Fix Identity Resolution

Sources/PackageModel/Manifest.swift

@@ -175,12 +175,12 @@ public final class Manifest {
         #if ENABLE_TARGET_BASED_DEPENDENCY_RESOLUTION
         // If we have already calculated it, returned the cached value.
         if let dependencies = self._requiredDependencies[productFilter] {
-            return self.dependencies
+            return dependencies
         } else {
             let targets = self.targetsRequired(for: productFilter)
             let dependencies = self.dependenciesRequired(for: targets, keepUnused: productFilter == .everything)
             self._requiredDependencies[productFilter] = dependencies
-            return self.dependencies
+            return dependencies
         }
         #else
         guard toolsVersion >= .v5_2 && !packageKind.isRoot else {
@@ -300,12 +300,27 @@ public final class Manifest {
             return nil
         }
 
+        return packageDependency(referencedBy: packageName)
+    }
+    private func packageDependency(
+        referencedBy packageName: String
+    ) -> PackageDependency? {
         return self.dependencies.first(where: {
             // rdar://80594761 make sure validation is case insensitive
             $0.nameForTargetDependencyResolutionOnly.lowercased() == packageName.lowercased()
         })
     }
 
+    /// Returns the package identity referred to by a target dependency string.
+    ///
+    /// This first checks if any declared package names (from 5.2) match.
+    /// If none is found, it is assumed that the string is the package identity itself
+    /// (although it may actually be a dangling reference diagnosed later).
+    private func packageIdentity(referencedBy packageName: String) -> PackageIdentity {
+        return packageDependency(referencedBy: packageName)?.identity
+        ?? .plain(packageName)
+    }
+
     /// Registers a required product with a particular dependency if possible, or registers it as unknown.
     ///
     /// - Parameters:
@@ -324,7 +339,7 @@ public final class Manifest {
             if let package = package { // ≥ 5.2
                 if !register(
                     product: product,
-                    inPackage: .plain(package),
+                    inPackage: packageIdentity(referencedBy: package),
                     registry: &registry.known,
                     availablePackages: availablePackages) {
                         // This is an invalid manifest condition diagnosed later. (No such package.)
@@ -347,7 +362,7 @@ public final class Manifest {
                 // If a by‐name entry is a product, it must be in a package of the same name.
                 if !register(
                     product: product,
-                    inPackage: .plain(product),
+                    inPackage: packageIdentity(referencedBy: product),
                     registry: &registry.known,
                     availablePackages: availablePackages) {
                         // If it doesn’t match a package, it should be a target, not a product.
@@ -381,7 +396,7 @@ public final class Manifest {
             if let package = package {
                 if !register(
                     product: name,
-                    inPackage: .plain(package),
+                    inPackage: packageIdentity(referencedBy: package),
                     registry: &registry.known,
                     availablePackages: availablePackages) {
                     // Invalid, diagnosed later; see the dependency version of this method.

Tests/BuildTests/BuildPlanTests.swift

@@ -1482,9 +1482,9 @@ final class BuildPlanTests: XCTestCase {
 
         #if ENABLE_TARGET_BASED_DEPENDENCY_RESOLUTION
         XCTAssertEqual(observability.diagnostics.count, 1)
-        let firstDiagnostic = observability.diagnostics.first.map({ $0.message.text })
+        let firstDiagnostic = observability.diagnostics.first.map({ $0.message })
         XCTAssert(
-            firstDiagnostic == "dependency 'C' is not used by any target",
+            firstDiagnostic == "dependency 'c' is not used by any target",
             "Unexpected diagnostic: " + (firstDiagnostic ?? "[none]")
         )
         #endif

