kc3-lang/libevent

2019-07-08T14:06:55

Enable _GNU_SOURCE for Android When targeting the Android NDK _GNU_SOURCE is not enabled by default: ``` /* * With bionic, you always get all C and POSIX API. * * If you want BSD and/or GNU extensions, _BSD_SOURCE and/or _GNU_SOURCE are * expected to be defined by callers before *any* standard header file is * included. * * In our header files we test against __USE_BSD and __USE_GNU. */ #if defined(_GNU_SOURCE) # define __USE_BSD 1 # define __USE_GNU 1 #endif ``` Because of this `pipe2` is not available: ``` #if defined(__USE_GNU) int pipe2(int __fds[2], int __flags) __INTRODUCED_IN(9); #endif ``` The function used to check if it does exist: ``` CHECK_FUNCTION_EXISTS_EX(pipe2 EVENT__HAVE_PIPE2) ``` Just check that the _linking_ succeeds, which it does, it's just not visible in the import, leading to a warning (or error): ``` evutil.c:2637:6: error: implicit declaration of function 'pipe2' is invalid in C99 [-Werror,-Wimplicit-function-declaration] if (pipe2(fd, O_NONBLOCK|O_CLOEXEC) == 0) ^ ``` When targeting the NDK it should be safe to always opt into this. Clang would pass the right flag for us automatically _if_ the source was C++ instead of C.