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"No ref mut behind &" on all editions

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This commit is contained in:
Jules Bertholet 2024-05-15 17:20:18 -04:00
parent 0746577fa2
commit af75014cc5
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GPG Key ID: 32034DAFC38C1BFC
2 changed files with 28 additions and 16 deletions
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35
compiler/rustc_hir_typeck/src/pat.rs
View File

@ -406,7 +406,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
pat: &'tcx Pat<'tcx>,
expected: Ty<'tcx>,
mut def_br: ByRef,
mut max_ref_mutability: MutblCap,
mut max_ref_mutbl: MutblCap,
) -> (Ty<'tcx>, ByRef, MutblCap) {
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,
@ -438,10 +438,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
});
}
if pat.span.at_least_rust_2024() && self.tcx.features().ref_pat_eat_one_layer_2024 {
def_br = def_br.cap_ref_mutability(max_ref_mutability.as_mutbl());
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_mutability = MutblCap::Not;
max_ref_mutbl = MutblCap::Not;
}
}
@ -453,7 +453,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
.insert(pat.hir_id, pat_adjustments);
}
(expected, def_br, max_ref_mutability)
(expected, def_br, max_ref_mutbl)
}
fn check_pat_lit(
@ -2130,18 +2130,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
mut expected: Ty<'tcx>,
mut pat_info: PatInfo<'tcx, '_>,
) -> Ty<'tcx> {
let new_match_ergonomics =
pat.span.at_least_rust_2024() && self.tcx.features().ref_pat_eat_one_layer_2024;
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;
if new_match_ergonomics {
let pat_prefix_span =
inner.span.find_ancestor_inside(pat.span).map(|end| pat.span.until(end));
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
@ -2179,8 +2183,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
.rust_2024_migration_desugared_pats_mut()
.insert(pat_info.top_info.hir_id);
}
pat_info.max_ref_mutbl = MutblCap::Mut;
}
let tcx = self.tcx;
@ -2195,16 +2197,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// 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 r_mutbl >= pat_mutbl && new_match_ergonomics => {
if r_mutbl == Mutability::Not {
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)
}
ty::Ref(_, r_ty, r_mutbl) if r_mutbl == pat_mutbl => (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);

9
tests/ui/pattern/no_ref_mut_behind_and.rs Normal file
View File

@ -0,0 +1,9 @@
//@ edition: 2021
//@ run-pass
#![allow(incomplete_features)]
#![feature(ref_pat_eat_one_layer_2024)]
fn main() {
let &[[x]] = &[&mut [42]];
let _: &i32 = x;
}