What if: ./lib1/foo.hpp: #ifndef FOO_HPP #define FOO_HPP ... #endif ./lib2/foo.hpp: #ifndef FOO_HPP #define FOO_HPP ... #endif ,/main.cpp #include "lib1/foo.hpp" #include "lib2/foo.hpp" Is there any cpp option which can warn that ./lib1/foo.hpp and ./lib2/foo.hpp have the same include guards? Based on: https://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html#Guard-Macros I would guess it would be simple to detect this since, according to that cppinternals link: _cpp_pop_file_buffer remembers the controlling macro associated with the file. Subsequent calls to stack_include_file result in no buffer being pushed if the controlling macro is defined, effecting the optimization. I recently had a need for this because boost/spirit has this problem and correcting it has been tedious :( -regards, Larry
