Backport 5f4ee5a2dfa9 to release/18.x

[DimitryAndric]

Fixes a crash on attaching doc comments (#78716), and similar issues from before:
Fixes #67979
Fixes #68524
Fixes #70550

/cherry-pick 5f4ee5a

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Dimitry Andric (DimitryAndric)

Fixes a crash on attaching doc comments (#78716), and similar issues from before: Fixes #67979 Fixes #68524 Fixes #70550

/cherry-pick 5f4ee5a

[llvmbot]

/pull-request #80620

[tstellar]

PR has been created, we will track the status there.