Ensure TARGET_TEMP_DIR values do not collide when package PIF targets differ only in case

Author: owenv

Sources/SWBCore/Settings/BuiltinMacros.swift

@@ -220,6 +220,7 @@ public final class BuiltinMacros {
     public static let TARGET_BUILD_DIR = BuiltinMacros.declarePathMacro("TARGET_BUILD_DIR")
     public static let TARGET_BUILD_SUBPATH = BuiltinMacros.declarePathMacro("TARGET_BUILD_SUBPATH")
     public static let TARGET_NAME = BuiltinMacros.declareStringMacro("TARGET_NAME")
+    public static let TARGET_NAME_CASE_SENSITIVITY_DISCRIMINATOR = BuiltinMacros.declareStringMacro("TARGET_NAME_CASE_SENSITIVITY_DISCRIMINATOR")
     public static let TARGET_TEMP_DIR = BuiltinMacros.declarePathMacro("TARGET_TEMP_DIR")
     // FIXME: This macro should be deprecated.
     public static let TARGETNAME = BuiltinMacros.declareStringMacro("TARGETNAME")
@@ -2376,6 +2377,7 @@ public final class BuiltinMacros {
         TARGET_DEVICE_OS_VERSION,
         TARGET_DEVICE_PLATFORM_NAME,
         TARGET_NAME,
+        TARGET_NAME_CASE_SENSITIVITY_DISCRIMINATOR,
         TARGET_TEMP_DIR,
         TEMP_DIR,
         TEMP_FILES_DIR,

Sources/SWBCore/Settings/Settings.swift

@@ -2953,14 +2953,26 @@ private class SettingsBuilder: ProjectMatchLookup {
         table.push(BuiltinMacros.PROJECT_DIR, literal: project.sourceRoot.str)
         table.push(BuiltinMacros.PROJECT_TEMP_DIR, Static { BuiltinMacros.namespace.parseString("$(OBJROOT)/$(PROJECT_NAME).build") })
 
+        do {
+            // A fair number of Swift packages have products/targets which only differ in case. In order to avoid collisions
+            // of build intermediates on case-insensitive file systems, add a discriminant if we detect this.
+            var seenTargetNames: Set<String> = []
+            for target in project.targets {
+                if !seenTargetNames.insert(target.name.lowercased()).inserted {
+                    table.push(BuiltinMacros.TARGET_NAME_CASE_SENSITIVITY_DISCRIMINATOR, Static { BuiltinMacros.namespace.parseString("$(TARGET_NAME:__md5)") })
+                    break
+                }
+            }
+        }
+
         if usePerConfigurationBuildLocations {
             table.push(BuiltinMacros.CONFIGURATION_BUILD_DIR, Static { BuiltinMacros.namespace.parseString("$(BUILD_DIR)/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME)") })
             table.push(BuiltinMacros.CONFIGURATION_TEMP_DIR, Static { BuiltinMacros.namespace.parseString("$(PROJECT_TEMP_DIR)/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME)") })
         } else {
             table.push(BuiltinMacros.CONFIGURATION_BUILD_DIR, Static { BuiltinMacros.namespace.parseString("$(BUILD_DIR)") })
             table.push(BuiltinMacros.CONFIGURATION_TEMP_DIR, Static { BuiltinMacros.namespace.parseString("$(PROJECT_TEMP_DIR)") })
         }
-        table.push(BuiltinMacros.TARGET_TEMP_DIR, Static { BuiltinMacros.namespace.parseString("$(CONFIGURATION_TEMP_DIR)/$(TARGET_NAME).build") })
+        table.push(BuiltinMacros.TARGET_TEMP_DIR, Static { BuiltinMacros.namespace.parseString("$(CONFIGURATION_TEMP_DIR)/$(TARGET_NAME)$(TARGET_NAME_CASE_SENSITIVITY_DISCRIMINATOR).build") })
         table.push(BuiltinMacros.TARGET_BUILD_DIR, Static { BuiltinMacros.namespace.parseString("$(CONFIGURATION_BUILD_DIR)$(TARGET_BUILD_SUBPATH)") })
         table.push(BuiltinMacros.BUILT_PRODUCTS_DIR, Static { BuiltinMacros.namespace.parseString("$(CONFIGURATION_BUILD_DIR)") })
         table.push(BuiltinMacros.DEVELOPMENT_LANGUAGE, literal: project.developmentRegion ?? "en")

Sources/SWBCore/Specs/CoreBuildSystem.xcspec

@@ -2987,7 +2987,7 @@ For more information on mergeable libraries, see [Configuring your project to us
             {
                 Name = "TARGET_TEMP_DIR";
                 Type = Path;
-                DefaultValue = "$(CONFIGURATION_TEMP_DIR)/$(TARGET_NAME).build";
+                DefaultValue = "$(CONFIGURATION_TEMP_DIR)/$(TARGET_NAME)$(TARGET_NAME_CASE_SENSITIVITY_DISCRIMINATOR).build";
                 Description = "Identifies the directory containing the target’s intermediate build files. Run Script build phases should place intermediate files at the location indicated by `DERIVED_FILE_DIR`, not the directory identified by this build setting.";
             },
             {

Tests/SWBBuildSystemTests/PackageBuildOperationTests.swift

@@ -470,6 +470,68 @@ fileprivate struct PackageBuildOperationTests: CoreBasedTests {
         }
     }
 
+    // Regression test which ensures we can build successfully when a project has two targets whose
+    // names only differ in case. Previously this would fail because the intermediate TARGET_TEMP_DIRs would
+    // collide.
+    @Test(.requireSDKs(.host))
+    func packageCaseInsensitiveCollisions() async throws {
+        try await withTemporaryDirectory { tmpDir in
+            let testWorkspace = try await TestWorkspace(
+                "Test",
+                sourceRoot: tmpDir.join("Test"),
+                projects: [
+                    TestProject(
+                        "aProject",
+                        groupTree: TestGroup(
+                            "Sources",
+                            children: [
+                                TestFile("file_1.swift"),
+                                TestFile("file_2.swift"),
+                            ]),
+                        buildConfigurations: [TestBuildConfiguration(
+                            "Debug",
+                            buildSettings: [
+                                "PRODUCT_NAME": "$(TARGET_NAME)",
+                                "SWIFT_VERSION": swiftVersion,
+                                "DSTROOT": tmpDir.join("dstroot").str,
+                            ])],
+                        targets: [
+                            TestStandardTarget(
+                                "Library",
+                                type: .staticLibrary,
+                                buildPhases: [
+                                    TestSourcesBuildPhase(["file_1.swift"]),
+                                ], dependencies: ["library"]),
+                            TestStandardTarget(
+                                "library",
+                                type: .staticLibrary,
+                                buildPhases: [
+                                    TestSourcesBuildPhase(["file_2.swift"]),
+                                ]),
+                        ])])
+
+            let tester = try await BuildOperationTester(getCore(), testWorkspace, simulated: false)
+
+            try await tester.fs.writeFileContents(testWorkspace.sourceRoot.join("aProject/file_1.swift")) { stream in
+                stream <<<
+            """
+            public let x = 42
+            """
+            }
+
+            try await tester.fs.writeFileContents(testWorkspace.sourceRoot.join("aProject/file_2.swift")) { stream in
+                stream <<<
+            """
+            public let y = 10
+            """
+            }
+
+            try await tester.checkBuild(runDestination: .host) { results in
+                results.checkNoDiagnostics()
+            }
+        }
+    }
+
     @Test(.requireSDKs(.macOS))
     func packageModuleAliasing() async throws {
         try await withTemporaryDirectory { tmpDirPath async throws -> Void in