Avoid hashing free type parameters by object/name identity in type
hashing and use traversal-local canonical IDs instead.
This keeps obfuscated field names stable across alpha-renamed generic
signatures (e.g. T vs newT), fixing interface/method mismatches.
The added test case fails without the fix:
> exec garble build
[stderr]
# test/main
YiaBFlNH.go:48: cannot use bT6psGs5O (variable of type *QdwRyqV[aEqmF4M, zpotHfQdnNB]) as E_OKfdHoPH[zpotHfQdnNB] value in return statement: *QdwRyqV[aEqmF4M, zpotHfQdnNB] does not implement E_OKfdHoPH[zpotHfQdnNB] (wrong type for method Redirect)
have Redirect(struct{palTavb zpotHfQdnNB})
want Redirect(struct{g3N8A_R zpotHfQdnNB})
The fix is Paul's; this is rebased on an updated version of typeutil,
and the test is now part of typeparams.txtar and much smaller.
Fixes#991.
Co-authored-by: Paul Scheduikat <lu4p@pm.me>
See the two "NOTE" comments below. In summary:
* struct field tags are not hashed
* named types are hashed by name rather than by pointer
We are keeping an eye on https://go.dev/issue/69420 as well.
Daniel Martí