Merge pull request swiftlang#35696 from nate-chandler/rdar72906989

[Test] Tested async cc's handling of constrained generic extensions.

Author: nate-chandler

test/IRGen/async/run-structinstance_generic-void-to-void-constrained.swift

@@ -0,0 +1,31 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift -Xfrontend -enable-experimental-concurrency %s -emit-ir -parse-as-library -module-name main | %FileCheck %s --check-prefix=CHECK-LL
+// RUN: %target-build-swift -Xfrontend -enable-experimental-concurrency %s -parse-as-library -module-name main -o %t/main %target-rpath(%t) 
+// RUN: %target-codesign %t/main
+// RUN: %target-run %t/main | %FileCheck %s
+
+// REQUIRES: executable_test
+// REQUIRES: swift_test_mode_optimize_none
+// REQUIRES: concurrency
+// UNSUPPORTED: use_os_stdlib
+
+import _Concurrency
+
+protocol Fooable {}
+extension String: Fooable {}
+
+extension Optional where Wrapped: Fooable {
+  // CHECK-LL: @"$sSq4mainAA7FooableRzlE22theConstrainedFunctionyyYFTu" = hidden global %swift.async_func_pointer
+  // CHECK-LL: define hidden swiftcc void @"$sSq4mainAA7FooableRzlE22theConstrainedFunctionyyYF"(%swift.task* {{%[0-9]+}}, %swift.executor* {{%[0-9]+}}, %swift.context* swiftasync {{%[0-9]+}}) {{#[0-9]*}} {
+  func theConstrainedFunction() async {
+    // CHECK: running Optional<String>.theConstrainedFunction
+    print("running \(Self.self).theConstrainedFunction")
+  }
+}
+
+@main struct Main {
+  static func main() async {
+    let a: String? = nil
+    await a.theConstrainedFunction()
+  }
+}