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add a temporary workaround for string_deref_patterns

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This commit is contained in:
dianne 2025-03-26 08:20:20 -07:00
parent 0a05677d22
commit 3779c6b797
1 changed files with 21 additions and 2 deletions
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23
compiler/rustc_mir_build/src/thir/pattern/mod.rs
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@ -11,7 +11,7 @@ use rustc_abi::{FieldIdx, Integer};
use rustc_errors::codes::*;
use rustc_hir::def::{CtorOf, DefKind, Res};
use rustc_hir::pat_util::EnumerateAndAdjustIterator;
use rustc_hir::{self as hir, RangeEnd};
use rustc_hir::{self as hir, LangItem, RangeEnd};
use rustc_index::Idx;
use rustc_middle::mir::interpret::LitToConstInput;
use rustc_middle::thir::{
@ -650,7 +650,26 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
// the pattern's type will be `&[u8]` whereas the literal's type is `&[u8; 3]`; using the
// pattern's type means we'll properly translate it to a slice reference pattern. This works
// because slices and arrays have the same valtree representation.
let ct_ty = pat_ty.unwrap_or_else(|| self.typeck_results.node_type(expr.hir_id));
// HACK: As an exception, use the literal's type if `pat_ty` is `String`; this can happen if
// `string_deref_patterns` is enabled. There's a special case for that when lowering to MIR.
// FIXME(deref_patterns): This hack won't be necessary once `string_deref_patterns` is
// superseded by a more general implementation of deref patterns.
let ct_ty = match pat_ty {
Some(pat_ty)
if let ty::Adt(def, _) = *pat_ty.kind()
&& self.tcx.is_lang_item(def.did(), LangItem::String) =>
{
if !self.tcx.features().string_deref_patterns() {
span_bug!(
expr.span,
"matching on `String` went through without enabling string_deref_patterns"
);
}
self.typeck_results.node_type(expr.hir_id)
}
Some(pat_ty) => pat_ty,
None => self.typeck_results.node_type(expr.hir_id),
};
let lit_input = LitToConstInput { lit: &lit.node, ty: ct_ty, neg };
let constant = self.tcx.at(expr.span).lit_to_const(lit_input);
self.const_to_pat(constant, ct_ty, expr.hir_id, lit.span).kind