review: add wrong number of arguments diagnostic

Author: inbelic

clang/lib/Sema/SemaHLSL.cpp

@@ -649,8 +649,10 @@ void SemaHLSL::emitLogicalOperatorFixIt(Expr *LHS, Expr *RHS,
 }
 
 void SemaHLSL::handleRootSignatureAttr(Decl *D, const ParsedAttr &AL) {
-  if (AL.getNumArgs() != 1)
+  if (AL.getNumArgs() != 1) {
+    Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 1;
     return;
+  }
 
   StringRef Signature;
   if (!SemaRef.checkStringLiteralArgumentAttr(AL, 0, Signature))

clang/test/SemaHLSL/RootSignature-err.hlsl

@@ -3,6 +3,11 @@
 // This file mirrors the diagnostics testing in ParseHLSLRootSignatureTest.cpp
 // to verify that the correct diagnostics strings are output
 
+// Attr test
+
+[RootSignature()] // expected-error {{'RootSignature' attribute takes one argument}}
+void bad_root_signature_0() {}
+
 // Lexer related tests
 
 #define InvalidToken \