Re: testsuite: introduce hostedlib effective target

[Alexandre Oliva <oliva@adacore.com>]

[adding libstdc++@]

On Nov  5, 2023, Mike Stump <mikestump@comcast.net> wrote:

> Ick.

Indeed ;-)

> I wish there were fewer changed lines and not 1 per test
> case. It feels like we've painted ourselves into a corner.

The libstdc++ testsuite took a different approach, detecting missing
headers (and libraries?) at error pruning time, and xfailing the tests,
which seems to be more in line with what you are looking for.

That approach, though more expedient, seems more fragile to me, in that
an actual bug that caused headers to go missing would cause tests to be
silently skipped rather than fail.

I expect the set of headers, and thus of affected tests, won't by very
dynamic, so it's kind of a one-shot change.

Of course new tests might be added that rely on such headers, and would
likely go unnoticed until someone tries them on a non-hosted libstdc++.
We could alleviate this if libstdc++ headers that are not installed on
hosted systems issued a warning (conditional on some macro defined by
the testsuite, say -D_GLIBCXX_WARN_HOSTED_ONLY).  For tests aimed
exclusively at hosted libstdc++, we'd then use a dg directive that both
implied this requirement, and changed the macro definition to suppress
the warning.  Then anyone who added a testcase that included hosted
headers without indicating its hostedlib requirement would get a fail
even when testing with a hosted libstdc++.

-- 
Alexandre Oliva, happy hacker            https://FSFLA.org/blogs/lxo/
   Free Software Activist                   GNU Toolchain Engineer
More tolerance and less prejudice are key for inclusion and diversity
Excluding neuro-others for not behaving ""normal"" is *not* inclusive