Re: [Plib-users] multiple definitions

[Steve B. <sjb...@ai...>]

Mat Davidson wrote:
> Im running Mac OSX Jaguar, GCC 3.1
> 
> I can compile the libs from source and install them without a problem. 
> When I try to use the libs though I get a ton of errors associated with 
> the use of "inline" translation functions and overloads used in header 
> files such as ul.h and sg.h. For example, the following code throws errors:
> 
> ul.h: line 275
> static inline void _ulEndianSwap(unsigned int *x) {
> *x = (( *x >> 24 ) & 0x000000FF ) |
> (( *x >> 8 ) & 0x0000FF00 ) |
> (( *x << 8 ) & 0x00FF0000 ) |
> (( *x << 24 ) & 0xFF000000 ) ;
> }
> 
> 
> static inline void _ulEndianSwap(unsigned short *x) {
> *x = (( *x >> 8 ) & 0x00FF ) |
> (( *x << 8 ) & 0xFF00 ) ;
> }
> 
> and also
> 
> 
> sg.h: line 835
> extern void sgReflectInPlaneVec3 ( sgVec3 dst, const sgVec3 src, const 
> sgVec4 plane ) ;
> inline void sgReflectInPlaneVec3 ( sgVec3 dst, const sgVec4 plane )
> {
> sgReflectInPlaneVec3 ( dst, dst, plane ) ;
> }
> 
> 
> 
> Im compiling the projects with g++. Has anyone ever run into this? 
> Theres no way I can use plib like this, hopefully theres a way to fix 
> this. Please let me know if you have any ideas.

This is weird, we've compiled PLIB with many C++ compilers and never seen
this kind of thing before.

I know GCC 3.1 is a lot tighter on the C++ standard than previous
revisions - but I can't see what we are doing wrong here.  I think
this is your own fault somehow.

It's almost as if you were using a C compiler instead of C++.

Since this doesn't show up as a problem when you compile the LIBRARIES,
but only when you compile the APPLICATION, that's not impossible.  After
all, PLIB includes those exact same functions - it would not have compiled
if there was an error in those function definitions.

   1) Are you sure you are compiling these headers into C++ programs?
      PLIB doesn't support C.

   2) Are you sure you didn't accidentally wrap the header with:

         extern "C"
         {
         #include <plib/ul.h>
         }

   3) Is it possible that you have an 'extern "C"{...}' wrapping some
      other header file...or inside some other header that might have
      a missing '}' ??

That's the only thing I can imagine this could be.

My suspicions were raised by the nature of the error message you
sent me earlier:

/usr/include/plib/ul.h:273: declaration of C function `void _ulEndianSwap(short unsigned int*)' conflicts with

Why "declaration of C function" ??  Why not just "declaration of function" ?

That leads me to think that for some reason the compiler thinks these are C functions
and not C++ - and of course function overloading is illegal in C.   Since C++ functions
with 'extern "C"' in front of them have to abide by C-style linkage conventions, they
*CANNOT* be overloaded - even if they happen to be written in C++.

That's my best shot - dunno if anyone else has any ideas.


---------------------------- Steve Baker -------------------------
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