[clang] [Clang][Sema]: Diagnose lambda to bool implicit casts (PR #83152)

[Aaron Ballman via cfe-commits]

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

Thank you for the fix!

There are some related test failures caught by precommit CI that need to be addressed.

The issue in dr18xx.cpp looks to be a case where we should replace `bool b = ` with `auto b = ` (it doesn't change the testing for what's discussed in http://wg21.link/cwg1837).

The issues in blocks.mm should get new expected warning markings for the improved diagnostics.

You should also add a release note to `clang/docs/ReleaseNotes.rst` so users know about the fix (and mention the issue number as well).

The changes should come with new test coverage, probably in one of the existing tests in `clang/test/SemaCXX/`.

https://github.com/llvm/llvm-project/pull/83152