[Refactoring] Add @completionHandlerAsync to sync function

When adding an async alternative, add the @completionHandlerAsync
attribute to the sync function. Check for this attribute in addition to
the name check, ie. convert a call if the callee has either
@completionHandlerAsync or a name that is completion-handler-like name.

The addition of the attribute is currently gated behind the experimental
concurrency flag.

Resolves rdar://77486504

Author: bnbarham

lib/IDE/Refactoring.cpp

@@ -4079,7 +4079,7 @@ struct AsyncHandlerDesc {
   HandlerType Type = HandlerType::INVALID;
   bool HasError = false;
 
-  static AsyncHandlerDesc get(const ValueDecl *Handler, bool ignoreName) {
+  static AsyncHandlerDesc get(const ValueDecl *Handler, bool RequireName) {
     AsyncHandlerDesc HandlerDesc;
     if (auto Var = dyn_cast<VarDecl>(Handler)) {
       HandlerDesc.Handler = Var;
@@ -4090,8 +4090,8 @@ struct AsyncHandlerDesc {
       return AsyncHandlerDesc();
     }
 
-    // Callback must have a completion-like name (if we're not ignoring it)
-    if (!ignoreName && !isCompletionHandlerParamName(HandlerDesc.getNameStr()))
+    // Callback must have a completion-like name
+    if (RequireName && !isCompletionHandlerParamName(HandlerDesc.getNameStr()))
       return AsyncHandlerDesc();
 
     // Callback must be a function type and return void. Doesn't need to have
@@ -4340,17 +4340,26 @@ struct AsyncHandlerDesc {
 /// information about that completion handler and its index within the function
 /// declaration.
 struct AsyncHandlerParamDesc : public AsyncHandlerDesc {
+  /// The function the completion handler is a parameter of.
+  const FuncDecl *Func = nullptr;
   /// The index of the completion handler in the function that declares it.
   int Index = -1;
 
   AsyncHandlerParamDesc() : AsyncHandlerDesc() {}
-  AsyncHandlerParamDesc(const AsyncHandlerDesc &Handler, int Index)
-      : AsyncHandlerDesc(Handler), Index(Index) {}
+  AsyncHandlerParamDesc(const AsyncHandlerDesc &Handler, const FuncDecl *Func,
+                        int Index)
+      : AsyncHandlerDesc(Handler), Func(Func), Index(Index) {}
 
-  static AsyncHandlerParamDesc find(const FuncDecl *FD, bool ignoreName) {
+  static AsyncHandlerParamDesc find(const FuncDecl *FD,
+                                    bool RequireAttributeOrName) {
     if (!FD || FD->hasAsync() || FD->hasThrows())
       return AsyncHandlerParamDesc();
 
+    bool RequireName = RequireAttributeOrName;
+    if (RequireAttributeOrName &&
+        FD->getAttrs().hasAttribute<CompletionHandlerAsyncAttr>())
+      RequireName = false;
+
     // Require at least one parameter and void return type
     auto *Params = FD->getParameters();
     if (Params->size() == 0 || !FD->getResultInterfaceType()->isVoid())
@@ -4364,10 +4373,30 @@ struct AsyncHandlerParamDesc : public AsyncHandlerDesc {
     if (Param->isAutoClosure())
       return AsyncHandlerParamDesc();
 
-    return AsyncHandlerParamDesc(AsyncHandlerDesc::get(Param, ignoreName),
+    return AsyncHandlerParamDesc(AsyncHandlerDesc::get(Param, RequireName), FD,
                                  Index);
   }
 
+  /// Print the name of the function with the completion handler, without
+  /// the completion handler parameter, to \p OS. That is, the name of the
+  /// async alternative function.
+  void printAsyncFunctionName(llvm::raw_ostream &OS) const {
+    if (!Func || Index < 0)
+      return;
+
+    DeclName Name = Func->getName();
+    OS << Name.getBaseName();
+
+    OS << tok::l_paren;
+    ArrayRef<Identifier> ArgNames = Name.getArgumentNames();
+    for (size_t I = 0; I < ArgNames.size(); ++I) {
+      if (I != (size_t)Index) {
+        OS << ArgNames[I] << tok::colon;
+      }
+    }
+    OS << tok::r_paren;
+  }
+
   bool operator==(const AsyncHandlerParamDesc &Other) const {
     return Handler == Other.Handler && Type == Other.Type &&
            HasError == Other.HasError && Index == Other.Index;
@@ -5546,8 +5575,12 @@ class AsyncConverter : private SourceEntityWalker {
         return addCustom(CE->getSourceRange(), [&]() { addHandlerCall(CE); });
 
