[clang] [clang-tools-extra] [clangd] Collect comments from function definitions into the index (PR #67802)

[Nathan Ridge via cfe-commits]

https://github.com/HighCommander4 requested changes to this pull request.

Thank you for the test case. Debugging it helped me better understand the changes to `ASTContext.cpp`.

I believe the fact that these changes are needed to get the tests to pass, tells us that there is a bug in `ASTContext::getRawCommentForAnyRedecl()`. However, I'm not sure that these changes are an appropriate fix for the bug.

I wrote a libAST unit test to demonstrate the bug, and filed https://github.com/llvm/llvm-project/issues/108145 about it. Hopefully folks more familiar with that code can suggest an appropriate fix there.

https://github.com/llvm/llvm-project/pull/67802