Module compiled with Swift 5.1 cannot be imported by the Swift 5.1.2 compiler

Question

I have a framework (in this instance it's RxSwift) which I've compiled using Xcode 11.0 into the traditional RxSwift.framework style package

This imported fine into Xcode 11.0 and also 11.1 never had any problems with it

Today, upon Apple's release of Xcode 11.2, I upgraded, and I am presented with the error:

Module compiled with Swift 5.1 cannot be imported by the Swift 5.1.2 compiler

I'm used to swift compiler mismatches, and I'm aware I can just recompile RxSwift using Xcode 11.2 and carry on, but the headline feature of Swift 5.1 was module stability.

I was under the impression that now that we have module stability, frameworks won't need to keep getting recompiled with every new Xcode release, yet this is clearly not the case.

If anyone can explain what is going on here I would much appreciate it. Is Xcode 11.2 exhibiting a bug? or did I somehow need to tell it I wanted module stability when I originally compiled with Xcode 11.0?

Linkwork

Related: Module compiled with Swift 5.0.1 cannot be imported by the Swift 5.1 compiler – Sixtyfourmo

For me Toolchain with older swift version worked: https://mcmap.net/q/16263/-how-can-i-choose-swift-compiler-version – Tamarind

Answer 1

OK, Turns out if you watch the WWDC video, they explain it: https://developer.apple.com/videos/play/wwdc2019/416/

You need to set the Build Settings > Build Options > Build Libraries for Distribution option to Yes in your framework's build settings, otherwise the swift compiler doesn't generate the neccessary .swiftinterface files which are the key to future compilers being able to load your old library.

This ends up in your project.pbxproj file as:

BUILD_LIBRARY_FOR_DISTRIBUTION = YES;

After setting this flag, a framework I compiled using Xcode 11.0 (swift 5.1) was able to be used by Xcode 11.2 (swift 5.1.2) and everything appears to be working correctly.

Hopefully this question/answer will serve as a useful reference for everyone who hasn't watched all the WWDC videos

If the error still persists go to Product > Clean Build Folder and Build again.

Linkwork

This does not help in my case. I set it to "YES" but I am still getting the error. Any ideas? – J

I'm working with Carthage and 10 frameworks...ish. Is carthage smart enough to pick this up from my .pbxproj file, or as @MihaiFratu says above, do all third party framework developers need to set this themselves in their framework projects? – Officialdom

@nteiss I believe Carthage is compiling the frameworks from source for you? In that case this setting doesn’t matter because you just recompile them again. It’s important for us because we distribute frameworks in binary form to other people. I used RxSwift above as an example – Linkwork

@J in my case it had to do with this known issue in Xcode 11.2: If a module is built with BUILD_LIBRARIES_FOR_DISTRIBUTION and contains a public type with the same name as the module itself, clients will fail to import the module. (19481048) (FB5863238) in the Xcode 11.2 release notes: developer.apple.com/documentation/xcode_release_notes/… – Dani

@RichardChirino Is there any workaround, but not to rename the module? – J

@HunaidHassan As the class is added via CocoaPod, I can not just rename it... – J

@J Sadly I haven't found a workaround. For us renaming the class is also not possible as it's the main class of our framework and would break our customer's code. If I build the framework using Xcode 11.2 then it does compile on Xcode 11.2 but it will not compile on 11.1 or earlier. Today's Xcode 11.2.1 GM release has not fixed the issue. Here's the ticket on the swift issue tracker in case you want to keep an eye on it: bugs.swift.org/browse/SR-11704 There's also a radar attached to it. – Dani

What if the package is built with SPM? – Communication

@RichardChirino I'm seeing this issue with Xcode 11.3, as well. – Anglicanism

The legacy build system does not support building projects with Swift when SWIFT_ENABLE_LIBRARY_EVOLUTION is enabled. How to fix this? – Zawde

This solution works fine up to xcode 11.3, but does not work in 11.3.1 – Hemisphere