Tests/PackageGraphTests/PackageGraphTests.swift

@@ -1855,6 +1855,43 @@ class PackageGraphTests: XCTestCase {
             XCTAssertNoDiagnostics(observability.diagnostics)
         }
     }
+
+    // test backwards compatibility 5.2 < 5.4
+    // TODO: remove this when we remove explicit dependency name
+    func testTargetDependencies_Post52_AliasFindsIdentity() throws {
+        let manifest = Manifest.createRootManifest(
+            name: "Package",
+            path: .init("/Package"),
+            toolsVersion: .v5_2,
+            dependencies: [
+                .localSourceControl(
+                    deprecatedName: "Alias",
+                    path: .init("/Identity"),
+                    requirement: .upToNextMajor(from: "1.0.0")
+                ),
+                .localSourceControl(
+                    path: .init("/Unrelated"),
+                    requirement: .upToNextMajor(from: "1.0.0")
+                )
+            ],
+            targets: [
+                try TargetDescription(
+                    name: "Target",
+                    dependencies: [
+                        .product(name: "Product", package: "Alias"),
+                        .product(name: "Unrelated", package: "Unrelated")
+                    ]
+                ),
+            ])
+        // Make sure aliases are found properly and do not fall back to pre‐5.2 behaviour, leaking across onto other dependencies.
+        let required = manifest.dependenciesRequired(for: .everything)
+        let unrelated = try XCTUnwrap(required.first(where: { $0.nameForTargetDependencyResolutionOnly == "Unrelated" }))
+        let requestedProducts = unrelated.productFilter
+        #if ENABLE_TARGET_BASED_DEPENDENCY_RESOLUTION
+        // Unrelated should not have been asked for Product, because it should know Product comes from Identity.
+        XCTAssertFalse(requestedProducts.contains("Product"), "Product requests are leaking.")
+        #endif
+    }
 }
 
 

Tests/PackageModelTests/ManifestTests.swift

@@ -144,9 +144,9 @@ class ManifestTests: XCTestCase {
             )
 
             #if ENABLE_TARGET_BASED_DEPENDENCY_RESOLUTION
-            XCTAssertEqual(manifest.dependenciesRequired(for: .specific(["Foo"])).map({ $0.name }).sorted(), [
-                "Bar1", // Foo → Foo1 → Bar1
-                "Bar2", // Foo → Foo1 → Foo2 → Bar2
+            XCTAssertEqual(manifest.dependenciesRequired(for: .specific(["Foo"])).map({ $0.identity.description }).sorted(), [
+                "bar1", // Foo → Foo1 → Bar1
+                "bar2", // Foo → Foo1 → Foo2 → Bar2
                 // (Bar3 is unreachable.)
             ])
             #endif

Tests/WorkspaceTests/WorkspaceTests.swift

@@ -2051,13 +2051,11 @@ final class WorkspaceTests: XCTestCase {
             ]
         )
 
-        #if ENABLE_TARGET_BASED_DEPENDENCY_RESOLUTION
         try workspace.checkPackageGraph(roots: ["Root"]) { _, diagnostics in
             testDiagnostics(diagnostics) { result in
-                result.check(diagnostic: .contains("Foo[Foo] 1.0.0..<2.0.0"), severity: .error)
+                result.check(diagnostic: .contains("'foo' 1.0.0..<2.0.0"), severity: .error)
             }
         }
-        #endif
     }
 
     func testToolsVersionRootPackages() throws {
@@ -2922,11 +2920,9 @@ final class WorkspaceTests: XCTestCase {
                 result.check(packages: "Foo")
                 result.check(targets: "Foo")
             }
-            #if ENABLE_TARGET_BASED_DEPENDENCY_RESOLUTION
             testDiagnostics(diagnostics) { result in
-                result.check(diagnostic: .contains("Bar[Bar] {1.0.0..<1.5.0, 1.5.1..<2.0.0} is forbidden"), severity: .error)
+                result.check(diagnostic: .contains("'bar' {1.0.0..<1.5.0, 1.5.1..<2.0.0} cannot be used"), severity: .error)
             }
-            #endif
         }
     }