       if (auto *CE = dyn_cast<CallExpr>(E)) {
+        // If the refactoring is on the call itself, do not require the callee
+        // to have the @completionHandlerAsync attribute or a completion-like
+        // name.
         auto HandlerDesc = AsyncHandlerParamDesc::find(
-            getUnderlyingFunc(CE->getFn()), StartNode.dyn_cast<Expr *>() == CE);
+            getUnderlyingFunc(CE->getFn()),
+            /*RequireAttributeOrName=*/StartNode.dyn_cast<Expr *>() != CE);
         if (HandlerDesc.isValid())
           return addCustom(CE->getSourceRange(),
                            [&]() { addHoistedCallback(CE, HandlerDesc); });
@@ -5818,8 +5851,8 @@ class AsyncConverter : private SourceEntityWalker {
 
       // The completion handler that is called as part of the \p CE call.
       // This will be called once the async function returns.
-      auto CompletionHandler = AsyncHandlerDesc::get(CallbackDecl,
-                                                     /*ignoreName=*/true);
+      auto CompletionHandler =
+          AsyncHandlerDesc::get(CallbackDecl, /*RequireAttributeOrName=*/false);
       if (CompletionHandler.isValid()) {
         if (auto CalledFunc = getUnderlyingFunc(CE->getFn())) {
           StringRef HandlerName = Lexer::getCharSourceRangeFromSourceRange(
@@ -6412,8 +6445,8 @@ bool RefactoringActionConvertCallToAsyncAlternative::isApplicable(
   if (!CE)
     return false;
 
-  auto HandlerDesc = AsyncHandlerParamDesc::find(getUnderlyingFunc(CE->getFn()),
-                                                 /*ignoreName=*/true);
+  auto HandlerDesc = AsyncHandlerParamDesc::find(
+      getUnderlyingFunc(CE->getFn()), /*RequireAttributeOrName=*/false);
   return HandlerDesc.isValid();
 }
 
@@ -6470,7 +6503,8 @@ bool RefactoringActionConvertToAsync::performChange() {
   assert(FD &&
          "Should not run performChange when refactoring is not applicable");
 
-  auto HandlerDesc = AsyncHandlerParamDesc::find(FD, /*ignoreName=*/true);
+  auto HandlerDesc =
+      AsyncHandlerParamDesc::find(FD, /*RequireAttributeOrName=*/false);
   AsyncConverter Converter(TheFile, SM, DiagEngine, FD, HandlerDesc);
   if (!Converter.convert())
     return true;
@@ -6487,7 +6521,8 @@ bool RefactoringActionAddAsyncAlternative::isApplicable(
   if (!FD)
     return false;
 
-  auto HandlerDesc = AsyncHandlerParamDesc::find(FD, /*ignoreName=*/true);
+  auto HandlerDesc =
+      AsyncHandlerParamDesc::find(FD, /*RequireAttributeOrName=*/false);
   return HandlerDesc.isValid();
 }
 
@@ -6504,21 +6539,37 @@ bool RefactoringActionAddAsyncAlternative::performChange() {
   assert(FD &&
          "Should not run performChange when refactoring is not applicable");
 
-  auto HandlerDesc = AsyncHandlerParamDesc::find(FD, /*ignoreName=*/true);
+  auto HandlerDesc =
+      AsyncHandlerParamDesc::find(FD, /*RequireAttributeOrName=*/false);
   assert(HandlerDesc.isValid() &&
          "Should not run performChange when refactoring is not applicable");
 
   AsyncConverter Converter(TheFile, SM, DiagEngine, FD, HandlerDesc);
   if (!Converter.convert())
     return true;
 
