[cxx-interop] Don't import exit from Darwin module, use the one from _SwiftConcurrency.h.

Author: zoecarver

lib/ClangImporter/ImportDecl.cpp

@@ -3213,13 +3213,14 @@ namespace {
                    d->getName() == "cos" || d->getName() == "exit";
           return false;
         };
-        if (decl->getOwningModule() &&
-            (decl->getOwningModule()
-                ->getTopLevelModule()
-                ->getFullModuleName() == "std" ||
-             decl->getOwningModule()
-                ->getTopLevelModule()
-                ->getFullModuleName() == "_SwiftConcurrencyShims")) {
+        auto topLevelModuleEq =
+            [](const clang::FunctionDecl *d, StringRef n) -> bool {
+          return d->getOwningModule() &&
+                 d->getOwningModule()
+                    ->getTopLevelModule()
+                    ->getFullModuleName() == n;
+        };
+        if (topLevelModuleEq(decl, "std")) {
           if (isAlternativeCStdlibFunctionFromTextualHeader(decl)) {
             return nullptr;
           }
@@ -3231,6 +3232,13 @@ namespace {
             return nullptr;
           }
         }
+        // Use the exit function from _SwiftConcurrency.h as it is platform
+        // agnostic.
+        if ((topLevelModuleEq(decl, "Darwin") ||
+             topLevelModuleEq(decl, "SwiftGlibc")) &&
+            decl->getDeclName().isIdentifier() && decl->getName() == "exit") {
+          return nullptr;
+        }
       }
 
       auto dc =

test/Interop/Cxx/stdlib/use-swift-concurrency.swift

@@ -0,0 +1,39 @@
+// RUN: %target-run-simple-swift(-I %S/Inputs -Xfrontend -enable-experimental-cxx-interop -Xfrontend -disable-availability-checking %import-libdispatch -parse-as-library)
+//
+// REQUIRES: executable_test
+// REQUIRES: concurrency
+// REQUIRES: libdispatch
+// REQUIRES: concurrency_runtime
+
+import StdlibUnittest
+
+import CxxStdlib
+import Cxx
+
+import _Concurrency
+import Dispatch
+
+@main struct Main {
+  static func main() async {
+    var ConcurrencyTestSuite = TestSuite("Concurrency")
+
+    ConcurrencyTestSuite.test("Task.sleep") {
+      let start = DispatchTime.now()
+      await Task.sleep(100_000_000)
+      let stop = DispatchTime.now()
+      expectTrue(stop >= (start + .nanoseconds(100_000_000)))
+    }
+
+    ConcurrencyTestSuite.test("Task.sleep (non-blocking)") {
+      let task = detach {
+        std.string("Hello, Swift!")
+      }
+
+      await Task.sleep(100_000_000)
+      expectEqual(await task.get(), "Hello, Swift!")
+    }
+    
+    await runAllTestsAsync()
+  }
+}
+