Best way to get various information from swift framework like function signature, mangled names etc.?

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1

Hey,
I hope this is the right place to ask this questions, I wasn't sure whether it belongs to "Source Tooling" or not.
I'm currently writing a library to bridge Java and Swift. For that I need various informations about the functions/types etc. in a swift library, to write java binding code.
These information include, but are not limited to:

  • Mangled name of functions and types
  • The function signature
  • the function declaration order (to calculate vtable offsets)

I have found multiple ways to parse some of the information, but they were all lacking something so far.

  1. Some librarys are shipped/build with a *.abi.json file. This file is ideal since it contains everything I need and is easy to parse. However, it doesn't seem to be always existent for swift librarys, so it is not feasable.
  2. Swiftlibrarys seem to get shipped with a *.swiftinterface file, which contains all declarations in correct order. This file can be parsed and traversed with something like SwiftSyntax, but it lacks mangled names. I also haven't found any easy to use a name mangler.
  3. Since the *.swiftinterface is pretty close to valid swift code, I tried to compile it (with a bit pre-processing) and produce a *.abi.json file for 1. While this works fine for smaller projects, converting the .swiftinterface file to valid swift code gets pretty hard.
  4. Using swift symbolgraph-extract on the *.swiftdoc file produces a .json with the function signature, mangled names etc., but the declaration order is messed up thus preventing the calculation of vtable offsets.

These were all the ideas I had and tried. Is there any good way to retrieve all the needed information from a swift library I oversaw?
The last option I see is combining 2. and 4., getting the declaration order from the *.swiftinterface file and getting the rest from the *.swiftdoc. However that is a bit complicated and ugly, so I wanted to ask here first whether someone knows a better way.

Thanks in advance!

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2

I just tested it and you should be able to generate the abi.json file for a module by passing -emit-abi-descriptor-path to a -compile-module-from-interface job. Here's an example of generating a descriptor for Foundation.framework:

xcrun swift-frontend -compile-module-from-interface /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX13.3.sdk/System/Library/Frameworks/Foundation.framework/Modules/Foundation.swiftmodule/arm64-apple-macos.swiftinterface -module-name Foundation -sdk `xcrun -sdk macosx --show-sdk-path` -emit-abi-descriptor-path ./abi.json

I'm not necessarily endorsing the use of the ABI descriptor file for your purposes; I don't know enough about what you want to achieve and what information you need to achieve it. If it seems like that file contains what you need then this should be a way to get one, though.

3

you cannot get the function signature of subscripts or computed properties through the symbolgraph, this information is only present for func declarations.

4

Ohhh, thank you very much! I was not aware of the -compile-module-from-interface command.
The created ABI file parses like a charm, so I think this solution should work for now!

Yeah I'm also not sure, I'm currently in a very early stage of the project, so not sure whether I'll stick to the ABI descriptor for retrieving the information. Currently I just need it to be able to test my Java - Swift bridging project against a larger amount of swift librarys, for which it works fine.

Ahh okay, I didn't realised! Thats good to know, thank you!

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