[clang] Return available function types for BindingDecls. (PR #102196)

[Samira Bazuzi via cfe-commits]

bazuzi wrote:

This is a bug fix, yes, but there are currently no tests at all for this function that I can find (and no test file corresponding to this file or its header), so I'm not sure what the scope of a new unit test should be. I also don't know how I would most realistically trigger the circumstance of a BindingDecl without a QualType set.

The recent changes to this function that introduced the issue, along with the previous two changes to this function (though 5 and 6 years ago now), do not include any tests or any mention of the changes in release notes (#89906 and #90495). I'm not aware of what magnitude of change qualifies for release notes, but this change seems pretty small to me.

https://github.com/llvm/llvm-project/pull/102196