[clang] [ItaniumMangle] Use mangleType instead of mangleNameOrStandardSubstitution in mangleCXXCtorVTable function (PR #109970)

[via cfe-commits]

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@@ -7326,11 +7326,13 @@ void ItaniumMangleContextImpl::mangleCXXCtorVTable(const CXXRecordDecl *RD,
                                                    raw_ostream &Out) {
   // <special-name> ::= TC <type> <offset number> _ <base type>
   CXXNameMangler Mangler(*this, Out);
+  QualType RDType = getASTContext().getRecordType(RD);
+  QualType TypeType = getASTContext().getRecordType(Type);
   Mangler.getStream() << "_ZTC";
-  Mangler.mangleNameOrStandardSubstitution(RD);
+  Mangler.mangleType(RDType);
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tcwzxx wrote:

> I'd prefer we fix `mangleNameOrStandardSubstitution` itself.
> We could rename it to `mangleCXXRecordDecl`, have it take a CXXRecordDecl*, and handle the substitutions there.
> This would avoid the same trap in a potential future user.

After rechecking the code, I found that the users of the `mangleNameOrStandardSubstitution` function are `mangleCXXCtorVTable`, `mangleCXXVTable`, and `mangleCXXVTT`. In the Itanium ABI documentation, these situations are considered as 'Type'. So, maybe we can remove `mangleNameOrStandardSubstitution` and then use `mangleType`.

https://github.com/llvm/llvm-project/pull/109970