fixed warnings

    if (line[0] == '\t') {

        if (current_rule) {

            current_rule->recipes.push_back(line.substr(1));

        }

            return;

        }

        // No active rule: GNU make does NOT treat a tab-indented line as a

        // recipe here. The leading tab is just whitespace and the line is

        // parsed as an ordinary makefile statement (commonly a variable

        // assignment). Kbuild relies on this, e.g.:

        //   quiet_cmd_bflags = GEN  $@

        //   \tcmd_bflags = sed ... $< > $@

        // where cmd_bflags is tab-indented yet must be defined. Fall through

        // to normal parsing (trim() below removes the leading tab).

    }

    // Strip inline comments (respecting $() nesting)

    std::string processed = line;