Issue 16537: Python’s setup.py raises a ValueError when self.extensions is empty

When disabled_module_list contains all the module names that are not built by Modules/Setup.dist, self.extensions in setup.py will be an empty list and when build_extensions tries to determine the max length of all extension names it raises a ValueError with the following traceback:

Traceback (most recent call last):
  File "./setup.py", line 2143, in <module>
    main()
  File "./setup.py", line 2138, in main
    'Lib/smtpd.py']
  File "/Users/pythonforios/Python_for_iOS/trunk/Python_for_iOS/python2.7/Lib/distutils/core.py", line 152, in setup
    dist.run_commands()
  File "/Users/pythonforios/Python_for_iOS/trunk/Python_for_iOS/python2.7/Lib/distutils/dist.py", line 953, in run_commands
    self.run_command(cmd)
  File "/Users/pythonforios/Python_for_iOS/trunk/Python_for_iOS/python2.7/Lib/distutils/dist.py", line 972, in run_command
    cmd_obj.run()
  File "/Users/pythonforios/Python_for_iOS/trunk/Python_for_iOS/python2.7/Lib/distutils/command/build.py", line 127, in run
    self.run_command(cmd_name)
  File "/Users/pythonforios/Python_for_iOS/trunk/Python_for_iOS/python2.7/Lib/distutils/cmd.py", line 326, in run_command
    self.distribution.run_command(command)
  File "/Users/pythonforios/Python_for_iOS/trunk/Python_for_iOS/python2.7/Lib/distutils/dist.py", line 972, in run_command
    cmd_obj.run()
  File "/Users/pythonforios/Python_for_iOS/trunk/Python_for_iOS/python2.7/Lib/distutils/command/build_ext.py", line 339, in run
    self.build_extensions()
  File "./setup.py", line 282, in build_extensions
    longest = max([len(e.name) for e in self.extensions])
ValueError: max() arg is an empty sequence
make: *** [sharedmods] Error 1

~~~ An example disabled_module_list from setup.py: ~~~

disabled_module_list = [
# Modules not compatible/not applicable for the iOS
'dl', 'nis', 'gdbm', 'spwd', '_bsddb', '_curses', '_tkinter', 'readline', 'bsddb185', 'ossaudiodev', 'sunaudiodev', '_curses_panel', 'linuxaudiodev',  
# Modules appended to inittab before embedded initialization
'_multiprocessing', 'future_builtins', '_ctypes_test', '_testcapi', '_sqlite3', '_hashlib', '_hotshot', '_scproxy', '_pybsddb', 'imageop', '_ctypes', '_lsprof', '_heapq', '_yaml', '_json', 'math', 'zlib', '_io', 'bz2', 'dbm'
]

~~~ Example Modules/Setup.dist: ~~~

DESTLIB=$(LIBDEST)
MACHDESTLIB=$(BINLIBDEST)
DESTPATH=
SITEPATH=
TESTPATH=
MACHDEPPATH=:plat-$(MACHDEP)
EXTRAMACHDEPPATH=
TKPATH=:lib-tk
OLDPATH=:lib-old
COREPYTHONPATH=$(DESTPATH)$(SITEPATH)$(TESTPATH)$(MACHDEPPATH)$(EXTRAMACHDEPPATH)$(TKPATH)$(OLDPATH)
PYTHONPATH=$(COREPYTHONPATH)

