[clang] [HLSL] Add implicit resource element type concepts to AST (PR #112600)

[Chris B via cfe-commits]

================
@@ -323,30 +324,127 @@ struct TemplateParameterListBuilder {
         S.Context, Builder.Record->getDeclContext(), SourceLocation(),
         SourceLocation(), /* TemplateDepth */ 0, Position,
         &S.Context.Idents.get(Name, tok::TokenKind::identifier),
-        /* Typename */ false,
-        /* ParameterPack */ false);
+        /* Typename */ true,
+        /* ParameterPack */ false,
+        /* HasTypeConstraint*/ false);
     if (!DefaultValue.isNull())
       Decl->setDefaultArgument(
           S.Context, S.getTrivialTemplateArgumentLoc(DefaultValue, QualType(),
                                                      SourceLocation()));
-
     Params.emplace_back(Decl);
     return *this;
   }
 
-  BuiltinTypeDeclBuilder &finalizeTemplateArgs() {
+  /*
+  The concept specialization expression (CSE) constructed below is constructed
+  so that it matches the CSE that is constructed when parsing
+  the below C++ code:
+
+  template<typename T>
+  concept is_typed_resource_element_compatible =sizeof(T) <= 16;
+
+  template<typename element_type> requires
+  is_typed_resource_element_compatible<element_type>
+
+  struct RWBuffer {
+      element_type Val;
+  };
+
+  int fn() {
+      RWBuffer<int> Buf;
+  }
+
+  When dumping the AST and filtering for "RWBuffer", the resulting AST
+  structure is what we're trying to construct below, specifically the
+  CSE portion.
+  */
+  ConceptSpecializationExpr *
+  constructConceptSpecializationExpr(Sema &S, ConceptDecl *CD) {
+    ASTContext &Context = S.getASTContext();
+    SourceLocation Loc = Builder.Record->getBeginLoc();
+    DeclarationNameInfo DNI(CD->getDeclName(), Loc);
+    NestedNameSpecifierLoc NNSLoc;
+    DeclContext *DC = Builder.Record->getDeclContext();
+    TemplateArgumentListInfo TALI(Loc, Loc);
+
+    // Assume that the concept decl has just one template parameter
+    // This parameter should have been added when CD was constructed
+    // in getTypedBufferConceptDecl
+    assert(CD->getTemplateParameters()->size() == 1 &&
+           "unexpected concept decl parameter count");
+    TemplateTypeParmDecl *ConceptTTPD = dyn_cast<TemplateTypeParmDecl>(
+        CD->getTemplateParameters()->getParam(0));
+
+    // this fake TemplateTypeParmDecl is used to construct a template argument
+    // that will be used to construct the ImplicitConceptSpecializationDecl
----------------
llvm-beanz wrote:

This sounds wrong... Like, completely wrong. You're absolutely adding it to the AST, that's what happens when you create a declaration and put it into a declaration context.

This also seems like we're putting this declaration into the wrong declaration context.

I don't see any of your tests verifying the AST shape of the concept declaration. Can you add tests for that so that we can see what the concept's AST looks like?

https://github.com/llvm/llvm-project/pull/112600