building 'math' extension$
gcc -fPIC -fno-strict-aliasing -g -O2 -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -I. -IInclude -I./Include -I/usr/local/include -I/usr/local/src/python/Python-2.7/Include -I/usr/local/src/python/Python-2.7 -c /usr/local/src/python/Python-2.7/Modules/mathmodule.c -o build/temp.solaris-2.9-sun4u-2.7/usr/local/src/python/Python-2.7/Modules/mathmodule.o$
gcc -fPIC -fno-strict-aliasing -g -O2 -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -I. -IInclude -I./Include -I/usr/local/include -I/usr/local/src/python/Python-2.7/Include -I/usr/local/src/python/Python-2.7 -c /usr/local/src/python/Python-2.7/Modules/_math.c -o build/temp.solaris-2.9-sun4u-2.7/usr/local/src/python/Python-2.7/Modules/_math.o$
gcc -shared build/temp.solaris-2.9-sun4u-2.7/usr/local/src/python/Python-2.7/Modules/mathmodule.obuild/temp.solaris-2.9-sun4u-2.7/usr/local/src/python/Python-2.7/Modules/_math.o -L/usr/local/lib -lm -o build/lib.solaris-2.9-sun4u-2.7/math.so$
*** WARNING: renaming "math" since importing it failed: ld.so.1: python: fatal: relocation error: file build/lib.solaris-2.9-sun4u-2.7/math.so: symbol round: referenced symbol not found$

The problem appears to be the lack of a round function in Solaris 9.  This compiles find in Solaris 10, but I need it in Solaris 9.

configure:11989: checking for round
configure:11989: gcc -o conftest -g -O2   conftest.c -lresolv -lsocket -lnsl -lrt -ldl  -lpthread -lm >&5
/var/tmp//ccWVF7bf.o: In function `main':
/usr/local/src/python/Python-2.7/conftest.c:287: undefined reference to `round'

Hmm.  There should be a configure-time test for 'round'.  Could you look for a line something like:

  checking for round... yes

in the configure output and tell me whether you've got a 'yes' or a 'no' there?

Ah.  Reading your second message more closely, you're presumably getting a 'no' there.  Could you double check that 'HAVE_ROUND' is not defined in pyconfig.h?

In that case, what's supposed to happen is that there's a substitute 'round' function defined in Python/pymath.c that gets used.  That's clearly working okay in the Python core, since it looks like your build doesn't fail until you get to the module build stage, and 'round' is used in Objects/floatobject.c in the core.

But I'm guessing that for some reason your Python executable isn't exporting that 'round' symbol that's defined in pymath.c.  I'm not sure why that would be.

The check for round failed during configure.  I included a bit of that in my second note above.  Here's a bit more of the output:

collect2: ld returned 1 exit status
configure:11989: $? = 1
configure: failed program was:
| /* confdefs.h */
| #define _GNU_SOURCE 1
| #define _NETBSD_SOURCE 1
<snip>
| /* Override any GCC internal prototype to avoid an error.
|    Use char because int might match the return type of a GCC
|    builtin and then its argument prototype would still apply.  */
| #ifdef __cplusplus
| extern "C"
| #endif
| char round ();
| /* The GNU C library defines this for functions which it implements
|     to always fail with ENOSYS.  Some functions are actually named
|     something starting with __ and the normal name is an alias.  */
| #if defined __stub_round || defined __stub___round
| choke me
| #endif
|
| int
| main ()
| {
| return round ();
|   ;
|   return 0;
| }
configure:11989: result: no

Thanks for your attention to this issue.  It sounds like you're onto something regarding the stand-in function not getting exported.  I'm not sure what to check next, though.

From pyconfig.h:

/* Define to 1 if you have the `round' function. */
/* #undef HAVE_ROUND */

From Python/pymath.c:

#ifndef HAVE_ROUND
double
round(double x)
{
    double absx, y;
    absx = fabs(x);
    y = floor(absx);
    if (absx - y >= 0.5)
    y += 1.0;
    return copysign(y, x);
}
#endif /* HAVE_ROUND */

Is there perhaps a work-around we could use to get this to compile and have a math module? Force it to export that 'round' symbol in the core, perhaps?

> Force it to export that 'round' symbol in the core, perhaps?

Sure.  That might involve first understanding why it's not being exported.  That's where I'm a bit stuck, especially without a Solaris system to test on.  If someone can figure out why the symbol isn't being exported in the first place, that would be helpful.

I have some knowledge of these things, so I'll try to find out what's going on, but I could also upload output and/or debug files here for you to examine, if that helps. If you give me the files you'd like to see from my build, or the commands you'd like the output of, I'd be happy to oblige. Thanks!

Doug:  thanks.  I think I may just be being stupid here. One thing you might try is replacing the line

  extern double round(double);

in Include/pymath.h, with:

  PyAPI_FUNC(double) round(double);

and see if that helps.

I unpacked a fresh tarball, made this change, then did a ./configure and make as normal. Exact same error as originally reported. :(

Hmm.  That's puzzling indeed.

I made a claim earlier that 'round' is already used in Objects/floatobject.c, but it occurs to me now that that's not true if PY_NO_SHORT_FLOAT_REPR is #defined.

Could you attach the pyconfig.h file produced by configure?

Certainly!

