From 0dfe7b6434f6aabbe9673a891ba74c7c7922661d Mon Sep 17 00:00:00 2001 From: David Tolnay Date: Sat, 26 Sep 2020 21:19:08 -0400 Subject: [PATCH] Add justification of the destructor filter --- .../src/transform/check_const_item_mutation.rs | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/compiler/rustc_mir/src/transform/check_const_item_mutation.rs b/compiler/rustc_mir/src/transform/check_const_item_mutation.rs index b556e2d217d..aae67949945 100644 --- a/compiler/rustc_mir/src/transform/check_const_item_mutation.rs +++ b/compiler/rustc_mir/src/transform/check_const_item_mutation.rs @@ -34,6 +34,18 @@ impl<'a, 'tcx> ConstMutationChecker<'a, 'tcx> { fn is_const_item_without_destructor(&self, local: Local) -> Option { 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) { Some(_) => None, None => Some(def_id),