Folly related build issue for ARM Ubuntu 18.04.5 LTS

[palabadiraphta]

Hello!!

I am having trouble building Watchman for Ubuntu 18.04.5 LTS running on ARM (Amazon EC2 t4g.X and Nvidia Jetson) I followed the steps listed on https://facebook.github.io/watchman/docs/install on watchman release/tag v2023.04.17.00. under the "build from source" section ... all seems to go well and fails in the ./autogen script with:

3/258] **Building CXX object CMakeFiles/folly_base.dir/folly/detail/SplitStringSimd.cpp.o FAILED: CMakeFiles/folly_base.dir/folly/detail/SplitStringSimd.cpp.o** /usr/bin/c++ -DFMT_LOCALE -DFOLLY_XLOG_STRIP_PREFIXES=\"/tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/repos/github.com-facebook-folly.git:/tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/build/folly\" -DGFLAGS_IS_A_DLL=0 -D_GNU_SOURCE -D_REENTRANT -I/tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/repos/github.com-facebook-folly.git -I. -I/tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/installed/zstd-8W66ne499tyG6JxX2P-odEpVDzvA2IOU0p2xqyMjyTw/include -I/tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/installed/fmt-p_48HiSrU8lUwJZFqGlh6cOutupL0o0PV17-5TCx_S4/include -O2 -g -DNDEBUG -g -std=gnu++1z -finput-charset=UTF-8 -fsigned-char -Wall -Wno-deprecated -Wno-deprecated-declarations -Wno-sign-compare -Wno-unused -Wuninitialized -Wunused-label -Wunused-result -Wshadow-compatible-local -Wno-noexcept-type -faligned-new -fopenmp -std=gnu++1z -MD -MT CMakeFiles/folly_base.dir/folly/detail/SplitStringSimd.cpp.o -MF CMakeFiles/folly_base.dir/folly/detail/SplitStringSimd.cpp.o.d -o CMakeFiles/folly_base.dir/folly/detail/SplitStringSimd.cpp.o -c /tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/repos/github.com-facebook-folly.git/folly/detail/SplitStringSimd.cpp In file included from /tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/repos/github.com-facebook-folly.git/folly/detail/SplitStringSimd.cpp:18:0: /tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/repos/github.com-facebook-folly.git/folly/detail/SplitStringSimdImpl.h: In static member function ‘static uint64_t folly::detail::StringSplitAarch64Platform::equal(folly::detail::StringSplitAarch64Platform::reg_t, char)’: /tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/repos/github.com-facebook-folly.git/folly/detail/SplitStringSimdImpl.h:129:44: note: use -flax-vector-conversions to permit conversions between vectors with differing element types or numbers of subparts return vget_lane_u64(vmovn_u16(u16s), 0); ^ /tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/repos/github.com-facebook-folly.git/folly/detail/SplitStringSimdImpl.h:129:44: error: cannot convert ‘uint8x8_t {aka __vector(8) unsigned char}’ to ‘uint64x1_t {aka __vector(1) long unsigned int}’ for argument ‘1’ to ‘uint64_t vget_lane_u64(uint64x1_t, int)’ [4/258] Building CXX object CMakeFiles/folly_base.dir/folly/detail/base64_detail/Base64SWAR.cpp.o ninja: build stopped: subcommand failed. Command '['/tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/installed/cmake-J-jQEVVitcB2L7F1RazoEEEDFP-zFFI00mpS-dD2XSE/bin/cmake', '--build', '/tmp/fbcode_builder_getdeps-ZhomeZssm-userZwatchman-2023.04.17.00ZbuildZfbcode_builder-root/build/folly', '--target', 'install', '--config', 'Release', '-j', '2']' returned non-zero exit status 1. !! Failed