[tonyarnold]

If I try to use a Swift package module alias for both FlyingFox and FlyingSocks, it fails to compile because SwiftPM omits the FlyingSocks alias from FlyingFox's compiler command.

This PR proposes a change that declares the existing CSystemLinux target as a direct conditional dependency of FlyingFox so that SwiftPM propagates both aliases.

The target and Linux/Android condition are already used by FlyingSocks. FlyingFox also checks canImport(CSystemLinux) when selecting its default socket pool, so making this dependency explicit matches an existing source-level relationship.

Ultimately, this is a compatibility workaround for SwiftPM's graph propagation bug.

In terms of compatibility:

• Existing products, module names, public APIs, deployment targets, and Swift source files are unchanged.
• Apple platforms do not build CSystemLinux because its condition excludes them.
• Linux/Android gain another edge to the same existing target; there is no new package dependency or duplicate C target. Those platform results still need upstream CI confirmation.

My use case here is bundling FlyingFox into a binary, closed source framework that will be linked into other apps at or post runtime — I am using Swift Package Manager's module aliasing feature to avoid namespace clashes if the user is already including FlyingFox in their app.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.72%. Comparing base (bd32d43) to head (1eed485).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #246   +/-   ##
=======================================
  Coverage   93.72%   93.72%           
=======================================
  Files          72       72           
  Lines        3777     3777           
=======================================
  Hits         3540     3540           
  Misses        237      237           

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[tonyarnold]

Thanks, Simon! It looks like Luke has fixes posted for what's failing in CI.