self.check_pat(inner, inner_ty, pat_info);
|
|
box_ty
|
|
}
|
|
|
|
fn check_pat_deref(
|
|
&self,
|
|
span: Span,
|
|
inner: &'tcx Pat<'tcx>,
|
|
expected: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx;
|
|
// Register a `DerefPure` bound, which is required by all `deref!()` pats.
|
|
self.register_bound(
|
|
expected,
|
|
tcx.require_lang_item(hir::LangItem::DerefPure, Some(span)),
|
|
self.misc(span),
|
|
);
|
|
// <expected as Deref>::Target
|
|
let ty = Ty::new_projection(
|
|
tcx,
|
|
tcx.require_lang_item(hir::LangItem::DerefTarget, Some(span)),
|
|
[expected],
|
|
);
|
|
let ty = self.normalize(span, ty);
|
|
let ty = self.try_structurally_resolve_type(span, ty);
|
|
self.check_pat(inner, ty, pat_info);
|
|
|
|
// Check if the pattern has any `ref mut` bindings, which would require
|
|
// `DerefMut` to be emitted in MIR building instead of just `Deref`.
|
|
// We do this *after* checking the inner pattern, since we want to make
|
|
// sure to apply any match-ergonomics adjustments.
|
|
if self.typeck_results.borrow().pat_has_ref_mut_binding(inner) {
|
|
self.register_bound(
|
|
expected,
|
|
tcx.require_lang_item(hir::LangItem::DerefMut, Some(span)),
|
|
self.misc(span),
|
|
);
|
|
}
|
|
|
|
expected
|
|
}
|
|
|
|
// Precondition: Pat is Ref(inner)
|
|
fn check_pat_ref(
|
|
&self,
|
|
pat: &'tcx Pat<'tcx>,
|
|
inner: &'tcx Pat<'tcx>,
|
|
pat_mutbl: Mutability,
|
|
mut expected: Ty<'tcx>,
|
|
mut pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
let no_ref_mut_behind_and = self.tcx.features().ref_pat_eat_one_layer_2024;
|
|
let new_match_ergonomics = pat.span.at_least_rust_2024() && no_ref_mut_behind_and;
|
|
|
|
let pat_prefix_span =
|
|
inner.span.find_ancestor_inside(pat.span).map(|end| pat.span.until(end));
|
|
|
|
if no_ref_mut_behind_and {
|
|
if pat_mutbl == Mutability::Not {
|
|
// Prevent the inner pattern from binding with `ref mut`.
|
|
pat_info.max_ref_mutbl = pat_info.max_ref_mutbl.cap_to_weakly_not(pat_prefix_span);
|
|
}
|
|
} else {
|
|
pat_info.max_ref_mutbl = MutblCap::Mut;
|
|
}
|
|
|
|
if new_match_ergonomics {
|
|
if let ByRef::Yes(inh_mut) = pat_info.binding_mode {
|
|
// ref pattern consumes inherited reference
|
|
|
|
if pat_mutbl > inh_mut {
|
|
// Tried to match inherited `ref` with `&mut`, which is an error
|
|
let err_msg = "cannot match inherited `&` with `&mut` pattern";
|
|
let err = if let Some(span) = pat_prefix_span {
|
|
let mut err = self.dcx().struct_span_err(span, err_msg);
|
|
err.span_suggestion_verbose(
|
|
span,
|
|
"replace this `&mut` pattern with `&`",
|
|
"&",
|
|
Applicability::MachineApplicable,
|
|
);
|
|
err
|
|
} else {
|
|
self.dcx().struct_span_err(pat.span, err_msg)
|
|
};
|
|
err.emit();
|
|
}
|
|
|
|
pat_info.binding_mode = ByRef::No;
|
|
self.typeck_results.borrow_mut().skipped_ref_pats_mut().insert(pat.hir_id);
|
|
self.check_pat(inner, expected, pat_info);
|
|
return expected;
|
|
}
|
|
} else {
|
|
// Reset binding mode on old editions
|
|
|
|
if pat_info.binding_mode != ByRef::No {
|
|
pat_info.binding_mode = ByRef::No;
|
|
|
|
self.typeck_results
|
|
.borrow_mut()
|
|
.rust_2024_migration_desugared_pats_mut()
|
|
.insert(pat_info.top_info.hir_id);
|
|
}
|
|
}
|
|
|
|
let tcx = self.tcx;
|
|
expected = self.try_structurally_resolve_type(pat.span, expected);
|
|
let (ref_ty, inner_ty) = match self.check_dereferenceable(pat.span, expected, inner) {
|
|
Ok(()) => {
|
|
// `demand::subtype` would be good enough, but using `eqtype` turns
|
|
// out to be equally general. See (note_1) for details.
