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[Python-Dev] Assertion in _PyManagedBuffer_FromObject()

Stefan Krah stefan at bytereef.org
Sun Mar 4 12:33:29 CET 2012 
Thomas Wouters <thomas at python.org> wrote:
> Do you test against pydebug builds of Python, or otherwise a build that
> actually enables asserts?

Yes, I do (and much more than that):

http://hg.python.org/features/cdecimal/file/40917e4b51aa/Modules/_decimal/python/runall-memorydebugger.sh
http://hg.python.org/features/cdecimal/file/40917e4b51aa/Modules/_decimal/python/runall.bat

It's automated, so it's not a big deal. You get 100% coverage, with and without
threads, all machine configurations, pydebug, refleaks, release build and
release build with Valgrind.

The version on PyPI has had the same tests for a long time (i.e. also
before I became involved with core development).


> Because I suspect most people don't, so they don't trigger the assert.
> Python is normally (that is, a release build on Windows or a regular,
> non-pydebug build on the rest) built without asserts. Asserts are
> disabled by the NDEBUG symbol, which Python passes for regular builds.

If many C-extension authors don't know the benefits of --with-pydebug and
the consensus here is to protect these authors and their users, then of
course I agree with the exception approach for a (now hypothetical) API
change.


I would have some comments about valid uses of explicit aborts in a library
that essentially perform the same function as compiling said library with
-D_FORTIFY_SOURCE=2 and -ftrapv (i.e. crash when an external program violates
a function contract), but I suspect that would be OT now.


Stefan Krah
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