I've got a program I'm attempting to port from Red Hat Enterprise Linux 3 to
Cygwin (on Windows).
g++ -v in Cygwin reveals: gcc version 3.4.4
g++ -v in Red Hat reveals: gcc version 3.2.3-52
There's the background. Here's the problem:
I'm attempting to cast a function pointer in the following C++ code:
------------------------------------------
/* ... includes and what not ... */
void tcbBegin(GLenum prim) {
cout << "BEGIN";
}
/* ... */
void tessellateTest() {
//Allocate a new GLU tessellation object
GLUtesselator *tess = gluNewTess();
//Assigning callbacks
//begin callback
gluTessCallback(tess,GLU_TESS_BEGIN, (void(*)()) tcbBegin); // THIS IS LINE
71 //
/* ... */
--------------------------------------
When compiling, this error happens in Cygwin:
test.cpp:72: error: invalid conversion from `void (*)()' to `void (*)()'
No error occurs in Red Hat. The cast works just fine, and I've used this code
with no problem for several months.
Not casting at all results in this error (on both Red Hat and Cygwin):
test.cpp:71: error: invalid conversion from `void (*)(GLenum)' to `void (*)()'
My compile line in Cygwin looks like:
$ g++ test.cpp -lglu32 -lopengl32
And in Red Hat it looks like:
$ g++ test.cpp -lGLU -lGL
Any idea whats going on? It seems to me that the cast should be legal. Have
the rules changed in g++ between the two versions? I have already tried using a
reinterpret_cast, but that didn't work.
Thanks,
Mike Day
Virtual Targets Center
https://modelexchange.army.mil/
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