|
|
|
|
// Take region, inner-type from expected type if we can,
|
|
// to avoid creating needless variables. This also helps with
|
|
// the bad interactions of the given hack detailed in (note_1).
|
|
debug!("check_pat_ref: expected={:?}", expected);
|
|
match *expected.kind() {
|
|
ty::Ref(_, r_ty, r_mutbl)
|
|
if (new_match_ergonomics && r_mutbl >= pat_mutbl)
|
|
|| r_mutbl == pat_mutbl =>
|
|
{
|
|
if no_ref_mut_behind_and && r_mutbl == Mutability::Not {
|
|
pat_info.max_ref_mutbl = MutblCap::Not;
|
|
}
|
|
|
|
(expected, r_ty)
|
|
}
|
|
|
|
_ => {
|
|
let inner_ty = self.next_ty_var(inner.span);
|
|
let ref_ty = self.new_ref_ty(pat.span, pat_mutbl, inner_ty);
|
|
debug!("check_pat_ref: demanding {:?} = {:?}", expected, ref_ty);
|
|
let err = self.demand_eqtype_pat_diag(
|
|
pat.span,
|
|
expected,
|
|
ref_ty,
|
|
pat_info.top_info,
|
|
);
|
|
|
|
// Look for a case like `fn foo(&foo: u32)` and suggest
|
|
// `fn foo(foo: &u32)`
|
|
if let Some(mut err) = err {
|
|
self.borrow_pat_suggestion(&mut err, pat);
|
|
err.emit();
|
|
}
|
|
(ref_ty, inner_ty)
|
|
}
|
|
}
|
|
}
|
|
Err(guar) => {
|
|
let err = Ty::new_error(tcx, guar);
|
|
(err, err)
|
|
}
|
|
};
|
|
self.check_pat(inner, inner_ty, pat_info);
|
|
ref_ty
|
|
}
|
|
|
|
/// Create a reference type with a fresh region variable.
|
|
fn new_ref_ty(&self, span: Span, mutbl: Mutability, ty: Ty<'tcx>) -> Ty<'tcx> {
|
|
let region = self.next_region_var(infer::PatternRegion(span));
|
|
Ty::new_ref(self.tcx, region, ty, mutbl)
|
|
}
|
|
|
|
fn try_resolve_slice_ty_to_array_ty(
|
|
&self,
|
|
before: &'tcx [Pat<'tcx>],
|
|
slice: Option<&'tcx Pat<'tcx>>,
|
|
span: Span,
|
|
) -> Option<Ty<'tcx>> {
|
|
if slice.is_some() {
|
|
return None;
|
|
}
|
|
|
|
let tcx = self.tcx;
|
|
let len = before.len();
|
|
let inner_ty = self.next_ty_var(span);
|
|
|
|
Some(Ty::new_array(tcx, inner_ty, len.try_into().unwrap()))
|
|
}
|
|
|
|
/// Used to determines whether we can infer the expected type in the slice pattern to be of type array.
