Bug: macOS build instructions use unavailable nproc command #1959

Describe the bug

Problem

The CPython Developer's Guide currently instructs contributors to compile CPython using the following command in getting-started/setup-building.rst, under the Unix build instructions:

make -s -j $(nproc)

However, nproc is a GNU coreutils utility that is not available by default on macOS.

When a contributor follows these instructions on a standard macOS installation, the shell reports:

zsh: command not found: nproc

As a result, the command substitution produces an empty string, effectively executing:

make -s -j

Without an explicit job count, GNU Make allows unlimited parallel jobs. This can result in excessive resource consumption during compilation.

Expected Behaviour

The build instructions should provide a macOS-compatible command that determines the available logical CPU count without requiring additional utilities.

Proposed Solution

Introduce separate Unix and macOS tabs for the compilation command, following the existing documentation conventions in:

• getting-started/quick-reference.rst
• development-tools/sanitizers.rst

Keep the existing Unix command:

make -s -j $(nproc)

For macOS, use:

make -s -j $(sysctl -n hw.logicalcpu)

This would allow macOS contributors to build CPython using the available logical CPU count without installing GNU coreutils.

Additional Context

A similar macOS compatibility issue was previously addressed in PR #1545, where nproc was replaced with a fixed job count in another section of the documentation.

However, the primary compilation instructions still contain the incompatible command.

This issue proposes applying the existing macOS-specific approach consistently to the main build instructions.

Screenshots

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Additional context

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