diff options
| -rw-r--r-- | ws_symbol_export.h | 85 |
1 files changed, 74 insertions, 11 deletions
diff --git a/ws_symbol_export.h b/ws_symbol_export.h index 92a864b348..1903c4b649 100644 --- a/ws_symbol_export.h +++ b/ws_symbol_export.h @@ -51,33 +51,96 @@ /* Originally copied from GCC Wiki at http://gcc.gnu.org/wiki/Visibility */ #if defined _WIN32 || defined __CYGWIN__ + /* Compiling for Windows, so we use the Windows DLL declarations. */ #ifdef WS_BUILD_DLL + /* + * Building a DLL; for all definitions, we want dllexport, and + * (presumably so source from DLL and source from a program using the + * DLL can both include a header that declares APIs and exported data + * for the DLL), for declarations, either dllexport or dllimport will + * work (they mean the same thing for a declaration when building a DLL). + */ #ifdef __GNUC__ -#define WS_DLL_PUBLIC __attribute__ ((dllexport)) + /* GCC */ +#define WS_DLL_PUBLIC_NOEXTERN __attribute__ ((dllexport)) #else /* ! __GNUC__ */ -#define WS_DLL_PUBLIC __declspec(dllexport) /* Note: actually gcc seems to also support this syntax. */ + /* + * Presumably MSVC. + * Note: actually gcc seems to also support this syntax. + */ +#define WS_DLL_PUBLIC_NOEXTERN __declspec(dllexport) #endif /* __GNUC__ */ - #else + #else /* WS_BUILD_DLL */ + /* + * Building a program; we should only see declarations, not definitions, + * with WS_DLL_PUBLIC, and they all represent APIs or data imported + * from a DLL, so use dllimport. + * + * For functions, export shouldn't be necessary; for data, it might + * be necessary, e.g. if what's declared is an array whose size is + * not given in the declaration. + */ #ifdef __GNUC__ -#define WS_DLL_PUBLIC __attribute__ ((dllimport)) + /* GCC */ +#define WS_DLL_PUBLIC_NOEXTERN __attribute__ ((dllimport)) #elif ! (defined ENABLE_STATIC) /* ! __GNUC__ */ -#define WS_DLL_PUBLIC __declspec(dllimport) /* Note: actually gcc seems to also support this syntax. */ + /* + * Presumably MSVC, and we're not building all-static. + * Note: actually gcc seems to also support this syntax. + */ +#define WS_DLL_PUBLIC_NOEXTERN __declspec(dllimport) #else /* ! __GNUC__ && ENABLE_STATIC */ -#define WS_DLL_PUBLIC + /* + * Presumably MSVC, and we're building all-static, so we're + * not building any DLLs. + */ +#define WS_DLL_PUBLIC_NOEXTERN #endif /* __GNUC__ */ #endif /* WS_BUILD_DLL */ - #define WS_DLL_PUBLIC_NOEXTERN WS_DLL_PUBLIC + + /* + * Symbols in a DLL are *not* exported unless they're specifically + * flagged as exported, so, for a non-static but non-exported + * symbol, we don't have to do anything. + */ #define WS_DLL_LOCAL -#else +#else /* defined _WIN32 || defined __CYGWIN__ */ + /* + * Compiling for UN*X, where the dllimport and dllexport stuff + * is neither necessary nor supported; just specify the + * visibility if we have a compiler that claims compatibility + * with GCC 4 or later. + */ #if __GNUC__ >= 4 -#define WS_DLL_PUBLIC __attribute__ ((visibility ("default"))) extern + /* + * Symbols exported from libraries. + */ #define WS_DLL_PUBLIC_NOEXTERN __attribute__ ((visibility ("default"))) + + /* + * Non-static symbols *not* exported from libraries. + */ #define WS_DLL_LOCAL __attribute__ ((visibility ("hidden"))) #else /* ! __GNUC__ >= 4 */ - #define WS_DLL_PUBLIC + /* + * We have no way to control visibility. + */ #define WS_DLL_PUBLIC_NOEXTERN - #define WS_DLL_LOCAL extern + #define WS_DLL_LOCAL #endif /* __GNUC__ >= 4 */ #endif +/* + * You *must* use this for exported data *declarations*; if you use + * WS_DLL_PUBLIC_NOEXTERN, some compilers, such as MSVC++, will complain + * about array definitions with no size. + * + * You must *not* use this for exported data *definitions*, as that + * will, for some compilers, cause warnings about items being initialized + * and declared extern. + * + * Either can be used for exported *function* declarations and definitions. + */ +#define WS_DLL_PUBLIC WS_DLL_PUBLIC_NOEXTERN extern + #endif /* SYMBOL_EXPORT_H */ |