[Importer] Make sure we drop "WithBlock" as a completion-handler suffix.

Fixes rdar://73641827.

Author: DougGregor

lib/Basic/StringExtras.cpp

@@ -1374,6 +1374,10 @@ Optional<StringRef> swift::stripWithCompletionHandlerSuffix(StringRef name) {
     return name.drop_back(strlen("WithCompletionBlock"));
   }
 
+  if (name.endswith("WithBlock")) {
+    return name.drop_back(strlen("WithBlock"));
+  }
+
   if (name.endswith("WithReplyTo")) {
     return name.drop_back(strlen("WithReplyTo"));
   }

test/ClangImporter/objc_async.swift

@@ -46,6 +46,7 @@ func testSlowServer(slowServer: SlowServer) async throws {
   slowServer.repeatTrick("jump") // expected-error{{missing argument for parameter 'completionHandler' in call}}
 
   _ = try await slowServer.oldAPI(); // expected-error{{'oldAPI()' is unavailable in macOS: APIs deprecated as of macOS 10.14 and earlier are not imported as 'async'}}
+  _ = try await slowServer.someAsyncMethod()
 }
 
 func testSlowServerSynchronous(slowServer: SlowServer) {

test/Inputs/clang-importer-sdk/usr/include/ObjCConcurrency.h

@@ -55,6 +55,8 @@ typedef void (^CompletionHandler)(NSString * _Nullable, NSString * _Nullable_res
 - (void)getSomeObjectWithCompletionHandler:(nullable void (^)(NSObject *_Nullable x, NSError *_Nullable error))handler;
 
 -(void)oldAPIWithCompletionHandler:(void (^ _Nonnull)(NSString *_Nullable, NSError *_Nullable))handler __attribute__((availability(macosx, deprecated=10.14)));
+
+-(void)someAsyncMethodWithBlock:(void (^ _Nonnull)(NSString *_Nullable, NSError *_Nullable))completionHandler;
 @end
 
 @protocol RefrigeratorDelegate<NSObject>