Method operator==

src/backward.h:726–729

        SourceLoc() : line(0), col(0) {}

        bool operator==(const SourceLoc& b) const
        {
            return function == b.function && filename == b.filename && line == b.line && col == b.col;
        }

        bool operator!=(const SourceLoc& b) const { return !(*this == b); }
    };