bpo-46602: Do not append conftest.c

[adanhawth]

The heredoc creation statements use >> to append conftest.c. This can cause
tricky build issues if the file is not correctly removed prior to its
name being reused (such name is reused several times for different
contextual tests during the build). One such result from appending may
cause #include <ac_nonexistent.h> to persist when testing to acquire
PLATFORM_TRIPLET. This can then lead to downstream issues concerning SOABI.

https://bugs.python.org/issue46602

[the-knights-who-say-ni]

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[arhadthedev]

You also need to change the corresponding lines of configure.ac (so both original configure.ac and generated configure are amended by this PR):

cpython/configure.ac

Lines 835 to 836 in bebaa95

	AC_MSG_CHECKING([for the platform triplet based on compiler characteristics])
	cat >> conftest.c <<EOF

cpython/configure.ac

Lines 1030 to 1031 in bebaa95

	AC_MSG_CHECKING([for the Android API level])
	cat >> conftest.c <<EOF

[ned-deily]

Thanks for the PR; the changes to configure.ac do not seem to present in it and those are more important than the auto-generated configure changes.

[arhadthedev]

@adanhawth Looking through a list of checks I noticed failed bedevere/news — No news entry in Misc/NEWS.d/next/ or "skip news" label found.

I forgot to say that you also need to add a short changelog entry using https://blurb-it.herokuapp.com/add_blurb. It can be, for example, Fix configure.ac so it fully regenerates conftest.c instead of appending to its previous content.

I cannot do it by myself because I have no push access to your PR, but it will look like this:

[ned-deily]

The changes look good to me. I gather from the comments that you have experienced "tricky build problems" as configure now stands. For that reason, I think it might be a good idea to add a NEWS item for this change since others might have also run into the problem, assuming the problem description can be meaningfully described in a few lines; see the description of blurb and blurb-it in the devguide.

[ned-deily]

@arhadthedev, sorry, I didn't see your comment before I made mine :)

[ned-deily]

Thanks again for the PR and congrats on your first cpython PR.

[adanhawth]

You're welcome. Thank you, both, for the timely feedback.