+  // Deprecate the synchronous function
   EditConsumer.accept(SM, FD->getAttributeInsertionLoc(false),
                       "@available(*, deprecated, message: \"Prefer async "
                       "alternative instead\")\n");
+
+  if (Ctx.LangOpts.EnableExperimentalConcurrency) {
+    // Add an attribute to describe its async alternative
+    llvm::SmallString<0> HandlerAttribute;
+    llvm::raw_svector_ostream OS(HandlerAttribute);
+    OS << "@completionHandlerAsync(\"";
+    HandlerDesc.printAsyncFunctionName(OS);
+    OS << "\", completionHandlerIndex: " << HandlerDesc.Index << ")\n";
+    EditConsumer.accept(SM, FD->getAttributeInsertionLoc(false),
+                        HandlerAttribute);
+  }
+
   AsyncConverter LegacyBodyCreator(TheFile, SM, DiagEngine, FD, HandlerDesc);
   if (LegacyBodyCreator.createLegacyBody()) {
     LegacyBodyCreator.replace(FD->getBody(), EditConsumer);
   }
+
+  // Add the async alternative
   Converter.insertAfter(FD, EditConsumer);
 
   return false;

test/refactoring/ConvertAsync/async_attribute_added.swift

@@ -0,0 +1,48 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %refactor-check-compiles -add-async-alternative -dump-text -source-filename %s -pos=%(line+1):1 -enable-experimental-concurrency | %FileCheck -check-prefix=SIMPLE %s
+func simple(completion: @escaping (String) -> Void) { }
+// SIMPLE: async_attribute_added.swift [[# @LINE-1]]:1 -> [[# @LINE-1]]:1
+// SIMPLE-NEXT: @available(*, deprecated, message: "Prefer async alternative instead")
+// SIMPLE-EMPTY:
+// SIMPLE-NEXT: async_attribute_added.swift [[# @LINE-4]]:1 -> [[# @LINE-4]]:1
+// SIMPLE-NEXT: @completionHandlerAsync("simple()", completionHandlerIndex: 0)
+// SIMPLE-EMPTY:
+// SIMPLE-NEXT: async_attribute_added.swift [[# @LINE-7]]:53 -> [[# @LINE-7]]:56
+// SIMPLE-NEXT: {
+// SIMPLE-NEXT: async {
+// SIMPLE-NEXT: let result = await simple()
+// SIMPLE-NEXT: completion(result)
+// SIMPLE-NEXT: }
+// SIMPLE-NEXT: }
+// SIMPLE-EMPTY:
+// SIMPLE-NEXT: async_attribute_added.swift [[# @LINE-15]]:56 -> [[# @LINE-15]]:56
+// SIMPLE-EMPTY:
+// SIMPLE-EMPTY:
+// SIMPLE-EMPTY:
+// SIMPLE-NEXT: async_attribute_added.swift [[# @LINE-19]]:56 -> [[# @LINE-19]]:56
+// SIMPLE-NEXT: func simple() async -> String { }
+
+// RUN: %refactor-check-compiles -add-async-alternative -dump-text -source-filename %s -pos=%(line+1):5 -enable-experimental-concurrency | %FileCheck -check-prefix=OTHER-ARGS %s
+func otherArgs(first: Int, second: String, completion: @escaping (String) -> Void) { }
+// OTHER-ARGS: @completionHandlerAsync("otherArgs(first:second:)", completionHandlerIndex: 2)
+
+// RUN: %refactor-check-compiles -add-async-alternative -dump-text -source-filename %s -pos=%(line+1):5 -enable-experimental-concurrency | %FileCheck -check-prefix=EMPTY-NAMES %s
+func emptyNames(first: Int, _ second: String, completion: @escaping (String) -> Void) { }
+// EMPTY-NAMES: @completionHandlerAsync("emptyNames(first:_:)", completionHandlerIndex: 2)
+
+// Not a completion handler named parameter, but should still be converted
+// during function conversion since it has been attributed
+@completionHandlerAsync("otherName()", completionHandlerIndex: 0)
+func otherName(notHandlerName: @escaping (String) -> (Void)) {}
+func otherName() async -> String {}
+
+// RUN: %refactor-check-compiles -convert-to-async -dump-text -source-filename %s -pos=%(line+1):5 -enable-experimental-concurrency | %FileCheck -check-prefix=OTHER-CONVERTED %s
+func otherStillConverted() {
+  otherName { str in
+    print(str)
+  }
+}
+// OTHER-CONVERTED: func otherStillConverted() async {
+// OTHER-CONVERTED-NEXT: let str = await otherName()
+// OTHER-CONVERTED-NEXT: print(str)

tools/swift-refactor/swift-refactor.cpp

@@ -118,6 +118,10 @@ static llvm::cl::opt<bool>
 IsNonProtocolType("is-non-protocol-type",
                   llvm::cl::desc("The symbol being renamed is a type and not a protocol"));
 