@SalehEnamShohag could you elaborate? I have binary frameworks built with Xcode 11.0 using BUILD_LIBRARY_FOR_DISTRIBUTION = YES and they worked perfectly under Xcode 11.3.1 and also under Xcode 11.4. What problem are you experiencing? – Linkwork

@OrionEdwards, I got the error "Module compiled with Swift 5.1 cannot be imported by the Swift 5.1.3 compiler:" – Hemisphere

Xcode 11.4.1 not work for me. any suggestions? please – Humorous

module compiled with Swift 5.0 cannot be imported by the Swift 5.2.2 compiler in xCode 11.4.1 for razorpay. Not working in XCode 11.4.1 for me. any help please? – Stylo

BUILD_LIBRARY_FOR_DISTRIBUTION = YES has been enabled, but it caused another problem which is <unknown>:0: error: using bridging headers with module interfaces is unsupported. Xcode version is 11.4.1.Swift version is 5.2.2. But also To submit to the App Store you must build your app using the version of Swift that comes included within Xcode.,original error is Module compiled with Swift 5.0.1 cannot be imported by the Swift 5.2.2 compiler,does that means I cannot use toolchain Swift 5.01 to solve this problem? – Tracytrade

no Help Still getting same error. Even i do and also clean build but no luck.! BUILD_LIBRARY_FOR_DISTRIBUTION = YES – Isobath

me too :( just downloaded the latest playground template from here developer.apple.com/download/more and it won't compile – Laurasia

@dev_ios999 If your project that reference third party's library that causing this kind of problem ,then this answer suits to that third party's library,NOT the project that use it.Hope it helps. – Tracytrade

@Tracytrade So basically i should ask the third party vendor to follow the guidelines in this answer when rebuilding and re-releasing their POD ? – Noranorah

@Noranorah I'm afraid the answer is yes.Or maybe you could have a version of XCode whose Swift version that is compatible with third party library. – Tracytrade

I take over a objc sdk project, and there's no BUILD_LIBRARY_FOR_DISTRIBUTION in Build Options section, how can I build a XCFramework from it? – Foppery

Answer 2

Module stability and Library evolution support for closed source

[ABI]

Swift v5.0 introduced stable ABI

Swift v5.1 shipped Module stability and Library evolution support which are applicable for closed source(binary) framework(library)(framework is build separately from consumer)

Check Swift version:

Swift Language Version(SWIFT_VERSION)

To enable it you should use Xcode from v11:

Build Libraries for Distribution (BUILD_LIBRARY_FOR_DISTRIBUTION)

Select framework target -> Build Settings -> Build Libraries for Distribution (BUILD_LIBRARY_FOR_DISTRIBUTION) -> Yes

swiftc flags:

-enable-library-evolution
-emit-module-interface

This setting generates .swiftinterface

Swift Module Interfaces (.swiftinterface)

Swift Module uses the same approach as Objective-C module uses - precompiled binary or Compiled Module.

Swift Module Interfaces is a textual representation of module's public API. It is an Swift's alternative for Objective-C's headers .h files.

//previously
consumer(app) -> import Module -> producer(framework) .swiftmodule

//using .swiftinterface
consumer(app) -> import Module -> .swiftinterface -> producer(framework) .swiftmodule

Despite of .swiftmodule which is changeable where you can get

Module compiled with _ cannot be imported by the _ compiler

.swiftinterface is stable and do not need to be update when something changed(e.g. Swift version)

no assamptions

It is located in next folder

<framework_name>.framework/Modules/<framework_name>.swiftmodule

It looks like:

// swift-interface-format-version: 1.0
// swift-compiler-version: Apple Swift version 5.2.4 (swiftlang-1103.0.32.9 clang-1103.0.32.53)
// swift-module-flags: -target x86_64-apple-ios12.2-simulator -enable-objc-interop -enable-library-evolution -swift-version 5 -enforce-exclusivity=checked -Onone -module-name UtilsSwiftFramework
import Foundation
import Swift
@_exported import UtilsSwiftFramework
@_inheritsConvenienceInitializers @objc public class GFISClassA : ObjectiveC.NSObject {
  @objc public static var shared: UtilsSwiftFramework.GFISClassA
  @objc public func GFISprintHelloWorld()
  @objc public func GFISprintHelloWorld(arg1: Swift.String, arg2: Swift.String)
  @objc deinit
  @objc override dynamic public init()
}

