Fix incorrect results caused by conflicting extensions

Author: ileitch

.swiftformat

@@ -1,5 +1,6 @@
 --swiftversion 6.0
 
+--exclude **/.build/
 --exclude Tests/Fixtures/
 --exclude Tests/AccessibilityTests/AccessibilityProject/
 --exclude Tests/XcodeTests/UIKitProject/

.swiftlint.yml

@@ -1,5 +1,5 @@
 excluded:
-  - .build
+  - "**/.build"
   - Tests/Fixtures
   - Tests/AccessibilityTests/AccessibilityProject
   - Tests/XcodeTests/UIKitProject

CHANGELOG.md

@@ -15,6 +15,7 @@
 - Fix building with Bazel on Linux by excluding Xcode support.
 - Fix slow baseline filtering for large projects with many results.
 - Fix inconsistent unused parameter results when the function is declared in a file that is a member of multiple targets.
+- Fix inconsistent results caused by identical extensions declared in different modules.
 
 ## 3.1.0 (2025-04-05)
 

Sources/Frontend/Scan.swift

@@ -17,7 +17,7 @@ final class Scan {
         self.configuration = configuration
         self.logger = logger
         self.swiftVersion = swiftVersion
-        graph = SourceGraph(configuration: configuration)
+        graph = SourceGraph(configuration: configuration, logger: logger)
     }
 
     func perform(project: Project) throws -> [ScanResult] {

Sources/Indexer/SwiftIndexer.swift

@@ -251,6 +251,7 @@ final class SwiftIndexer: Indexer {
         private var referencesByUsr: [String: Set<Reference>] = [:]
         private var danglingReferences: [Reference] = []
         private var varParameterUsrs: Set<String> = []
+        private var extensionUsrMap: [String: String] = [:]
 
         private func establishDeclarationHierarchy() {
             graph.withLock {
@@ -366,7 +367,6 @@ final class SwiftIndexer: Indexer {
                 decl.modifiers = Set(result.modifiers)
                 decl.commentCommands = Set(result.commentCommands)
                 decl.declaredType = result.variableType
-                decl.hasCapitalSelfFunctionCall = result.hasCapitalSelfFunctionCall
                 decl.hasGenericFunctionReturnedMetatypeParameters = result.hasGenericFunctionReturnedMetatypeParameters
 
                 for ref in decl.references.union(decl.related) {
@@ -487,6 +487,17 @@ final class SwiftIndexer: Indexer {
                 return nil
             }
 
+            var usr = usr
+
+            if kind.isExtensionKind {
+                // Identical extensions in different modules have the same USR, which leads to conflicts and incorrect
+                // results. Here we append the module names to form a unique USR. The only references to this
+                // extension will exist in the same file, so we only need a file-local mapping for the USR.
+                let newUsr = "\(usr)-\(location.file.modules.sorted().joined(separator: "-"))"
+                extensionUsrMap[usr] = newUsr
+                usr = newUsr
+            }
+
             let decl = RawDeclaration(
                 usr: usr,
                 kind: kind,
@@ -526,6 +537,10 @@ final class SwiftIndexer: Indexer {
             for rel in relations {
                 if rel.roles.contains(.childOf) {
                     if let parentUsr = rel.symbol.usr {
+                        var parentUsr = parentUsr
+                        if rel.symbol.kind == .extension {
+                            parentUsr = extensionUsrMap[parentUsr] ?? parentUsr
+                        }
                         childDeclsByParentUsr[parentUsr, default: []].insert(decl)
                     }
                 }

Sources/SourceGraph/Elements/Declaration.swift

@@ -224,7 +224,6 @@ public final class Declaration {
     public var commentCommands: Set<CommentCommand> = []
     public var references: Set<Reference> = []
     public var declaredType: String?
-    public var hasCapitalSelfFunctionCall: Bool = false
     public var hasGenericFunctionReturnedMetatypeParameters: Bool = false
     public var parent: Declaration?
     public var related: Set<Reference> = []

Sources/SourceGraph/Mutators/ExtensionReferenceBuilder.swift

@@ -34,10 +34,6 @@ final class ExtensionReferenceBuilder: SourceGraphMutator {
             extendedDeclaration.references.formUnion(extensionDeclaration.references)
             extendedDeclaration.related.formUnion(extensionDeclaration.related)
 
-            if extensionDeclaration.hasCapitalSelfFunctionCall {
-                extendedDeclaration.hasCapitalSelfFunctionCall = true
-            }
-
             extensionDeclaration.declarations.forEach { $0.parent = extendedDeclaration }
             extensionDeclaration.references.forEach { $0.parent = extendedDeclaration }
             extensionDeclaration.related.forEach { $0.parent = extendedDeclaration }

Sources/SourceGraph/SourceGraph.swift

@@ -1,5 +1,6 @@
 import Configuration
 import Foundation
+import Logger
 import Shared
 
 public final class SourceGraph {
@@ -26,9 +27,11 @@ public final class SourceGraph {
     private var moduleToExportingModules: [String: Set<String>] = [:]
 
     private let configuration: Configuration
+    private let logger: Logger
 
-    public init(configuration: Configuration) {
+    public init(configuration: Configuration, logger: Logger) {
         self.configuration = configuration
+        self.logger = logger
     }
 
