[clang] [Clang] Recover GLTemplateParameterList for generic lambdas in RebuildLambdaScopeInfo (PR #118176)

[Erich Keane via cfe-commits]

https://github.com/erichkeane approved this pull request.

a few nits on the comment, else feel free to commit once those are fixed.

https://github.com/llvm/llvm-project/pull/118176