Swift 6 toolchain doesn't emit `.swiftmodules` files for dynamic library?

Using Swift
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I'm trying to compile and link code against a dynamic library. It used to work until Swift 5.10. It fails on Swift 6

I build my library like this

swift build -c debug --product AWSLambdaDeploymentDescriptor

with this line in Package.swift

.library(name: "AWSLambdaDeploymentDescriptor", type: .dynamic, targets: ["AWSLambdaDeploymentDescriptor"]),

And it produces

ls .build/debug/*AWSLambdaDeployment*   
.build/debug/libAWSLambdaDeploymentDescriptor.dylib

.build/debug/AWSLambdaDeploymentDescriptor.build:
AWSLambdaDeploymentDescriptor-Swift.h       DeploymentDescriptor.swiftdeps              FileDigest.d                                module.modulemap
AWSLambdaDeploymentDescriptor.emit-module.d DeploymentDescriptorBuilder.d               FileDigest.swift.o                          output-file-map.json
DeploymentDescriptor.d                      DeploymentDescriptorBuilder.swift.o         FileDigest.swiftdeps                        sources
DeploymentDescriptor.swift.o                DeploymentDescriptorBuilder.swiftdeps       master.priors

.build/debug/AWSLambdaDeploymentDescriptor.product:
Objects.LinkFileList

.build/debug/libAWSLambdaDeploymentDescriptor.dylib.dSYM:
Contents

When I try to compile against it

swiftc -I .build/debug -L .build/debug -lAWSLambdaDeploymentDescriptor Deploy.swift
Deploy.swift:4:19: error: cannot find 'Queue' in scope
  2 | 
  3 | // example of a shared resource
  4 | let sharedQueue = Queue(
    |                   `- error: cannot find 'Queue' in scope
  5 |   logicalName: "SharedQueue",
  6 |   physicalName: "swift-lambda-shared-queue")

The compiler can not find the public symbols exported.

I noticed there is no .swiftmodule being generated like before. I understand these are similar to headers files with the list of symbols. This probably explains the compiler errors I observe.

I tried to add -Xswiftc -emit-module when compiling the dynamic library, but it doesn't generate the .swiftmodule directory

Any idea ? How can I compile and run code that links to a dynamic library using Swift 6 ? How should I invoke the toolchain when building the library to generate required symbols to use it ?

1 Like
2

Look under .build/debug/Modules for modules built for the target and .build/debug/Modules-tool for modules built for the host. Note that these paths are implementation details of SwiftPM and are subject to change.

Notably the paths changed in SwiftPM 6.0 to support cross compilation with macros and plugins in the graph. (This is required for things like swift-mmio, etc...)

2 Likes
3

Thank you Rauhul, it helped.
Now the compiler finds the symbol and the linker finds the library.

Huge thanks