[libcxx] [ci] Enable LIBCXX_ENABLE_WERROR where possible

[mstorsjo]

Summary

Only opt out from it in the few configs where there still are build
warnings.

[mstorsjo]

Also cc @philnik, regarding silencing GCC warnings.

[philnik]

I think you should put the -DLIBCXX_ENABLE_WERROR=NO in the cmake cache files. Why isn't there a cmake cache file for generic-gcc @ldionne?

[mstorsjo]

In D119573#3315185, @philnik wrote:

I think you should put the -DLIBCXX_ENABLE_WERROR=NO in the cmake cache files. Why isn't there a cmake cache file for generic-gcc @ldionne?

There’s probably none, because no specific configuration is needed.

I don’t think we should involve the cmake cache files regarding LIBCXX_ENABLE_WERROR overall. Also, I think a command line argument (when enabled in run-buildbot) overrides what’s set in a cache file.

And I don’t think we should be enabling that option anywhere in the cache files. When building libcxx with the intent of *using* the library, we don’t want LIBCXX_ENABLE_WERROR enabled, because if it builds successfully, it’s probably fine to use even if it produced warnings. Enabling it should be strictly a CI thing (and when developing the library , if such a setup is wanted).

[mstorsjo]

Rebase after fixing a missed instance of no_unique_address.

[Mordante]

In D119573#3315185, @philnik wrote:

I think you should put the -DLIBCXX_ENABLE_WERROR=NO in the cmake cache files.

I prefer not to for the reasons @mstorsjo mentioned. I love using -Werror, but I feel it should always be an opt-in.
I want to see the CI green before approving.

[mstorsjo]

In D119573#3317080, @Mordante wrote:

In D119573#3315185, @philnik wrote:

I think you should put the -DLIBCXX_ENABLE_WERROR=NO in the cmake cache files.

I prefer not to for the reasons @mstorsjo mentioned. I love using -Werror, but I feel it should always be an opt-in.
I want to see the CI green before approving.

Yep, I noticed that there were some more warnings in the Ryu code. (I had tested building with clang-cl for aarch64, where those warnings weren't present.) I'll soon post a patch that should silence them.

[Mordante]

LGTM, provided D119647 fixes the CI failures.

[mstorsjo]

Rebased on top of latest git main, now the clang-cl configs should be green.

libcxx/utils/ci/run-buildbot

 function generate-cmake-base() {
     echo "--- Generating CMake"
     ${CMAKE} \
           -S "${MONOREPO_ROOT}/runtimes" \
           -B "${BUILD_DIR}" \
           -GNinja -DCMAKE_MAKE_PROGRAM="${NINJA}" \
           -DCMAKE_BUILD_TYPE=RelWithDebInfo \
           -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}" \
+          -DLIBCXX_ENABLE_WERROR=YES \
           -DLLVM_LIT_ARGS="-sv --show-unsupported --xunit-xml-output test-results.xml" \
           "${@}"
 }
 
 function generate-cmake() {
     generate-cmake-base \
           -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" \
           -DLIBCXX_CXX_ABI=libcxxabi \
generate-cmake -DLIBCXX_TEST_CONFIG="llvm-libc++-shared.cfg.in" \
                    -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
     check-runtimes
 ;;
 generic-gcc)
     export CC=gcc-11
     export CXX=g++-11
     clean
     generate-cmake -DLIBCXX_TEST_CONFIG="llvm-libc++-shared-gcc.cfg.in" \
-                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
+                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in" \
+                   -DLIBCXX_ENABLE_WERROR=NO
     check-runtimes
 ;;
 generic-gcc-cxx11)
     export CC=gcc-11
     export CXX=g++-11
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-cxx11.cmake" \
                    -DLIBCXX_TEST_CONFIG="llvm-libc++-shared-gcc.cfg.in" \
-                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
+                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in" \
+                   -DLIBCXX_ENABLE_WERROR=NO
     check-runtimes
 ;;
 generic-asan)
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-asan.cmake" \
                    -DLIBCXX_TEST_CONFIG="llvm-libc++-shared.cfg.in" \
                    -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
     check-runtimes