Fetch full documentation in code completion

Sources/Csourcekitd/include/CodeCompletionSwiftInterop.h

@@ -324,6 +324,12 @@ typedef struct {
     void (^_Null_unspecified handler)(const char *_Null_unspecified)
   );
 
+  void (*_Nullable completion_item_get_doc_full_copy)(
+    _Nonnull swiftide_api_completion_response_t,
+    _Nonnull swiftide_api_completion_item_t,
+    void (^_Nonnull handler)(char *_Nullable)
+  );
+
   void (*_Nonnull completion_item_get_associated_usrs)(
     _Null_unspecified swiftide_api_completion_response_t,
     _Null_unspecified swiftide_api_completion_item_t,

Sources/SourceKitD/sourcekitd_functions.swift

@@ -146,6 +146,7 @@ extension sourcekitd_ide_api_functions_t {
       completion_item_get_source_text: try loadRequired("swiftide_completion_item_get_source_text"),
       completion_item_get_type_name: try loadRequired("swiftide_completion_item_get_type_name"),
       completion_item_get_doc_brief: try loadRequired("swiftide_completion_item_get_doc_brief"),
+      completion_item_get_doc_full_copy: loadOptional("swiftide_completion_item_get_doc_full_copy"),
       completion_item_get_associated_usrs: try loadRequired("swiftide_completion_item_get_associated_usrs"),
       completion_item_get_kind: try loadRequired("swiftide_completion_item_get_kind"),
       completion_item_get_associated_kind: try loadRequired("swiftide_completion_item_get_associated_kind"),

Sources/SourceKitLSP/Swift/CodeCompletionSession.swift

@@ -574,13 +574,23 @@ class CodeCompletionSession {
           fileContents: nil
         )
       }
-      if let docString: String = documentationResponse?[sourcekitd.keys.docBrief] {
+
+      if let response = documentationResponse,
+         let docString = documentationString(from: response, sourcekitd: sourcekitd) {
         item.documentation = .markupContent(MarkupContent(kind: .markdown, value: docString))
       }
     }
     return item
   }
 
+  private static func documentationString(from response: SKDResponseDictionary, sourcekitd: SourceKitD) -> String? {
+    if let docFullAsXML: String = response[sourcekitd.keys.docFullAsXML] {
+      return try? xmlDocumentationToMarkdown(docFullAsXML)
+    }
+
+    return response[sourcekitd.keys.docBrief]
+  }
+
   private func computeCompletionTextEdit(
     completionPos: Position,
     requestPosition: Position,

Sources/SwiftSourceKitPlugin/ASTCompletion/CompletionSession.swift

@@ -241,6 +241,17 @@ struct ExtendedCompletionInfo {
     return result
   }
 
+  var fullDocumentation: String? {
+    var result: String? = nil
+    session.sourcekitd.ideApi.completion_item_get_doc_full_copy?(session.response, rawItem) {
+      if let cstr = $0 {
+        result = String(cString: cstr)
+        free(cstr)
+      }
+    }
+    return result
+  }
+
   var associatedUSRs: [String] {
     var result: [String] = []
     session.sourcekitd.ideApi.completion_item_get_associated_usrs(session.response, rawItem) { ptr, len in

Sources/SwiftSourceKitPlugin/CompletionProvider.swift

@@ -262,10 +262,17 @@ actor CompletionProvider {
   func handleCompletionDocumentation(_ request: SKDRequestDictionaryReader) throws -> SKDResponseDictionaryBuilder {
     let info = try handleExtendedCompletionRequest(request)
 
-    return request.sourcekitd.responseDictionary([
-      request.sourcekitd.keys.docBrief: info.briefDocumentation,
-      request.sourcekitd.keys.associatedUSRs: info.associatedUSRs as [SKDResponseValue]?,
+    let response = request.sourcekitd.responseDictionary([
+      request.sourcekitd.keys.associatedUSRs: info.associatedUSRs as [SKDResponseValue]?
     ])
+
+    if let fullDocumentation = info.fullDocumentation {
+      response.set(request.sourcekitd.keys.docFullAsXML, to: fullDocumentation)
+    } else {
+      response.set(request.sourcekitd.keys.docBrief, to: info.briefDocumentation)
+    }
+
+    return response
   }
 
   func handleCompletionDiagnostic(_ dict: SKDRequestDictionaryReader) throws -> SKDResponseDictionaryBuilder {

Tests/SourceKitLSPTests/SwiftCompletionTests.swift

@@ -10,10 +10,13 @@
 //
 //===----------------------------------------------------------------------===//
 
