Re: libiberty.a and getopt problem

[David Fritz]

The opt* variables are declared __declspec(dllimport) in Cygwin's 
headers. So when you're program refers to optarg after having included 
Cygwin's <getopt.h> (or <unistd.h>), the symbol your program links to is 
called __imp__optarg. Presumably, the opt* variables were not declared 
dllimport when libiberty was compiled. So when you link to libiberty, 
your program and libiberty's getopt() are referring to two different 
optarg variables.

You can work around this problem by not including <getopt.h> or 
<unistd.h>. Though, obviously, this is not a long-term solution.

#include <stdio.h>

extern char *optarg;

int main(int argc, char **argv)
{
    int opt;
    while ((opt = getopt(argc, argv, "avzdrkp:s:o:R:")) != -1) {
        printf("opt = %d,%c\n", opt, opt);
        printf("optarg = %s\n", optarg);
    }
}
-----

~$ gcc test.c
Info: resolving _optarg by linking to __imp__optarg (auto-import)
~$ ./a -s 1
opt = 115,s
optarg = 1
~$ gcc test.c -liberty
~$ ./a -s 1
opt = 115,s
optarg = 1
~$
Cheers

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