Fixed/silenced various absurd GCC warnings from outer space (#626)

imgui.cpp

@@ -613,12 +613,12 @@
 #pragma clang diagnostic ignored "-Wexit-time-destructors"  // warning : declaration requires an exit-time destructor       // exit-time destruction order is undefined. if MemFree() leads to users code that has been disabled before exit it might cause problems. ImGui coding style welcomes static/globals.
 #pragma clang diagnostic ignored "-Wglobal-constructors"    // warning : declaration requires a global destructor           // similar to above, not sure what the exact difference it.
 #pragma clang diagnostic ignored "-Wsign-conversion"        // warning : implicit conversion changes signedness             //
-#pragma clang diagnostic ignored "-Wmissing-noreturn"       // warning : function xx could be declared with attribute 'noreturn' warning    // GetDefaultFontData() asserts which some implementation makes it never return.
+#pragma clang diagnostic ignored "-Wint-to-void-pointer-cast" // warning : cast to 'void *' from smaller integer type 'int' //
-#pragma clang diagnostic ignored "-Wint-to-void-pointer-cast" // warning : cast to 'void *' from smaller integer type 'int'
 #endif
 #ifdef __GNUC__
 #pragma GCC diagnostic ignored "-Wunused-function"          // warning: 'xxxx' defined but not used
 #pragma GCC diagnostic ignored "-Wint-to-pointer-cast"      // warning: cast to pointer from integer of different size
+#pragma GCC diagnostic ignored "-Wformat"                   // warning: format '%p' expects argument of type 'void*', but argument 6 has type 'ImGuiWindow*'
 #endif
 
 //-------------------------------------------------------------------------

imgui_draw.cpp

@@ -58,7 +58,7 @@ namespace IMGUI_STB_NAMESPACE
 
 #ifdef _MSC_VER
 #pragma warning (push)
-#pragma warning (disable: 4456) // declaration of 'xx' hides previous local declaration
+#pragma warning (disable: 4456)                             // declaration of 'xx' hides previous local declaration
 #endif
 
 #ifdef __clang__
@@ -68,6 +68,11 @@ namespace IMGUI_STB_NAMESPACE
 #pragma clang diagnostic ignored "-Wmissing-prototypes"
 #endif
 
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wtype-limits"              // warning: comparison is always true due to limited range of data type [-Wtype-limits]
+#endif
+
 #define STBRP_ASSERT(x)    IM_ASSERT(x)
 #ifndef IMGUI_DISABLE_STB_RECT_PACK_IMPLEMENTATION
 #define STBRP_STATIC
@@ -86,6 +91,10 @@ namespace IMGUI_STB_NAMESPACE
 #endif
 #include "stb_truetype.h"
 
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
+
 #ifdef __clang__
 #pragma clang diagnostic pop
 #endif