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

[via cfe-commits]

================
@@ -1516,6 +1516,23 @@ void ASTContext::InitBuiltinTypes(const TargetInfo &Target,
     MSGuidTagDecl = buildImplicitRecord("_GUID");
     getTranslationUnitDecl()->addDecl(MSGuidTagDecl);
   }
+
+  // size_t (C99TC3 6.5.3.4), signed size_t (C++23 5.13.2) and
+  // ptrdiff_t (C99TC3 6.5.6) Although these types are not built-in, they are
+  // part of the core language and are widely used.
+  if (!LangOpts.HLSL) {
+    // Using PredefinedSugarType makes these types as named sugar types rather
+    // than standard integer types, enabling better hints and diagnostics.
+    using Kind = PredefinedSugarType::Kind;
+    SizeType = getPredefinedSugarType(llvm::to_underlying(Kind::SizeT));
+    SignedSizeType =
+        getPredefinedSugarType(llvm::to_underlying(Kind::SignedSizeT));
+    PtrdiffType = getPredefinedSugarType(llvm::to_underlying(Kind::PtrdiffT));
+  } else {
+    SizeType = getFromTargetType(Target.getSizeType());
+    SignedSizeType = getFromTargetType(Target.getSignedSizeType());
+    PtrdiffType = getFromTargetType(Target.getPtrDiffType(LangAS::Default));
+  }
----------------
YexuanXiao wrote:

I have restored HLSL support, and the tests now pass.

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