Am Mittwoch 15 Juli 2009 17:21:38 schrieb Mike Jackson: > On Wed, Jul 15, 2009 at 2:18 AM, Hendrik Sattler<p...@hendrik-sattler.de> wrote: > > Zitat von Benjamin Schindler <bschind...@inf.ethz.ch>: > >> I'm working on a project which builds both on linux and windows. I > >> generated an eclipse project out of it which works basically fine but > >> it's not able to recognize i.e. the __GNUC__ macro (and probably any > >> other macro defined per default on gcc) are not recognized by eclipse. > >> That means that by using a header like: > >> > >> #if defined(_MSC_VER) && (_MSC_VER >= 1300) > >> #ifdef FLOW_DLL_EXPORT > >> #define FLOW_DLL _declspec(dllexport) > >> #else > >> #define FLOW_DLL _declspec(dllimport) > >> #endif > >> #else > >> #ifdef __GNUC__ > >> #define FLOW_DLL > >> #endif > >> #endif > > > > I know that it's unrelated to your question but this code is slightly > > wrong. For the windows version of gcc, it also understands the > > _declspec() thing. You don't make it compiler-specific but > > system-specific. > > Additionally, on non-windows systems, you can use the visibility > > attribute to achieve something similar. > > That's why the gcc people suggest the following at > > http://gcc.gnu.org/wiki/Visibility (I simplified it): > > #if defined _WIN32 || defined __CYGWIN__ > > #ifdef FLOW_DLL_EXPORT > > #define FLOW_DLL __declspec(dllexport) > > #else > > #define FLOW_DLL __declspec(dllimport) > > #endif > > #elif __GNUC__ >= 4 > > #define FLOW_DLL __attribute__ ((visibility("default"))) > > #define DLL_LOCAL __attribute__ ((visibility("hidden"))) > > #endif > > #ifndef FLOW_DLL > > #define FLOW_DLL > > #endif > > #ifndef DLL_LOCAL > > #define DLL_LOCAL > > #endif > > > > You only need to add -fvisibility=hidden to gcc command line on > > non-windows systems. > > The above still has the flaw you use _declspec(dllimport) when compiling > > the library as static library. That's ok if you don't intend to do so > > else easy to fix. > > > > Additionally, eclipse may not select the right choice but the macros will > > not error out as they are _always_ defined in some way. > > > > Have fun > > > > HS > > I think I need some explanation on this logic. > > This line: > > #if defined _WIN32 || defined __CYGWIN__ > > will always be true on msvc, mingw and cygwin because _WIN32 is > defined for the MS compilers and when MinGW is being used so the > "#elif" will _never_ get executed? Where am I going wrong on this?
You don't. It is always right on Windows, at least with all MSVC and gcc compilers. Using any MSVC older that 7 (.NET 2003) is insane and that works there. The elif case if for systems like Linux with GCC >= 4. HS _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Follow this link to subscribe/unsubscribe: http://www.cmake.org/mailman/listinfo/cmake