|
|
/// This is only possible if we're in an irrefutable pattern. If we were to allow this in refutable
|
|
/// patterns we wouldn't e.g. report ambiguity in the following situation:
|
|
///
|
|
/// ```ignore(rust)
|
|
/// struct Zeroes;
|
|
/// const ARR: [usize; 2] = [0; 2];
|
|
/// const ARR2: [usize; 2] = [2; 2];
|
|
///
|
|
/// impl Into<&'static [usize; 2]> for Zeroes {
|
|
/// fn into(self) -> &'static [usize; 2] {
|
|
/// &ARR
|
|
/// }
|
|
/// }
|
|
///
|
|
/// impl Into<&'static [usize]> for Zeroes {
|
|
/// fn into(self) -> &'static [usize] {
|
|
/// &ARR2
|
|
/// }
|
|
/// }
|
|
///
|
|
/// fn main() {
|
|
/// let &[a, b]: &[usize] = Zeroes.into() else {
|
|
/// ..
|
|
/// };
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// If we're in an irrefutable pattern we prefer the array impl candidate given that
|
|
/// the slice impl candidate would be rejected anyway (if no ambiguity existed).
|
|
fn pat_is_irrefutable(&self, decl_origin: Option<DeclOrigin<'_>>) -> bool {
|
|
match decl_origin {
|
|
Some(DeclOrigin::LocalDecl { els: None }) => true,
|
|
Some(DeclOrigin::LocalDecl { els: Some(_) } | DeclOrigin::LetExpr) | None => false,
|
|
}
|
|
}
|
|
|
|
/// Type check a slice pattern.
|
|
///
|
|
/// Syntactically, these look like `[pat_0, ..., pat_n]`.
|
|
/// Semantically, we are type checking a pattern with structure:
|
|
/// ```ignore (not-rust)
|
|
/// [before_0, ..., before_n, (slice, after_0, ... after_n)?]
|
|
/// ```
|
|
/// The type of `slice`, if it is present, depends on the `expected` type.
|
|
/// If `slice` is missing, then so is `after_i`.
|
|
/// If `slice` is present, it can still represent 0 elements.
|
|
fn check_pat_slice(
|
|
&self,
|
|
span: Span,
|
|
before: &'tcx [Pat<'tcx>],
|
|
slice: Option<&'tcx Pat<'tcx>>,
|
|
after: &'tcx [Pat<'tcx>],
|
|
expected: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> Ty<'tcx> {
|
|
let expected = self.try_structurally_resolve_type(span, expected);
|
|
|
|
// If the pattern is irrefutable and `expected` is an infer ty, we try to equate it
|
|
// to an array if the given pattern allows it. See issue #76342
|
|
if self.pat_is_irrefutable(pat_info.decl_origin) && expected.is_ty_var() {
|
|
if let Some(resolved_arr_ty) =
|
|
self.try_resolve_slice_ty_to_array_ty(before, slice, span)
|
|
{
|
|
debug!(?resolved_arr_ty);
|
|
self.demand_eqtype(span, expected, resolved_arr_ty);
|
|
}
|
|
}
|
|
|
|
let expected = self.structurally_resolve_type(span, expected);
|
|
debug!(?expected);
|
|
|
|
let (element_ty, opt_slice_ty, inferred) = match *expected.kind() {
|
|
// An array, so we might have something like `let [a, b, c] = [0, 1, 2];`.
|
|
ty::Array(element_ty, len) => {
|
|
let min = before.len() as u64 + after.len() as u64;
|
|
let (opt_slice_ty, expected) =
|
|
self.check_array_pat_len(span, element_ty, expected, slice, len, min);
|
|
// `opt_slice_ty.is_none()` => `slice.is_none()`.
|
|
// Note, though, that opt_slice_ty could be `Some(error_ty)`.
|
|
assert!(opt_slice_ty.is_some() || slice.is_none());
|
|
(element_ty, opt_slice_ty, expected)
|
|
}
|
|
ty::Slice(element_ty) => (element_ty, Some(expected), expected),
|
|
// The expected type must be an array or slice, but was neither, so error.
|
|
_ => {
|
|
let guar = expected.error_reported().err().unwrap_or_else(|| {
|
|
self.error_expected_array_or_slice(span, expected, pat_info)
|
|
});
|
|
let err = Ty::new_error(self.tcx, guar);
|
|
(err, Some(err), err)
|
|
}
|
|
};
|
|
|
|
// Type check all the patterns before `slice`.
