Xcode: command line tools only version detection prevents pip install

[StevenACoffman]

When installing this library with only the XCode command line tools installed (xcode-select --install), setup.py fails without the full XCode installed, but the error is confusing and doesn't explain the cause.

In https://github.com/ronaldoussoren/pyobjc/blob/master/pyobjc-framework-AddressBook/pyobjc_setup.py#L473 (and all the similar places) when you are most likely on a system with the Xcode command line tools installed (without the full XCode) the following command is executed and the output is then parsed for the version number:

/usr/bin/xcrun -sdk macosx --show-sdk-path

This output will then fail to yield a parseable numeric version value:

/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk

However, this is the correctly parseable output with a full XCode installed:

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk

When only the command line tools are installed, you can still find the numeric XCode version this way:

pkgutil --pkg-info=com.apple.pkg.CLTools_Executables

Which will output:

package-id: com.apple.pkg.CLTools_Executables
version: 13.4.0.0.1.1651278267
volume: /
location: /
install-time: 1654038856
groups: com.apple.FindSystemFiles.pkg-group

You can also run xcode-select -p: which will output on a machine that only has the X Code command line tools:

/Library/Developer/CommandLineTools

but on a machine that has the full XCode will output:

/Applications/Xcode.app/Contents/Developer

**# Xcode version output output bash
This is a hacky way to look up the version in bash:

if pkgutil --pkgs=com.apple.pkg.Xcode >/dev/null; then
    echo Xcode: $(pkgutil --pkg-info=com.apple.pkg.Xcode | awk '/version:/ {print $2}')
else
    echo Xcode: not installed
fi

# Command Line Tools for Xcode
if pkgutil --pkgs=com.apple.pkg.CLTools_Executables >/dev/null; then
    echo CommandLineTools: $(pkgutil --pkg-info=com.apple.pkg.CLTools_Executables | awk '/version:/ {print $2}')
else
    echo CommandLineTools: not installed
fi

[ronaldoussoren]

The code you reference primarily looks for SDKSettings.plist in the SDK to determine the SDK version, extracting the SDK version from the filesystem path is a fallback for older systems.

That code is not looking for the Xcode version, but for the SDK version (e.g. which OS version is this SDK for).

I guess I'll have to spin up a VM where I can install the command-line tools to check what's going on here.

[StevenACoffman]

I encountered the problem when I was trying to install pyobjc's very old version 5.3 on Python 2.7 on a new M1 laptop to run a legacy program, and the latest version of the pyobjc_setup.py code has changed, so this may not be an issue anymore. I hacked up a local fork to hard code the version number and was able to install that way.

if this is not an issue for modern versions of pyobjc pyobjc_setup.py, then feel free to close and ignore this, but I thought I would mention it in case it is helpful to you or others.