MacroExpander: bump expansionCount before peeking for "("

src/compiler/preprocessor/MacroExpander.cpp

@@ -87,10 +87,15 @@ void MacroExpander::lex(Token *token)
             token->setExpansionDisabled(true);
             break;
         }
+
+        // Bump the expansion count before peeking if the next token is a '('
+        // otherwise there could be a #undef of the macro before the next token.
+        macro.expansionCount++;
         if ((macro.type == Macro::kTypeFunc) && !isNextTokenLeftParen())
         {
             // If the token immediately after the macro name is not a '(',
             // this macro should not be expanded.
+            macro.expansionCount--;
             break;
         }
 
@@ -157,8 +162,6 @@ bool MacroExpander::pushMacro(const Macro &macro, const Token &identifier)
     ASSERT(identifier.type == Token::IDENTIFIER);
     ASSERT(identifier.text == macro.name);
 
-    macro.expansionCount++;
-
     std::vector<Token> replacements;
     if (!expandMacro(macro, identifier, &replacements))
         return false;

src/tests/preprocessor_tests/define_test.cpp

@@ -955,3 +955,19 @@ TEST_F(DefineTest, UndefineInInvocation)
 
     preprocess(input, expected);
 }
+
+// Undefining a macro before its invocation parameters produces and error
+TEST_F(DefineTest, UndefineInInvocationPreLParen)
+{
+    const char *input =
+        "#define G(a, b) a b\n"
+        "G\n"
+        "#undef G\n"
+        "(1, 2)\n";
+    const char *expected = "\n\n\n1 2\n";
+
+    EXPECT_CALL(mDiagnostics, print(pp::Diagnostics::PP_MACRO_UNDEFINED_WHILE_INVOKED,
+                                    pp::SourceLocation(0, 3), _));
+
+    preprocess(input, expected);
+}