implement handling of extensions to external types as enabled by swiftlang/swift#59047

 - introduce transformation generating internal Extended Types Symbol Graph Format from
   the Extension Block Symbol Graph Format emmitted by the compiler
 - register symbols and relationships used by Extended Types Symbol Graph Format
 - adapt reference collision detection logic to deal with emitted path components that
   occur when extending external nested types
 - adapt reference resolution logic to first search for paths in the local module
   by default and introduce shorthand absolute syntax with "/" prefix to mark paths
   as absolute (to be searched for only in the global scope)
 - adapt SymbolGraphLoader to automatically detect if input Symbol Graph Files use the
   Extension Block Symbol Graph Format and apply the ExtendedTypesFormatTransformation
   in case
 - improve Swift title token parsing to correctly identify Symbol titles of nested types,
   which contain "." infixes

Author: theMomax

Package.resolved

@@ -39,10 +39,10 @@
       },
       {
         "package": "SymbolKit",
-        "repositoryURL": "https://github.com/apple/swift-docc-symbolkit",
+        "repositoryURL": "https://github.com/themomax/swift-docc-symbolkit",
         "state": {
-          "branch": "main",
-          "revision": "da6cedd103e0e08a2bc7b14869ec37fba4db72d9",
+          "branch": "docc-extensions-to-external-types-base",
+          "revision": "dba9c2dc32a3c02d5be84b67e9b2c4af108d3ba0",
           "version": null
         }
       },

Package.swift

@@ -124,7 +124,7 @@ if ProcessInfo.processInfo.environment["SWIFTCI_USE_LOCAL_DEPS"] == nil {
         .package(name: "swift-markdown", url: "https://github.com/apple/swift-markdown.git", .branch("main")),
         .package(name: "CLMDB", url: "https://github.com/apple/swift-lmdb.git", .branch("main")),
         .package(url: "https://github.com/apple/swift-argument-parser", .upToNextMinor(from: "1.0.1")),
-        .package(name: "SymbolKit", url: "https://github.com/apple/swift-docc-symbolkit", .branch("main")),
+        .package(name: "SymbolKit", url: "https://github.com/themomax/swift-docc-symbolkit", .branch("docc-extensions-to-external-types-base")),
         .package(url: "https://github.com/apple/swift-crypto.git", .upToNextMinor(from: "1.1.2")),
     ]
 

Sources/SwiftDocC/Coverage/DocumentationCoverageOptions.swift

@@ -185,15 +185,15 @@ extension DocumentationCoverageOptions.KindFilterOptions {
         /// Converts given ``DocumentationNode.Kind`` to corresponding `BitFlagRepresentation` if possible. Returns `nil` if the given Kind is not representable.
         fileprivate init?(kind: DocumentationNode.Kind) {
             switch kind {
-            case .module: // 1
+            case .module, .extendedModule: // 1
                 self = .module
-            case .class: // 2
+            case .class, .extendedClass: // 2
                 self = .class
-            case .structure: // 3
+            case .structure, .extendedStructure: // 3
                 self = .structure
-            case .enumeration: // 4
+            case .enumeration, .extendedEnumeration: // 4
                 self = .enumeration
-            case .protocol: // 5
+            case .protocol, .extendedProtocol: // 5
                 self = .protocol
             case .typeAlias: // 6
                 self = .typeAlias

Sources/SwiftDocC/Indexing/Navigator/NavigatorIndex+Ext.swift

@@ -76,7 +76,7 @@ public class FileSystemRenderNodeProvider: RenderNodeProvider {
 
 extension RenderNode {
     private static let typesThatShouldNotUseNavigatorTitle: Set<NavigatorIndex.PageType> = [
-        .framework, .class, .structure, .enumeration, .protocol, .typeAlias, .associatedType
+        .framework, .class, .structure, .enumeration, .protocol, .typeAlias, .associatedType, .extension
     ]
 
     /// Returns a navigator title preferring the fragments inside the metadata, if applicable.

Sources/SwiftDocC/Infrastructure/CoverageDataEntry.swift

@@ -243,7 +243,11 @@ extension CoverageDataEntry {
                 .protocol,
                 .typeAlias,
                 .associatedType,
-                .typeDef:
+                .typeDef,
+                .extendedClass,
+                .extendedStructure,
+                .extendedEnumeration,
+                .extendedProtocol:
                 self = .types
             case .localVariable,
                 .instanceProperty,
@@ -256,7 +260,7 @@ extension CoverageDataEntry {
                 .typeSubscript,
                 .instanceSubscript:
                 self = .members
-            case .function, .module, .globalVariable, .operator:
+            case .function, .module, .globalVariable, .operator, .extendedModule:
                 self = .globals
             case let kind where SummaryCategory.allKnownNonSymbolKindNames.contains(kind.name):
                 self = .nonSymbol
@@ -297,46 +301,46 @@ extension CoverageDataEntry {
             context: DocumentationContext
         ) throws {
             switch documentationNode.kind {
-            case DocumentationNode.Kind.class:
+            case .class, .extendedClass:
                 self = try .class(
                     memberStats: KindSpecificData.extractChildStats(
                         documentationNode: documentationNode,
                         context: context))
-            case DocumentationNode.Kind.enumeration:
+            case .enumeration, .extendedEnumeration:
                 self = try .enumeration(
                     memberStats: KindSpecificData.extractChildStats(
                         documentationNode: documentationNode,
                         context: context))
-            case DocumentationNode.Kind.structure:
+            case .structure, .extendedStructure:
                 self = try .structure(
                     memberStats:  KindSpecificData.extractChildStats(
                         documentationNode: documentationNode,
                         context: context))
-            case DocumentationNode.Kind.protocol:
-                self = try .enumeration(
+            case .protocol, .extendedProtocol:
+                self = try .protocol(
                     memberStats: KindSpecificData.extractChildStats(
                         documentationNode: documentationNode,
                         context: context))
 
-            case DocumentationNode.Kind.instanceMethod:
+            case .instanceMethod:
                 self = try .instanceMethod(
                     parameterStats: CoverageDataEntry.KindSpecificData.extractFunctionSignatureStats(
                         documentationNode: documentationNode,
                         context: context
                         , fieldName: "method parameters"))
-            case DocumentationNode.Kind.operator:
+            case .operator:
                 self = try .`operator`(
                     parameterStats: CoverageDataEntry.KindSpecificData.extractFunctionSignatureStats(
                         documentationNode: documentationNode,
                         context: context,
                         fieldName: "operator parameters"))
-            case DocumentationNode.Kind.function:
+            case .function:
                 self = try .`operator`(
                     parameterStats: CoverageDataEntry.KindSpecificData.extractFunctionSignatureStats(
                         documentationNode: documentationNode,
                         context: context,
                         fieldName: "function parameters"))
-            case DocumentationNode.Kind.initializer:
+            case .initializer:
                 self = try .`operator`(
                     parameterStats: CoverageDataEntry.KindSpecificData.extractFunctionSignatureStats(
                         documentationNode: documentationNode,