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Add justification of the destructor filter

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David Tolnay 2020-09-26 21:19:08 -04:00
parent 17db1cb5d5
commit 0dfe7b6434
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1 changed files with 12 additions and 0 deletions
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12
compiler/rustc_mir/src/transform/check_const_item_mutation.rs
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@ -34,6 +34,18 @@ impl<'a, 'tcx> ConstMutationChecker<'a, 'tcx> {
fn is_const_item_without_destructor(&self, local: Local) -> Option<DefId> { fn is_const_item_without_destructor(&self, local: Local) -> Option<DefId> {
let def_id = self.is_const_item(local)?; let def_id = self.is_const_item(local)?;
// We avoid linting mutation of a const item if the const's type has a
// Drop impl. The Drop logic observes the mutation which was performed.
//
// struct Log { msg: &'static str }
// const LOG: Log = Log { msg: "" };
// impl Drop for Log {
// fn drop(&mut self) { println!("{}", self.msg); }
// }
//
// LOG.msg = "wow"; // prints "wow"
//
match self.tcx.adt_def(def_id).destructor(self.tcx) { match self.tcx.adt_def(def_id).destructor(self.tcx) {
Some(_) => None, Some(_) => None,
None => Some(def_id), None => Some(def_id),