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gcc multiple definitions problem

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Started by cignox1 April 07, 2006 06:11 PM

10 comments, last by cignox1 18 years ago

cignox1

736

Author

April 07, 2006 06:11 PM

Ok, as usual, the multiple definitions error appears when I don't expect it... Following the tutorials on the net, in order to use VBO with openGL I need to write the following functions definitions:


PFNGLBINDBUFFERARBPROC glBindBufferARB = NULL;
PFNGLGENBUFFERSARBPROC glGenBuffersARB = NULL;
PFNGLBUFFERDATAARBPROC glBufferDataARB = NULL;
PFNGLDELETEBUFFERSARBPROC glDeleteBuffersARB = NULL;

Gcc doesn't like them, and complaints that all the three functions were already been defined in locale_facets.tcc.

Quote: .objs\util.o: In function `ZSt17__verify_groupingPKcjRKSs': C:/Programmi/CodeBlocks/bin/../lib/gcc/mingw32/3.4.4/../../../../include/c++/3.4.4/bits/locale_facets.tcc:2497: multiple definition of `glBindBufferARB' .objs\main.o:C:/Programmi/CodeBlocks/bin/../lib/gcc/mingw32/3.4.4/../../../../include/c++/3.4.4/bits/locale_facets.tcc:2497: first defined here

I gave a look to this file, but wasn't able to find that string. What's wrong? Thank you.

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MrEvil

970

April 07, 2006 09:30 PM

Interesting, locale_facets.tcc has nothing to do with OpenGL!

The source here is:

/*2494*/  bool/*2495*/  __verify_grouping(const char* __grouping, size_t __grouping_size,/*2496*/		    const string& __grouping_tmp)/*2497*/  {/*2498*/    const size_t __n = __grouping_tmp.size() - 1;/*2499*/    const size_t __min = std::min(__n, __grouping_size - 1);/*2500*/    size_t __i = __n;/*2501*/    bool __test = true;/*2502*/    /*2503*/    // Parsed number groupings have to match the/*2504*/    // numpunct::grouping string exactly, starting at the

I have no idea how that might happen other than some sort of macro substitution going on somewhere. Maybe it's something to do with where you declared these things...

The internet seems to have very little to say about this problem.

smart_idiot

1,298

April 07, 2006 10:00 PM

Wierd.

Maybe GCC was hashing variable names internally for the sake of lookup and two things ended up with the same value. That's my only guess, and it's a long shot.

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cignox1

736

Author

April 08, 2006 02:28 AM

Yes, that file has nothing to do with openGL. One more strange thing is that if I comment out those definitions, the compiler says that the functions have not been declared :-(
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MrEvil

970

April 08, 2006 02:34 AM

How about if you change their names? It should rule out some causes..

cignox1

736

Author

April 08, 2006 03:48 AM

I tried, but the result is the same: if I remove ARB from the names, it keeps to say that it was already defined.
I prefer not to use external libraries to load the extensions, because this is the first time I use them and would like to use the old way.
And this error makes me *?!=!!!

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Nitage

1,107

April 08, 2006 03:52 AM

Is that in a source file or a header file?

bubu LV

1,436

April 08, 2006 05:16 AM

Is PFNGLBINDBUFFERARBPROC defined somewhere?

cignox1

736

Author

April 08, 2006 06:07 AM

Quote:Original post by Nitage
Is that in a source file or a header file?

If I put them in a source file, then other sources may be unable to see them. In fact, if I put them in a cpp, the compiler tells me that when I try to use them they are undefined (I suppose that this is bound to the order of compilation?)

Quote:
Is PFNGLBINDBUFFERARBPROC defined somewhere?

Should be defined in the file glext.h, than I include from my own headers that need it.

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Anonymous

April 08, 2006 07:35 AM

They should be placed in a CPP file, and in a header file you should declare them as extern.

cpp:

PFNGLBINDBUFFERARBPROC glBindBufferARB = NULL;
PFNGLGENBUFFERSARBPROC glGenBuffersARB = NULL;
PFNGLBUFFERDATAARBPROC glBufferDataARB = NULL;
PFNGLDELETEBUFFERSARBPROC glDeleteBuffersARB = NULL;

h:
extern PFNGLBINDBUFFERARBPROC glBindBufferARB;
extern PFNGLGENBUFFERSARBPROC glGenBuffersARB;
extern PFNGLBUFFERDATAARBPROC glBufferDataARB;
extern PFNGLDELETEBUFFERSARBPROC glDeleteBuffersARB;

gcc multiple definitions problem

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gcc multiple definitions problem

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