Question: I have a Numpy as a dependency in Poetry pyproject.toml file and it fails to install.  error: the clang compiler does not support 'faltivec', please use -maltivec and include altivec.h explicitly error: Command "clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk -DNPY_INTERNAL_BUILD=1 -DHAVE_NPY_CONFIG_H=1 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE=1 -D_LARGEFILE64_SOURCE=1 -DNO_ATLAS_INFO=3 -DHAVE_CBLAS -Ibuild/src.macosx-12-arm64-3.9/numpy/core/src/umath -Ibuild/src.macosx-12-arm64-3.9/numpy/core/src/npymath -Ibuild/src.macosx-12-arm64-3.9/numpy/core/src/common -Inumpy/core/include -Ibuild/src.macosx-12-arm64-3.9/numpy/core/include/numpy -Inumpy/core/src/common -Inumpy/core/src -Inumpy/core -Inumpy/core/src/npymath -Inumpy/core/src/multiarray -Inumpy/core/src/umath -Inumpy/core/src/npysort -I/Users/moo/Library/Caches/pypoetry/virtualenvs/dex-ohlcv-qY1n4duk-py3.9/include -I/opt/homebrew/Cellar/python@3.9/3.9.12/Frameworks/Python.framework/Versions/3.9/include/python3.9 -Ibuild/src.macosx-12-arm64-3.9/numpy/core/src/common -Ibuild/src.macosx-12-arm64-3.9/numpy/core/src/npymath -c numpy/core/src/multiarray/array_assign_scalar.c -o build/temp.macosx-12-arm64-3.9/numpy/core/src/multiarray/array_assign_scalar.o -MMD -MF build/temp.macosx-12-arm64-3.9/numpy/core/src/multiarray/array_assign_scalar.o.d -faltivec -I/System/Library/Frameworks/vecLib.framework/Headers" failed with exit status 1 [end of output] note: This error originates from a subprocess, and is likely not a problem with pip. ERROR: Failed building wheel for numpy Failed to build numpy   macOS Big Sur Python 3.9 installed through Homebrew  How to solve it? If I install Numpy with pip it installs fine.

Answer: Make sure you have OpenBLAS installed from Homebrew: brew install openblas  Then before running any installation script, make sure you tell your shell environment to use Homebrew OpenBLAS installation export OPENBLAS="$(brew --prefix openblas)" poetry install  If you get an error  File "/private/var/folders/tx/50wn88yd40v2_6_7fvfr98z00000gn/T/pip-build-env-uq7qd2ba/overlay/lib/python3.9/site-packages/wheel/bdist_wheel.py", line 252, in get_tag plat_name = get_platform(self.bdist_dir) File "/private/var/folders/tx/50wn88yd40v2_6_7fvfr98z00000gn/T/pip-build-env-uq7qd2ba/overlay/lib/python3.9/site-packages/wheel/bdist_wheel.py", line 48, in get_platform result = calculate_macosx_platform_tag(archive_root, result) File "/private/var/folders/tx/50wn88yd40v2_6_7fvfr98z00000gn/T/pip-build-env-uq7qd2ba/overlay/lib/python3.9/site-packages/wheel/macosx_libfile.py", line 356, in calculate_macosx_platform_tag assert len(base_version) == 2 AssertionError  This should have been fixed in the recent enough Python packaging tools. Make sure  Poetry is recent enough version Numpy is recent enough version Any dependency using Numpy, like Scipy or Pyarrrow are also the most recent version  For example in your pyproject.toml [tool.poetry.dependencies] # For Scipy compatibility python = ">=3.9,<3.11" scipy = "^1.8.0" pyarrow = "^7.0.0"  Even if this still fails you can try to preinstall scipy with pip before running poetry install in Poetry virtualenv (enter with poetry shell) This should pick up the precompiled scipy wheel. When the precompiled wheel is present, Poetry should not try to install it again and then fail it the build step. poetry shell pip install scipy  Collecting scipy Downloading scipy-1.8.0-cp39-cp39-macosx_12_0_arm64.whl (28.7 MB) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 28.7/28.7 MB 6.0 MB/s eta 0:00:00 Requirement already satisfied: numpy<1.25.0,>=1.17.3 in /Users/moo/Library/Caches/pypoetry/virtualenvs/dex-ohlcv-qY1n4duk-py3.9/lib/python3.9/site-packages (from scipy) (1.22.3) Installing collected packages: scipy Successfully installed scipy-1.8.0  After this run Poetry normally: poetry install