[libc-commits] [libc] [libc][math][c23] Temporarily disable float16 on 32-bit Arm (PR #95027)

[via libc-commits]

overmighty wrote:

> That buildbot link above isn't loading for me; do you recall what the error was, specifically?

It sends a request that 404's. After a recent Buildbot maintenance, builder IDs changed and we also lost all build logs.

I believe this was the error:

```
FAILED: projects/libc/test/src/math/libc.test.src.math.cosf_test.__unit__.__build__ 
: && /usr/bin/clang++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -g  projects/libc/test/src/math/CMakeFiles/libc.test.src.math.cosf_test.__unit__.__build__.dir/cosf_test.cpp.o -o projects/libc/test/src/math/libc.test.src.math.cosf_test.__unit__.__build__  projects/libc/src/errno/CMakeFiles/libc.src.errno.errno.__internal__.dir/./libc_errno.cpp.o  projects/libc/src/__support/OSUtil/linux/CMakeFiles/libc.src.__support.OSUtil.linux.linux_util.dir/./exit.cpp.o  projects/libc/src/math/generic/CMakeFiles/libc.src.math.generic.cosf.__internal__.dir/./cosf.cpp.o  projects/libc/src/__support/StringUtil/CMakeFiles/libc.src.__support.StringUtil.error_to_string.dir/./error_to_string.cpp.o  lib/liblibcMPFRWrapper.a  -lmpfr  -lgmp  lib/libLibcFPTestHelpers.unit.a  lib/libLibcDeathTestExecutors.unit.a  lib/libLibcTest.unit.a  -lmpfr  -lgmp && :
/usr/bin/arm-linux-gnueabihf-ld: lib/liblibcMPFRWrapper.a(MPFRUtils.cpp.o): in function `_Float16 __llvm_libc_19_0_0_git::testing::mpfr::MPFRNumber::as<_Float16>() const':
/llvm/libc_worker/worker/libc-arm32-debian/libc-arm32-debian-dbg/llvm-project/libc/utils/MPFRWrapper/MPFRUtils.cpp:606: undefined reference to `__aeabi_d2h'
/usr/bin/arm-linux-gnueabihf-ld: lib/liblibcMPFRWrapper.a(MPFRUtils.cpp.o): in function `void __llvm_libc_19_0_0_git::testing::mpfr::internal::explain_unary_operation_single_output_error<_Float16>(__llvm_libc_19_0_0_git::testing::mpfr::Operation, _Float16, _Float16, double, __llvm_libc_19_0_0_git::fputil::testing::RoundingMode)':
/llvm/libc_worker/worker/libc-arm32-debian/libc-arm32-debian-dbg/llvm-project/libc/utils/MPFRWrapper/MPFRUtils.cpp:606: undefined reference to `__aeabi_d2h'
/usr/bin/arm-linux-gnueabihf-ld: lib/liblibcMPFRWrapper.a(MPFRUtils.cpp.o): in function `_Float16 __llvm_libc_19_0_0_git::testing::mpfr::MPFRNumber::as<_Float16>() const':
/llvm/libc_worker/worker/libc-arm32-debian/libc-arm32-debian-dbg/llvm-project/libc/utils/MPFRWrapper/MPFRUtils.cpp:606: undefined reference to `__aeabi_d2h'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```

It was due to these changes:

https://github.com/llvm/llvm-project/pull/94383/files#diff-fddc5593e05324c6f1d04aac0c1b47cb5ebd02d8ab21e58c85e17f124ed5f963R602-R609

https://github.com/llvm/llvm-project/pull/95027