Fix compilation of wx/scopeguard.h with g++ -fno-exceptions.

Don't use try/catch in public headers if exceptions support is disabled with a
compiler switch.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63474 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/except.h

@@ -18,13 +18,22 @@
 // macros working whether wxUSE_EXCEPTIONS is 0 or 1
 // ----------------------------------------------------------------------------
 
-#if wxUSE_EXCEPTIONS
-    #define wxTRY try
-    #define wxCATCH_ALL(code) catch ( ... ) { code }
-#else // !wxUSE_EXCEPTIONS
+// even if the library itself was compiled with exceptions support, the user
+// code using it might be compiling with a compiler switch disabling them in
+// which cases we shouldn't use try/catch in the headers -- this results in
+// compilation errors in e.g. wx/scopeguard.h with at least g++ 4
+#if !wxUSE_EXCEPTIONS || \
+        (defined(__GNUG__) && !defined(__EXCEPTIONS))
+    #define wxNO_EXCEPTIONS
+#endif
+
+#ifdef wxNO_EXCEPTIONS
     #define wxTRY
     #define wxCATCH_ALL(code)
-#endif // wxUSE_EXCEPTIONS/!wxUSE_EXCEPTIONS
+#else // do use exceptions
+    #define wxTRY try
+    #define wxCATCH_ALL(code) catch ( ... ) { code }
+#endif // wxNO_EXCEPTIONS/!wxNO_EXCEPTIONS
 
 #endif // _WX_EXCEPT_H_