Summary:

This change addresses a compatibility issue arising from the use of the macOS-specific -X flag in the cp command withing a shell script called during the npm run ios command.

The -X flag prevents the copying of Extended Attributes and resource forks, which indeed prevents possible issues on macOS. However the flag is not supported by GNU's cp, commonly installed via homebrew on macOS systems, and usually added to the user's PATH.

This fix basically does a feature test to figure out if the -X flag is available, and only uses it is the test is positive.

The intended behavior of not copying Extended Attributes and resources forks is still preserved in the script even if GNU's cp is in the path, as GNU's cp doesn't copy these by default.

In short, the script will behave correctly regardless of the cp version installed, but the script will now be more POSIX compatible.

The fix helps prevent unnecessary debugging time as, in my experience, the source of this error is not always displayed in the output of npm run ios.

As mentioned in:

• https://github.com/facebook/react-native/issues/42112#issuecomment-1922990774
• https://github.com/facebook/react-native/issues/39734#issuecomment-1932644315

Relevant Documentation

• GNU's cp documentation
• macOS's cp man page

Changelog:

[IOS] [FIXED] - Fix compatibility issue with 'cp' command in shell script.

Test Plan:

# with GNU's cp in path
npm run ios
# observe build passing (this is the fix)

# remove GNU's cp from path
npm run ios
# observe build passing (no regression)

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Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	17,885,653	+4,104
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	21,240,052	+21
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: 8ff05b5a18db85ab699323d1745a5f17cdc8bf6c Branch: main

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Is there a tmp fix for that?

Looks like this was done already: https://github.com/blakef/react-native/commit/e70076a23409b9a4920e4c6b2d7d3f840e738cc5