Fix PR9488: 'auto' type substitution can fail (for instance, if it creates a reference-to-void type). Don't crash if it does.
Also fix an issue where type source information for the resulting type was being lost.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@127811 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed