Using the new build system causes the second build to fail with "unable to resolve module dependency"

[itingliu]

I was trying to run swift-foundation benchmark with

USE_PACKAGE=1 BENCHMARK_DISABLE_JEMALLOC=1 swift package benchmark --target InternationalizationBenchmarks

It works the first time, but fails the second time with

error: unable to resolve module dependency: '_FoundationCShims'
error: SwiftDriver ArgumentParser normal arm64 com.apple.xcode.tools.swift.compiler failed with a nonzero exit code.

The same command works with the native build system, i.e.

USE_PACKAGE=1 BENCHMARK_DISABLE_JEMALLOC=1 swift package --build-system native benchmark --target InternationalizationBenchmarks

To Reproduce

Check out swift-foundaiton's main branch

cd Benchmark, and run

USE_PACKAGE=1 BENCHMARK_DISABLE_JEMALLOC=1 swift package benchmark --target InternationalizationBenchmarks

Observe that it succeeds. Then run the same command again. Observe that it fails.

Now try again with

USE_PACKAGE=1 BENCHMARK_DISABLE_JEMALLOC=1 swift package --build-system native benchmark --target InternationalizationBenchmarks

And observe that it succeeds.

[itingliu]

repro-swiftbuild-canimport.zip

Here's a minimal repro that doesn't require building swift-foundation. There's a BUG_REPORT.md in that that explains the counterparts and how to reproduce.

[jmschonfeld]

@owenv I figured you might be interested in this since you've looked at some of the issues swift-foundation has had with the new build system in the past