Make non-static a variable that doesn't need to be static.

[metze/wireshark/wip.git] / ws_symbol_export.h

diff --git a/ws_symbol_export.h b/ws_symbol_export.h
index fc257ce8e388f3f8cc47d7aac476b7cd5d5b6314..ed49ba80aebb211c7966d2c08ecab702e44f9213 100644 (file)
--- a/ws_symbol_export.h
+++ b/ws_symbol_export.h
@@ -20,35 +20,125 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+/** Reset symbol export behavior.
+ * If you {un}define WS_BUILD_DLL on the fly you'll have to define this
+ * as well.
+ */
+#ifdef RESET_SYMBOL_EXPORT
+
+#ifdef SYMBOL_EXPORT_H
+#undef SYMBOL_EXPORT_H
+#endif
+
+#ifdef WS_DLL_PUBLIC
+#undef WS_DLL_PUBLIC
+#endif
+
+#ifdef WS_DLL_PUBLIC_DEF
+#undef WS_DLL_PUBLIC_DEF
+#endif
+
+#ifdef WS_DLL_LOCAL
+#undef WS_DLL_LOCAL
+#endif
+
+#endif /* RESET_SYMBOL_EXPORT */
+
 #ifndef SYMBOL_EXPORT_H
 #define SYMBOL_EXPORT_H
 
 /* 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_DEF __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_DEF __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_DEF __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_DEF __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_DEF
     #endif /* __GNUC__ */
   #endif /* WS_BUILD_DLL */
+
+  /*
+   * 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")))
+    /*
+     * Symbols exported from libraries.
+     */
+#define WS_DLL_PUBLIC_DEF __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_DEF
     #define WS_DLL_LOCAL
   #endif /* __GNUC__ >= 4 */
 #endif
 
+/*
+ * You *must* use this for exported data *declarations*; if you use
+ * WS_DLL_PUBLIC_DEF, 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_DEF extern
+
 #endif /* SYMBOL_EXPORT_H */