Teach -Wdangling-field to warn about temporaries bound to references as
well.

Also, clean up the flow of the code a bit, and factor things more
nicely.

Finally, add the test case that was missing from my previous
commit (sorry), with new tests added to cover temporaries and other fun
cases.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@139077 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed