Promote -swift-module-file= to a driver flag

[artemcm]

Companion change to:
swiftlang/swift#87823

[artemcm]

@swift-ci test

[cachemeifyoucan]

I think this needs to be a lot more complicated for explicit module build.

For explicit module build, the flag should be only passed to scanner, and the scanner will plan the build and return the dependency graph with the module file passed as part of it. That is the only way for caching build to be supported.

I don't know if this matters for implicit build, but implicit build can just pass the flag to frontend.

[artemcm]

@swift-ci test

[artemcm]

For explicit module build, the flag should be only passed to scanner, and the scanner will plan the build and return the dependency graph with the module file passed as part of it. That is the only way for caching build to be supported.

I don't know if this matters for implicit build, but implicit build can just pass the flag to frontend.

Good catch. Done.

[cachemeifyoucan]

Can we add a test for explicit module build?

[cachemeifyoucan]

is isPlanJobForExplicitModule always true when kind == .scanDependencies?

[artemcm]

I expect it to be, yes.

[artemcm]

Can we add a test for explicit module build?

There already is a test for explicit module build. What do you have in mind that's not covered there?

[cachemeifyoucan]

There already is a test for explicit module build. What do you have in mind that's not covered there?

I want to see scanner returns the correct result when you pass -swift-module-file to it.