Re: impure_ptr/Mingw and Cygwin

["Peter A. Castro" <doctor at fruitbat dot org>]

On Fri, 22 Nov 2002, Andrew DeFaria wrote:

> Peter A. Castro wrote:
>       On Fri, 22 Nov 2002, Andrew DeFaria wrote:
> 
>             I wish to use -mno-cygwin to produce an
>             executable that can work without Cygwin
>             installed. I have successfully done this before.
>             Now I'm adding some functionality to my program
>             and it is no longer working! I've worked it out
>             such that it will compile and link but when my
>             program runs it simply stops returning an exit
>             code of 5. Running this under gdb produces a
>             SIGSIGV Segmentation fault then you attempt to
>             run it.
> 
>             I've whittled it down to the bare minimum to
>             reproduce the problem.  Seems to me the problem
>             is somewhere between newer versions of gcc 3.X
>              and Mingw.
> 
>             File: foo.c:
> 
>             #include <stdio.h>
>             int main (void) {
>             printf ("Hello World\n");
>             fprintf (stderr, "%s\n", "Hello World 2");
>             }
> 
>             $ gcc -g foo.c -mno-cygwin -I/usr/include -o foo
>             -liberty -lcrtdll -lg
>             $ foo
>             $
> 
>             Note that if I do not put -lg then I get:
> 
>             /tmp/ccKAyr4S.o(.text+0x4b): In function `main':
>             /dview/defaria_2.0/salira/neopon/build/maketools/foo.c:4:
>             undefined
>             reference to `_impure_ptr'
> 
>             Any ideas?
> 
>       Well, for one thing, linking with -lg will pull in cygwin.dll
>       since /lib/libg.a is a symlink to libcygwin.a. So your
>       program won't be Cygwin-free, if that's your goal.
> 
> Hey I didn't know that. I saw undefined references to _impure_ptr and
> looked for where it was defined and wham, libg.a came up.
>       However, I got it to work with the following command:
> 
>       $ gcc -g foo.c -mno-cygwin -mwindows -o foo -liberty
>       -lmingw32
>       $ ./foo.exe > x
>       $ cat x
>       Hello World
> 
> Thanks. I got this contrived example foo.c to work to. However pluging
> these values into my real world problem still fails:

What you show below is only linking.  I believe you need to re-compile
all of your source with -mno-cygwin -mwindows as well to make the
_impure_ptr references go away.

> /bin/gcc mksf.o mksfOpts.o mksfIO.o flmCrc.o -mno-cygwin -mwindows
> -liberty -lmingw32 -o mksf
> mksf.o(.text+0x60f): In function `main':
> /dview/defaria_2.0/salira/neopon/build/maketools/mksf.c:29: undefined
> reference to `_impure_ptr'
> mksf.o(.text+0x874):/dview/defaria_2.0/salira/neopon/build/maketools/mksf.c:66:
> undefined reference to `_impure_ptr'
> mksfOpts.o(.text+0x309): In function `usage':
> /dview/defaria_2.0/salira/neopon/build/maketools/mksfOpts.c:13: undefined
> reference to `_impure_ptr'
> mksfOpts.o(.text+0x331):/dview/defaria_2.0/salira/neopon/build/maketools/mksfOp
> s.c:14: undefined reference to `_impure_ptr'
> mksfOpts.o(.text+0x352):/dview/defaria_2.0/salira/neopon/build/maketools/mksfOp
> s.c:15: undefined reference to `_impure_ptr'
> mksfOpts.o(.text+0x36a):/dview/defaria_2.0/salira/neopon/build/maketools/mksfOp
> s.c:16: more undefined references to `_impure_ptr' follow
> make: *** [mksf] Error 1
> 
> Again the _impure_ptr things come up. Where is this supposed to be
> resolved from?
> 
> --
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> Andrew DeFaria
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-- 
Peter A. Castro <doctor@fruitbat.org> or <Peter.Castro@oracle.com>
	"Cats are just autistic Dogs" -- Dr. Tony Attwood


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