Cannot @testable import executable target with --build-tests flag

[bo2themax]

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

Similar error with #7596

./swift-java/Tests/SwiftJavaToolTests/JavaRepositoryTests.swift:17:18: error: no such module 'SwiftJavaTool'
 15 | import Foundation
 16 | @testable import SwiftJavaConfigurationShared
 17 | @testable import SwiftJavaTool
    |                  `- error: no such module 'SwiftJavaTool'
 18 | import Testing

• swift build --build-tests --disable-sandbox failed to build
• swift build --disable-sandbox && swift test succeeded

Steps to reproduce

swift build --build-tests --disable-sandbox with swift-java #374 on 967ccafcf1b6f88b14fd6e1288bc76693cf66369

git clone https://github.com/swiftlang/swift-java.git swift-java-apple && cd swift-java-apple
gh pr checkout 374
git checkout 967ccaf
swift build --build-tests --disable-sandbox

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

swift-driver version: 1.127.14.1 Apple Swift version 6.2 (swiftlang-6.2.0.19.9 clang-1700.3.19.1)
Target: arm64-apple-macosx26.0
Darwin 25.0.0 Darwin Kernel Version 25.0.0: Thu Aug 14 22:03:34 PDT 2025; root:xnu-12377.1.8~5/RELEASE_ARM64_T6030 arm64

[bkhouri]

I cloned te swift-java repository at the tip of branch main (at commit ID e187ad6f6ef72122218778b7b8af8bbd4c871a3e) and I was able to build the project using the steps to reproduce.

I then checkout out swiftlang/swift-java#374 using gh pr checkout 374 and was able to build the project. I used the following toolchain versions.

❯ swiftly use    
6.2-snapshot-2025-08-21 (/Users/bkhouri/Documents/git/public/swiftlang_ci/swift-java/.swift-version)

❯ swift --version    
Apple Swift version 6.2-dev (LLVM bc9310bd0a6ef8e, Swift a57432aae96a36b)
Target: arm64-apple-macosx26.0
Build config: +assertions

and

❯ /usr/bin/swift --version                            
swift-driver version: 1.127.14.1 Apple Swift version 6.2 (swiftlang-6.2.0.19.9 clang-1700.3.19.1)
Target: arm64-apple-macosx26.0

Is there something I'm missing?

[bo2themax]

@bkhouri Hi, thank you for trying this yourself🙏🏻. I've pushed some changes after I opened this, by abstracting the core logic from an executable target to a normal target. That’s why this pr builds successfully now. Can you try switching to 967ccafcf1b6f88b14fd6e1288bc76693cf66369?

The head should be like this:

git clone https://github.com/swiftlang/swift-java.git swift-java-apple && cd swift-java-apple
gh pr checkout 374
git checkout 967ccaf
swift build --build-tests --disable-sandbox

[bkhouri]

Here are steps that reproduced the failure.

git clone https://github.com/swiftlang/swift-java.git swift-java-apple && cd swift-java-apple
git fetch origin pull/374/e && git co FETCH_HEAD 
git checkout 967ccaf
swift package reset  # in case the project was previously built
swift build --build-tests --disable-sandbox

I spoke with @ktoso offline, who indicated the issue is not gating any work at the moment.