[libc++] Test suite adjustments on macOS (#95835)

This patch makes a few adjustments to the way we run the tests in the
Apple configuration on macOS:

First, we stop using DYLD_LIBRARY_PATH. Using that environment variable
leads to libc++.dylib being replaced by the just-built one for the whole
process, and that assumes compatibility between the system-provided
dylib and the just-built one. Unfortunately, that is not the case
anymore due to typed allocation, which is only available in the system
one. Instead, we want to layer the just-built libc++ on top of the
system-provided one, which seems to be what happens when we set a rpath
instead.

Second, add a missing XFAIL for a std::print test that didn't work as
expected when building with availability annotations enabled. When we
enable these annotations, std::print falls back to a non-unicode and
non-terminal output, which breaks the test.

Author: ldionne

libcxx/cmake/caches/Apple.cmake

@@ -15,6 +15,3 @@ set(LIBCXXABI_HERMETIC_STATIC_LIBRARY ON CACHE BOOL "")
 set(LIBCXXABI_ENABLE_ASSERTIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_FORGIVING_DYNAMIC_CAST ON CACHE BOOL "")
 set(LIBCXXABI_USE_LLVM_UNWINDER OFF CACHE BOOL "") # libunwind is built separately
-
-set(LIBCXX_TEST_CONFIG "apple-libc++-shared.cfg.in" CACHE STRING "")
-set(LIBCXXABI_TEST_CONFIG "apple-libc++abi-shared.cfg.in" CACHE STRING "")

libcxx/test/configs/apple-libc++-shared.cfg.in

@@ -11,6 +11,11 @@
 
 // XFAIL: availability-fp_to_chars-missing
 
+// When std::print is unavailable, we don't rely on an implementation of
+// std::__is_terminal and we always assume a non-unicode and non-terminal
+// output.
+// XFAIL: availability-print-missing
+
 // Clang modules do not work with the definiton of _LIBCPP_TESTING_PRINT_IS_TERMINAL
 // XFAIL: clang-modules-build
 // <ostream>

libcxx/test/libcxx/input.output/iostream.format/output.streams/ostream.formatted/ostream.formatted.print/vprint_unicode.pass.cpp

@@ -127,9 +127,9 @@ for arch in ${architectures}; do
                 -DCMAKE_OSX_ARCHITECTURES="${arch}" \
                 -DLIBCXXABI_LIBRARY_VERSION="${version}" \
                 -DLIBCXX_LIBRARY_VERSION="${version}" \
-                -DLIBCXX_TEST_PARAMS="target_triple=${target}" \
-                -DLIBCXXABI_TEST_PARAMS="target_triple=${target}" \
-                -DLIBUNWIND_TEST_PARAMS="target_triple=${target}"
+                -DLIBCXX_TEST_PARAMS="target_triple=${target};stdlib=apple-libc++" \
+                -DLIBCXXABI_TEST_PARAMS="target_triple=${target};stdlib=apple-libc++" \
+                -DLIBUNWIND_TEST_PARAMS="target_triple=${target};stdlib=apple-libc++"
 
     if [ "$headers_only" = true ]; then
         xcrun cmake --build "${build_dir}/${arch}" --target install-cxx-headers install-cxxabi-headers -- -v