IRGen: Emit the protocol requirement descriptor async flag for initializers

rdar://88180938

Author: aschwaighofer

lib/IRGen/GenMeta.cpp

@@ -240,8 +240,12 @@ static bool needsForeignMetadataCompletionFunction(IRGenModule &IGM,
 
 template <class Flags>
 static Flags getMethodDescriptorFlags(ValueDecl *fn) {
-  if (isa<ConstructorDecl>(fn))
-    return Flags(Flags::Kind::Init); // 'init' is considered static
+  if (isa<ConstructorDecl>(fn)) {
+    auto flags = Flags(Flags::Kind::Init); // 'init' is considered static
+    if (auto *afd = dyn_cast<AbstractFunctionDecl>(fn))
+      flags = flags.withIsAsync(afd->hasAsync());
+    return flags;
+  }
 
   auto kind = [&] {
     auto accessor = dyn_cast<AccessorDecl>(fn);

test/IRGen/async/protocol_req_descriptor.swift

@@ -0,0 +1,14 @@
+// RUN: %target-swift-frontend -emit-ir  -disable-availability-checking %s | %FileCheck -check-prefix CHECK -check-prefix CHECK-%target-cpu -check-prefix CHECK-%target-import-type %s
+// REQUIRES: concurrency
+
+// Make sure that the protocol requirement descriptor includes the async flag.
+// CHECK: @"$s23protocol_req_descriptor12RepoProtocolMp" = {{.*}}%swift.protocol_requirement { i32 34, i32 0 }, %swift.protocol_requirement { i32 49, i32 0 } }>
+protocol RepoProtocol {
+ init() async
+ func run() async
+}
+
+actor Impl: RepoProtocol {
+  init() async {}
+  func run() async {}
+}