On Tue, 7 Nov 2023 at 10:04, Alexandre Oliva <ol...@adacore.com> wrote: > > [adding libstdc++@] > > On Nov 5, 2023, Mike Stump <mikest...@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 don't think we XFAIL based on missing headers. We XFAIL based on a specific #error message in certain headers. If a header goes missing, we'll still XFAIL. > > 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++. Since GCC 13 you don't need to build a non-hosted libstdc++ to test it, you can just add -ffreestanding to the runtestflags. > 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). That's exactly what happens (except #error not #warning) when you compile with -ffreestanding. > 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++. I don't think we need to add checks for a new macro and then use that when testing, you can just test with -ffreestanding instead. This already works today.
