self-review: improve error messaging for expected end of parameters

Author: Finn Plummer

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1830,4 +1830,8 @@ def err_hlsl_virtual_function
 def err_hlsl_virtual_inheritance
     : Error<"virtual inheritance is unsupported in HLSL">;
 
+// HLSL Root Siganture diagnostic messages
+def err_hlsl_unexpected_end_of_params
+    : Error<"expected %0 to denote end of parameters, or, another valid parameter of %1">;
+
 } // end of Parser diagnostics

clang/include/clang/Lex/HLSLRootSignatureTokenKinds.def

@@ -69,6 +69,7 @@ PUNCTUATOR(plus,    '+')
 PUNCTUATOR(minus,   '-')
 
 // RootElement Keywords:
+KEYWORD(RootSignature) // used only for diagnostic messaging
 KEYWORD(DescriptorTable)
 
 // DescriptorTable Keywords:

clang/lib/Parse/ParseHLSLRootSignature.cpp

@@ -39,7 +39,13 @@ bool RootSignatureParser::parse() {
       break;
   }
 
-  return consumeExpectedToken(TokenKind::end_of_stream, diag::err_expected);
+  if (!tryConsumeExpectedToken(TokenKind::end_of_stream)) {
+    getDiags().Report(CurToken.TokLoc, diag::err_hlsl_unexpected_end_of_params)
+        << /*expected=*/TokenKind::end_of_stream
+        << /*param of=*/TokenKind::kw_RootSignature;
+    return true;
+  }
+  return false;
 }
 
 bool RootSignatureParser::parseDescriptorTable() {
@@ -64,9 +70,12 @@ bool RootSignatureParser::parseDescriptorTable() {
       break;
   }
 
-  if (consumeExpectedToken(TokenKind::pu_r_paren, diag::err_expected_after,
-                           CurToken.Kind))
+  if (!tryConsumeExpectedToken(TokenKind::pu_r_paren)) {
+    getDiags().Report(CurToken.TokLoc, diag::err_hlsl_unexpected_end_of_params)
+        << /*expected=*/TokenKind::pu_r_paren
+        << /*param of=*/TokenKind::kw_DescriptorTable;
     return true;
+  }
 
   Elements.push_back(Table);
   return false;

clang/unittests/Lex/LexHLSLRootSignatureTest.cpp

@@ -85,6 +85,8 @@ TEST_F(LexHLSLRootSignatureTest, ValidLexAllTokensTest) {
 
     (),|=+-
 
+    RootSignature
+
     DescriptorTable
 
     CBV SRV UAV Sampler

clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp

@@ -196,7 +196,7 @@ TEST_F(ParseHLSLRootSignatureTest, InvalidParseUnexpectedTokenTest) {
   hlsl::RootSignatureParser Parser(Elements, Lexer, *PP);
 
   // Test correct diagnostic produced
-  Consumer->setExpected(diag::err_expected);
+  Consumer->setExpected(diag::err_hlsl_unexpected_end_of_params);
   ASSERT_TRUE(Parser.parse());
 
   ASSERT_TRUE(Consumer->isSatisfied());
@@ -216,7 +216,7 @@ TEST_F(ParseHLSLRootSignatureTest, InvalidParseInvalidTokenTest) {
   hlsl::RootSignatureParser Parser(Elements, Lexer, *PP);
 
   // Test correct diagnostic produced - invalid token
-  Consumer->setExpected(diag::err_expected);
+  Consumer->setExpected(diag::err_hlsl_unexpected_end_of_params);
   ASSERT_TRUE(Parser.parse());
 
   ASSERT_TRUE(Consumer->isSatisfied());