🍒[5.9][Concurrency] Handle missing Job type in old SDKs in tryDiagnoseExecutor

lib/Sema/TypeCheckConcurrency.cpp

@@ -1283,19 +1283,21 @@ void swift::tryDiagnoseExecutorConformance(ASTContext &C,
     if (funcDecl->getParameters()->size() != 1)
       continue;
     if (auto param = funcDecl->getParameters()->front()) {
-      StructDecl* jobDecl;
-      if (auto decl = C.getExecutorJobDecl()) {
-        jobDecl = decl;
-      } else if (auto decl = C.getJobDecl()) {
+      StructDecl *unownedJobDecl = C.getUnownedJobDecl();
+      StructDecl *jobDecl = nullptr;
+      if (auto executorJobDecl = C.getExecutorJobDecl()) {
+        jobDecl = executorJobDecl;
+      } else if (auto plainJobDecl = C.getJobDecl()) {
         // old standard library, before we introduced the `typealias Job = ExecutorJob`
-        jobDecl = decl;
+        jobDecl = plainJobDecl;
       }
 
       if (jobDecl &&
           param->getType()->isEqual(jobDecl->getDeclaredInterfaceType())) {
         assert(moveOnlyEnqueueRequirement == nullptr);
         moveOnlyEnqueueRequirement = funcDecl;
-      } else if (param->getType()->isEqual(C.getUnownedJobDecl()->getDeclaredInterfaceType())) {
+      } else if (unownedJobDecl &&
+                 param->getType()->isEqual(unownedJobDecl->getDeclaredInterfaceType())) {
         assert(unownedEnqueueRequirement == nullptr);
         unownedEnqueueRequirement = funcDecl;
       }
@@ -1306,7 +1308,6 @@ void swift::tryDiagnoseExecutorConformance(ASTContext &C,
       break; // we're done looking for the requirements
   }
 
-
   auto conformance = module->lookupConformance(nominalTy, proto);
   auto concreteConformance = conformance.getConcrete();
   assert(unownedEnqueueRequirement && "could not find the enqueue(UnownedJob) requirement, which should be always there");

test/Concurrency/Runtime/custom_executors_tryDiagnoseExecutorConformance_with_sdk_missing_job_type.swift

@@ -0,0 +1,23 @@
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-concurrency-without-job) -typecheck -parse-as-library %s -verify
+
+// REQUIRES: concurrency
+// REQUIRES: libdispatch
+
+// rdar://106849189 move-only types should be supported in freestanding mode
+// UNSUPPORTED: freestanding
+
+// UNSUPPORTED: back_deployment_runtime
+// REQUIRES: concurrency_runtime
+
+import _Concurrency
+
+// NOTE: This test simulates what happens when we have an SDK with some missing concurrency types.
+// Specifically, we're missing the ExecutorJob and Job declarations.
+// This simulates a pre-Swift-5.9 SDK being used with a Swift 5.9+ compiler,
+// which would have failed previously due to missing handling of missing types.
+//
+// This is a regression test for that situation
+
+final class FakeExecutor: SerialExecutor {
+  func enqueue(_ job: UnownedJob) {}
+}

test/Inputs/clang-importer-sdk/swift-modules-concurrency-without-job/_Concurrency.swift

@@ -0,0 +1,10 @@
+
+// This simulates a pre-Swift5.9 concurrency library with `Job` and `ExecutorJob` not being defined at all.
+// This is used to verify missing type handling in the SDK when a latest compiler is used.
+
+public struct UnownedJob {}
+
+public protocol SerialExecutor {
+  // pretend to be a broken, empty serial executor
+  func enqueue(_ job: UnownedJob)
+}

test/lit.cfg

@@ -607,6 +607,20 @@ config.substitutions.append(('%build-clang-importer-objc-overlays',
                              '%target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource -I %t) -enable-objc-interop -emit-module -o %t %clang-importer-sdk-path/swift-modules/CoreFoundation.swift && '
                              '%target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource -I %t) -enable-objc-interop -emit-module -o %t %clang-importer-sdk-path/swift-modules/Foundation.swift'))
 
+
+# FIXME: BEGIN -enable-source-import hackaround
+config.substitutions.append(('%clang-importer-sdk-concurrency-without-job-path',
+                             '%r' % (make_path(config.test_source_root, 'Inputs', 'clang-importer-sdk'))))
+
+config.substitutions.append(('%clang-importer-sdk-concurrency-without-job-nosource',
+                             '-sdk %r' % (make_path(config.test_source_root, 'Inputs', 'clang-importer-sdk'))))
+# FIXME: END -enable-source-import hackaround
+
+config.substitutions.append(('%clang-importer-sdk-concurrency-without-job',
+                             '-enable-source-import -sdk %r -I %r ' % (make_path(config.test_source_root, 'Inputs', 'clang-importer-sdk'),
+                                                                       make_path(config.test_source_root, 'Inputs', 'clang-importer-sdk', 'swift-modules-concurrency-without-job'))))
+
+
 # FIXME: BEGIN -enable-source-import hackaround
 config.substitutions.append(('%clang-importer-sdk-path',
                              '%r' % (make_path(config.test_source_root, 'Inputs', 'clang-importer-sdk'))))