While trying to avoid deduplication in some cases (where it destroys useful information for debugging "what specific part of the source code caused this invalid type to be generated"), I came across the special-casing for zombies in make_dedupe_key (which avoids other unwanted cases of zombie deduplications).

But gather_annotations should be processing all decorations including the OpDecorateString used for the "custom decorations" system that includes zombies, it just looks like an accidental omission in the past.

The other change here is to ignore some "type mismatches" that result from slightly-different zombies annotations showing up on otherwise-identical types from different crates (likely the first Span passed to SpirvType::def gets cached, so the codegen order influences this).

The reason they're safe to ignore is that "zombies" (i.e. deferred errors) have only two possible outcomes:

• if sufficiently "kept around" (i.e. "not dead"): the error is actually emitted
  • (and is likely more useful than any "meta errors" about some kind of mismatch in the details of that error)
• if not actually needed (i.e. "dead code"): it's removed from the SPIR-V module entirely
  • (and so any type issues within that definition go away with the definition itself)