distutils's checking for MSVC compiler

[jwfang]

BPO	14708
Nosy	@loewis

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

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GitHub fields:

assignee = None
closed_at = <Date 2012-05-03.08:46:57.423>
created_at = <Date 2012-05-03.03:10:44.327>
labels = ['type-bug']
title = "distutils's checking for MSVC compiler"
updated_at = <Date 2012-05-03.08:46:57.421>
user = 'https://bugs.python.org/jwfang'

bugs.python.org fields:

activity = <Date 2012-05-03.08:46:57.421>
actor = 'loewis'
assignee = 'none'
closed = True
closed_date = <Date 2012-05-03.08:46:57.423>
closer = 'loewis'
components = []
creation = <Date 2012-05-03.03:10:44.327>
creator = 'jwfang'
dependencies = []
files = []
hgrepos = []
issue_num = 14708
keywords = []
message_count = 5.0
messages = ['159833', '159834', '159835', '159842', '159843']
nosy_count = 2.0
nosy_names = ['loewis', 'jwfang']
pr_nums = []
priority = 'normal'
resolution = 'works for me'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue14708'
versions = ['Python 2.7']

[jwfang]

I am using python 2.7.2 installed via the pre-built installer package, and my SDK version is v7.1.

1. The MSSdk environment variable is not set by lastest SDK's SetEnv.cmd anymore, but distutils still check for it.

2. I have also install MSVC 2010 Express Edition, and its vcvarsall.bat
   can't be found.

Off-side question:
a) Can i use different version of MSVC from which python is built for extension development ?
b) Can i use mingw compiler to develop extension for the pre-built windows binary python ?

[loewis]

1. The MSSdk environment variable is not set by lastest SDK's
   SetEnv.cmd anymore, but distutils still check for it.

This is intentional. Older SDKs still set the variable, so there
is nothing wrong with checking it.

2. I have also install MSVC 2010 Express Edition, and its
   vcvarsall.bat can't be found.

MSVC 2010 is not supported for building Python 2.7 extension modules.

a) Can i use different version of MSVC from which python is built for
extension development ?

No. Because of the way the MSVCRT works, this can cause crashes.

b) Can i use mingw compiler to develop extension for the pre-built
windows binary python ?

Yes, in principle. In practice, it may fail because of gcc limitations.

[jwfang]

Thanks for your replying.

Here is my understanding of how the compiler chosen logic works, correct me if i am wrong:

1. If using MSVC, we should ALWAYS stick the compiler to the version which python was compiled with;
2. But we can change SDK version through DISTUTILS_USE_SDK with SetEnv.cmd already called.
3. It's the compiler version that matters, not SDK version.

But from distutils source:

if "DISTUTILS_USE_SDK" in os.environ and "MSSdk" in os.environ and ...:
                                    ^^^^^
does this mean i can not use lastest SDK since it does not set MSSdk variable?

[loewis]

DISTUTILS_USE_SDK really means "shut up, I know what I'm doing". So if this is the case (i.e. you *really* know what you are doing), just set MsSdk as well.

I don't actually know whether the latest SDK is able to build correct extensions for Python 2.7 - I haven't looked at the latest SDK. It may be that MS stopped setting MsSdk for a reason.

[loewis]

In any case, it appears that there is no bug report in this issue, so I'm closing this as "works for me".