preprocessor: output '3' flag for system headers

diff --git a/preprocessor.c b/preprocessor.c
index 0bd535e..4c5f1d4 100644 (file)
--- a/preprocessor.c
+++ b/preprocessor.c
@@ -1383,6 +1383,9 @@ static void print_line_directive(const source_position_t *pos, const char *add)
                fputc(' ', out);
                fputs(add, out);
        }
+       if (pos->is_system_header) {
+               fputs(" 3", out);
+       }
 
        printed_input_name = pos->input_name;
        input.output_line  = pos->lineno-1;