[clang] [llvm] [clang][LLVM Demangler] Add a diagnostic that validates that all mang… (PR #111391)

[Erich Keane via cfe-commits]

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@@ -462,6 +462,9 @@ ENUM_CODEGENOPT(ZeroCallUsedRegs, llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind,
 /// non-deleting destructors. (No effect on Microsoft ABI.)
 CODEGENOPT(CtorDtorReturnThis, 1, 0)
 
+/// Whether to issue a diagnostic if a produced mangled name can not be demangled with the LLVM demangler.
+CODEGENOPT(DemanglingFailures, 1, 0)
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erichkeane wrote:

```suggestion
CODEGENOPT(DiagDemanglerFailures, 1, 0)
```

https://github.com/llvm/llvm-project/pull/111391