[clang] [clang] Fix for Assertion `(T->hasSignedIntegerRepresentation() || T->isSignedFixedPointType()) && "Unexpected signed integer or fixed point type"' failed. (PR #195945)

[via cfe-commits]

================
@@ -525,13 +519,12 @@ Bug Fixes in This Version
 - Clang now emits an error for friend declarations of lambda members. (#GH26540)
 - Fixed a crash caused by lambda capture handling in delayed default arguments. (#GH176534)
 - Fixed a crash when parsing invalid ``static_assert`` declarations with string-literal messages (#GH187690).
+- Fixed an assert/crash in ``__builtin_va_arg`` when the argument type is an enum without a correspoding signed type (#GH191698).
----------------
PrabbyDD wrote:

I used the word corresponding because, as far as I am aware, most unsigned data types have some sort of signed counterpart. Except for the two that I explicitly check for, the `char16_t` and `char32_t`. Can you elaborate what you mean by "the type of the enum is the enum itself"? The underlying type in the assert should be the `char16_t` and `chat32_t` types correct? 

https://github.com/llvm/llvm-project/pull/195945