Fix task ordering where stub executor does not depend on debug dylib link task (rdar://171933514) (#1330)

Long standing race bug where the stub executor link task is not properly ordered after the debug dylib link task. That means we've been getting lucky to have them scheduled in the right order most of the time.

The fix makes the stub executor depend on the lipo'd debug dylib.

Added single arch and multi-arch tests to verify the ordering invariant. Without the fix, the tests fail with this assertion:

    task 'Ld .../AppTarget normal' has no edge forcing it to follow 'Ld .../AppTarget.debug.dylib normal'

We've seen some intermittent code sign issues as well, so added extra assertions to validate that the code signing follows the debug dylib and stub executor link tasks, too.

Author: jonathanpenn

Sources/SWBTaskConstruction/TaskProducers/BuildPhaseTaskProducers/SourcesTaskProducer.swift

@@ -1252,7 +1252,7 @@ package final class SourcesTaskProducer: FilesBasedBuildPhaseTaskProducerBase, F
                                     scope: scope,
                                     inputs: linkerInputs,
                                     output: output,
-                                    commandOrderingInputs: additionalLinkerOrderingInputs,
+                                    commandOrderingInputs: additionalLinkerOrderingInputs + [linkedBinaryPreviewDylibNode].compactMap { $0 },
                                     commandOrderingOutputs: commandOrderingOutputs
                                 ),
                                 delegate,

Tests/SWBTaskConstructionTests/PreviewsTaskConstructionTests.swift

@@ -1222,4 +1222,181 @@ fileprivate struct PreviewsTaskConstructionTests: CoreBasedTests {
         }
     }
 
