Some individual test files verify the CPO under test satisfies
`semiregular` concept. This is redundant since it is already part of the test
in verifying whether the entity is indeed a CPO in
`libcxx/test/std/library/description/conventions/customization.point.object/cpo.compile.pass.cpp`.
Differential Revision: https://reviews.llvm.org/D116173
Before this patch, the new test's `CountedInvocable<int*, int*>`
would hard-error instead of SFINAEing and cleanly returning false.
Notice that views::counted specifically does NOT work with pipes;
`counted(42)` is ill-formed. This is because `counted`'s first argument
is supposed to be an iterator, not a range.
Also, mark `views::counted(it, n)` as [[nodiscard]], and test that.
(We have a general policy now that range adaptors are consistently
marked [[nodiscard]], so that people don't accidentally think that
they have side effects. This matters mostly for `reverse` and
`transform`, arguably `drop`, and just generally let's be consistent.)
Differential Revision: https://reviews.llvm.org/D115177
Since we officially don't support several older compilers now, we can
drop a lot of the markup in the test suite. This helps keep the test
suite simple and makes sure that UNSUPPORTED annotations don't rot.
This is the first patch of a series that will remove annotations for
compilers that are now unsupported.
Differential Revision: https://reviews.llvm.org/D107787