diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/gvn.rs | 19 |
1 files changed, 5 insertions, 14 deletions
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs index bfdefd5a7d6..23124523f17 100644 --- a/compiler/rustc_mir_transform/src/gvn.rs +++ b/compiler/rustc_mir_transform/src/gvn.rs @@ -987,23 +987,14 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { // `*const [T]` -> `*const T` which remove metadata. // We run on potentially-generic MIR, though, so unlike codegen // we can't always know exactly what the metadata are. - // Thankfully, equality on `ptr_metadata_ty_or_tail` gives us - // what we need: `Ok(meta_ty)` if the metadata is known, or - // `Err(tail_ty)` if not. Matching metadata is ok, but if - // that's not known, then matching tail types is also ok, - // allowing things like `*mut (?A, ?T)` <-> `*mut (?B, ?T)`. + // To allow things like `*mut (?A, ?T)` <-> `*mut (?B, ?T)`, + // it's fine to get a projection as the type. // FIXME: Would it be worth trying to normalize, rather than - // passing the identity closure? Or are the types in the + // just accepting the projection? Or are the types in the // Cast realistically about as normalized as we can get anyway? Value::Cast { kind: CastKind::PtrToPtr, value: inner, from, to } - if from - .builtin_deref(true) - .unwrap() - .ptr_metadata_ty_or_tail(self.tcx, |t| t) - == to - .builtin_deref(true) - .unwrap() - .ptr_metadata_ty_or_tail(self.tcx, |t| t) => + if from.pointee_metadata_ty_or_projection(self.tcx) + == to.pointee_metadata_ty_or_projection(self.tcx) => { arg_index = *inner; was_updated = true; |