Issue Description:

When I try to add a package dependency to my app with the repository URL (eg, https://github.com/signalapp/libsignal-protocol-c.git) of a library that uses CMake to manage its build process, I get the error:

https://github.com/signalapp/libsignal-protocol-c.git has no Package.swift manifest for version 2.3.3

It'd be nice if the Swift Package Manager (SwiftPM) could recognize when a project uses CMake and then use CMake to compile that project.

Possible Solutions

1. Maybe Xcode could come with CMake, and then SwiftPM could use CMake to build such projects when added as package dependencies. One problem with this approach for the project I used as an example (above) is that its maintainers set (via CMake) the project name to signal-protocol-c, but I don't think that's a valid name for a Swift module. So either SwiftPM could automatically set the module name to SignalProtocolC or allow me to specify a name when adding it as a package dependency. (I'd rather call it SignalProtocol anyway.) [Aside: Does SwiftPM even allow me to set the name of a package dependency? That'd especially be useful to resolve naming collisions, in cases where I wanted to add two or more different package dependencies with the same name.]

2. Even if I had to install CMake myself and fork the libsignal-protocol-c repository and add a `Package.swift` file to it, it'd still be nice if I could put something in the `Package.swift` file that told SwiftPM to just use CMake to build the package. This would be helpful because I don't want to have to respecify all of the build configurations that are already specified in the project's CMakeLists.txt files.

Related

• https://forums.swift.org/t/swiftpm-is-it-possible-to-specify-openssl-as-a-dependency/26568

• https://stackoverflow.com/questions/61444720/how-to-include-libsignal-protocol-c-in-my-swift-ios-app