Thanks.  I'm still stuck, though.  Since I'm pretty much at the wild guesses stage, here's one:

<wild idea> Perhaps the pymath.o object file isn't being included in the Python executable at all, because none of its functions are needed.  Now that doesn't seem to make sense, since the round function is needed, and used, in Objects/floatobject.c (that is, if PY_NO_SHORT_FLOAT_REPR is *not* defined;  I'm still not clear on whether that's the case or not---if you can get as far as launching an interpreter, then the result of sys.float_repr_style would be 'short' in that case).  But gcc (depending on the version, I guess) has builtin versions of some standard C library functions, including 'round'.  So if it were using the builtin then there would be no need to link to the pymath.o file, so it might be left out of the python executable.  But I'm not sure why the same doesn't happen when compiling the math module.

Neither am I sure how one might go about testing the above hypothesis.

> ./python
Python 2.7 (r27:82500, Nov 22 2010, 10:06:14)
[GCC 3.3.2] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print sys.float_repr_style
short

So it appears, if I follow you, that PY_NO_SHORT_FLOAT_REPR is not defined.

Glancing through the Makefile, pymath.o is included in the PYTHON_OBJS variable, which is in turn included in the LIBRARY_OBJS variable, which is used in all the libpython* targets.

I'm going to try to turn on some debugging on the commands that build those targets, and see if anything jumps out at me. Maybe it'll be obvious that pymath.o is being left out for one reason or another that'll sync up with your "wild guess". :/

I don't think there's anything wrong with the setup we've been looking at so far, per se. The libpython2.7.a file produced has the 'round' function like it should:

> nm libpython2.7.a | grep round
[116] |      1360|     696|FUNC |GLOB |0    |2      |_Py_double_round
[218] |         0|       0|NOTY |GLOB |0    |UNDEF  |_Py_double_round
[10] |     15268|     236|FUNC |LOCL |0    |2      |builtin_round
[48] |      9912|     198|OBJT |LOCL |0    |4      |round_doc
[8] |         0|      96|FUNC |GLOB |0    |2      |round

However, the python executable itself, compiled against that archive, does *not* have it:

> nm python | grep round
[4805] |    244408|     696|FUNC |GLOB |0    |9      |_Py_double_round
[1735] |    640836|     236|FUNC |LOCL |0    |9      |builtin_round
[1770] |   1533576|     198|OBJT |LOCL |0    |16     |round_doc

So, for some reason, the gcc command that builds that python executable is leaving it out:

gcc -o python \
       Modules/python.o \
       libpython2.7.a -lresolv -lsocket -lnsl -lrt -ldl -lpthread -lm

Just an update. Going to try to debug that command and see if I can find out why.

Running

gcc -Wl,-R/usr/local/lib,-R/usr/lib  -o python Python/pymath.o Modules/python.o libpython2.7.a -lresolv -lsocket -lnsl -lrt -ldl  -lpthread   -lm

mv build/lib.solaris-2.8-sun4u-2.7/math_failed.so build/lib.solaris-2.8-sun4u-2.7/math.so

seems to have made math module import correctly and work:

bash-2.03$ ./python
Python 2.7 (r27:82500, Nov 23 2010, 14:49:30)
[GCC 3.4.6] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> import math
>>> math.floor(2.4)
2.0


I suppose it's more a workaround than a solution, but hopefully it makes using math module possible and confirms the suggestion there might be something wrong with ar/gcc linking the .a file.

It's actually not quite a solution, either. Working your changes into the build process, I *do* get a math module... but it does *not* have a round function.

> python
Python 2.7 (r27, Nov 23 2010, 11:54:39)
[GCC 3.3.2] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> import math;
>>> print math.round(2.5);
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'round'
>>> print math.floor(2.5);
2.0

A step in the right direction, though, I'd think. Thanks.

> I *do* get a math module... but it does *not* have a round function.

Not a problem:  the math module isn't supposed to have a round function. :-)

The round function is used as part of the calculations that produce the gamma function.  So if the gamma function is working, then all's well:

>>> from math import gamma
>>> gamma(3.1)
2.197620278392477

Python support,

This issue with not being able to build on Solaris 9 is easily fixed.  I have attached a patch with the fix for Python 2.7.

When linking with libpython-2.7.a, the linker will only extract modules that satisfy dependencies emanating from python.o.  There may be objects in the archive that are not needed to satisfy any of these dependencies and those WILL NOT be included in the executable.

The GNU linker supports two options that can be use to force the linker to include ALL objects in the archive.  Thus if you change the python link line from:


 $(BUILDPYTHON):  Modules/python.o $(LIBRARY) $(LDLIBRARY)
     $(LINKCC) $(LDFLAGS) $(LINKFORSHARED) -o $@ \
         Modules/python.o \
         $(BLDLIBRARY) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)

to:

 $(BUILDPYTHON): Modules/python.o $(LIBRARY) $(LDLIBRARY)
     $(LINKCC) $(LDFLAGS) $(LINKFORSHARED) -o $@ \
         Modules/python.o \
         -Wl,--whole-archive $(BLDLIBRARY) -Wl,--no-whole-archive \
         $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)

Then the problem is resolved.

For compiler toolchains that do not support the --whole-library option, you can change the link to link with the individual .o files and not use the archive library at all.

Let me know if I can be of any more help.

Reid Madsen

I encountered this problem when updating from 2.6.4 to 2.7.1 on Solaris 8, which also doesn't have 'round'.  I tried srmadsen's --whole-archive option, but it wasn't recognized by the (somewhat ancient) tools on that machine.

I solved the problem by just editing the $(BUILDPYTHON) target to include Python/pymath.o, as Jerzy Kozera did.

Should configure perhaps take care of this when it detects no round?  It seems like this has slipped in simply because very few people still use systems without round.