Linking against a fat dynamic framework fails in arm64

Using Swift
1

Hi,
I'm having issues when I try to compile a Swift file and link it against a fat dynamic framework in an arm64 environment. The library is built following the steps in this blog post:

swift build --configuration release --triple arm64-apple-macosx
swift build --configuration release --triple x86_64-apple-macosx
lipo -create -output package .build/arm64-apple-macosx/release/package .build/x86_64-apple-macosx/release/package

The output tha we get from that compilation is 4 files:

  • ProjectDescription.swiftdoc
  • ProjectDescription.swiftmodule
  • ProjectDescription.swiftinterface
  • libProjectDescription.dylib

Then, the compiler command that we use is the following:

/usr/bin/xcrun swift\
  --supress-warnings\
 -I include/search/path\
 -F framework/search/path\
 -L library/search/path
 -lProjectDescription
 -framework ProjectDescription

But it fails with the following error:

The 'swift' command exited with error code 1 and message:
/path/main.swift:1:8: error: module 'ProjectDescription' was created for incompatible target arm64-apple-macosx10.15: /path/to/module/ProjectDescription.swiftmodule
import ProjectDescription
       ^

Do I need any extra argument when compiling the Swift file? Of is it something related to the way the .swiftmodule of the framework is generated?

2

In the include path, you need to have the swiftmodule for the target you are compiling for. It seems like here you are compiling for x86_64 with the xcrun swift command, but your include path is ending up looking at the arm64 swiftmodule for ProjectDescription. Usually, the swiftmodule is a directory which contains individual swiftmodule files on a per-target basis (but it can also be a file). If you include that directory and it does have individual files for different targets, then it ought to work.

3

Thanks for the response @typesanitizer. One question that I have regarding the .swiftmodule is how should the files be named inside the directory? Let's say I have the following .swiftomdule s:

.build/arm64-apple-macosx/release/MyFramework.swiftmodule
./build/x86_64-apple-macosx/release/MyFramework.swiftmodule

Should I copy them into a MyFramework.swiftmodule directory following the right naming convention?

4

Is it something like?

MyFramework.swiftmodule/
  arm64.swiftmodule
  x86_64.swiftmodule

What happens withe the .swiftinterface and .swiftdoc counterparts?

5

Usually it would use the full "triple" like so:

MyFramework.swiftmodule/
  arm64-apple-macosx.swiftmodule
  x86_64-apple-macosx.swiftmodule
1 Like
6

thanks for the awesome information.

7

I've tried the suggested full "triple" and now when I try to compile a Swift file and link it against that framework, I get the following error:

could not find module 'ProjectDescription' for target 'arm64-apple-macos'; found: x86_64-apple-macosx, arm64-apple-macosx
import ProjectDescription
       ^

Note the macos vs macosx difference that seems to be causing the issue. I'm not entirely sure where that is coming from.

8

thanks for the awesome information.