[clang] [PAC] Add support for __ptrauth type qualifier (PR #100830)

[Aaron Ballman via cfe-commits]

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@@ -2850,6 +2850,26 @@ void CXXNameMangler::mangleQualifiers(Qualifiers Quals, const DependentAddressSp
   if (Quals.hasUnaligned())
     mangleVendorQualifier("__unaligned");
 
+  // __ptrauth.  Note that this is parameterized.
+  if (PointerAuthQualifier PtrAuth = Quals.getPointerAuth()) {
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AaronBallman wrote:

Oops, I missed the question that was here, but this does still need to be addressed.

We don't need MS to be involved, we can pick our own mangling and try to avoid potential conflicts by making it ugly (we do this for plenty of other extensions). But we're missing test coverage because we have no C++ tests for mangling or demangling (Microsoft or Itanium). I think we're missing the demangling implementation entirely, but we lately have been trying to get folks to do them at the same time so the demangler stays closer in sync with the mangler.

(Test coverage would be: CodeGen tests with an Itanium and a Microsoft ABI making sure we emit the expected manglings in C++ with a FileCheck test + `llvm/test/Demangle` tests to make sure the generated manglings will demangle back to an expected signature.)

https://github.com/llvm/llvm-project/pull/100830