Failure to build with MACOSX_DEPLOYMENT_TARGET=11 on Big Sur

[fxcoudert]

BPO	42504
Nosy	@ronaldoussoren, @ned-deily, @ambv, @mattip, @miss-islington, @fxcoudert, @lonnylot
PRs	bpo-42504: fix for MACOSX_DEPLOYMENT_TARGET=11 #23556 [3.9] bpo-42504: fix for MACOSX_DEPLOYMENT_TARGET=11 (GH-23556) #23622 bpo-42504: Ensure that get_config_var('MACOSX_DEPLOYMENT_TARGET') is a string #24341 [3.9] bpo-42504: Ensure that get_config_var('MACOSX_DEPLOYMENT_TARGET') is a string (GH-24341) #24410 [3.8] bpo-41100: Support macOS 11 Big Sur and Apple Silicon Macs #25806

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2021-05-02.09:31:51.401>
created_at = <Date 2020-11-29.15:16:04.604>
labels = ['OS-mac', 'build', '3.8', '3.9', '3.10']
title = 'Failure to build with MACOSX_DEPLOYMENT_TARGET=11 on Big Sur'
updated_at = <Date 2021-05-02.09:31:51.401>
user = 'https://github.com/fxcoudert'

bugs.python.org fields:

activity = <Date 2021-05-02.09:31:51.401>
actor = 'ned.deily'
assignee = 'none'
closed = True
closed_date = <Date 2021-05-02.09:31:51.401>
closer = 'ned.deily'
components = ['Build', 'macOS']
creation = <Date 2020-11-29.15:16:04.604>
creator = 'fxcoudert'
dependencies = []
files = []
hgrepos = []
issue_num = 42504
keywords = ['patch']
message_count = 16.0
messages = ['382071', '382116', '382371', '382372', '382402', '382420', '382439', '382440', '382442', '382789', '385502', '385715', '385718', '386053', '386054', '392681']
nosy_count = 7.0
nosy_names = ['ronaldoussoren', 'ned.deily', 'lukasz.langa', 'mattip', 'miss-islington', 'fxcoudert', 'lonnylot']
pr_nums = ['23556', '23622', '24341', '24410', '25806']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'compile error'
url = 'https://bugs.python.org/issue42504'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

[fxcoudert]

With macOS Big Sur (11.y.z), the major version is 11 (instead of the earlier 10.15, 10.14, etc). Therefore, MACOSX_DEPLOYMENT_TARGET=11 has become a valid setting. It is accepted by system tools:

$ MACOSX_DEPLOYMENT_TARGET=11 clang a.c && echo $?
0

But it leads to failure in Python compilation in setup.py:

DYLD_FRAMEWORK_PATH=/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0 CC='clang' LDSHARED='clang -bundle -undefined dynamic_lookup -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk   ' OPT='-DNDEBUG -g -fwrapv -O3 -Wall'   _TCLTK_INCLUDES='' _TCLTK_LIBS=''       ./python.exe -E ./setup.py  build
running build
running build_ext
Traceback (most recent call last):
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/./setup.py", line 2614, in <module>
    main()
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/./setup.py", line 2584, in main
    setup(# PyPI Metadata (PEP 301)
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/Lib/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/Lib/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/Lib/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/Lib/distutils/command/build.py", line 135, in run
    self.run_command(cmd_name)
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/Lib/distutils/cmd.py", line 313, in run_command
    self.distribution.run_command(command)
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/Lib/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/Lib/distutils/command/build_ext.py", line 340, in run
    self.build_extensions()
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/./setup.py", line 470, in build_extensions
    self.detect_modules()
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/./setup.py", line 1807, in detect_modules
    self.detect_readline_curses()
  File "/private/tmp/python@3.9-20201127-81873-q9b09s/Python-3.9.0/./setup.py", line 1038, in detect_readline_curses
    (tuple(int(n) for n in dep_target.split('.')[0:2])
AttributeError: 'int' object has no attribute 'split'
make: *** [sharedmods] Error 1

See the full report here: Homebrew/brew#9329

The problem is here: https://github.com/python/cpython/blob/master/setup.py#L1015
When MACOSX_DEPLOYMENT_TARGET=11, this call:
sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET')
returns an int (with value 11) instead of a string (as is the case if 11.0, 10.15, etc).

And therefore the subsequent call to: dep_target.split('.')[0:2] fails, because split() cannot be called on an int.

[ronaldoussoren]

Good catch.

[ned-deily]

New changeset 5291639 by FX Coudert in branch 'master':
bpo-42504: fix for MACOSX_DEPLOYMENT_TARGET=11 (GH-23556)
5291639