[runtimes] Officially deprecate the legacy testing configuration system

[ldionne]

Summary

Add a warning and tweak the release note to explain that the deprecation
targets libc++, libc++abi and libuwnind as well.

Also, as a fly-by, ensure that our CI runs the legacy testing configuration
for libc++, libc++abi and libunwind. This doesn't matter too much since
it's deprecated, but we might as well test it properly.

[ldionne]

@vvereschaka I was going through the CMake caches looking for variables that implied usage of the legacy testing configuration system, and clang/cmake/caches/CrossWinToARMLinux.cmake seems to contain several of those. Just making sure you don't miss this.

[vvereschaka]

Hi @ldionne. Got it, thank you! I'll check our cmake cache file out and remove any deprecated variables.

[ldionne]

In D126478#3540747, @vvereschaka wrote:

Hi @ldionne. Got it, thank you! I'll check our cmake cache file out and remove any deprecated variables.

FWIW, my expectation is that you would need a special configuration file to run your tests, and you'd configure CMake with something like:

-DLIBCXX_TEST_CONFIG="cross-win-linux.cfg.in" \
-DLIBCXXABI_TEST_CONFIG="cross-win-linux.cfg.in" \
-DLIBUNWIND_TEST_CONFIG="cross-win-linux.cfg.in"

Where cross-win-linux.cfg.in can be based on libcxx/test/configs/llvm-libc++-shared.cfg.in (and similarly for libc++abi and libunwind).

[ldionne]

Rebase. I will ship this if CI passes, since it's effectively non-breaking. It's just a heads up.

[vvereschaka]

@ldionne ,
I have checked out our cmake cache for win-to-linux cross builds and I found that we already use the "new-style" test configuration files all libs accordingly: llvm-libc++-static.cfg.in, llvm-libc++abi-static.cfg.in and llvm-libunwind-static.cfg.in. It works fine for the builds currently.
We provide <lib>_TARGET_INFO=libcxx.test.target_info.LinuxRemoteTI and <lib>_EXECUTOR cmake vars only for these configurations.
Actually, the tests work without <lib>_TARGET_INFO also, but because there is still an appropriate parameter I did keep them there just in case.

So, it looks fine for now I guess.

[ldionne]

In D126478#3541693, @vvereschaka wrote:

@ldionne ,
I have checked out our cmake cache for win-to-linux cross builds and I found that we already use the "new-style" test configuration files all libs accordingly: llvm-libc++-static.cfg.in, llvm-libc++abi-static.cfg.in and llvm-libunwind-static.cfg.in. It works fine for the builds currently.
We provide <lib>_TARGET_INFO=libcxx.test.target_info.LinuxRemoteTI and <lib>_EXECUTOR cmake vars only for these configurations.
Actually, the tests work without <lib>_TARGET_INFO also, but because there is still an appropriate parameter I did keep them there just in case.

So, it looks fine for now I guess.

Oh, awesome, thanks for checking! I have an upcoming patch that will remove some of your CMake variables. I'll ping you on the patch when I update it.

It will only land after we branch for LLVM 15.

libcxx/docs/ReleaseNotes.rst

- Previously, the C++ ABI library headers would be installed inside ``<prefix>/include/c++/v1``
   alongside the libc++ headers as part of building libc++. This is not the case anymore -- the
   ABI library is expected to install its headers where it wants them as part of its own build.
   Note that no action is required for most users, who build libc++ against libc++abi, since
   libc++abi already installs its headers in the right location. However, vendors building
   libc++ against alternate ABI libraries should make sure that their ABI library installs
   its own headers.
 
 - The legacy testing configuration is now deprecated and will be removed in the next release. For
-  most users, this should not have any impact. However, if you are testing libc++ in a configuration
-  or on a platform that used to be supported by the legacy testing configuration and isn't supported
-  by one of the configurations in ``libcxx/test/configs``, please reach out to the libc++ developers
-  to get your configuration supported officially.
+  most users, this should not have any impact. However, if you are testing libc++, libc++abi or
+  libunwind in a configuration or on a platform that used to be supported by the legacy testing
+  configuration and isn't supported by one of the configurations in ``libcxx/test/configs``,
+  ``libcxxabi/test/configs`` or ``libunwind/test/configs``, please move to one of those
+  configurations or define your own.

libcxx/test/configs/legacy.cfg.in

 import libcxx.test.format
 config.test_format = libcxx.test.format.CxxStandardLibraryTest()
 
 lit_config.note('Using configuration variant: {}'.format(config.configuration_variant))
 import libcxx.test.config
 configuration = libcxx.test.config.Configuration(lit_config, config)
 configuration.configure()
 configuration.print_config_info()
+
+lit_config.warning("This is a legacy testing configuration which will be removed in LLVM 16. "
+                   "Please use one of the configurations in libcxx/test/configs or define your own.")

libcxx/utils/ci/run-buildbot

bootstrapping-build)
     echo "+++ Running the libc++ and libc++abi tests"
     ${NINJA} -C "${BUILD_DIR}" check-runtimes
 
     echo "--- Installing libc++ and libc++abi to a fake location"
     ${NINJA} -C "${BUILD_DIR}" install-runtimes
 ;;
 legacy-test-config)
     clean
-    generate-cmake -DLIBCXX_TEST_CONFIG="legacy.cfg.in"
+    generate-cmake -DLIBCXX_TEST_CONFIG="legacy.cfg.in" \
+                   -DLIBCXXABI_TEST_CONFIG="${MONOREPO_ROOT}/libcxxabi/test/lit.site.cfg.in" \
+                   -DLIBUNWIND_TEST_CONFIG="${MONOREPO_ROOT}/libunwind/test/lit.site.cfg.in"
     check-runtimes
 ;;
 legacy-project-build)
     clean
 
     echo "--- Generating CMake"
     ${CMAKE} \
           -S "${MONOREPO_ROOT}/llvm" \

libcxxabi/test/lit.site.cfg.in

 import libcxx.test.format
 config.test_format = libcxx.test.format.CxxStandardLibraryTest()
 
 lit_config.note('Using configuration variant: libcxxabi')
 import libcxxabi.test.config
 configuration = libcxxabi.test.config.Configuration(lit_config, config)
 configuration.configure()
 configuration.print_config_info()
+
+lit_config.warning("This is a legacy testing configuration which will be removed in LLVM 16. "
+                   "Please use one of the configurations in libcxxabi/test/configs or define your own.")

libunwind/test/lit.site.cfg.in

 import libcxx.test.format
 config.test_format = libcxx.test.format.CxxStandardLibraryTest()
 
 lit_config.note('Using configuration variant: libunwind')
 import libunwind.test.config
 configuration = libunwind.test.config.Configuration(lit_config, config)
 configuration.configure()
 configuration.print_config_info()
+
+lit_config.warning("This is a legacy testing configuration which will be removed in LLVM 16. "
+                   "Please use one of the configurations in libunwind/test/configs or define your own.")