Expand __VA_ARGS__ when used as per the nonstandard gcc/clang extension for empty varargs, to yield gcc-like behavior also in cases where varargs isn't empty (#66)

Author: datadiode

simplecpp.cpp

@@ -1895,6 +1895,11 @@ namespace simplecpp {
                     if (sameline(tok, tok->next) && tok->next && tok->next->op == '#' && tok->next->next && tok->next->next->op == '#') {
                         if (!sameline(tok, tok->next->next->next))
                             throw invalidHashHash::unexpectedNewline(tok->location, name());
+                        if (tok->op == ',' && tok->next->next->next->str() == "__VA_ARGS__") {
+                            output->push_back(newMacroToken(tok->str(), loc, isReplaced(expandedmacros), tok));
+                            tok = expandToken(output, loc, tok->next->next->next, macros, expandedmacros, parametertokens2);
+                            continue;
+                        }
                         TokenList new_output(files);
                         if (!expandArg(&new_output, tok, parametertokens2))
                             output->push_back(newMacroToken(tok->str(), loc, isReplaced(expandedmacros), tok));

test.cpp

@@ -1074,6 +1074,14 @@ static void hashhash4()    // nonstandard gcc/clang extension for empty varargs
     ASSERT_EQUALS("\n\na ( 1 ) ;", preprocess(code));
 }
 
+static void hashhash4a()
+{
+    const char code[] = "#define GETMYID(a) ((a))+1\n"
+                        "#define FIGHT_FOO(c, ...) foo(c, ##__VA_ARGS__)\n"
+                        "FIGHT_FOO(1, GETMYID(a));";
+    ASSERT_EQUALS("\n\nfoo ( 1 , ( ( a ) ) + 1 ) ;", preprocess(code));
+}
+
 static void hashhash5()
 {
     ASSERT_EQUALS("x1", preprocess("x##__LINE__"));
@@ -2909,6 +2917,7 @@ int main(int argc, char **argv)
     TEST_CASE(hashhash2);
     TEST_CASE(hashhash3);
     TEST_CASE(hashhash4);
+    TEST_CASE(hashhash4a); // #66
     TEST_CASE(hashhash5);
     TEST_CASE(hashhash6);
     TEST_CASE(hashhash7); // # ## #  (C standard; 6.10.3.3.p4)