Suppress -Wsuggest-override warnings in user code for gcc too

This was already done for clang -Winconsistent-missing-override, but
gcc has a similar warning since 5.1 and, moreover, latest versions of
clang support this gcc warning as well, so add a special macro which
handles both compilers and use it in all wx macros defining virtual
functions instead of just disabling one of the clang warnings.

Closes https://github.com/wxWidgets/wxWidgets/pull/2000

include/wx/defs.h

@@ -708,6 +708,28 @@ typedef short int WXTYPE;
 #    define wxCLANG_WARNING_RESTORE(x)
 #endif
 
+/*
+    Specific macro for disabling warnings related to not using override: this
+    has to be done differently for gcc and clang and is only supported since
+    gcc 5.1.
+ */
+#if defined(__clang__)
+#   define wxWARNING_SUPPRESS_MISSING_OVERRIDE() \
+        wxCLANG_WARNING_SUPPRESS(suggest-override) \
+        wxCLANG_WARNING_SUPPRESS(inconsistent-missing-override)
+#   define wxWARNING_RESTORE_MISSING_OVERRIDE() \
+        wxCLANG_WARNING_RESTORE(inconsistent-missing-override) \
+        wxCLANG_WARNING_RESTORE(suggest-override)
+#elif wxCHECK_GCC_VERSION(5, 1)
+#   define wxWARNING_SUPPRESS_MISSING_OVERRIDE() \
+        wxGCC_WARNING_SUPPRESS(suggest-override)
+#   define wxWARNING_RESTORE_MISSING_OVERRIDE() \
+        wxGCC_WARNING_RESTORE(suggest-override)
+#else
+#   define wxWARNING_SUPPRESS_MISSING_OVERRIDE()
+#   define wxWARNING_RESTORE_MISSING_OVERRIDE()
+#endif
+
 /*
     Combination of the two variants above: should be used for deprecated
     functions which are defined inline and are used by wxWidgets itself.

include/wx/event.h

@@ -4273,10 +4273,10 @@ typedef void (wxEvtHandler::*wxPressAndTapEventFunction)(wxPressAndTapEvent&);
     private:                                                            \
         static const wxEventTableEntry sm_eventTableEntries[];          \
     protected:                                                          \
-        wxCLANG_WARNING_SUPPRESS(inconsistent-missing-override)         \
+        wxWARNING_SUPPRESS_MISSING_OVERRIDE()                           \
         const wxEventTable* GetEventTable() const;                      \
         wxEventHashTable& GetEventHashTable() const;                    \
-        wxCLANG_WARNING_RESTORE(inconsistent-missing-override)          \
+        wxWARNING_RESTORE_MISSING_OVERRIDE()                            \
         static const wxEventTable        sm_eventTable;                 \
         static wxEventHashTable          sm_eventHashTable
 

include/wx/richtext/richtextuicustomization.h

@@ -103,13 +103,13 @@ protected:
 /// of the formatting dialog.
 
 #define DECLARE_HELP_PROVISION() \
-    wxCLANG_WARNING_SUPPRESS(inconsistent-missing-override) \
+    wxWARNING_SUPPRESS_MISSING_OVERRIDE() \
     virtual long GetHelpId() const { return sm_helpInfo.GetHelpId(); } \
     virtual void SetHelpId(long id) { sm_helpInfo.SetHelpId(id); } \
     virtual wxRichTextUICustomization* GetUICustomization() const { return sm_helpInfo.GetUICustomization(); } \
     virtual void SetUICustomization(wxRichTextUICustomization* customization) { sm_helpInfo.SetUICustomization(customization); } \
     virtual bool ShowHelp(wxWindow* win) { return sm_helpInfo.ShowHelp(win); } \
-    wxCLANG_WARNING_RESTORE(inconsistent-missing-override) \
+    wxWARNING_RESTORE_MISSING_OVERRIDE() \
 public: \
     static wxRichTextHelpInfo& GetHelpInfo() { return sm_helpInfo; }\
 protected: \

include/wx/rtti.h

@@ -140,9 +140,9 @@ WXDLLIMPEXP_BASE wxObject *wxCreateDynamicObject(const wxString& name);
 #define wxDECLARE_ABSTRACT_CLASS(name)                                        \
     public:                                                                   \
         static wxClassInfo ms_classInfo;                                      \
-        wxCLANG_WARNING_SUPPRESS(inconsistent-missing-override)               \
+        wxWARNING_SUPPRESS_MISSING_OVERRIDE()                                 \
-        virtual wxClassInfo *GetClassInfo() const                             \
+        virtual wxClassInfo *GetClassInfo() const;                            \
-        wxCLANG_WARNING_RESTORE(inconsistent-missing-override)
+        wxWARNING_RESTORE_MISSING_OVERRIDE()
 
 #define wxDECLARE_DYNAMIC_CLASS_NO_ASSIGN(name)                               \
     wxDECLARE_NO_ASSIGN_CLASS(name);                                          \