bjoernager/rust
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Support let &mut x = &&mut 0;

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This commit is contained in:
Jules Bertholet 2024-04-05 22:07:57 -04:00
parent 4cd87c463c
commit b6c409723b
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GPG key ID: 32034DAFC38C1BFC
4 changed files with 60 additions and 10 deletions
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23
compiler/rustc_hir_typeck/src/pat.rs
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@ -299,18 +299,24 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
if mutbls_match {
(expected, INITIAL_BM, true)
} else {
let mut new_bm = def_bm;
if new_bm.0 == ByRef::Yes(Mutability::Mut) && mutbl == Mutability::Not {
new_bm.0 = ByRef::Yes(Mutability::Not);
}
(expected, new_bm, false)
let (new_ty, new_bm) = if mutbl == Mutability::Mut {
self.peel_off_references(pat, expected, def_bm, Mutability::Not)
} else {
let new_byref = if def_bm.0 == ByRef::Yes(Mutability::Mut) {
ByRef::Yes(Mutability::Not)
} else {
def_bm.0
};
(expected, BindingAnnotation(new_byref, def_bm.1))
};
(new_ty, new_bm, false)
}
} else {
(expected, INITIAL_BM, mutbls_match)
}
}
AdjustMode::Peel => {
let peeled = self.peel_off_references(pat, expected, def_bm);
let peeled = self.peel_off_references(pat, expected, def_bm, Mutability::Mut);
(peeled.0, peeled.1, false)
}
}
@ -392,6 +398,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
pat: &'tcx Pat<'tcx>,
expected: Ty<'tcx>,
mut def_bm: BindingAnnotation,
max_mutability: Mutability,
) -> (Ty<'tcx>, BindingAnnotation) {
let mut expected = self.try_structurally_resolve_type(pat.span, expected);
// Peel off as many `&` or `&mut` from the scrutinee type as possible. For example,
@ -403,7 +410,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
//
// See the examples in `ui/match-defbm*.rs`.
let mut pat_adjustments = vec![];
while let ty::Ref(_, inner_ty, inner_mutability) = *expected.kind() {
while let ty::Ref(_, inner_ty, inner_mutability) = *expected.kind()
&& inner_mutability <= max_mutability
{
debug!("inspecting {:?}", expected);
debug!("current discriminant is Ref, inserting implicit deref");