Swift sometimes puts .d, .o and .swiftdeps in the root directory of a SPM project

[Jomy10]

Description

Sometimes, when building with Swift Package Manager, it will put .d, .o and .swiftdeps in the root directory of the Swift Package.

Reproduction

I have encountered this bug multiple times, but have not found a reliable way to fix it.

Files are added to the root directory:

This comes to my attention because an error occures during build:

error: link command failed with exit code 1 (use -v to see invocation)
ld: file cannot be open()ed, errno=2 path=/Users/jonaseveraert/Documents/projects/Beaver/.build/arm64-apple-macosx/debug/Beaver.build/GlobalCache.swift.o in '/Users/jonaseveraert/Documents/projects/Beaver/.build/arm64-apple-macosx/debug/Beaver.build/GlobalCache.swift.o'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I started seeing this bug when I upgraded from Swift 5.7 to Swift 6

Expected behavior

These files should be put in the build directory.

Environment

swift-driver version: 1.115.1 Apple Swift version 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)
Target: arm64-apple-macosx15.0

Additional information

No response

[tayloraswift]

this is probably a duplicate of #7930

[jakepetroules]

Are those files produced by a build tool plugin?

[Jomy10]

I was not using a build tool plugin at the time.

[dschaefer2]

Yes, there's more info there.