Drop support of MS-DOS (DJGPP compiler)

[vstinner]

BPO	22591
Nosy	@pitrou, @vstinner, @serhiy-storchaka
Files	drop_msdos_support.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 2014-10-10.09:57:04.399>
created_at = <Date 2014-10-09.21:15:43.717>
labels = []
title = 'Drop support of MS-DOS (DJGPP compiler)'
updated_at = <Date 2014-10-10.09:57:04.398>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2014-10-10.09:57:04.398>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2014-10-10.09:57:04.399>
closer = 'vstinner'
components = []
creation = <Date 2014-10-09.21:15:43.717>
creator = 'vstinner'
dependencies = []
files = ['36856']
hgrepos = []
issue_num = 22591
keywords = ['patch']
message_count = 8.0
messages = ['228913', '228916', '228920', '228922', '228924', '228974', '228975', '228976']
nosy_count = 5.0
nosy_names = ['pitrou', 'vstinner', 'Arfrever', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue22591'
versions = ['Python 3.5']

[vstinner]

In the C code of Python 3.5, there are still preprocessor commands checking for defines:

• __BORLANDC__: Borland C compiler
• __WATCOMC__: Watcom C compiler
• __DJGPP__: MS-DOS port of GCC

In 2014, it's time to drop this old code. OS/2 support was already removed in Python 3.4 (see the PEP-11).

I'm quite sure that Python 3.5 cannot be compiled on MS-DOS and/or will not work on MS-DOS. I don't think that anyone tried Python 3 on MS-DOS. The MS-DOS support was simply inherited from Python 2, Python 3 source code is based on Python 2.

I don't want to drop support of custom compilers, only removing code specific to MS-DOS, see:
http://bugs.python.org/issue22579#msg228908

[serhiy-storchaka]

AFAIK Borland and Watcom compilers supported Windows.

[vstinner]

AFAIK Borland and Watcom compilers supported Windows.

It looks like Borland C++ Builder 5.5 was released in 2000, 14 years ago. Yes, it supports Windows and MS-DOS, but do we really want to support this very old proprietary compiler?

For Watcom, it's a different story. The compiler was released under an open source license. It's now hosted at github and the project is actively developed (last commit a few hours ago):
https://github.com/open-watcom/open-watcom-v2/

It would be interesting to support OpenWatcom compiler on Windows to not depend on the proprietary Microsoft compiler.

[pitrou]

AFAIK Borland and Watcom compilers supported Windows.

AFAIU Victor only proposes to remove the MSDOS-specific conditionals. But it's hard to tell, since he didn't post a patch ;-)

[vstinner]

Here is my huge patch :-) It only changes osdefs.h.

In fact, I expected more code checking for __DJGPP__.

For __WATCOMC__, it's unclear for me yet if the code is specific to MS-DOS or to the Watcom compiler. For example, timemodule.c includes <i86.h> to get the delay() function. On Linux, I would prefer to use select(), on Windows, I would prefer to use the Windows code. We should check if OpenWatcom provides select() on Linux. I'm trying to build OpenWatcom for this ;)

I created the issue bpo-22592 to propose to drop the support of the Borland C compiler.

[vstinner]

I hope that "MS_WINDOWS" is also defined when Python is compiled by the Borland C compiler or OpenWatcom. IMO if it's not the case, it's a bug and it should be fixed.

It means that my patch drop_msdos_support.patch only drops support for the DJGPP compiler in fact. DJGPP is (was) the MS-DOS port of GCC.

So, what do you think of drop_msdos_support.patch? Is it ok for Python 3.5?

[pitrou]

Yes!

[python-dev]

New changeset a1605d2508af by Victor Stinner in branch 'default':
Issue bpo-22591: Drop support of MS-DOS
https://hg.python.org/cpython/rev/a1605d2508af