As you see it additionally it contains:

swift-interface-format-version
swift-compiler-version
swift-module-flags

*You can get next error if you use dynamic without @objc^[About]

Marking non-'@objc' Swift declaration 'dynamic' in library evolution mode is not supported

XCFramework^[About] forces you to use it

Apple recommends to use .swiftinterface for closed source and Swift Package Manager^[About] for open source

Valerle

Thank you so much for the answer, but i see it more complex than the problem itself :( – Pongid

Answer 3

Distribution (BUILD_LIBRARY_FOR_DISTRIBUTION) -> Yes & Pod update - the error went away for me.

Prasad

"Pod update = pod deintegrate + pod install" worked for me – Interspace

Answer 4

I had the same error importing 3rd party libraries. I fixed it using toolchains in Xcode and taking the release September 19 2019 from here https://swift.org/download/#releases. After that I had to re-import my libraries and it worked.

Alectryomancy

I have problem on framework Module compiled with Swift 5.1.2 cannot be imported by the Swift 5.2.2 how can we solve this problem ? – Novena

Answer 5

I experienced this on repo after moving back to Xcode 11.3.1 from Xcode 12.3. I had summarily updated my Command Line Tools and needed to revert them to the earlier version in order to get my dependency building.

Partook

Answer 6

One other way I managed to fix this was just double checking the module you're using and seeing if there's an update for it. I was using ViewControllerPresentationSpy to test alert controllers in my project. I did a pod reintegrate, then pod install, to update the version from 5.1 to 6.0 as the author of that module had since released an update for it. I removed the previous module's folder in my project. Then for the new version, I was able to drag and drop the project just above all my tests after cleaning the build and going the project navigator and adding it to the Copy Files section for the VC Presentation Spy to the project.

Long story short, double check where you got your module from and check for an update and add it again to your Xcode project.

Katrinakatrine

Answer 7

Sometimes can help for run app on Apple M1

try also in terminal:

arch -x86_64 pod install

Fenestella

Answer 8

This made my compiler error go away.

1. carthage bootstrap --platform ios
2. brew bundle
3. pod repo update

Cangue

brew bundle? what does it do? – Thready

Downvote because with carthage you're rebuilding your library on the new compiler. The question is explicitly about loading binary libraries built by the previous compiler – Linkwork

I ran the above commands, and still getting similar build errors: ~"Skipped installing RxSwift.framework binary due to the error: Incompatible Swift version - framework was built with 5.2.2 (swiftlang-1103.0.32.6 clang-1103.0.32.51) and the local version is 5.1.3 (swiftlang-1100.0.282.1 clang-1100.0.33.15)." – Schistosomiasis

Answer 9

If even after trying all the steps mentioned above, it is not resolved then try to see what all prebuild folders are present in your repo which is not directly related to your project. Delete all of them, delete pods folder and podfile.lock and clean derived data and then try to build.

It worked for me :D

Pothead

Answer 10

I had the similar issue once I moved from xcode 13.4 to xcode 14.1 Solution was to set appropriate compiler in Xcode - Preferences - Command Line Tools

Orbicular

Answer 11

I ran into the same issue where I only switched branches. I deleted derived data + clean build a few times. It didn't work until I restarted Xcode

Impermissible

Answer 12

You can use Carthage to add the RxSwift framework.

Basically, Carthage gives you a similar traditional RxSwift.framework style package.

Then try carthage update --no-use-binaries.

Mccalla

Downvote because with carthage you're just rebuilding your library on the new compiler. The question is explicitly about loading binary libraries built by the previous compiler – Linkwork