[bug] Incorrect macOS M1 arch value

Environment Details (include every applicable attribute)

• Operating System+version: macOS 12
• Compiler+version: Apple Clang 13
• Conan version: 1.49
• Python version: 3.10.4

Steps to reproduce (Include if Applicable)

conan profile new default --detect --force

Logs (Executed commands with output) (Include/Attach if Applicable)

[settings]
os=Macos
os_build=Macos
arch=armv8
arch_build=armv8
compiler=apple-clang
compiler.version=13
compiler.libcxx=libc++
build_type=Release
[options]
[build_requires]
[env]

i.e. arch_build=armv8

Meanwhile, CmakeFiles/3.23.2/CMakeSystem.cmake:

set(CMAKE_HOST_SYSTEM "Darwin-21.5.0")
set(CMAKE_HOST_SYSTEM_NAME "Darwin")
set(CMAKE_HOST_SYSTEM_VERSION "21.5.0")
set(CMAKE_HOST_SYSTEM_PROCESSOR "arm64")

set(CMAKE_SYSTEM "Darwin-21.5.0")
set(CMAKE_SYSTEM_NAME "Darwin")
set(CMAKE_SYSTEM_VERSION "21.5.0")
set(CMAKE_SYSTEM_PROCESSOR "arm64")

set(CMAKE_CROSSCOMPILING "FALSE")

set(CMAKE_SYSTEM_LOADED 1)

i.e. CMAKE_SYSTEM_PROCESSOR "arm64

and clang --version:

Apple clang version 13.1.6 (clang-1316.0.21.2.5)
Target: arm64-apple-darwin21.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

i.e. Target: arm64

Also, arm64 value is absent in the default settings.yml.

Using of armv8 instead of native arm64 does not match other tools and requires values mapping in build scripts.

[SSE4]

ARMv8 is an official architecture name, it’s used by official ARM documents (specificstions). AArch64 is an execution state (another one is AArch32). A64 is an instruction set corresponding to the AArch64. ARM64 is not an official name, but it’s wide-spread and synonimous to ARMv8. used in Apple world, as well as by some Linux distros. I understand it introduces a lot of headache and confusion, but I would stick to an officiial name, as it’s used besides Apple, but also for Linux, Windows, Android, etc.

[DmitrySokolov]

thanks for providing a concrete example.

It’s MWE. Actually, the usual method is to iterate through ${CMAKE_OSX_ARCHITECTURES}.

would not portable across systems

It should not be portable, it should be good enough to pass it to underlying native toolchain. Even on Windows it is good enough to pass vcvarsall.bat -host_arch=${CMAKE_SYSTEM_PROCESSOR}.

Other compilers on macOS

Which one? The vast majority use Apple-clang. It’s hard to use other compilers on macOS for other than “HelloWorld” apps.

or Android it mentions arm64-v8

Yep. Because it just pass it to underlying NDK.

The Qt mkspecs

Obsolete. The new Qt build system uses CMake, and follows CMake settings.

one would have to provide a mapping between …

Yep. We have to. Cause “You can’t just take it and pass it to …” ))