Output from failed platform_triplet.c compilation is not logged

[jmroot]

Bug report

Bug description:

In #117886, building platform_triplet.c was failing, but the only output in config.log was:

configure:6892: checking for the platform triplet based on compiler characteristics
configure:6900: result: none

At least in the case of failure, the compile command and output should be logged.

CPython versions tested on:

3.13

Operating systems tested on:

macOS

[erlend-aasland]

Do you wish to propose a PR?

[jmroot]

I'm not really sure where to begin for this one, so I don't think I'll be able to propose a fix in the near future.

[erlend-aasland]

So, for this check, we pipe stderr into /dev/null and go on to fetch the platform triplet if the C preprocessor was successfully able to parse platform_triplet.c. If the C preprocessor failed, none is logged (as you noticed).

One thing to consider, is to fail early; that is use AC_MSG_ERROR instead of AC_MSG_RESULT for this case. I think this would be an improvement over the current behaviour.

We could also consider to pipe stderr into a file and dump that to stdout if the platform triplet check fails.