[PD-dev] mingw/autotools/libtool, some success (flext and gnu/windows - 'undefined reference' with pd global vars?)

[dmotd]

i decided to build pure-data from scratch to see how a mingw derived dll 
would change things. i had to clean up the autotools scripts to get 
anything to build and added some new methods to build the dll and link 
to pd.exe. so pd now builds with autotools on mingw with minimal kludge.

the new mingw based pd.dll seems to have cleaned up the undefined 
references with the flext lib. so there is obviously an incompatibility 
between millers pd.dll (msvc?) and the mingw g++ linker. does this occur 
with gem too?

now for some hairy issues with libtool.. libtool has it's own namespace 
search globbing facility for finding libraries, and naturally doesn't 
want to find a library without a 'lib' prefix. this is contrary to gnu 
ld, which will search for both libfoo and foo when -lfoo is specified.
to change this behaviour you have to specify the libname_spec variable from:
---
   libname_spec="lib\$name"
---
to:
---
   libname_spec="\$name"
---
without this change libtool can't find pd.dll and building of shared 
externals will break:
---
*** Warning: linker path does not have real file for library -lpd.
*** I have the capability to make that library automatically link in whe
*** 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 libpd but no candidates were found. (...for file magic test)
---
but after the change the opposite is true and libs with a 'lib' prefix 
will be ignored. i have no idea how this can't be more commonplace, but 
i've struggled to find anything much about this on the net, aside from a 
bit of autoconf kludge in an apache module to workaround:
---
https://issues.apache.org/jira/browse/COUCHDB-440?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
---
referencing:
---
https://svn.apache.org/repos/asf/couchdb/trunk/configure.ac
---
i guess that libtool is not particularly popular on windows for these 
reasons! another workaround may be distributing our own patched libtool.m4.

i'll submit a patch for pd autotools to the bugtracker when i've cleaned 
up my code and confirmed it doesn't break anything in osx/linux..

the good news is that i now have a flext lib for pd built in mingw and 
tested this against my autotools build scripts for vasp. vasp runs in 
millers pd distribution and the mingw build i compiled against.

the bottom line, mingw + autotools is some kinda headache! so where to now?

cheers,
dmotd

On 04/04/2011 11:33 PM, dmotd wrote:
> fwd'd from flext list..
>
> background: i've been working on a new autotools template for flext
> based libs and started testing on windows platform with cygwin + mingw,
> immediate issues with building flext lib itself.
>
> have any pd-devs experienced this 'undefined reference' issue with the
> linker?
>
> i'm testing against millers pd-0.43-0.msw.zip on win2k and winxp
> virtualbox images. build logs attached.
>
> cheers,
> dmotd
>
> -------- Original Message --------
> Subject: Re: [flext] autotools builders - flext and gnu/windows
> Date: Mon, 4 Apr 2011 14:27:52 +0200
> From: Thomas Grill <gr at grrrr.org>
> To: dmotd <inaudible at simplesuperlativ.es>
> CC: flext at grrrr.org
>
> hi dmotd, many thanks for your efforts,
>
>> mingw (gcc 4.5.2):
>> with both your buildsys (cmd prompt) and autoconf (msys shell),
>> mingw will build all the static libs, but fails at the linker stage
>> when building the dynamic library, with a bunch of undefined
>> references (see attachment).
>>
>> i have attempted to encourage the build further by passing linker
>> flags (-Wl,--as-needed and -Wl,--no-undefined *plus numerous others/
>> combinations*) but nothing seems to make it budge. i'm not sure if
>> the compiler is being pedantic or i'm just not understanding
>> something.
>>
>
> I can remember that problem - it is connected to the way how global
> variables (like garray_class, s_float etc.) in Pd are defined for the
> linker.
> I must have found a solution once....
>
>> cygwin (gcc 3.4.4)
>> cygwin breaks with your buildsys due to what appears to be an issue
>> with the environment (see attachment). with autoconf it acts much
>> like mingw - it can successfully build static libs but fails to make
>> the shared dll, a few more undefined references than with mingw (see
>> attachment).
>>
>
> The flext-build output seems to indicate a c++ namespace problem which
> should not be too hard to fix.
> The autoconf output seems different, probably a mixture of problems.
>
> i'm not sure if i can spare any time for that soon but it's good to
> know the weak spots.
>
> all the best,
> Thomas
>
>
>
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