distutils default compiler API is incomplete

[stefanseefeld]

BPO	26033
Nosy	@stefanseefeld, @merwok, @dstufft

^{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 2020-10-22.21:46:33.795>
created_at = <Date 2016-01-07.00:32:48.646>
labels = ['type-bug', 'library']
title = 'distutils default compiler API is incomplete'
updated_at = <Date 2020-10-22.21:46:33.795>
user = 'https://github.com/stefanseefeld'

bugs.python.org fields:

activity = <Date 2020-10-22.21:46:33.795>
actor = 'eric.araujo'
assignee = 'none'
closed = True
closed_date = <Date 2020-10-22.21:46:33.795>
closer = 'eric.araujo'
components = ['Distutils']
creation = <Date 2016-01-07.00:32:48.646>
creator = 'stefan'
dependencies = []
files = []
hgrepos = []
issue_num = 26033
keywords = []
message_count = 2.0
messages = ['257663', '379363']
nosy_count = 3.0
nosy_names = ['stefan', 'eric.araujo', 'dstufft']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue26033'
versions = ['Python 2.7', 'Python 3.5']

[stefanseefeld]

I'm trying to use the distutil compiler to preprocess some header (to be used with the cffi package).
The code is

    compiler = distutils.ccompiler.new_compiler()
    compiler.add_include_dir(join(sys.prefix, 'include'))
    compiler.preprocess(source)

This raises this exception (on Linux):

File ".../distutils/unixccompiler.py", line 88, in preprocess
pp_args = self.preprocessor + pp_opts
TypeError: unsupported operand type(s) for +: 'NoneType' and 'list'

caused by 'set.preprocessor' to be set to None (with the preceding comment:

# The defaults here
# are pretty generic; they will probably have to be set by an outsider
# (eg. using information discovered by the sysconfig about building
# Python extensions).

Seems that code never got fully implemented.
Further, the MSVC version of the compiler (msvccompiler.py) doesn't even implement a "preprocess()" method, so this falls back to the CCompiler.preprocess() default, which does nothing !

[merwok]

Distutils does not evolve anymore — if CFFI still needs something like this, I think it should build on setuptools and request features there.