[Concurrency] Drop "Asynchronously" suffix from imported 'async' methods.

The "Asynchronously" is a needless word for an "async" function. Remove
it.

Author: DougGregor

lib/Basic/StringExtras.cpp

@@ -1301,6 +1301,15 @@ bool swift::omitNeedlessWords(StringRef &baseName,
       splitBaseName(baseName, argNames[0], paramTypes[0], firstParamName))
     anyChanges = true;
 
+  // For a method imported as "async", drop the "Asynchronously" suffix from
+  // the base name. It is redundant with 'async'.
+  const StringRef asynchronously = "Asynchronously";
+  if (isAsync && camel_case::getLastWord(baseName) == asynchronously &&
+      baseName.size() > asynchronously.size()) {
+    baseName = baseName.drop_back(asynchronously.size());
+    anyChanges = true;
+  }
+
   // Omit needless words based on parameter types.
   for (unsigned i = 0, n = argNames.size(); i != n; ++i) {
     // If there is no corresponding parameter, there is nothing to

test/ClangImporter/objc_async.swift

@@ -20,6 +20,7 @@ func testSlowServer(slowServer: SlowServer) async throws {
   // expected-error@-1{{call is 'async' but is not marked with 'await'}}
 
   let _: String? = await try slowServer.fortune()
+  let _: Int = await try slowServer.magicNumber(withSeed: 42)
 }
 
 func testSlowServerSynchronous(slowServer: SlowServer) {

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

@@ -10,7 +10,8 @@
 -(void)findAnswerAsynchronously:(void (^)(NSString *_Nullable, NSError * _Nullable))handler __attribute__((swift_name("findAnswer(completionHandler:)")));
 -(BOOL)findAnswerFailinglyWithError:(NSError * _Nullable * _Nullable)error completion:(void (^)(NSString *_Nullable, NSError * _Nullable))handler __attribute__((swift_name("findAnswerFailingly(completionHandler:)")));
 -(void)doSomethingFun:(NSString *)operation then:(void (^)(void))completionHandler;
--(void)getFortuneWithCompletionHandler:(void (^)(NSString *_Nullable, NSError * _Nullable))handler;
+-(void)getFortuneAsynchronouslyWithCompletionHandler:(void (^)(NSString *_Nullable, NSError * _Nullable))handler;
+-(void)getMagicNumberAsynchronouslyWithSeed:(NSInteger)seed completionHandler:(void (^)(NSInteger, NSError * _Nullable))handler;
 @property(readwrite) void (^completionHandler)(NSInteger);
 
 -(void)doSomethingConflicted:(NSString *)operation completionHandler:(void (^)(NSInteger))handler;