|
|
for elt in before {
|
|
self.check_pat(elt, element_ty, pat_info);
|
|
}
|
|
// Type check the `slice`, if present, against its expected type.
|
|
if let Some(slice) = slice {
|
|
self.check_pat(slice, opt_slice_ty.unwrap(), pat_info);
|
|
}
|
|
// Type check the elements after `slice`, if present.
|
|
for elt in after {
|
|
self.check_pat(elt, element_ty, pat_info);
|
|
}
|
|
inferred
|
|
}
|
|
|
|
/// Type check the length of an array pattern.
|
|
///
|
|
/// Returns both the type of the variable length pattern (or `None`), and the potentially
|
|
/// inferred array type. We only return `None` for the slice type if `slice.is_none()`.
|
|
fn check_array_pat_len(
|
|
&self,
|
|
span: Span,
|
|
element_ty: Ty<'tcx>,
|
|
arr_ty: Ty<'tcx>,
|
|
slice: Option<&'tcx Pat<'tcx>>,
|
|
len: ty::Const<'tcx>,
|
|
min_len: u64,
|
|
) -> (Option<Ty<'tcx>>, Ty<'tcx>) {
|
|
let len = match len.eval(self.tcx, self.param_env, span) {
|
|
Ok((_, val)) => val
|
|
.try_to_scalar()
|
|
.and_then(|scalar| scalar.try_to_scalar_int().ok())
|
|
.map(|int| int.to_target_usize(self.tcx)),
|
|
Err(ErrorHandled::Reported(..)) => {
|
|
let guar = self.error_scrutinee_unfixed_length(span);
|
|
return (Some(Ty::new_error(self.tcx, guar)), arr_ty);
|
|
}
|
|
Err(ErrorHandled::TooGeneric(..)) => None,
|
|
};
|
|
|
|
let guar = if let Some(len) = len {
|
|
// Now we know the length...
|
|
if slice.is_none() {
|
|
// ...and since there is no variable-length pattern,
|
|
// we require an exact match between the number of elements
|
|
// in the array pattern and as provided by the matched type.
|
|
if min_len == len {
|
|
return (None, arr_ty);
|
|
}
|
|
|
|
self.error_scrutinee_inconsistent_length(span, min_len, len)
|
|
} else if let Some(pat_len) = len.checked_sub(min_len) {
|
|
// The variable-length pattern was there,
|
|
// so it has an array type with the remaining elements left as its size...
|
|
return (Some(Ty::new_array(self.tcx, element_ty, pat_len)), arr_ty);
|
|
} else {
|
|
// ...however, in this case, there were no remaining elements.
|
|
// That is, the slice pattern requires more than the array type offers.
|
|
self.error_scrutinee_with_rest_inconsistent_length(span, min_len, len)
|
|
}
|
|
} else if slice.is_none() {
|
|
// We have a pattern with a fixed length,
|
|
// which we can use to infer the length of the array.
|
|
let updated_arr_ty = Ty::new_array(self.tcx, element_ty, min_len);
|
|
self.demand_eqtype(span, updated_arr_ty, arr_ty);
|
|
return (None, updated_arr_ty);
|
|
} else {
|
|
// We have a variable-length pattern and don't know the array length.
|
|
// This happens if we have e.g.,
|
|
// `let [a, b, ..] = arr` where `arr: [T; N]` where `const N: usize`.
|
|
self.error_scrutinee_unfixed_length(span)
|
|
};
|
|
|
|
// If we get here, we must have emitted an error.
