This is to modify a list of libcxx tests written under the assumption
that iterators for std::array, std::string_view, and std::string are
pointers. The motivation for this PR is to make the tests more universal
and potentially being used to test other C++ standard library
implementations, for example
[microsoft/STL](https://github.com/microsoft/STL).
I can confirm that this patch makes a number of tests compatible with
microsoft STL:
`Failed : 204 (2.12%)` -> `Failed : 136 (1.42%)`
, and does not break any tests on `libcxx`.
This is not a complete list of such incompatibilities, but I am hoping
this will start a discussion about whether we are open to accepting such
changes.
When we ship LLVM 16, <ranges> won't be considered experimental anymore.
We might as well do this sooner rather than later.
Differential Revision: https://reviews.llvm.org/D132151
All supported compilers that support C++20 now support concepts. So, remove
`_LIB_LIBCPP_HAS_NO_CONCEPTS` in favor of `_LIBCPP_STD_VER > 17`. Similarly in
the tests, remove `// UNSUPPORTED: libcpp-no-concepts`.
Differential Revision: https://reviews.llvm.org/D121528
