diff options
Diffstat (limited to 'compiler/rustc_const_eval/src/transform/validate.rs')
| -rw-r--r-- | compiler/rustc_const_eval/src/transform/validate.rs | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs index 2dfe226030a..d3bf6b49f12 100644 --- a/compiler/rustc_const_eval/src/transform/validate.rs +++ b/compiler/rustc_const_eval/src/transform/validate.rs @@ -206,7 +206,13 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> { } if self.reachable_blocks.contains(location.block) && context.is_use() { - // Uses of locals must occur while the local's storage is allocated. + // We check that the local is live whenever it is used. Technically, violating this + // restriction is only UB and not actually indicative of not well-formed MIR. This means + // that an optimization which turns MIR that already has UB into MIR that fails this + // check is not necessarily wrong. However, we have no such optimizations at the moment, + // and so we include this check anyway to help us catch bugs. If you happen to write an + // optimization that might cause this to incorrectly fire, feel free to remove this + // check. self.storage_liveness.seek_after_primary_effect(location); let locals_with_storage = self.storage_liveness.get(); if !locals_with_storage.contains(local) { |