Fix MSVC compiler warnings in test/icon.cxx (#109)

Also:

- remove unnecessary 'size_t' conversions from FL/fl_casts.H
- add reverse conversions from integer types to 'void *'

2 files changed, 17 insertions, 21 deletions

diff --git a/FL/fl_casts.H b/FL/fl_casts.H
index 965f12eb1..1d0d881cd 100644
--- a/FL/fl_casts.H
+++ b/FL/fl_casts.H
@@ -17,22 +17,18 @@
 
 #include <FL/platform_types.h>
 
-inline char fl_char(void *v) { return (char)(fl_intptr_t)v; }
-inline int  fl_int(void *v)  { return (int)(fl_intptr_t)v; }
-inline long fl_long(void *v) { return (long)(fl_intptr_t)v; }
+inline char fl_char(void *v)             { return (char)(fl_intptr_t)v; }
+inline int  fl_int(void *v)              { return (int)(fl_intptr_t)v; }
+inline long fl_long(void *v)             { return (long)(fl_intptr_t)v; }
 
-inline unsigned char fl_uchar(void *v) { return (unsigned char)(fl_uintptr_t)v; }
-inline unsigned int  fl_uint(void *v)  { return (unsigned int)(fl_uintptr_t)v; }
-inline unsigned long fl_ulong(void *v) { return (unsigned long)(fl_uintptr_t)v; }
+inline unsigned char fl_uchar(void *v)   { return (unsigned char)(fl_uintptr_t)v; }
+inline unsigned int  fl_uint(void *v)    { return (unsigned int)(fl_uintptr_t)v; }
+inline unsigned long fl_ulong(void *v)   { return (unsigned long)(fl_uintptr_t)v; }
 
-#if 0 /* not necessary */
+// the following conversions can be used to silence MSVC warning C4312:
+// 'type cast': conversion from '<type>' to 'void *' of greater size
 
-inline char fl_char(size_t v) { return (char)v; }
-inline int  fl_int(size_t v)  { return (int)v; }
-inline long fl_long(size_t v) { return (long)v; }
-
-inline unsigned char fl_uchar(size_t v) { return (unsigned char)v; }
-inline unsigned int  fl_uint(size_t v)  { return (unsigned int)v; }
-inline unsigned long fl_ulong(size_t v) { return (unsigned long)v; }
-
-#endif /* not necessary */
+inline void *fl_voidptr(int v)           { return (void *)(fl_intptr_t)v; }
+inline void *fl_voidptr(unsigned int v)  { return (void *)(fl_uintptr_t)v; }
+inline void *fl_voidptr(long v)          { return (void *)(fl_intptr_t)v; }
+inline void *fl_voidptr(unsigned long v) { return (void *)(fl_uintptr_t)v; }
diff --git a/test/icon.cxx b/test/icon.cxx
index c36e9a066..3bf565ff9 100644
--- a/test/icon.cxx
+++ b/test/icon.cxx
@@ -1,7 +1,7 @@
 //
 // Icon test program for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2010 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -22,7 +22,7 @@
 static Fl_Double_Window *win;
 
 void choice_cb(Fl_Widget *, void *v) {
-  Fl_Color c = (Fl_Color)(fl_intptr_t)v;
+  Fl_Color c = (Fl_Color)fl_uint(v);
   uchar buffer[32*32*3];
   Fl_RGB_Image icon(buffer, 32, 32, 3);
   icon.color_average(c, 0.0);
@@ -30,9 +30,9 @@ void choice_cb(Fl_Widget *, void *v) {
 }
 
 Fl_Menu_Item choices[] = {
-  {"Red",0,choice_cb,(void*)FL_RED},
-  {"Green",0,choice_cb,(void*)FL_GREEN},
-  {"Blue",0,choice_cb,(void*)FL_BLUE},
+  {"Red",   0, choice_cb, fl_voidptr(FL_RED)},
+  {"Green", 0, choice_cb, fl_voidptr(FL_GREEN)},
+  {"Blue",  0, choice_cb, fl_voidptr(FL_BLUE)},
   {0}
 };