+    /// rdar://171933514 — The stub executor link task must be ordered after the debug.dylib link task.
+    /// Without this, llbuild can schedule them concurrently, causing "no such file or directory" for
+    /// the debug.dylib when the stub executor link starts before the debug.dylib link completes.
+    @Test(.requireSDKs(.iOS))
+    func previewsDylibStubExecutorDependsOnDebugDylib() async throws {
+        let core = try await getCore()
+
+        let testProject = try await TestProject(
+            "ProjectName",
+            groupTree: TestGroup(
+                "Sources", path: "Sources",
+                children: [
+                    TestFile("File.swift"),
+                    TestFile("Info.plist"),
+                ]),
+            targets: [
+                TestStandardTarget(
+                    "AppTarget",
+                    type: .application,
+                    buildConfigurations: [
+                        TestBuildConfiguration("Debug", buildSettings: [
+                            "SDKROOT": "iphoneos",
+                            "PRODUCT_NAME": "$(TARGET_NAME)",
+                            "SWIFT_OPTIMIZATION_LEVEL": "-Onone",
+                            "SWIFT_EXEC": swiftCompilerPath.str,
+                            "SWIFT_VERSION": swiftVersion,
+                            "ENABLE_PREVIEWS": "NO",
+                            "ENABLE_XOJIT_PREVIEWS": "YES",
+                            "ENABLE_DEBUG_DYLIB": "YES",
+                            "INFOPLIST_FILE": "Sources/Info.plist",
+                            "CODE_SIGN_IDENTITY": "-",
+                        ]),
+                    ],
+                    buildPhases: [
+                        TestSourcesBuildPhase([
+                            TestBuildFile("File.swift"),
+                        ]),
+                    ])
+            ])
+        let tester = try TaskConstructionTester(core, testProject)
+
+        let fs = PseudoFS()
+        try fs.writeSimulatedPreviewsJITStubExecutorLibraries(sdk: core.loadSDK(.iOSSimulator))
+
+        await tester.checkBuild(runDestination: .iOSSimulator, fs: fs) { results in
+            results.checkNoDiagnostics()
+
+            let ldDebugDylib = results.checkTask(.matchRuleType("Ld"), .matchRuleItemPattern(.suffix(".debug.dylib"))) { $0 }
+            let ldPreviewDylib = results.checkTask(.matchRuleType("Ld"), .matchRuleItemPattern(.suffix("__preview.dylib"))) { $0 }
+            let ldStubExecutor = results.checkTask(.matchRuleType("Ld"), .matchRuleItemPattern(.suffix("/AppTarget"))) { $0 }
+
+            let signDebugDylib = results.checkTask(.matchRuleType("CodeSign"), .matchRuleItemPattern(.suffix(".debug.dylib"))) { $0 }
+            let signPreviewDylib = results.checkTask(.matchRuleType("CodeSign"), .matchRuleItemPattern(.suffix("__preview.dylib"))) { $0 }
+            let signApp = results.checkTask(.matchRuleType("CodeSign"), .matchRuleItemPattern(.suffix(".app"))) { $0 }
+
+            // Stub executor must wait for debug.dylib to be linked
+            if let ldStubExecutor, let ldDebugDylib {
+                results.checkTaskFollows(ldStubExecutor, antecedent: ldDebugDylib)
+            }
+
+            // CodeSign must wait for all three linking tasks
+            if let ldDebugDylib, let signDebugDylib {
+                results.checkTaskFollows(signDebugDylib, antecedent: ldDebugDylib)
+            }
+            if let ldPreviewDylib, let signPreviewDylib {
+                results.checkTaskFollows(signPreviewDylib, antecedent: ldPreviewDylib)
+            }
+            if let ldStubExecutor, let signApp {
+                results.checkTaskFollows(signApp, antecedent: ldStubExecutor)
+            }
+            if let ldDebugDylib, let signApp {
+                results.checkTaskFollows(signApp, antecedent: ldDebugDylib)
+            }
+            if let ldPreviewDylib, let signApp {
+                results.checkTaskFollows(signApp, antecedent: ldPreviewDylib)
+            }
+        }
+    }
+
+    /// rdar://171933514 — Same ordering invariant as above, but for multi-arch builds where
+    /// per-arch link tasks go through lipo. The per-arch stub executor link must be ordered
+    /// after the lipo'd debug.dylib.
+    @Test(.requireSDKs(.macOS))
+    func previewsDylibStubExecutorDependsOnDebugDylibMultiArch() async throws {
+        let core = try await getCore()
+        let archs = ["arm64", "x86_64"]
+        let archsJoined = archs.joined(separator: " ")
+
+        let testProject = try await TestProject(
+            "ProjectName",
+            groupTree: TestGroup(
+                "Sources", path: "Sources",
+                children: [
+                    TestFile("File.swift"),
+                    TestFile("Info.plist"),
+                    TestFile("Entitlements.plist"),
+                ]),
+            targets: [
+                TestStandardTarget(
+                    "AppTarget",
+                    type: .application,
+                    buildConfigurations: [
+                        TestBuildConfiguration("Debug", buildSettings: [
+                            "PRODUCT_NAME": "$(TARGET_NAME)",
+                            "SWIFT_OPTIMIZATION_LEVEL": "-Onone",
+                            "SWIFT_EXEC": swiftCompilerPath.str,
+                            "SWIFT_VERSION": swiftVersion,
+                            "ARCHS": archsJoined,
+                            "ENABLE_PREVIEWS": "NO",
+                            "ENABLE_XOJIT_PREVIEWS": "YES",
+                            "ENABLE_DEBUG_DYLIB": "YES",
+                            "ENABLE_DEBUG_DYLIB_OVERRIDE": "YES",
+                            "DEFINES_MODULE": "NO",
+                            "INFOPLIST_FILE": "Sources/Info.plist",
+                            "CODE_SIGN_ENTITLEMENTS": "Sources/Entitlements.plist",
+                            "CODE_SIGN_IDENTITY": "-",
+                        ]),
+                    ],
+                    buildPhases: [
+                        TestSourcesBuildPhase([
+                            TestBuildFile("File.swift"),
+                        ]),
+                    ])
+            ])
+        let tester = try TaskConstructionTester(core, testProject)
+
+        await tester.checkBuild(runDestination: .anyMac, fs: localFS) { results in
+            results.checkNoDiagnostics()
+
+            var ldDebugDylibs: [any PlannedTask] = []
+            var ldPreviewDylibs: [any PlannedTask] = []
+            var ldStubExecutors: [any PlannedTask] = []
+
+            for arch in archs {
+                let ldDebugDylib = results.checkTask(.matchRuleType("Ld"), .matchRuleItemPattern(.suffix(".debug.dylib")), .matchRuleItem(arch)) { $0 }
+                let ldPreviewDylib = results.checkTask(.matchRuleType("Ld"), .matchRuleItemPattern(.suffix("__preview.dylib")), .matchRuleItem(arch)) { $0 }
+                let ldStubExecutor = results.checkTask(.matchRuleType("Ld"), .matchRuleItemPattern(.suffix("/AppTarget")), .matchRuleItem(arch)) { $0 }
+
+                // Stub executor must wait for lipo'd debug.dylib
+                if let ldStubExecutor, let ldDebugDylib {
+                    results.checkTaskFollows(ldStubExecutor, antecedent: ldDebugDylib)
+                }
+
+                if let ldDebugDylib { ldDebugDylibs.append(ldDebugDylib) }
+                if let ldPreviewDylib { ldPreviewDylibs.append(ldPreviewDylib) }
+                if let ldStubExecutor { ldStubExecutors.append(ldStubExecutor) }
+            }
+
+            let signDebugDylib = results.checkTask(.matchRuleType("CodeSign"), .matchRuleItemPattern(.suffix(".debug.dylib"))) { $0 }
+            let signPreviewDylib = results.checkTask(.matchRuleType("CodeSign"), .matchRuleItemPattern(.suffix("__preview.dylib"))) { $0 }
+            let signApp = results.checkTask(.matchRuleType("CodeSign"), .matchRuleItemPattern(.suffix(".app"))) { $0 }
+
+            // CodeSign must wait for all linking tasks
+            for ldDebugDylib in ldDebugDylibs {
+                if let signDebugDylib {
+                    results.checkTaskFollows(signDebugDylib, antecedent: ldDebugDylib)
+                }
+                if let signApp {
+                    results.checkTaskFollows(signApp, antecedent: ldDebugDylib)
+                }
+            }
+            for ldPreviewDylib in ldPreviewDylibs {
+                if let signPreviewDylib {
+                    results.checkTaskFollows(signPreviewDylib, antecedent: ldPreviewDylib)
+                }
+                if let signApp {
+                    results.checkTaskFollows(signApp, antecedent: ldPreviewDylib)
+                }
+            }
+            for ldStubExecutor in ldStubExecutors {
+                if let signApp {
+                    results.checkTaskFollows(signApp, antecedent: ldStubExecutor)
+                }
+            }
+        }
+    }
+
 }