Aer does not build on arm64 macs

[nonhermitian]

Informations

• Qiskit Aer version: 0.8.1 and earlier
• Python version: 3.9
• Operating system: OSX

What is the current behavior?

Building Aer natively for arm64 on OSX fails with the error (also see Qiskit/qiskit#1201):

-- Conan executing: /Users/paul/mambaforge/envs/qiskit/bin/conan install . -s build_type=Release -s compiler=apple-clang -s compiler.version=12.0 -s compiler.libcxx=libc++ -e=CONAN_CMAKE_PROGRAM=/Users/paul/Downloads/qiskit-aer-0.8.1/.eggs/cmake-3.18.4.post1-py3.9-macosx-10.9-arm64.egg/cmake/data/CMake.app/Contents/bin/cmake -g=cmake --build=missing
ERROR: Invalid setting 'arm64' is not a valid 'settings.arch' value.
Possible values are ['armv4', 'armv4i', 'armv5el', 'armv5hf', 'armv6', 'armv7', 'armv7hf', 'armv7k', 'armv7s', 'armv8', 'armv8.3', 'armv8_32', 'asm.js', 'avr', 'mips', 'mips64', 'ppc32', 'ppc32be', 'ppc64', 'ppc64le', 's390', 's390x', 'sh4le', 'sparc', 'sparcv9', 'wasm', 'x86', 'x86_64']
Read "http://docs.conan.io/en/latest/faq/troubleshooting.html#error-invalid-setting"
CMake Error at cmake/conan.cmake:402 (message):
  Conan install failed='1'

Steps to reproduce the problem

Try to build

What is the expected behavior?

Aer builds

Suggested solutions

[mtreinish]

On top of the conan issue, which we might be able to workaround with disabling conan (set the environment variable DISABLE_CONAN=1) and installing the required libs manually, there is an issue with scikit-build that will block actually building aer when it gets to that part.

I've been planning to add a wheel job for this (similar to Qiskit/qiskit#6252) but am blocked because scikit-build doesn't work for cross-builds on macOS (if ignores the architecture flags set and hard codes x86_64 when it calls cmake) there is an issue and PR someone opened to fix scikit-build but until that PR merges and is included in a scikit-build release adding arm64 macOS builds will be blocked.

[vvilpas]

It seems Conan should correctly detect M1 Macs since version 1.34.0. Can you update conan to check if it works with M1 Macs (pip install -U conan)?

[nonhermitian]

So I think that resolved the conan issue, but then one hits another:

Compiling the CXX compiler identification source file "CMakeCXXCompilerId.cpp" failed.
Compiler: /Library/Developer/CommandLineTools/usr/bin/c++ 
Build flags: 
Id flags:  

The output was:
1
ld: library not found for -lc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)


Compiling the C compiler identification source file "CMakeCCompilerId.c" failed.
Compiler: /Library/Developer/CommandLineTools/usr/bin/cc 
Build flags: 
Id flags:  

The output was:
1
ld: library not found for -lSystem
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I am using the default Xcode compiler:

Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: arm64-apple-darwin20.3.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

[nonhermitian]

scikit-build master now supports arm64 macs, but conan (I think) is trying to build a ton of dependencies from source and crashes on SciPy. Why it is trying to build SciPy is beyond me.

[vvilpas]

That shouldn't be happening. Can you post the full logs (Doing from a fresh clone VERBOSE=1 python ./setup.py bdist_wheel 2>&1|tee build.log) ?

[vvilpas]

Closing this one. Check #1286