+import Csourcekitd
 import LanguageServerProtocol
 import SKTestSupport
+import SourceKitD
 import SourceKitLSP
 import SwiftExtensions
+import ToolchainRegistry
 import XCTest
 
 final class SwiftCompletionTests: XCTestCase {
@@ -67,7 +70,16 @@ final class SwiftCompletionTests: XCTestCase {
     if let abc = abc {
       XCTAssertEqual(abc.kind, .property)
       XCTAssertEqual(abc.detail, "Int")
-      XCTAssertEqual(abc.documentation, .markupContent(MarkupContent(kind: .markdown, value: "Documentation for abc.")))
+      try await assertDocumentation(
+        documentation: abc.documentation,
+        expectedBrief: "Documentation for abc.",
+        expectedFull: """
+          ```swift
+          var abc: Int
+          ```
+          Documentation for `abc`.
+          """
+      )
       XCTAssertEqual(abc.filterText, "abc")
       XCTAssertEqual(abc.textEdit, .textEdit(TextEdit(range: Range(positions["1️⃣"]), newText: "abc")))
       XCTAssertEqual(abc.insertText, "abc")
@@ -87,7 +99,16 @@ final class SwiftCompletionTests: XCTestCase {
       // If we switch to server-side filtering this will change.
       XCTAssertEqual(abc.kind, .property)
       XCTAssertEqual(abc.detail, "Int")
-      XCTAssertEqual(abc.documentation, .markupContent(MarkupContent(kind: .markdown, value: "Documentation for abc.")))
+      try await assertDocumentation(
+        documentation: abc.documentation,
+        expectedBrief: "Documentation for abc.",
+        expectedFull: """
+          ```swift
+          var abc: Int
+          ```
+          Documentation for `abc`.
+          """
+      )
       XCTAssertEqual(abc.filterText, "abc")
       XCTAssertEqual(abc.textEdit, .textEdit(TextEdit(range: positions["1️⃣"]..<offsetPosition, newText: "abc")))
       XCTAssertEqual(abc.insertText, "abc")
@@ -1187,9 +1208,45 @@ final class SwiftCompletionTests: XCTestCase {
     let item = try XCTUnwrap(completions.items.only)
     XCTAssertNil(item.documentation)
     let resolvedItem = try await testClient.send(CompletionItemResolveRequest(item: item))
-    XCTAssertEqual(
-      resolvedItem.documentation,
-      .markupContent(MarkupContent(kind: .markdown, value: "Creates a true value"))
+    try await assertDocumentation(
+      documentation: resolvedItem.documentation,
+      expectedBrief: "Creates a true value",
+      expectedFull: """
+        ```swift
+        func makeBool() -> Bool
+        ```
+        Creates a true value
+        """
+    )
+  }
+
+  func testCompletionBriefDocumentationFallback() async throws {
+    try await SkipUnless.sourcekitdSupportsPlugin()
+
+    let fullDocumentationSupported = try await sourcekitdSupportsFullDocumentation()
+    try XCTSkipUnless(fullDocumentationSupported)
+
+    let testClient = try await TestSourceKitLSPClient()
+    let uri = DocumentURI(for: .swift)
+
+    // We test completion for result builder build functions since they don't have full documentation
+    // but still have brief documentation.
+    let positions = testClient.openDocument(
+      """
+      @resultBuilder
+      struct AnyBuilder {
+        static func 1️⃣
+      }
+      """,
+      uri: uri
+    )
+    let completions = try await testClient.send(
+      CompletionRequest(textDocument: TextDocumentIdentifier(uri), position: positions["1️⃣"])
+    )
+    let item = try XCTUnwrap(completions.items.filter { $0.label.contains("buildBlock") }.only)
+    assertMarkdown(
+      documentation: item.documentation,
+      expected: "Required by every result builder to build combined results from statement blocks"
     )
   }
 
@@ -1253,6 +1310,39 @@ private func countFs(_ response: CompletionList) -> Int {
   return response.items.filter { $0.label.hasPrefix("f") }.count
 }
 
+private func assertMarkdown(
+  documentation: StringOrMarkupContent?,
+  expected: String,
+  file: StaticString = #filePath,
+  line: UInt = #line
+) {
+  XCTAssertEqual(documentation, .markupContent(MarkupContent(kind: .markdown, value: expected)))
+}
+
+/// Asserts that documentation matches the expected values based on whether full documentation is supported in sourcekitd or not.
+private func assertDocumentation(
+  documentation: StringOrMarkupContent?,
+  expectedBrief: String,
+  expectedFull: String,
+  file: StaticString = #filePath,
+  line: UInt = #line
+) async throws {
+  let supportsFullDocumentation = try await sourcekitdSupportsFullDocumentation()
+  let expected = supportsFullDocumentation ? expectedFull : expectedBrief
+
+  assertMarkdown(documentation: documentation, expected: expected, file: file, line: line)
+}
+
+private func sourcekitdSupportsFullDocumentation() async throws -> Bool {
+  let sourcekitdPath = await ToolchainRegistry.forTesting.default!.sourcekitd!
+  let sourcekitd = try await SourceKitD.getOrCreate(
+    dylibPath: sourcekitdPath,
+    pluginPaths: sourceKitPluginPaths
+  )
+
+  return sourcekitd.ideApi.completion_item_get_doc_full_copy != nil
+}
+
 fileprivate extension Position {
   func adding(columns: Int) -> Position {
     return Position(line: line, utf16index: utf16index + columns)

