Wasm GC: assertion failed: types.is_subtype(actual_ty, expected_ty)

[fitzgen]

The second one is the case with the serialization. It fails even in the standalone version of Wasmtime with assertion failed: types.is_subtype(actual_ty, expected_ty) error.

assertion_failed__types_is_subtype.wasm.zip

Originally posted by @epsylonix in #9714

[fitzgen]

What would really help with diagnosing and fixing this bug is a test case reduction. Hard to figure out what is going on with a 235KiB test case.

FWIW, we have some docs on using wasm-shrink to reduce test cases here, although we would probably want to use creduce on the .wat disassembly of this .wasm instead, since wasm-shrink doesn't have Wasm GC support yet.

[fitzgen]

This is passing on main, at least as of 5b9e87650.

Going to go ahead and close this, but please open a new issue if you find anything else, @epsylonix!