[GRASSLIST:1905] RE: configuring Grass5.03 on Debian

[Jim Browne]

configure:4535: gcc -o conftest -g -O2    conftest.c  1>&5
configure:4597: checking for socket
Glynn,

  Yes, this is a mystery. I use Debian because it is low on quirks and 
glitches.

  The problem is with the -lz switch. When I compile my test code with:
   cc -lz testdeflate.c
it also returns:
   cannot find -lz

  It seems like everything is where it should be. zlib is in /usr/lib. I added 
additional links to /usr/liblibz.so and /usr/lib/libz to 
/usr/lib/libz.so.1.1.4 just in case that was the problem.

  I also tried --with-zlib-libs=/usr/lib, but the problem remained.

  This must be rare and quirky, I Googled it and found problems only on Sun 
and OsX machines.

Here is the full section:


configure:4623: gcc -o conftest -g -O2    conftest.c  1>&5
configure:4694: checking for location of zlib includes
configure:4720: checking for zlib.h
configure:4728: gcc -E   conftest.c >/dev/null 2>conftest.out
configure:4762: checking for location of zlib library
configure:4787: checking for deflate in -lz
configure:4804: gcc -o conftest -g -O2     conftest.c -lz   1>&5
/usr/bin/ld cannot find -lz
collect2 ld returned 1 exit status
configure: failed program was:
#line 4793 "configure"
#include "confdefs.h"
/* Override any gcc2 internal prototype to avoid an error.  */
/* We use char because int might match the return type of a gcc2
    builtin and then its argument prototype would still apply.  */
char deflate();

int main() {
deflate()
; return 0; }

  Oh, and I knew that my code wouldn't work as such, I was just hoping to 
duplicate and isolate the same test so I could trouble shoot it without adding 
more to the list server. It would now be easier to run the Grass5.02 binaries, 
like I have on other machines, but this is bothering me now. Here I am anyway.


   Thanks for the input.

              Jim

>===== Original Message From Glynn Clements <glynn.clements at virgin.net> =====
>Jim Browne wrote:
>
>>   The last part of the logfile states:
>>
>> configure: failed program was:
>
>I need to see the lines immediately before that, which will contain
>the actual error messages. In general, you should quote everything
>related to that check, i.e. from the "checking ..." line down to the
>start of the next check (including the first line of the following
>check confirms that you really have included everything).
>
>However, given the limited number of things which can go wrong with a
>library as simple as zlib, the error is probably "cannot find -lz" (or
>something with an equivalent meaning).
>
>In which case, you would need to use --with-zlib-libs=???, where ???
>is the directory where zlib (e.g. libz.a, libz.so) resides (e.g.
>/usr/local/lib).
>
>However, I find it rather odd that zlib isn't found automatically on a
>Linux system. Every Linux system I've ever seen has zlib installed,
>and has it in /usr/lib, where the linker will find it without the need
>for any -L switches.
>
>On commercial Unices, it is often elsewhere (e.g. /usr/local/lib,
>/sw/lib), and non-Unix systems (e.g. Windows/Cygwin or MacOSX) may not
>even have it, but it's pretty common nowadays (zlib implements the
>"gzip" compression/decompression algorithms).
>
>> #line 4793 "configure"
>> #include "confdefs.h"
>> /* Override any gcc2 internal prototype to avoid and error. */
>> /* We use char because int might match the return type of a gcc2
>>     builtin and then its argument prototype would still apply. */
>> char deflate();
>>
>> int main() {
>> deflate()
>> ; return 0; }
>>
>> If this is a small test program, I don't see what it does.
>
>The compiled object (.o) file will have a dependency upon the
>deflate() function, so the program won't link if the deflate()
>function isn't available from the libraries against which it is
>linked.
>
>The test program is never run; the test only checks whether it is
>linked successfully.
>
>> When compiled on
>> its own, the compiler complains "undefined reference to deflate" and stops.
>
>That is to be expected. The actual test will use the -lz switch, and
>possibly one or more -L switches (if you used --with-zlib-libs=...).
>The deflate() function isn't likely to be in the C library (libc), so
>linking won't succeed without additional libraries. The function will
>certainly be in zlib, so the only remaining factor is to ensure that
>the -lz switch works given whichever -L switches are used.
>
>> However, when I add:
>>   #include <zlib.h>
>> then it only complains of "too few arguments to function 'deflate'" before 
it
>> stops.
>
>That is also to be expected. Given that the program is never actually
>run, it only matters that a call to the function occurs. It doesn't
>matter whether the call has the correct arguments.
>
>> What is this testing, and how do I get around this?
>
>It's testing that programs which depend upon deflate() can be built.
>In practice, that means that it's testing whether it can find zlib,
>i.e. whether --with-zlib-libs=... is necessary and, if so, that it was
>used, and with a suitable argument.
>
>--
>Glynn Clements <glynn.clements at virgin.net>