|
|
(Some(Ty::new_error(self.tcx, guar)), arr_ty)
|
|
}
|
|
|
|
fn error_scrutinee_inconsistent_length(
|
|
&self,
|
|
span: Span,
|
|
min_len: u64,
|
|
size: u64,
|
|
) -> ErrorGuaranteed {
|
|
struct_span_code_err!(
|
|
self.dcx(),
|
|
span,
|
|
E0527,
|
|
"pattern requires {} element{} but array has {}",
|
|
min_len,
|
|
pluralize!(min_len),
|
|
size,
|
|
)
|
|
.with_span_label(span, format!("expected {} element{}", size, pluralize!(size)))
|
|
.emit()
|
|
}
|
|
|
|
fn error_scrutinee_with_rest_inconsistent_length(
|
|
&self,
|
|
span: Span,
|
|
min_len: u64,
|
|
size: u64,
|
|
) -> ErrorGuaranteed {
|
|
struct_span_code_err!(
|
|
self.dcx(),
|
|
span,
|
|
E0528,
|
|
"pattern requires at least {} element{} but array has {}",
|
|
min_len,
|
|
pluralize!(min_len),
|
|
size,
|
|
)
|
|
.with_span_label(
|
|
span,
|
|
format!("pattern cannot match array of {} element{}", size, pluralize!(size),),
|
|
)
|
|
.emit()
|
|
}
|
|
|
|
fn error_scrutinee_unfixed_length(&self, span: Span) -> ErrorGuaranteed {
|
|
struct_span_code_err!(
|
|
self.dcx(),
|
|
span,
|
|
E0730,
|
|
"cannot pattern-match on an array without a fixed length",
|
|
)
|
|
.emit()
|
|
}
|
|
|
|
fn error_expected_array_or_slice(
|
|
&self,
|
|
span: Span,
|
|
expected_ty: Ty<'tcx>,
|
|
pat_info: PatInfo<'tcx, '_>,
|
|
) -> ErrorGuaranteed {
|
|
let PatInfo { top_info: ti, current_depth, .. } = pat_info;
|
|
|
|
let mut err = struct_span_code_err!(
|
|
self.dcx(),
|
|
span,
|
|
E0529,
|
|
"expected an array or slice, found `{expected_ty}`"
|
|
);
|
|
if let ty::Ref(_, ty, _) = expected_ty.kind()
|
|
&& let ty::Array(..) | ty::Slice(..) = ty.kind()
|
|
{
|
|
err.help("the semantics of slice patterns changed recently; see issue #62254");
|
|
} else if self
|
|
.autoderef(span, expected_ty)
|
|
.any(|(ty, _)| matches!(ty.kind(), ty::Slice(..) | ty::Array(..)))
|
|
&& let Some(span) = ti.span
|
|
&& let Some(_) = ti.origin_expr
|
|
&& let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
|
|
{
|
|
let resolved_ty = self.resolve_vars_if_possible(ti.expected);
|
|
let (is_slice_or_array_or_vector, resolved_ty) =
|
|
self.is_slice_or_array_or_vector(resolved_ty);
|
|
match resolved_ty.kind() {
|
|
ty::Adt(adt_def, _)
|
|
if self.tcx.is_diagnostic_item(sym::Option, adt_def.did())
|
|
|| self.tcx.is_diagnostic_item(sym::Result, adt_def.did()) =>
|
|
{
|
|
// Slicing won't work here, but `.as_deref()` might (issue #91328).
|
|
err.span_suggestion(
|
|
span,
|
|
"consider using `as_deref` here",
|
|
format!("{snippet}.as_deref()"),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
_ => (),
|
|
}
|
|
|
|
let is_top_level = current_depth <= 1;
|
|
if is_slice_or_array_or_vector && is_top_level {
|
|
err.span_suggestion(
|
|
span,
|
|
"consider slicing here",
|
|
format!("{snippet}[..]"),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
err.span_label(span, format!("pattern cannot match with input type `{expected_ty}`"));
|
|
err.emit()
|
|
}
|
|
|
|
fn is_slice_or_array_or_vector(&self, ty: Ty<'tcx>) -> (bool, Ty<'tcx>) {
|
|
match ty.kind() {
|
|
ty::Adt(adt_def, _) if self.tcx.is_diagnostic_item(sym::Vec, adt_def.did()) => {
|
|
(true, ty)
|
|
}
|
|
ty::Ref(_, ty, _) => self.is_slice_or_array_or_vector(*ty),
|
|
ty::Slice(..) | ty::Array(..) => (true, ty),
|
|
_ => (false, ty),
|
|
}
|
|
}
|
|
}
|