64addd6521
This is the last PR that's needed (for now) to get libc++'s tests working with MSVC's STL. The ADDITIONAL_COMPILE_FLAGS machinery is very useful, but also very problematic for MSVC, as it doesn't understand most of Clang's compiler options. We've been dealing with this by simply marking anything that uses ADDITIONAL_COMPILE_FLAGS as FAIL or SKIPPED, but that creates significant gaps in test coverage. Fortunately, ADDITIONAL_COMPILE_FLAGS also supports "features", which can be slightly enhanced to send Clang-compatible and MSVC-compatible options to the right compilers. This patch adds the gcc-style-warnings and cl-style-warnings Lit features, and uses that to pass the appropriate warning flags to tests. It also uses TEST_MEOW_DIAGNOSTIC_IGNORED for a few local suppressions of MSVC warnings.
Test Naming and Directory Structure =================================== The directory structure for the unique_ptr class templates differs from the normal test directory naming conventions (e.g. matching the stable name in the standard). Instead of having a [unique.ptr.single] and [unique.ptr.runtime] directory, each containing their own tests, a single directory, "unique.ptr.class", contains both sets of tests. This allows the common behavior of the two unique_ptr specializations to be tested in the same place without duplication. Tests specific to [unique.ptr.single] have the suffix ".single.pass.cpp" and those specific to [unique.ptr.runtime] are named "*.runtime.pass.cpp". Tests for both specializations are named normally.