Swift API generated from Objective-C code doesn't re... | jpsim/SourceKitten

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We noticed that there are issues with the listing of Swift name and declaration in the SourceKitten output for Objective-C API that includes forward declarations.
When using a forward declaration of e.g. a protocol, the Swift name/declaration is missing completely.

Consider the following two files in a project, and an umbrella header importing both of those:

PSPDFProtocol.h

#import <Foundation/Foundation.h>

@protocol PSPDFProtocol
@end

PSPDFClass.h

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@protocol PSPDFProtocol;

@interface PSPDFClass

- (id<PSPDFProtocol>)protocolAPI;

@end

NS_ASSUME_NONNULL_END

The SourceKitten doc command results in the following output:

PSPDFKit.json

[
  {
    "PSPDFClass.h" : {
      "key.diagnostic_stage" : "",
      "key.substructure" : [
        {
          "key.always_deprecated" : false,
          "key.always_unavailable" : false,
          "key.deprecation_message" : "",
          "key.doc.column" : 12,
          "key.doc.file" : "PSPDFClass.h",
          "key.doc.line" : 7,
          "key.filepath" : "PSPDFClass.h",
          "key.kind" : "sourcekitten.source.lang.objc.decl.class",
          "key.name" : "PSPDFClass",
          "key.parsed_declaration" : "@interface PSPDFClass\n\n- (id<PSPDFProtocol>)protocolAPI;\n\n@end",
          "key.parsed_scope.end" : 11,
          "key.parsed_scope.start" : 7,
          "key.substructure" : [
            {
              "key.always_deprecated" : false,
              "key.always_unavailable" : false,
              "key.deprecation_message" : "",
              "key.doc.column" : 22,
              "key.doc.file" : "PSPDFClass.h",
              "key.doc.line" : 9,
              "key.filepath" : "PSPDFClass.h",
              "key.kind" : "sourcekitten.source.lang.objc.decl.method.instance",
              "key.name" : "-protocolAPI",
              "key.parsed_declaration" : "- (id<PSPDFProtocol>)protocolAPI;",
              "key.parsed_scope.end" : 9,
              "key.parsed_scope.start" : 9,
              "key.unavailable_message" : "",
              "key.usr" : "c:objc(cs)PSPDFClass(im)protocolAPI"
            }
          ],
          "key.swift_declaration" : "class PSPDFClass",
          "key.swift_name" : "PSPDFClass",
          "key.unavailable_message" : "",
          "key.usr" : "c:objc(cs)PSPDFClass"
        }
      ]
    }
  },
  {
    "PSPDFProtocol.h" : {
      "key.diagnostic_stage" : "",
      "key.substructure" : [
        {
          "key.always_deprecated" : false,
          "key.always_unavailable" : false,
          "key.deprecation_message" : "",
          "key.doc.column" : 11,
          "key.doc.file" : "PSPDFProtocol.h",
          "key.doc.line" : 3,
          "key.filepath" : "PSPDFProtocol.h",
          "key.kind" : "sourcekitten.source.lang.objc.decl.protocol",
          "key.name" : "PSPDFProtocol",
          "key.parsed_declaration" : "@protocol PSPDFProtocol\n@end",
          "key.parsed_scope.end" : 4,
          "key.parsed_scope.start" : 3,
          "key.swift_declaration" : "protocol PSPDFProtocol",
          "key.swift_name" : "PSPDFProtocol",
          "key.unavailable_message" : "",
          "key.usr" : "c:objc(pl)PSPDFProtocol"
        }
      ]
    }
  }
]

Note that the swift_name and swift_declaration are missing from the protocolAPI symbol.

One solution to this would be to replace the forward declaration with an actual import of the file that includes the protocol, but in some cases this is not a viable solution as it results in circular dependencies.

Is there any way that the Swift API for this could be generated correctly?

Reproduce the report with PSPDFProtocol.h, PSPDFClass.h, and the umbrella header, then run SourceKitten’s doc command and compare the protocolAPI output. Read the generated JSON and the SourceKitten path handling Objective-C declarations; done means the forward-declared protocol method includes the expected swift_name and swift_declaration fields without introducing a circular import.

Written by the indexing model from the issue text.

Swift API generated from Objective-C code doesn't resolve forward declarations

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