Do not build Programs/_freeze_importlib when cross-compiling

[thp]

BPO	27641
Nosy	@xdegaye, @vadmium, @moreati, @thp
Files	python-freeze-importlib-cross-compiling.patch: Only build Programs/_freeze_importlib when it is going to be used comment-out-regen.patch

^{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 2016-08-04.04:12:12.030>
created_at = <Date 2016-07-28.11:04:44.797>
labels = ['type-bug', 'build']
title = 'Do not build Programs/_freeze_importlib when cross-compiling'
updated_at = <Date 2016-08-04.04:12:12.028>
user = 'https://github.com/thp'

bugs.python.org fields:

activity = <Date 2016-08-04.04:12:12.028>
actor = 'martin.panter'
assignee = 'none'
closed = True
closed_date = <Date 2016-08-04.04:12:12.030>
closer = 'martin.panter'
components = ['Cross-Build']
creation = <Date 2016-07-28.11:04:44.797>
creator = 'thomas.perl'
dependencies = []
files = ['43920', '43933']
hgrepos = []
issue_num = 27641
keywords = ['patch']
message_count = 8.0
messages = ['271519', '271606', '271647', '271737', '271760', '271936', '271942', '271947']
nosy_count = 5.0
nosy_names = ['xdegaye', 'python-dev', 'martin.panter', 'Alex.Willmer', 'thomas.perl']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue27641'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6']

[thp]

Based on http://bugs.python.org/issue27490 and http://bugs.python.org/msg271495, here is a patch that makes sure Programs/_freeze_importlib is only built when not cross-compiling.

[vadmium]

Here is another possible option. It is still a bit of a hack, because the configure script inserts comments into the makefile, but this is already done e.g. with @EXPORT_MACOSX_DEPLOYMENT_TARGET@. The advantage is we get to keep the filenames of the dependencies in the makefile, so it should be easier to read and maintain. And we get to eliminate the $(cross_compiling) check as well.

In native compiling mode, everything should be as normal. When cross-compiling, the rules for regenerating files should read like

Python/importlib.h: # $(srcdir)/Lib/importlib/_bootstrap.py Programs/_freeze_importlib
./Programs/_freeze_importlib \
$(srcdir)/Lib/importlib/_bootstrap.py Python/importlib.h

Since the Python/importlib.h should already exist, the rule in this form (dependencies commented out) won’t be run, and Make won’t need to build Programs/_freeze_importlib either.

[xdegaye]

Nice.

FWIW cross-compilation for Android works fine with comment-out-regen.patch.

In native compiling mode, everything should be as normal. When cross-compiling, the rules for regenerating files should read like

Python/importlib.h: # $(srcdir)/Lib/importlib/_bootstrap.py Programs/_freeze_importlib
./Programs/_freeze_importlib \
$(srcdir)/Lib/importlib/_bootstrap.py Python/importlib.h

They do read like this.

[thp]

+1 on comment-out-regen.patch, makes things much cleaner and removes the shell "if" in the rule body.

Just a small bikeshed issue: Instead of COMMENT_REGEN, maybe call it "CROSS_COMPILE_COMMENT" or "GENERATED_COMMENT" or "COMMENT_IF_CROSS" or somesuch? This way, might be easier to read/understand the makefile rules ("COMMENT_IF_CROSS" -> "a comment character will be inserted here if cross-compiling")?

[vadmium]

Thanks for the feedback. I did wonder about the name. Perhaps I will go with GENERATED_COMMENT:

GENERATED_COMMENT='#'

Python/importlib_external.h: @GENERATED_COMMENT@ $(srcdir)/Lib/importlib/_bootstrap_external.py Programs/_freeze_importlib

[python-dev]

New changeset bc677cb34889 by Martin Panter in branch '3.5':
Issue bpo-27641: Comment out regeneration rules when cross compiling
https://hg.python.org/cpython/rev/bc677cb34889

New changeset fc034d3607a8 by Martin Panter in branch 'default':
Issue bpo-27641: Merge cross-compiling improvement from 3.5
https://hg.python.org/cpython/rev/fc034d3607a8

[python-dev]

New changeset e3757f3e1848 by Martin Panter in branch '2.7':
Issue bpo-27641: Comment out regeneration rules when cross compiling
https://hg.python.org/cpython/rev/e3757f3e1848

[vadmium]

_freeze_import is only in Python 3, but I backported my final change because it is more general and also affects pgen.