SPM: allow overriding the autolinking config command

[chrfalch]

Summary:

The SwiftPM autolinking flow hardcodes @react-native-community/cli config to generate autolinking.json (generate-spm-autolinking-config.js). Apps that replace community autolinking — most notably Expo, which ships expo-modules-autolinking instead of @react-native-community/cli — had no way to override that command, and any failure was swallowed. The result: the config command fails, autolinking.json is never written, the Autolinked SwiftPM package comes out empty, and import Expo (and every Expo module) fails to resolve — surfacing much later as an inscrutable unable to resolve module dependency: 'Expo'.

CocoaPods already solves the injection half: use_native_modules!(config_command = $default_command) accepts the command as a parameter, so an Expo Podfile passes expo-modules-autolinking react-native-config in place of the @rncli default. This PR adds the equivalent hook to the SwiftPM path and closes the silent-failure trap.

1. Allow overriding the config command

generateAutolinkingConfig already accepted a configCommand option internally; it was just never reachable. Two ways to supply it, mirroring the CocoaPods hook:

• --config-command '<json>' — CLI flag taking a JSON array of the argv.
• RCT_SPM_AUTOLINKING_CONFIG_COMMAND — env var in the same JSON-array format. This is the vehicle for the injected Xcode build phase, which usually can't rewrite the script's argv but can read env.

Both go through one parseConfigCommandJson validator (rejects non-JSON, non-arrays, empty arrays, and non-string / empty-string elements, with a source-named error). Precedence: --config-command > RCT_SPM_AUTOLINKING_CONFIG_COMMAND > default (local @rncli → npx --no-install fallback, unchanged). JSON (rather than whitespace-splitting) because real commands contain dashed flags and quoted script strings.

The value is the command to execute — its stdout is captured as the config JSON and written verbatim — exactly matching CocoaPods, not a precomputed result. An Expo app feeds the same argv it already builds for use_native_modules!:

RCT_SPM_AUTOLINKING_CONFIG_COMMAND='["node","--no-warnings","--eval","require('expo/bin/autolinking')","expo-modules-autolinking","react-native-config","--json","--platform","ios","--source-dir","/abs/path"]'

(Use --platform ios: the generator requires project.ios.sourceDir and everything downstream is iOS-only.)

2. Fail closed when the config command errors

Previously main() swallowed a config-command failure as a warning and continued, which is what let the empty package be produced silently. That policy is now extracted into generateAutolinkingConfigOrFailClosed: on a config-command error (non-zero exit, unparseable output, or a config missing project.ios.sourceDir) it logs an actionable message naming RCT_SPM_AUTOLINKING_CONFIG_COMMAND / --config-command, sets process.exitCode = 2 (a hard Xcode build-phase error, matching the existing RemoteVersionError path), and stops.

The guard is deliberately narrow: a genuinely native-module-free app never reaches the error path — its command exits 0 with valid, empty-dependency JSON, so the generator returns normally and the legitimate empty-package path stays valid. Only an erroring command fails the build.

Changelog:

[IOS] [ADDED] - Allow overriding the SwiftPM autolinking config command via --config-command / RCT_SPM_AUTOLINKING_CONFIG_COMMAND
[IOS] [CHANGED] - Fail closed with an actionable error when the SwiftPM autolinking config command fails, instead of silently emitting an empty Autolinked package

Test Plan:

New unit tests, developed red → green:

• generate-spm-autolinking-config-test.js — env var honored; explicit configCommand beats env; invalid-JSON and invalid-shape ([], [1,2]) throw with the source name; env unset falls back to the default command; env state saved/restored per test.
• setup-apple-spm-test.js — parseArgs parses --config-command into an argv array, defaults to null when omitted, and throws on an invalid value; generateAutolinkingConfigOrFailClosed returns the result on success (exit code untouched), passes projectRoot/configCommand through, and on a config-command error returns null, sets exit 2, and logs an actionable error that names the env var and preserves the underlying cause.

$ yarn jest --no-cache -i \
packages/react-native/scripts/spm/__tests__/generate-spm-autolinking-config-test.js \
packages/react-native/scripts/spm/__tests__/setup-apple-spm-test.js
Test Suites: 2 passed, 2 total
Tests: 39 passed, 39 total

prettier and eslint clean on all changed files.

[meta-codesync]

@cipolleschi has imported this pull request. If you are a Meta employee, you can view this in D113554857.

[meta-codesync]

@cipolleschi merged this pull request in a7ba4ce.