+static llvm::cl::opt<bool> EnableExperimentalConcurrency(
+    "enable-experimental-concurrency",
+    llvm::cl::desc("Whether to enable experimental concurrency or not"));
+
 enum class DumpType {
   REWRITTEN,
   JSON,
@@ -273,7 +277,9 @@ int main(int argc, char *argv[]) {
   Invocation.getLangOptions().AttachCommentsToDecls = true;
   Invocation.getLangOptions().CollectParsedToken = true;
   Invocation.getLangOptions().BuildSyntaxTree = true;
-  Invocation.getLangOptions().EnableExperimentalConcurrency = true;
+
+  if (options::EnableExperimentalConcurrency)
+    Invocation.getLangOptions().EnableExperimentalConcurrency = true;
 
   for (auto FileName : options::InputFilenames)
     Invocation.getFrontendOptions().InputsAndOutputs.addInputFile(FileName);

utils/refactor-check-compiles.py

@@ -21,16 +21,17 @@ def parse_args():
         formatter_class=argparse.RawDescriptionHelpFormatter,
         description="""
         A drop-in replacement for a 'swift-refactor -dump-text' call that
-        1. Checkes that the file still compiles after the refactoring by doing
+        1. Checks that the file still compiles after the refactoring by doing
            'swift-refactor -dump-rewritten' and feeding the result to
            'swift-frontend -typecheck'
         2. Outputting the result of the 'swift-refactor -dump-text' call
 
-        All arguments other than the following will be forwarded to :
+        All arguments other than the following will be forwarded to
         'swift-refactor':
          - swift-frontend
          - swift-refactor
          - temp-dir
+         - enable-experimental-concurrency (sent to both)
         """)
 
     parser.add_argument(
@@ -61,30 +62,44 @@ def parse_args():
         '-pos',
         help='The position to invoke the refactoring at'
     )
+    parser.add_argument(
+        '-enable-experimental-concurrency',
+        action='store_true',
+        help='''
+        Whether to enable experimental concurrency in both swift-refactor and
+        swift-frontend
+        '''
+    )
 
     return parser.parse_known_args()
 
 
 def main():
-    (args, unknown_args) = parse_args()
+    (args, extra_refactor_args) = parse_args()
     temp_file_name = os.path.split(args.source_filename)[-1] + '.' + \
         args.pos.replace(':', '.')
     temp_file_path = os.path.join(args.temp_dir, temp_file_name)
+
+    extra_frontend_args = []
+    if args.enable_experimental_concurrency:
+        extra_refactor_args.append('-enable-experimental-concurrency')
+        extra_frontend_args.append('-enable-experimental-concurrency')
+
     # FIXME: `refactor-check-compiles` should generate both `-dump-text` and
     # `dump-rewritten` from a single `swift-refactor` invocation (SR-14587).
     dump_text_output = run_cmd([
         args.swift_refactor,
         '-dump-text',
         '-source-filename', args.source_filename,
         '-pos', args.pos
-    ] + unknown_args, desc='producing edit').decode("utf-8")
+    ] + extra_refactor_args, desc='producing edit').decode("utf-8")
 
     dump_rewritten_output = run_cmd([
         args.swift_refactor,
         '-dump-rewritten',
         '-source-filename', args.source_filename,
         '-pos', args.pos
-    ] + unknown_args, desc='producing rewritten file')
+    ] + extra_refactor_args, desc='producing rewritten file')
     with open(temp_file_path, 'wb') as f:
         f.write(dump_rewritten_output)
 
@@ -93,7 +108,7 @@ def main():
         '-typecheck',
         temp_file_path,
         '-disable-availability-checking'
-    ], desc='checking that rewritten file compiles')
+    ] + extra_frontend_args, desc='checking that rewritten file compiles')
     sys.stdout.write(dump_text_output)