Unused import detection is broken in protoc-gen-buf-lint when the image contains an incompatible version of protovalidate than the one buf was compiled with

[jchadwick-buf]

GitHub repository with your minimal reproducible example (do not fill out this field with "github.com/bufbuild/buf" or we will automatically close your issue, see the instructions above!)

https://github.com/jchadwick-buf/protoc-gen-buf-lint-unused-ext-import-issue

Commands

protoc -I . --buf-lint_out=. $(find ./test -name '*.proto')

Output

--buf-lint_out: test/c.proto:5:1:Import "test/a.proto" is unused.

Expected Output

I expect no lint failures.

Anything else?

This is caused because protoplugin uses proto.Unmarshal, using the default proto.UnmarshalOptions. This causes the Resolver to be protoregistry.GlobalTypes, resulting in all of the extensions from gencode imported by the Buf CLI code being prematurely resolved before the reparse phase. In this case, it happens due to protovalidate.

This is blocking bufbuild/protovalidate#246. When the import tracker for protoc-gen-buf-lint tries to mark imports as used, it tries to mark all of the extensions for options as used, but it hits an unexpected case when it sees the extensions for the shared protovalidate constraint, because it resolves to the fullname buf.validate.priv.field, but the PR renames the priv package to shared.

Fixing this will require some kind of modification to protoplugin, but a change that will fix this issue is very likely to change the behavior in other cases, so I think this warrants the creation of a new option in protoplugin.

[jchadwick-buf]

This is fixed at HEAD after merging #3307.