# Is \`module.modulemap\` required for C/Objc targets? **URL:** \ **Category:** Package Manager\ **Tags:** module\ **Created:** [July 16, 2026, 12:57pm UTC](https://forums.swift.org/t/is-module-modulemap-required-for-c-objc-targets/88332 "2026-07-16T12:57:47Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Frizlab](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/frizlab/32/416_2.png) [@Frizlab](https://forums.swift.org/u/Frizlab)\ **Post date:** [July 16, 2026, 12:57pm UTC](https://forums.swift.org/t/is-module-modulemap-required-for-c-objc-targets/88332/1 "2026-07-16T12:57:47Z")
I have [an issue](https://github.com/swiftlang/swift/issues/90687) with `swift run --repl` when using Swift 6.4 beta (`swift-driver version: 1.168.4 Apple Swift version 6.4 (swiftlang-6.4.0.25.4 clang-2100.3.25.1) – Target: arm64-apple-macosx27.0.0`). The problem happens when running the command in a package that has a target (or that has a dependency which has a target) which is not written in Swift (tested with C, ObjC), and that does not have a `module.modulemap` file in the `include` folder. The package compiles fine when using `swift build`, but when using the REPL we get a “missing module” error, for the modules that are not written in Swift. Adding the `module.modulemap` fixes the issue (ignoring _another_ issue, where the REPL is launched using standalone `-I` options (with no value) randomly in the command-line, which hides actual, useful `-I` options, but that’s another problem…) My question is: Is the `module.modulemap` file technically required? If it is, it’s the build step that is at fault, and it should fail. If not, the REPL run should generate the `module.modulemap` file(s) and add them in the search path for Swift’s invocation. ---
**Author:** ![allevato](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/allevato/32/385_2.png) [@allevato](https://forums.swift.org/u/allevato)\ **Post date:** [July 16, 2026, 1:08pm UTC](https://forums.swift.org/t/is-module-modulemap-required-for-c-objc-targets/88332/2 "2026-07-16T13:08:12Z")
Yes, module maps are required—Swift only understands C headers at the module level, not the individual header level. I would expect SwiftPM using `swift run --repl` to pass the required flags to the REPL invocation the same way it passes them to the compiler when doing a regular build. If that doesn't work, it sounds like a SwiftPM bug (so your issue is probably better filed under swift-package-manager instead of swift, but I'll let the owners of that project make that determination). ---
**Author:** ![Frizlab](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/frizlab/32/416_2.png) [@Frizlab](https://forums.swift.org/u/Frizlab)\ **Post date:** [July 16, 2026, 1:44pm UTC](https://forums.swift.org/t/is-module-modulemap-required-for-c-objc-targets/88332/3 "2026-07-16T13:44:48Z")
Thanks! That’s true even if I have made an umbrella header in the `include` folder, right? ---
**Author:** ![allevato](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/allevato/32/385_2.png) [@allevato](https://forums.swift.org/u/allevato)\ **Post date:** [July 16, 2026, 1:47pm UTC](https://forums.swift.org/t/is-module-modulemap-required-for-c-objc-targets/88332/4 "2026-07-16T13:47:03Z")
I should clarify, the module map is required _by the compiler_. SwiftPM, sitting on top of the compiler, will automatically generate a module map for you if you have headers in your `include` folder if you don't supply one yourself. So the compiler does require it (the directory it's in must be passed via `-I`), but SwiftPM adds the extra convenience on top. ---
**Author:** ![Frizlab](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/frizlab/32/416_2.png) [@Frizlab](https://forums.swift.org/u/Frizlab)\ **Post date:** [July 16, 2026, 1:48pm UTC](https://forums.swift.org/t/is-module-modulemap-required-for-c-objc-targets/88332/5 "2026-07-16T13:48:30Z")
Oh so that looks definitely like an SPM bug, specifically for the `run --repl` command. I’ll move my issue there. ---
**Author:** ![Frizlab](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/frizlab/32/416_2.png) [@Frizlab](https://forums.swift.org/u/Frizlab)\ **Post date:** [July 16, 2026, 8:01pm UTC](https://forums.swift.org/t/is-module-modulemap-required-for-c-objc-targets/88332/6 "2026-07-16T20:01:06Z")
Done > > > \### Is it reproducible with SwiftPM command-line tools: \`swift build\`, \`swift te…st\`, \`swift package\` etc? > > \- \[x\] 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 > > This is a re-write of https://github.com/swiftlang/swift/issues/90687, because I’ve been told the package manager is a better location for the bug. > > Setup: > A package that has a target (e.g. \`Dest\`) depending on non-Swift target(s) (e.g. \`Dep1\` and \`Dep2\`, tested with C, ObjC), and whose target(s) do not contain a \`module.modulemap\`. > > Issue: > Running \`swift run --repl\` gives a REPL in which \`Dest\` cannot be imported (we get a “missing required module” error, for the modules \`Dep1\` and \`Dep2\`, other dependencies work fine). > > \### Expected behavior > > The import should work. > > \### Actual behavior > > We get the error \`missing required modules: 'CMacroExports', 'CNSTaskHelptender'\`. > > \### Steps to reproduce > > 1. git clone https://github.com/xcode-actions/swift-process-invocation.git > 2. cd swift-process-invocation > 3. swift run --repl > 4. Once in the REPL (if you can get there; there is another issue I’ll open that can prevent getting there, but relaunching should do the trick), try to \`import ProcessInvocation\`. > > \### Swift Package Manager version/commit hash > > Swift Package Manager - Swift 6.4.0-dev (Xcode 27.0 beta 3 (27A5218g)) > > \### Swift & OS version (output of \`swift --version ; uname -a\`) > > swift-driver version: 1.168.4 Apple Swift version 6.4 (swiftlang-6.4.0.25.4 clang-2100.3.25.1) > Target: arm64-apple-macosx27.0.0 > Darwin Frizlabs-MacBook-Pro-Beta-Mojo.local 27.0.0 Darwin Kernel Version 27.0.0: Mon Jun 29 21:26:19 PDT 2026; root:xnu-13432.0.50.501.3~1/RELEASE\_ARM64\_T6031 arm64