Re: [Mingw-users] libtool, dlls and -lm

[Pierre O. <os...@ce...>]

Michael Gerdau wrote:
>>The main polypaudio library is supposed to become a DLL. When trying to 
>>link it though, libtool complains loudly about only finding a static 
>>version of libm. I'm at a loss what should be done to remedy this.
> 
> 
> I'm not sure I understand what you do but it seems you explicitly
> invoke libtool. Why ?
> 
> Or phrased differently:
> Why don't you just invoke gcc/g++ with the appropriate options
> and let it do all the dirty details ?
> 

It's autotooled so libtool handles all the library stuff. The point is 
adding mingw support to the current structure and not creating an entire 
new build system just for one platform.

> 
> If the above is beside the point it might be helpful if you post
> the exact commands you are executing.
> 

automake & co generates the makefile, so there's few additions on my 
part. But here is what is finally executed:

/bin/sh ../libtool --mode=link i386-mingw32msvc-gcc -D_GNU_SOURCE 
-I/home/ossman/polypaudio  -I/usr/local/cross-w32//include 
-I/usr/local/cross-w32//include 
-DDLSEARCHPATH=\"/usr/local/cross-w32//lib/polypaudio-0.8\" 
-DDEFAULT_CONFIG_DIR=\"/usr/local/cross-w32//etc/polypaudio\" 
-DPOLYPAUDIO_BINARY=\"/usr/local/cross-w32//bin/polypaudio\" 
'-DDEBUG_TRAP=__asm__("int $3")' -g -O2 -pipe -W -Wall -pedantic 
-std=gnu9x -Wno-unused-parameter -no-undefined  -o 
libpolyp-simple-0.8.la -rpath /usr/local/cross-w32//lib -version-info 
0:0:0 libpolyp_simple_0.8_la-polyplib-simple.lo  libpolyp-0.8.la 
libpolyp-mainloop-0.8.la -lm

Which gives me:

*** Warning: linker path does not have real file for library -lm.
*** I have the capability to make that library automatically link in when
*** you link to this library.  But I can only do this if you have a
*** shared version of the library, which you do not appear to have
*** because I did check the linker path looking for a file starting
*** with libm and none of the candidates passed a file format test
*** using a file magic. Last file checked: 
/usr/local/cross-w32/lib/gcc-lib/i386-mingw32msvc/3.2/../../../../i386-mingw32msvc/lib//libm.a
*** The inter-library dependencies that have been dropped here will be
*** automatically added whenever a program is linked with this library
*** or is declared to -dlopen it.

*** Since this library must not contain undefined symbols,
*** because either the platform does not support them or
*** it was explicitly requested with -no-undefined,
*** libtool will only create a static version of it.

If I bastardise libtool and remove the check for the above, it links 
fine. I haven't gotten to the point of linking the library to something 
functional yet so I don't know if it produces a correct dll.

-- 
Pierre Ossman                Telephone: +46-13-21 46 00
Cendio AB                    Web: http://www.cendio.com