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Bypass const_item_mutation if const's type has Drop impl

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This commit is contained in:
David Tolnay 2020-09-26 21:14:31 -04:00
parent b218b952f8
commit 17db1cb5d5
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GPG Key ID: F9BA143B95FF6D82
1 changed files with 11 additions and 2 deletions
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13
compiler/rustc_mir/src/transform/check_const_item_mutation.rs
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@ -31,6 +31,15 @@ impl<'a, 'tcx> ConstMutationChecker<'a, 'tcx> {
None
}
}
fn is_const_item_without_destructor(&self, local: Local) -> Option<DefId> {
let def_id = self.is_const_item(local)?;
match self.tcx.adt_def(def_id).destructor(self.tcx) {
Some(_) => None,
None => Some(def_id),
}
}
fn lint_const_item_usage(
&self,
const_item: DefId,
@ -59,7 +68,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ConstMutationChecker<'a, 'tcx> {
// Assigning directly to a constant (e.g. `FOO = true;`) is a hard error,
// so emitting a lint would be redundant.
if !lhs.projection.is_empty() {
if let Some(def_id) = self.is_const_item(lhs.local) {
if let Some(def_id) = self.is_const_item_without_destructor(lhs.local) {
// Don't lint on writes through a pointer
// (e.g. `unsafe { *FOO = 0; *BAR.field = 1; }`)
if !matches!(lhs.projection.last(), Some(PlaceElem::Deref)) {
@ -89,7 +98,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ConstMutationChecker<'a, 'tcx> {
fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, loc: Location) {
if let Rvalue::Ref(_, BorrowKind::Mut { .. }, place) = rvalue {
let local = place.local;
if let Some(def_id) = self.is_const_item(local) {
if let Some(def_id) = self.is_const_item_without_destructor(local) {
// If this Rvalue is being used as the right-hand side of a
// `StatementKind::Assign`, see if it ends up getting used as
// the `self` parameter of a method call (as the terminator of our current