[android] Guard spawn.h import

[modocache]

What's in this pull request?

spawn.h isn't available on Android. Put its import behind an #if defined(__ANDROID__) in order to fix the Android build.

/cc @compnerd, who added the import in #2006. Does this modification work for you?

Resolved bug number: None

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[gribozavr]

Could you move it above the #define above?

[gribozavr]

Triggering the CI, but waiting for a response from @compnerd before merging.

@swift-ci Please test

[compnerd]

Just me or isn't this Subprocess.swift also built on android? (There seems to be a os(Android) check). If so, that should also go through the stubs. Otherwise, why not just remove building this subdirectory for the Android build?

[modocache]

why not just remove building this subdirectory for the Android build?

We include this directory on Android for the spawnChild() function, not for the spawn.h shims. The spawnChild() function is defined in Subprocess.swift and is used by StdlibUnittest. spawn.h isn't available on Android, so when targeting Android, we include an implementation of spawnChild() in Subprocess.swift that doesn't rely on spawn.h.

[compnerd]

Oh, I see. Yeah, Id just wrap the entire file (including the macro which is currently not guarded) with it. Alternatively, you could just not add it to the source list in the CMakeList.txt. But the change itself seems fine to me.

[modocache]

Great! Looks like the tests passed as well. I'll move #if !defined(__ANDROID__) above the #define availability(...), then this should be good to go.

[gribozavr]

@modocache Sounds good! Please merge directly when you are ready!

[modocache]

Thanks everyone! 🙇