Tests/SwiftSourceKitPluginTests/SwiftSourceKitPluginTests.swift

@@ -203,7 +203,8 @@ final class SwiftSourceKitPluginTests: XCTestCase {
     XCTAssertEqual(result2.items.count, 1)
     XCTAssertEqual(result2.items[0].name, "")
     let doc = try await sourcekitd.completeDocumentation(id: result2.items[0].id)
-    XCTAssertEqual(doc.docBrief, nil)
+    XCTAssertNil(doc.docFullAsXML)
+    XCTAssertNil(doc.docBrief)
   }
 
   func testMultipleFiles() async throws {
@@ -436,14 +437,46 @@ final class SwiftSourceKitPluginTests: XCTestCase {
     let sym3 = try unwrap(result.items.first(where: { $0.name == "foo3()" }), "did not find foo3; got \(result.items)")
 
     let sym1Doc = try await sourcekitd.completeDocumentation(id: sym1.id)
-    XCTAssertEqual(sym1Doc.docBrief, "Protocol P foo1")
+    assertDocumentation(
+      full: sourcekitd.supportsFullDocumentationInCompletion,
+      documentation: sym1Doc,
+      expectedBrief: "Protocol P foo1",
+      expectedFull: """
+        <Function file="\(path)" line="3" column="8">\
+        <Name>foo1()</Name>\
+        <USR>s:1a1PP4foo1yyF</USR>\
+        <Declaration>func foo1()</Declaration>\
+        <CommentParts>\
+        <Abstract><Para>Protocol P foo1</Para></Abstract>\
+        <Discussion><Note>\
+        <Para>This documentation comment was inherited from <codeVoice>P</codeVoice>.</Para>\
+        </Note></Discussion>\
+        </CommentParts>\
+        </Function>
+        """
+    )
     XCTAssertEqual(sym1Doc.associatedUSRs, ["s:1a1SV4foo1yyF", "s:1a1PP4foo1yyF"])
 
     let sym2Doc = try await sourcekitd.completeDocumentation(id: sym2.id)
-    XCTAssertEqual(sym2Doc.docBrief, "Struct S foo2")
+    assertDocumentation(
+      full: sourcekitd.supportsFullDocumentationInCompletion,
+      documentation: sym2Doc,
+      expectedBrief: "Struct S foo2",
+      expectedFull: """
+        <Function file="\(path)" line="8" column="8">\
+        <Name>foo2()</Name>\
+        <USR>s:1a1SV4foo2yyF</USR>\
+        <Declaration>func foo2()</Declaration>\
+        <CommentParts>\
+        <Abstract><Para>Struct S foo2</Para></Abstract>\
+        </CommentParts>\
+        </Function>
+        """
+    )
     XCTAssertEqual(sym2Doc.associatedUSRs, ["s:1a1SV4foo2yyF"])
 
     let sym3Doc = try await sourcekitd.completeDocumentation(id: sym3.id)
+    XCTAssertNil(sym3Doc.docFullAsXML)
     XCTAssertNil(sym3Doc.docBrief)
     XCTAssertEqual(sym3Doc.associatedUSRs, ["s:1a1SV4foo3yyF"])
   }
@@ -1767,11 +1800,13 @@ fileprivate struct CompletionResult: Equatable, Sendable {
 
 fileprivate struct CompletionDocumentation {
   var docBrief: String? = nil
+  var docFullAsXML: String? = nil
   var associatedUSRs: [String] = []
 
   init(_ dict: SKDResponseDictionary) {
     let keys = dict.sourcekitd.keys
     self.docBrief = dict[keys.docBrief]
+    self.docFullAsXML = dict[keys.docFullAsXML]
     self.associatedUSRs = dict[keys.associatedUSRs]?.asStringArray ?? []
   }
 }
@@ -2049,6 +2084,10 @@ fileprivate extension SourceKitD {
     try await openDocument(path, contents: textWithoutMarker, compilerArguments: [path])
     return (positions["1️⃣"], recent)
   }
+
+  nonisolated var supportsFullDocumentationInCompletion: Bool {
+    return ideApi.completion_item_get_doc_full_copy != nil
+  }
 }
 
 private struct ExpectationNotFulfilledError: Error {}
@@ -2071,3 +2110,21 @@ private func runAsync<T: Sendable>(_ body: @escaping @Sendable () async throws -
   }
   return try result.get()
 }
+
+/// Asserts that documentation matches the expected values based on whether full documentation is supported in sourcekitd or not.
+private func assertDocumentation(
+  full: Bool,
+  documentation: CompletionDocumentation,
+  expectedBrief: String,
+  expectedFull: String,
+  file: StaticString = #filePath,
+  line: UInt = #line
+) {
+  if full {
+    XCTAssertEqual(documentation.docFullAsXML, expectedFull, file: file, line: line)
+    XCTAssertNil(documentation.docBrief, "Expected brief documentation to not be available", file: file, line: line)
+  } else {
+    XCTAssertEqual(documentation.docBrief, expectedBrief, file: file, line: line)
+    XCTAssertNil(documentation.docFullAsXML, "Expected full documentation to not be available", file: file, line: line)
+  }
+}