[SwiftBuild] SwiftPM on SwiftBuild failed to build projects with Linux SDK's generated by the SDK Generator

[bkhouri]

The current SwiftPM on SwiftBuild effort fails to build projects with Linux SDKs generated by the SDK Generator.

[jakepetroules]

Can you provide more details? What errors do you see and which host platform(s) does this impact?

[dschaefer2]

The swift-sdk-generator takes a Linux host toolchain for a distro/arch combo and extracts what it needs to create a Swift SDK for cross compilation. If using that SDK from a Linux host that's using a different distro, you'll end up with the host and target with the same triple but are actually different platforms since the libc's, etc. will be different.

@bkhouri we need to test this to make sure that's what we see, i.e. the destination build ends up using the same binaries as the host build.

Using Linux as the platform isn't sufficient to differentiate the multitude of Linux platforms. Longer term we need finer grain detail when describing a platform that is "Linux", e.g. various contents of the os-release file, the version and potentially contents of the libc library, etc.

I run into this with prebuilts where I use the finer grained PrebuiltsPlatform and use the os-releases file to differentiate.

cc @rconnell9