Output file maps are generated for modules that aren't built.

[dschaefer2]

Is it reproducible with SwiftPM command-line tools: swift build, swift test, swift package etc?

• Confirmed reproduction steps with SwiftPM CLI. The description text must include reproduction steps with either of command-line SwiftPM commands, swift build, swift test, swift package etc.

Description

On Windows, I was trying out using the x86_64 toolchain to build for the arm64 arch. That seemed to work well. I did notice a lot of directories in the build output for both arches for all the modules in swift-syntax for non "-tool" builds. They only contain the output-file-map.json file. Looks like we are generating that all the time even if it's not in the build graph.

Expected behavior

Don't generate these files for modules that aren't built.

Actual behavior

No response

Steps to reproduce

swift package init --type macro
swift build --arch arm64

Swift Package Manager version/commit hash

No response

Swift & OS version (output of swift --version ; uname -a)

Swift version 6.1-dev (LLVM 393ce0eca916d0f, Swift 26e888e45e6ede4)
Target: x86_64-unknown-windows-msvc