*static*

posix posixmodule.c
errno errnomodule.c
pwd pwdmodule.c
_sre _sre.c
_codecs _codecsmodule.c
zipimport zipimport.c
_symtable symtablemodule.c
array arraymodule.c
cmath cmathmodule.c _math.c
_struct _struct.c
time timemodule.c -lm
operator operator.c
_weakref _weakref.c
_random _randommodule.c
_collections _collectionsmodule.c
itertools itertoolsmodule.c
strop stropmodule.c
_functools _functoolsmodule.c
_elementtree -I$(srcdir)/Modules/expat -DHAVE_EXPAT_CONFIG_H -DUSE_PYEXPAT_CAPI _elementtree.c
datetime datetimemodule.c
_bisect _bisectmodule.c
unicodedata unicodedata.c
_locale _localemodule.c
fcntl fcntlmodule.c
grp grpmodule.c
select selectmodule.c
mmap mmapmodule.c
_csv _csv.c
_socket socketmodule.c
SSL=/usr/local/OpenSSL_for_iOS
_ssl _ssl.c -DUSE_SSL -I$(SSL)/include -I$(SSL)/include/openssl -L$(SSL)/lib -lssl -lcrypto
crypt cryptmodule.c
termios termios.c
resource resource.c
audioop audioop.c
imageop imageop.c
_md5 md5module.c md5.c
_sha shamodule.c
_sha256 sha256module.c
_sha512 sha512module.c
timing timingmodule.c
syslog syslogmodule.c
binascii binascii.c
parser parsermodule.c
cStringIO cStringIO.c
cPickle cPickle.c
fpectl fpectlmodule.c
fpetest fpetestmodule.c
pyexpat expat/xmlparse.c expat/xmlrole.c expat/xmltok.c pyexpat.c -I$(srcdir)/Modules/expat -DHAVE_EXPAT_CONFIG_H -DUSE_PYEXPAT_CAPI
_multibytecodec cjkcodecs/multibytecodec.c
_codecs_cn cjkcodecs/_codecs_cn.c
_codecs_hk cjkcodecs/_codecs_hk.c
_codecs_iso2022 cjkcodecs/_codecs_iso2022.c
_codecs_kr cjkcodecs/_codecs_kr.c
_codecs_tw cjkcodecs/_codecs_tw.c
_codecs_jp cjkcodecs/_codecs_jp.c
xxsubtype xxsubtype.c

setup.py patch for 2.7.3

setup.py patch for 3.0.1

setup.py patch for 3.1.5

setup.py patch for 3.2.3

setup.py patch for 3.3.0

Thanks for the patches.
3.1 and 2.6 only receive security fixes, and 3.0 is not maintained anymore, so I removed them from the versions.  Usually it's enough to upload a single patch, especially if the fix is the same on all branches.
The patch should also include tests if possible.
Is also not necessary to add a comment when you add a file.

LGTM.

Patch LGTM to me too; someone can probably just commit it.

New changeset a169ee4f254a by Berker Peksag in branch '3.4':
Issue #16537: Check whether self.extensions is empty in setup.py.
https://hg.python.org/cpython/rev/a169ee4f254a

New changeset 491a4d3e2bdd by Berker Peksag in branch 'default':
Issue #16537: Check whether self.extensions is empty in setup.py.
https://hg.python.org/cpython/rev/491a4d3e2bdd

New changeset 6946036f21ef by Berker Peksag in branch '2.7':
Issue #16537: Check whether self.extensions is empty in setup.py.
https://hg.python.org/cpython/rev/6946036f21ef

Committed. Thanks for the patch, Jonathan!

You can use the default parameter of max() in 3.4+.

New changeset 1ef4e3a125bf by Berker Peksag in branch '3.4':
Issue #16537: Use the new *default* parameter of max().
https://hg.python.org/cpython/rev/1ef4e3a125bf

New changeset 37d896c3604a by Berker Peksag in branch 'default':
Issue #16537: Use the new *default* parameter of max().
https://hg.python.org/cpython/rev/37d896c3604a

assignee: berker.peksag
versions: + Python 3.5, - Python 3.2, Python 3.3
nosy: + berker.peksag

messages: + msg227719
resolution: fixed
stage: commit review -> resolved

messages: + msg216194
stage: patch review -> commit review

messages: + msg176187
title: setup.py throws a ValueError when self.extensions is empty -> Python’s setup.py raises a ValueError when self.extensions is empty

messages: + msg176148

stage: patch review

messages: + msg176147

messages: + msg176146

messages: + msg176145

messages: + msg176144

messages: + msg176143