[clang] [clang-tools-extra] [libcxx] [lldb] [Clang] Make the SizeType, SignedSizeType and PtrdiffType be named sugar types instead of built-in types (PR #143653)

[Matheus Izvekov via cfe-commits]

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@@ -7248,6 +7248,12 @@ QualType TreeTransform<Derived>::TransformDependentBitIntType(
   return Result;
 }
 
+template <typename Derived>
+QualType TreeTransform<Derived>::TransformPredefinedSugarType(
+    TypeLocBuilder &TLB, PredefinedSugarTypeLoc TL) {
+  llvm_unreachable("This type does not need to be transformed.");
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mizvekov wrote:

If we somehow got here, we would need to rebuild the typeloc.

But no in-tree users are doing anything funky with 'AlreadyTransformed' which would cause us to reach here.
If any out of tree user were, it would be better from a performance standpoint to just make sure it always returns false for a PredefinedSugarType.

https://github.com/llvm/llvm-project/pull/143653