     public func indexingComplete() {
@@ -103,16 +106,22 @@ public final class SourceGraph {
     public func add(_ declaration: Declaration) {
         allDeclarations.insert(declaration)
         allDeclarationsByKind[declaration.kind, default: []].insert(declaration)
-        declaration.usrs.forEach { allDeclarationsByUsr[$0] = declaration }
+        for usr in declaration.usrs {
+            if let existingDecl = allDeclarationsByUsr[usr] {
+                logger.warn("""
+                Declaration conflict detected: a declaration with the USR '\(usr)' has already been indexed.
+                This issue can cause inconsistent and incorrect results.
+                Existing declaration: \(existingDecl), declared in modules: \(existingDecl.location.file.modules.sorted())
+                Conflicting declaration: \(declaration), declared in modules: \(declaration.location.file.modules.sorted())
+                To resolve this warning, make sure all build modules are uniquely named.
+                """)
+            }
+            allDeclarationsByUsr[usr] = declaration
+        }
     }
 
     public func add(_ declarations: Set<Declaration>) {
-        allDeclarations.formUnion(declarations)
-
-        for declaration in declarations {
-            allDeclarationsByKind[declaration.kind, default: []].insert(declaration)
-            declaration.usrs.forEach { allDeclarationsByUsr[$0] = declaration }
-        }
+        declarations.forEach { add($0) }
     }
 
     public func remove(_ declaration: Declaration) {
@@ -258,7 +267,7 @@ public final class SourceGraph {
     func extendedDeclaration(forExtension extensionDeclaration: Declaration) throws -> Declaration? {
         guard let extendedReference = try extendedDeclarationReference(forExtension: extensionDeclaration) else { return nil }
 
-        if let extendedDeclaration = allDeclarationsByUsr[extendedReference.usr] {
+        if let extendedDeclaration = declaration(withUsr: extendedReference.usr) {
             return extendedDeclaration
         }
 

Sources/SyntaxAnalysis/DeclarationSyntaxVisitor.swift

@@ -19,14 +19,12 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
         variableInitFunctionCallLocations: Set<Location>,
         functionCallMetatypeArgumentLocations: Set<Location>,
         typeInitializerLocations: Set<Location>,
-        hasCapitalSelfFunctionCall: Bool,
         hasGenericFunctionReturnedMetatypeParameters: Bool
     )
 
     private let sourceLocationBuilder: SourceLocationBuilder
     private let typeSyntaxInspector: TypeSyntaxInspector
     private(set) var results: [Result] = []
-    private var didVisitCapitalSelfFunctionCall: Bool = false
 
     public var resultsByLocation: [Location: Result] {
         results.reduce(into: [Location: Result]()) { dict, result in
@@ -47,7 +45,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
             inheritanceClause: node.inheritanceClause,
             genericParameterClause: node.genericParameterClause,
             genericWhereClause: node.genericWhereClause,
-            consumeCapitalSelfFunctionCalls: true,
             at: node.name.positionAfterSkippingLeadingTrivia
         )
     }
@@ -60,7 +57,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
             inheritanceClause: node.inheritanceClause,
             genericParameterClause: node.genericParameterClause,
             genericWhereClause: node.genericWhereClause,
-            consumeCapitalSelfFunctionCalls: true,
             at: node.name.positionAfterSkippingLeadingTrivia
         )
     }
@@ -84,7 +80,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
             inheritanceClause: node.inheritanceClause,
             genericParameterClause: node.genericParameterClause,
             genericWhereClause: node.genericWhereClause,
-            consumeCapitalSelfFunctionCalls: true,
             at: node.name.positionAfterSkippingLeadingTrivia
         )
     }
@@ -131,7 +126,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
             trivia: node.commentCommandTrivia,
             inheritanceClause: node.inheritanceClause,
             genericWhereClause: node.genericWhereClause,
-            consumeCapitalSelfFunctionCalls: true,
             at: position
         )
     }
@@ -288,14 +282,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
         )
     }
 
-    public func visit(_ node: FunctionCallExprSyntax) {
-        if let identifierExpr = node.calledExpression.as(DeclReferenceExprSyntax.self),
-           identifierExpr.baseName.tokenKind == .keyword(.Self)
-        {
-            didVisitCapitalSelfFunctionCall = true
-        }
-    }
-
     // MARK: - Private
 
     private func parse(
@@ -312,7 +298,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
         genericWhereClause: GenericWhereClauseSyntax? = nil,
         variableInitFunctionCallExpr: FunctionCallExprSyntax? = nil,
         typeInitializerClause: TypeInitializerClauseSyntax? = nil,
-        consumeCapitalSelfFunctionCalls: Bool = false,
         at position: AbsolutePosition
     ) {
         let modifierNames = modifiers?.map(\.name.text) ?? []
@@ -321,13 +306,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
             AttributeSyntax($0)?.attributeName.trimmedDescription ?? AttributeSyntax($0)?.attributeName.firstToken(viewMode: .sourceAccurate)?.text
         } ?? []
         let location = sourceLocationBuilder.location(at: position)
-
-        var didVisitCapitalSelfFunctionCall = false
-        if consumeCapitalSelfFunctionCalls {
-            didVisitCapitalSelfFunctionCall = self.didVisitCapitalSelfFunctionCall
-            self.didVisitCapitalSelfFunctionCall = false
-        }
-
         let returnClauseTypeLocations = typeNameLocations(for: returnClause)
         let parameterClauseTypes = parameterClause?.parameters.map(\.type) ?? []
         let closureParameterClauseTypes = closureParameterClause?.parameters.compactMap(\.type) ?? []
@@ -360,7 +338,6 @@ public final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
             variableInitFunctionCallLocations: locations(for: variableInitFunctionCallExpr),
             functionCallMetatypeArgumentLocations: functionCallMetatypeArgumentLocations(for: variableInitFunctionCallExpr),
             typeInitializerLocations: typeLocations(for: typeInitializerClause?.value),
-            hasCapitalSelfFunctionCall: didVisitCapitalSelfFunctionCall,
             hasGenericFunctionReturnedMetatypeParameters: hasGenericFunctionReturnedMetatypeParameters
         ))
     }