Build Question: How to Add -Wl, --option Before Objects In Setup.py?

[Cyd Haselton]

On Tue, Oct 28, 2014 at 4:01 PM, Ned Deily <nad at acm.org> wrote:
> In article
> <CAHu5Pra68EDgkvFYHTQ+SrmB6syew9A1SAbB5CEmLuzqbs5vQg at mail.gmail.com>,
>  Cyd Haselton <chaselton at gmail.com> wrote:
>
>> On Tue, Oct 28, 2014 at 3:11 AM, Ned Deily <nad at acm.org> wrote:
>> > In article
>> > <CAHu5PrY-T=DT3wOg-Y+Va9WgwBV3w9d7M-tu=_N-CNgWsSzGpg at mail.gmail.com>,
>> >  Cyd Haselton <chaselton at gmail.com> wrote:
>> > [...]
>> >> I'm building python on an Android device in the KBOX
>> >> environment...which simulates a Unix type filesystem.
>> >> Python isn't installed; I'm building from sources (2.7.8) with GCC
>> >> 4.8.0 and make.
>> >>
>> >> The problem with the LDFLAGS approach is that some of the libraries
>> >> that must be linked (-lc -ldl) do not need the --allow-shlib-undefined
>> >> option...it's only the lpython2.7 that does.  Any way to do this?
>> >
>> > Sorry, I have no experience with that environment nor an understanding
>> > of why you need to specify --allow-shlib-undefined (it seems to be the
>> > default in some versions of ld).  You could look at and, if necessary,
>> > modify Lib/distutils, the part of the Python standard library that
>> > builds extension modules from setup.py.
>
>> No need to apologize.  Also no need to have an understanding of the
>> environment; with a few rare exceptions it behaves just like a
>> Unix/Linux one.
>>
>> The reason why I need to specify --allow-shlib-undefined is for the
>> python library; it's throwing undefined references to sincos even
>> though the symbol is there. Specifying that option is the only fix
>> I've found.
>>
>> As mentioned earlier, i'm not familiar with python or its build
>> system; which file in the distutils dir do I need to modify?
>
> Perhaps I should apologize for not asking earlier what you are really
> trying to do before suggesting heading down the path of modifying
> Distutils :)  So the issue is with an undefined reference to sincos?  It
> appears that that routine is often supplied in libm.  Is that the case
> on your platform?

Yes it is.

> And, if so, the right fix might be to supply it
> manually or, better, ensure that Python supplies it as a result of
> running ./configure.

If the Makefile generated is a result of running ./configure, then
Python is indeed finding the library...what it is doing with it after
finding it may be something else entirely.  I've tried everything from
adding the -Wl,--no-allow-shlib-undefined option to adding #include
<math.h> to the complexobject.c code...I still get an undefined
reference to sincos.  Running
grep "sincos" libpython2.7.* turns up the offending symbol (function?
declaration?) but re-running "make" after that still throws the same
error.

The only fix I've found is adding the -Wl,--allow-shlib-undefined
before the python library...which I do by hacking the Makefile.  That
allows the build to continue, which it does until it hits the part
where setup.py is run.

> Also, what version of Python are you building?

2.7.8.  I thought that it would be easier to build it on Android

>
> --
>  Ned Deily,
>  nad at acm.org
>
> --
> https://mail.python.org/mailman/listinfo/python-list