Reapply "[SwiftLexicalLookup] New unqualified lookup implementation validation"

[rintaro]

With linking AST wit hASTGen

[rintaro]

@swift-ci Please Build Toolchain Ubuntu 24.04

[rintaro]

@swift-ci Please smoke test

[bnbarham]

CC @MAJKFL turns out that this doesn't actually introduce any cycle that isn't already there.

@rintaro could you add the new library to swift-installer-scripts? https://github.com/swiftlang/swift-installer-scripts/blob/6cecc7c46d1170a3bc3e1ff8838181418e037397/platforms/Windows/bld/bld.wxs#L418

[rintaro]

swiftlang/swift-installer-scripts#360
@swift-ci Please smoke test

[rintaro]

swiftlang/swift-installer-scripts#360
@swift-ci Please build toolchain Windows

[MAJKFL]

CC @MAJKFL turns out that this doesn't actually introduce any cycle that isn't already there.

Thank you @bnbarham and @rintaro so much for investigating and finding the fix! I hope it wasn't too much trouble for you.

Loose thought: Would it be a good idea to include some kind of check for this in the ci to catch this issue earlier on in the future? Would it be feasible?

[rintaro]

Would it be a good idea to include some kind of check for this in the ci to catch this issue earlier on in the future? Would it be feasible?

With my understanding we're not PR testing gold linker at all. We should switch to Ubuntu 24.04 (from 20.04) for PR testing. cc: @shahmishal

[bnbarham]

Yeah, IMO we run into more issues with gold than with lld, so it probably makes more sense to use 24.04 rather than 20.04.