[clang] [clang-tools-extra] [Attributes][HLSL] Teach EnumArgument to refer to an external enum (PR #70835)

[Justin Bogner via cfe-commits]

================
@@ -930,77 +936,83 @@ namespace {
       OS << getLowerName() << "(" << getUpperName() << ")";
     }
     void writeCtorDefaultInitializers(raw_ostream &OS) const override {
-      OS << getLowerName() << "(" << type << "(0))";
+      OS << getLowerName() << "(" << fullType << "(0))";
     }
     void writeCtorParameters(raw_ostream &OS) const override {
-      OS << type << " " << getUpperName();
+      OS << fullType << " " << getUpperName();
     }
     void writeDeclarations(raw_ostream &OS) const override {
-      auto i = uniques.cbegin(), e = uniques.cend();
-      // The last one needs to not have a comma.
-      --e;
+      if (!isExternal) {
+        auto i = uniques.cbegin(), e = uniques.cend();
+        // The last one needs to not have a comma.
+        --e;
+
+        OS << "public:\n";
+        OS << "  enum " << shortType << " {\n";
+        for (; i != e; ++i)
+          OS << "    " << *i << ",\n";
+        OS << "    " << *e << "\n";
+        OS << "  };\n";
+      }
 
-      OS << "public:\n";
-      OS << "  enum " << type << " {\n";
-      for (; i != e; ++i)
-        OS << "    " << *i << ",\n";
-      OS << "    " << *e << "\n";
-      OS << "  };\n";
       OS << "private:\n";
-      OS << "  " << type << " " << getLowerName() << ";";
+      OS << "  " << fullType << " " << getLowerName() << ";";
     }
 
     void writePCHReadDecls(raw_ostream &OS) const override {
-      OS << "    " << getAttrName() << "Attr::" << type << " " << getLowerName()
-         << "(static_cast<" << getAttrName() << "Attr::" << type
-         << ">(Record.readInt()));\n";
+      OS << "    " << fullType << " " << getLowerName()
+         << "(static_cast<" << fullType << ">(Record.readInt()));\n";
     }
 
     void writePCHReadArgs(raw_ostream &OS) const override {
       OS << getLowerName();
     }
 
     void writePCHWrite(raw_ostream &OS) const override {
-      OS << "Record.push_back(SA->get" << getUpperName() << "());\n";
+      OS << "Record.push_back(static_cast<uint64_t>(SA->get" << getUpperName()
+         << "()));\n";
     }
 
     void writeValue(raw_ostream &OS) const override {
       // FIXME: this isn't 100% correct -- some enum arguments require printing
       // as a string literal, while others require printing as an identifier.
       // Tablegen currently does not distinguish between the two forms.
-      OS << "\\\"\" << " << getAttrName() << "Attr::Convert" << type << "ToStr(get"
-         << getUpperName() << "()) << \"\\\"";
+      OS << "\\\"\" << " << getAttrName() << "Attr::Convert" << shortType
+         << "ToStr(get" << getUpperName() << "()) << \"\\\"";
     }
 
     void writeDump(raw_ostream &OS) const override {
       OS << "    switch(SA->get" << getUpperName() << "()) {\n";
       for (const auto &I : uniques) {
-        OS << "    case " << getAttrName() << "Attr::" << I << ":\n";
+        OS << "    case " << fullType << "::" << I << ":\n";
         OS << "      OS << \" " << I << "\";\n";
         OS << "      break;\n";
       }
+      if (isExternal) {
+        OS << "    default:\n";
+        OS << "      llvm_unreachable(\"Invalid attribute value\");\n";
+      }
----------------
bogner wrote:

It's used in [clang::TextNodeDumper](https://clang.llvm.org/doxygen/classclang_1_1TextNodeDumper.html). I'm not really familiar what that's used for, but it doesn't look like it would be easy to use return here, as it goes through each attribute in order:
```c++
  void VisitHLSLResourceAttr(const HLSLResourceAttr *A) {
    const auto *SA = cast<HLSLResourceAttr>(A); (void)SA;
    switch(SA->getResourceClass()) {
    case llvm::hlsl::ResourceClass::SRV:
      OS << " SRV";
      break;
    case llvm::hlsl::ResourceClass::UAV:
      OS << " UAV";
      break;
    case llvm::hlsl::ResourceClass::CBuffer:
      OS << " CBuffer";
      break;
    case llvm::hlsl::ResourceClass::Sampler:
      OS << " Sampler";
      break;
    default:
      llvm_unreachable("Invalid attribute value");
    }
    switch(SA->getResourceKind()) {
    case llvm::hlsl::ResourceKind::Texture1D:
      OS << " Texture1D";
      break;
    case llvm::hlsl::ResourceKind::Texture2D:
      OS << " Texture2D";
      break;
...
```

https://github.com/llvm/llvm-project/pull/70835