[Concurrency] Use completion/completionHandler parameter names for async import

Extend the check for completion handler parameters to also consider the
name of the parameter (not its argument label). If it's `completion` or
`completionHandler`, we have a completion handler. This extends our
API coverage for importing Objective-C methods with completion
handlers as 'async'.

Author: DougGregor

lib/ClangImporter/ImportName.cpp

@@ -1213,10 +1213,13 @@ NameImporter::considerAsyncImport(
   // handler.
   Optional<StringRef> newBaseName;
   if (isCompletionHandlerParamName(paramNames[completionHandlerParamNameIndex])) {
-    // The parameter itself has an appropriate name.
+    // The argument label itself has an appropriate name.
   } else if (!hasCustomName && completionHandlerParamIndex == 0 &&
              (newBaseName = isCompletionHandlerInBaseName(baseName))) {
     // The base name implies that the first parameter is a completion handler.
+  } else if (isCompletionHandlerParamName(
+                 params[completionHandlerParamIndex]->getName())) {
+    // The parameter has an appropriate name.
   } else {
     return None;
   }
@@ -1238,6 +1241,10 @@ NameImporter::considerAsyncImport(
   if (isInitializer)
     return notAsync("initializers cannot be async");
 
+  // Accessors are never imported as async.
+  if (clangDecl->isPropertyAccessor())
+    return notAsync("method is a property accessor");
+
   // Check whether we method has a suitable return type.
   if (clangDecl->getReturnType()->isVoidType()) {
     // 'void' is the common case; the method produces no synchronous result.
@@ -1515,7 +1522,8 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
       else if (parsedName.IsSetter)
         result.info.accessorKind = ImportedAccessorKind::PropertySetter;
 
-      if (method && parsedName.IsFunctionName) {
+      if (method && parsedName.IsFunctionName &&
+          result.info.accessorKind == ImportedAccessorKind::None) {
         // Get the parameters.
         ArrayRef<const clang::ParmVarDecl *> params{method->param_begin(),
                                                     method->param_end()};
@@ -1787,16 +1795,6 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
         result.info.errorInfo = *errorInfo;
     }
 
-    if (version.supportsConcurrency()) {
-      if (auto asyncInfo = considerAsyncImport(
-              objcMethod, baseName, argumentNames, params, isInitializer,
-              /*hasCustomName=*/false,
-              result.getErrorInfo())) {
-        result.info.hasAsyncInfo = true;
-        result.info.asyncInfo = *asyncInfo;
-      }
-    }
-
     isFunction = true;
 
     // Is this one of the accessors for subscripts?
@@ -1814,6 +1812,17 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
         result.info.accessorKind = ImportedAccessorKind::SubscriptSetter;
     }
 
+    if (version.supportsConcurrency() &&
+        result.info.accessorKind == ImportedAccessorKind::None) {
+      if (auto asyncInfo = considerAsyncImport(
+              objcMethod, baseName, argumentNames, params, isInitializer,
+              /*hasCustomName=*/false,
+              result.getErrorInfo())) {
+        result.info.hasAsyncInfo = true;
+        result.info.asyncInfo = *asyncInfo;
+      }
+    }
+
     break;
   }
   }

test/ClangImporter/objc_async.swift

@@ -11,6 +11,8 @@ func testSlowServer(slowServer: SlowServer) async {
   let _: String = await slowServer.findAnswerFailingly() ?? "nope"
   // FIXME: expected-error@-2{{call can throw, but it is not marked with 'try'}}
   // FIXME: expected-error@-2{{call can throw, but it is not marked with 'try'}}
+  let _: Void = await slowServer.doSomethingFun("jump")
+  let _: (Int) -> Void = slowServer.completionHandler
 }
 
 func testSlowServerOldSchool(slowServer: SlowServer) {

test/IDE/print_clang_objc_async.swift

@@ -16,4 +16,5 @@
 // CHECK-DAG:     func findAnswer() async throws -> String?
 // CHECK-DAG:     func findAnswerFailingly(completionHandler handler: @escaping (String?, Error?) -> Void) throws
 // CHECK-DAG:     func findAnswerFailingly() async throws -> String?
+// CHECK-DAG:     func doSomethingFun(_ operation: String) async
 // CHECK: {{^[}]$}}

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

@@ -9,6 +9,8 @@
 -(void)checkAvailabilityWithCompletionHandler:(void (^)(BOOL isAvailable))completionHandler;
 -(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;
+@property(readwrite) void (^completionHandler)(NSInteger);
 @end
 
 #pragma clang assume_nonnull end