add diagnostic for repeated parametr

Author: inbelic

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1809,4 +1809,5 @@ def err_hlsl_packoffset_invalid_reg : Error<"invalid resource class specifier '%
 // HLSL Root Signature Parser Diagnostics
 def err_hlsl_rootsig_unexpected_eos : Error<"unexpected end to token stream">;
 def err_hlsl_rootsig_unexpected_token_kind : Error<"expected the %select{following|one of the following}0 token kinds '%1'">;
+def err_hlsl_rootsig_repeat_param : Error<"specified the same parameter '%0' multiple times">;
 } // end of Parser diagnostics

clang/lib/Parse/ParseHLSLRootSignature.cpp

@@ -371,6 +371,8 @@ bool RootSignatureParser::ParseOptionalParams(
 
     TokenKind ParamKind = CurTok->Kind;
     if (Seen.contains(ParamKind)) {
+      Diags.Report(CurTok->TokLoc, diag::err_hlsl_rootsig_repeat_param)
+          << FormatTokenKinds(ParamKind);
       return true;
     }
     Seen.insert(ParamKind);

clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp

@@ -429,4 +429,30 @@ TEST_F(ParseHLSLRootSignatureTest, InvalidParseUnexpectedTokenTest) {
   ASSERT_TRUE(Consumer->IsSatisfied());
 }
 
+TEST_F(ParseHLSLRootSignatureTest, InvalidParseRepeatedParamTest) {
+  const llvm::StringLiteral Source = R"cc(
+    DescriptorTable(
+      CBV(b0, numDescriptors = 3, numDescriptors = 1)
+    )
+  )cc";
+
+  TrivialModuleLoader ModLoader;
+  auto PP = CreatePP(Source, ModLoader);
+  auto TokLoc = SourceLocation();
+
+  // Test correct diagnostic produced
+  Consumer->SetExpected(diag::err_hlsl_rootsig_repeat_param);
+  hlsl::RootSignatureLexer Lexer(Source, TokLoc, *PP);
+
+  SmallVector<hlsl::RootSignatureToken> Tokens;
+  ASSERT_FALSE(Lexer.Lex(Tokens));
+
+  SmallVector<RootElement> Elements;
+  hlsl::RootSignatureParser Parser(Elements, Tokens, Diags);
+
+  ASSERT_TRUE(Parser.Parse());
+
+  ASSERT_TRUE(Consumer->IsSatisfied());
+}
+
 } // anonymous namespace