[libc++][test] std/containers/views/mdspan/mdspan/conversion.pass.cpp Fails on PowerPC targets

[amy-kwan]

This test was introduced in https://reviews.llvm.org/D154367.

Assertion seen:

Command Output (stdout):
--
$ ":" "COMPILED WITH"
$ "/home/amyk/llvm/community/build/bootstrap/stage1/build/./bin/clang++" "/home/amyk/llvm/community/llvm-project/libcxx/test/std/containers/views/mdspan/mdspan/conversion.pass.cpp" "-pthread" "--target=powerpc64le-unknown-linux-gnu" "-nostdinc++" "-I" "/home/amyk/llvm/community/build/bootstrap/stage1/build/include/c++/v1" "-I" "/home/amyk/llvm/community/build/bootstrap/stage1/build/include/powerpc64le-unknown-linux-gnu/c++/v1" "-I" "/home/amyk/llvm/community/llvm-project/libcxx/test/support" "-std=c++26" "-Werror" "-Wall" "-Wctad-maybe-unsupported" "-Wextra" "-Wshadow" "-Wundef" "-Wunused-template" "-Wno-unused-command-line-argument" "-Wno-attributes" "-Wno-pessimizing-move" "-Wno-noexcept-type" "-Wno-atomic-alignment" "-Wno-reserved-module-identifier" "-Wno-user-defined-literals" "-Wno-tautological-compare" "-Wsign-compare" "-Wunused-variable" "-Wunused-parameter" "-Wunreachable-code" "-Wno-unused-local-typedef" "-Wno-local-type-template-args" "-Wno-c++11-extensions" "-Wno-unknown-pragmas" "-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER" "-D_LIBCPP_ENABLE_EXPERIMENTAL" "-Werror=thread-safety" "-Wuser-defined-warnings" "-lc++experimental" "-nostdlib++" "-L" "/home/amyk/llvm/community/build/bootstrap/stage1/build/./lib/powerpc64le-unknown-linux-gnu" "-Wl,-rpath,/home/amyk/llvm/community/build/bootstrap/stage1/build/./lib/powerpc64le-unknown-linux-gnu" "-lc++" "-o" "/home/amyk/llvm/community/build/bootstrap/stage1/build/runtimes/runtimes-bins/test/std/containers/views/mdspan/mdspan/Output/conversion.pass.cpp.dir/t.tmp.exe"
$ ":" "EXECUTED AS"
$ "/usr/bin/python3.8" "/home/amyk/llvm/community/llvm-project/libcxx/test/../utils/run.py" "--execdir" "/home/amyk/llvm/community/build/bootstrap/stage1/build/runtimes/runtimes-bins/test/std/containers/views/mdspan/mdspan/Output/conversion.pass.cpp.dir" "--" "/home/amyk/llvm/community/build/bootstrap/stage1/build/runtimes/runtimes-bins/test/std/containers/views/mdspan/mdspan/Output/conversion.pass.cpp.dir/t.tmp.exe"
# command stderr:
t.tmp.exe: /home/amyk/llvm/community/llvm-project/libcxx/test/std/containers/views/mdspan/mdspan/conversion.pass.cpp:87: void test_conversion(FromMDS) [ToMDS = std::mdspan<const int, std::extents<int>, std::layout_left, conv_test_accessor_c<int, false, true, true, true>>, FromMDS = std::mdspan<int, std::extents<int>, std::layout_left, conv_test_accessor_nc<int, true, true>>]: Assertion `to_mds.data_handle() == from_mds.data_handle()' failed.

error: command failed with exit status: 250

This issue occurs on both LLVM 17.0.0 rc1 and main.

[llvmbot]

@llvm/issue-subscribers-backend-powerpc

[amy-kwan]

@crtrott Just wanted to let you know that I have discovered this when testing libc++.

[crtrott]

This looks suspiciously simmilar to the MinGW issue reported by me #64077. I will have a look.

[crtrott]

We should try the godbolt example seen in #64077 on PowerPC and check whether it has the same issue there.

[crtrott]

I confirmed that the godbolt example https://godbolt.org/z/KK8aj5bs7 (minus the concept and span include which isn't needed) fails on PowerPC with Clang 14 too. No extra options needed just clang++ main.cpp -std=c++20; ./a.out will do it.

[mstorsjo]

https://reviews.llvm.org/D157332 has got a potential fix for this issue.