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Don't fire const_item_mutation lint on writes through a pointer

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Fixes #77321
This commit is contained in:
Aaron Hill 2020-09-28 23:51:57 -04:00
parent fc2daaae61
commit c6107c53d7
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GPG key ID: B4087E510E98B164
3 changed files with 44 additions and 29 deletions
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14
compiler/rustc_mir/src/transform/check_const_item_mutation.rs
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@ -60,11 +60,15 @@ impl<'a, 'tcx> Visitor<'tcx> for ConstMutationChecker<'a, 'tcx> {
// so emitting a lint would be redundant.
if !lhs.projection.is_empty() {
if let Some(def_id) = self.is_const_item(lhs.local) {
self.lint_const_item_usage(def_id, loc, |lint| {
let mut lint = lint.build("attempting to modify a `const` item");
lint.note("each usage of a `const` item creates a new temporary - the original `const` item will not be modified");
lint
})
// Don't lint on writes through a pointer
// (e.g. `unsafe { *FOO = 0; *BAR.field = 1; }`)
if !matches!(lhs.projection.last(), Some(PlaceElem::Deref)) {
self.lint_const_item_usage(def_id, loc, |lint| {
let mut lint = lint.build("attempting to modify a `const` item");
lint.note("each usage of a `const` item creates a new temporary - the original `const` item will not be modified");
lint
})
}
}
}
// We are looking for MIR of the form: