I want to write a shared C library to be used from Perl. In a desperate attempt to figure h2xs out, I have written the following: 
// libtwintree.h:
int return_one( void );
int return_zero( void );

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// libtwintree.c:
#include "libtwintree.h"
int return_one( void ) { return 1; }
int return_zero( void ) { return 0; }

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Obviously these are just placeholders for the real functions that this library will implement, it's just that before I write tons of code I really need to get the h2xs monster to cooperate. Anyway, here's the Makefile I'm using to try and fit the pieces together: 
TwinTree.pm : TwinTree.xs
        cd TwinTree && \
        perl Makefile.PL && \
        make && \
        make test && \
        make install

TwinTree.xs : libtwintree.so install
        mkdir -p TwinTree && \
        cp libtwintree.h TwinTree && \
        h2xs -Oxan TwinTree -L/usr/local/lib -llibtwintree libtwintree
+.h 

libtwintree.so : libtwintree.o
        gcc -shared -Wl,-soname,libtwintree.so -o libtwintree.so libtw
+intree.o -lc

libtwintree.o : 
        gcc -fPIC -g -c -Wall libtwintree.c

clean :
        rm -Rf *.o *.so TwinTree 

install : libtwintree.so
        cp libtwintree.so /usr/local/lib && \
        ldconfig -n /usr/local/lib

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According to the h2xs manpage, the -x switch is supposed to "Automatically generate XSUBs basing on function declarations in the header file". So... why is it that the generated TwinTree.xs looks like this? 
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#include "ppport.h"

#include "const-c.inc"

MODULE = TwinTree               PACKAGE = TwinTree

INCLUDE: const-xs.inc

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No XSUBs, the entire module is basically 500K of absolutely nothing. What am I missing that's so obvious nobody seems to think it's worth mentioning in the manpage?

Not that I think it matters, but I'm running perl 5.8.8 and uname -a is Linux atlas.atc.no 2.6.27-briullov.1 #1 SMP Fri Apr 3 19:34:58 MSD 2009 i686 i686 i386 GNU/Linux.

Edit: pasted the proper contents of twintree.c

-- Time flies when you don't know what you're doing

In reply to Why does the h2xs -x switch not generate XSUBs? by FloydATC

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