Runtimes: attempt to embed a SxS manifest for swiftCore

[compnerd]

This will allow us to have multiple parallel installations of swiftCore with the same DLL name allowing us to side-step the ABI instability without resorting to SOVERSIONing.

[etcwilde]

But also, what's wrong with SOVERSIONing?

[compnerd]

But also, what's wrong with SOVERSIONing?

SOVERSIONING is done by changing the name of the module. If we are open to renaming swiftCore.dylib on each release (breaking binary compatibility), we can consider that. Otherwise, this is the better choice - it gives us the binary compatibility story and maintains parity with Darwin. Note that the library name change would also require further enhancements to the swift compiler to know about the library name (as the current macro metaprogramming is dependent on that).

[etcwilde]

Otherwise, this is the better choice - it gives us the binary compatibility story and maintains parity with Darwin. Note that the library name change would also require further enhancements to the swift compiler to know about the library name (as the current macro metaprogramming is dependent on that).

We still have Linux to figure out (nicely) though, so we may still want a way to optionally SOVERSION the library on platforms that aren't ABI-stable. Unless you know of a way to get this behavior out of the Linux loader too?

[compnerd]

@swift-ci please smoke test

[compnerd]

@swift-ci please test Windows platform

[compnerd]

@swift-ci please smoke test Linux platform