I've migrated the toolchain autoupdate scripts here, I just need a
little more time to do the explorer side (which I need to check
performance, that may require multithreading as we do in the current
script). However, this felt substantial enough to share and it means I
can handle autoupdate in more of the toolchain, including preparatory
work for autoupdate on multi-file tests.
Once explorer is done I'll remove the old script.
This is sufficient to convert remaining toolchain tests to file_test. %s
and %t are currently used. While #2978 might use %T with lit, I think
that's resolving a lit-specific issue that's not necessary when
TEST_TMPDIR is readily available for any necessary operations (i.e.,
setting the working directory). With ARGS, I think it's feasible to
switch to file_test without %T.
Also adds documentation to file_test_base.h, which was starting to feel
like a significant gap.
This is not yet handled by autoupdate, but I'm eyeing that next.