[Concurrency] Minor fixes for parsing and syntax of 'async'

Author: DougGregor

lib/Parse/ParsePattern.cpp

@@ -785,19 +785,12 @@ Parser::parseFunctionSignature(Identifier SimpleName,
                                    defaultArgs);
   FullName = DeclName(Context, SimpleName, NamePieces);
 
-  // Check for the 'async' keyword.
-  if (Context.LangOpts.EnableExperimentalConcurrency &&
-      Tok.isContextualKeyword("async")) {
-    asyncLoc = consumeToken();
-  }
-
   // Check for the 'async' and 'throws' keywords.
   rethrows = false;
   parseAsyncThrows(SourceLoc(), asyncLoc, throwsLoc, &rethrows);
 
-  SourceLoc arrowLoc;
-
   // If there's a trailing arrow, parse the rest as the result type.
+  SourceLoc arrowLoc;
   if (Tok.isAny(tok::arrow, tok::colon)) {
     SyntaxParsingContext ReturnCtx(SyntaxContext, SyntaxKind::ReturnClause);
     if (!consumeIf(tok::arrow, arrowLoc)) {
@@ -817,14 +810,14 @@ Parser::parseFunctionSignature(Identifier SimpleName,
     Status |= ResultType;
     if (Status.isError())
       return Status;
+
+    // Check for 'throws' and 'rethrows' after the type and correct it.
+    parseAsyncThrows(arrowLoc, asyncLoc, throwsLoc, &rethrows);
   } else {
     // Otherwise, we leave retType null.
     retType = nullptr;
   }
 
-  // Check for 'throws' and 'rethrows' after the type and correct it.
-  parseAsyncThrows(arrowLoc, asyncLoc, throwsLoc, &rethrows);
-
   return Status;
 }
 

tools/swift-syntax-test/swift-syntax-test.cpp

@@ -610,6 +610,7 @@ int parseFile(
   Invocation.getLangOptions().VerifySyntaxTree = options::VerifySyntaxTree;
   Invocation.getLangOptions().RequestEvaluatorGraphVizPath = options::GraphVisPath;
   Invocation.getLangOptions().DisablePoundIfEvaluation = true;
+  Invocation.getLangOptions().EnableExperimentalConcurrency = true;
 
   Invocation.getFrontendOptions().InputsAndOutputs.addInputFile(InputFileName);
 

utils/gyb_syntax_support/DeclNodes.py

@@ -76,8 +76,8 @@
     Node('FunctionSignature', kind='Syntax',
          children=[
              Child('Input', kind='ParameterClause'),
-             Child('AsyncKeyword', kind='Token', text_choices=['async'],
-                   is_optional=True),
+             Child('AsyncKeyword', kind='ContextualKeywordToken',
+                   text_choices=['async'], is_optional=True),
              Child('ThrowsOrRethrowsKeyword', kind='Token',
                    is_optional=True,
                    token_choices=[

utils/gyb_syntax_support/ExprNodes.py

@@ -183,8 +183,8 @@
     # NOTE: This appears only in SequenceExpr.
     Node('ArrowExpr', kind='Expr',
          children=[
-             Child('AsyncKeyword', kind='Token', text_choices=['async'],
-                   is_optional=True),
+             Child('AsyncKeyword', kind='ContextualKeywordToken',
+                   text_choices=['async'], is_optional=True),
              Child('ThrowsToken', kind='ThrowsToken',
                    is_optional=True),
              Child('ArrowToken', kind='ArrowToken'),