update the resolved file format

[tomerd]

motivation: resolved file now encodes the package name which is redundant. it also does not include the identity of the package so that needs to be computed frmo the url and could be incorrect in case of "creative" mirroring. it will also pose issues as we transition to registry based dependencies

changes:

• create V2 of the resolved file format
• in new format, encode identity and not name
• adjust tests

[tomerd]

@swift-ci please smoke test

[tomerd]

looks like some ci infra issue failed the linux PR check

@swift-ci please smoke test linux

[abertelrud]

In case a V2 file is written out and then SwiftPM 5.5 tries to open it, I think the result will be an internal error, right? I realize that 5.5 is the way it is already, just wanting to get a sense of how this will be experienced after using SwiftPM 5.6+ and then going back.

[tomerd]

In case a V2 file is written out and then SwiftPM 5.5 tries to open it, I think the result will be an internal error, right? I realize that 5.5 is the way it is already, just wanting to get a sense of how this will be experienced after using SwiftPM 5.6+ and then going back

@abertelrud it will give an error message saying that Package.resolved version 2 is not valid and ask the user to fix it, which I think is the most we can do. wdyt?

[abertelrud]

In case a V2 file is written out and then SwiftPM 5.5 tries to open it, I think the result will be an internal error, right? I realize that 5.5 is the way it is already, just wanting to get a sense of how this will be experienced after using SwiftPM 5.6+ and then going back

@abertelrud it will give an error message saying that Package.resolved version 2 is not valid and ask the user to fix it, which I think is the most we can do. wdyt?

Ok, an error makes sense. I thought I saw a precondition which would cause a crash but was mistaken.

[tomerd]

❯ swift package update
error: Package.resolved file is corrupted or malformed; fix or delete the file to continue: unsupported schema version 2