[Concurrency] Add Syntax support for 'async'.

Add 'async' to the syntax tree for types, function declarations, and
the "arrow" expression.

Author: DougGregor

lib/Parse/ParseType.cpp

@@ -465,6 +465,8 @@ ParserResult<TypeRepr> Parser::parseType(Diag<> MessageID,
       ParsedFunctionTypeSyntaxBuilder Builder(*SyntaxContext);
       Builder.useReturnType(std::move(*SyntaxContext->popIf<ParsedTypeSyntax>()));
       Builder.useArrow(SyntaxContext->popToken());
+      if (asyncLoc.isValid())
+        Builder.useAsyncKeyword(SyntaxContext->popToken());
       if (throwsLoc.isValid())
         Builder.useThrowsOrRethrowsKeyword(SyntaxContext->popToken());
 

test/Syntax/Parser/tree.swift.result

@@ -2,7 +2,7 @@
 // RUN: %swift-syntax-parser-test %s -dump-tree > %t.result
 // RUN: diff -u %s.result %t.result
 
-|func| </t6><t105>|test|</t105><NULL/><s110><s108><t88>|(|</t88><s174></s174><t89>|)| </t89></s108><NULL/><NULL/></s110><NULL/><s93><t90>|{|</t90><s163><s92><s48><NULL/><t102>
+|func| </t6><t105>|test|</t105><NULL/><s110><s108><t88>|(|</t88><s174></s174><t89>|)| </t89></s108><NULL/><NULL/><NULL/></s110><NULL/><s93><t90>|{|</t90><s163><s92><s48><NULL/><t102>
   |"|</t102><s168><s104><t104>|a|</t104></s104><s105><t100>|\|</t100><NULL/><t88>|(|</t88><s165><s97><NULL/><NULL/><s28><t105>|b|</t105><NULL/></s28><NULL/></s97></s165><t101>|)|</t101></s105><s104><t104>|c|</t104></s104></s168><t102>|"|</t102><NULL/></s48><NULL/><NULL/></s92></s163><t91>
 |}|</t91></s93></s13><NULL/><NULL/></s92></s163><t0>
 ||</t0></s118>

test/incrParse/Outputs/incrementalTransfer.json

@@ -91,6 +91,7 @@
                       "presence": "Present"
                     },
                     null,
+                    null,
                     null
                   ],
                   "presence": "Present"

unittests/Syntax/DeclSyntaxTests.cpp

@@ -389,7 +389,7 @@ FunctionSignatureSyntax getCannedFunctionSignature() {
   auto Int = SyntaxFactory::makeTypeIdentifier("Int", {}, Trivia::spaces(1));
   auto Return = SyntaxFactory::makeReturnClause(Arrow, Int);
 
-  return SyntaxFactory::makeFunctionSignature(Parameter, Throws, Return);
+  return SyntaxFactory::makeFunctionSignature(Parameter, None, Throws, Return);
 }
 
 TEST(DeclSyntaxTests, FunctionSignatureMakeAPIs) {
@@ -426,7 +426,7 @@ TEST(DeclSyntaxTests, FunctionSignatureGetAPIs) {
 
   auto Sig = SyntaxFactory::makeFunctionSignature(
     SyntaxFactory::makeParameterClause(LParen, List, RParen),
-    Throws,
+    None, Throws,
     SyntaxFactory::makeReturnClause(Arrow, Int));
 
   ASSERT_EQ(LParen.getRaw(), Sig.getInput().getLeftParen().getRaw());

unittests/Syntax/TypeSyntaxTests.cpp

@@ -471,6 +471,8 @@ TEST(TypeSyntaxTests, FunctionTypeMakeAPIs) {
   auto Int = SyntaxFactory::makeTypeIdentifier("Int", {}, {});
   auto IntArg = SyntaxFactory::makeBlankTupleTypeElement()
     .withType(Int);
+  auto Async = SyntaxFactory::makeContextualKeyword(
+      "async", { }, { Trivia::spaces(1) });
   auto Throws = SyntaxFactory::makeThrowsKeyword({}, { Trivia::spaces(1) });
   auto Rethrows = SyntaxFactory::makeRethrowsKeyword({},
                                                        { Trivia::spaces(1) });
@@ -498,13 +500,43 @@ TEST(TypeSyntaxTests, FunctionTypeMakeAPIs) {
     SyntaxFactory::makeFunctionType(LeftParen,
                                     TypeList,
                                     RightParen,
+                                    Async,
                                     Throws,
                                     Arrow,
                                     Int)
       .print(OS);
-    ASSERT_EQ(OS.str().str(), "(x: Int, y: Int) throws -> Int");
+    ASSERT_EQ(OS.str().str(), "(x: Int, y: Int) async throws -> Int");
   }
 
+  {
+    SmallString<48> Scratch;
+    llvm::raw_svector_ostream OS(Scratch);
+
+    auto x = SyntaxFactory::makeIdentifier("x", {}, {});
+    auto y = SyntaxFactory::makeIdentifier("y", {}, {});
+    auto xArg = SyntaxFactory::makeBlankTupleTypeElement()
+      .withName(x)
+      .withColon(Colon)
+      .withType(Int)
+      .withTrailingComma(Comma);
+    auto yArg = SyntaxFactory::makeBlankTupleTypeElement()
+      .withName(y)
+      .withColon(Colon)
+      .withType(Int);
+
+    auto TypeList = SyntaxFactory::makeTupleTypeElementList({
+      xArg, yArg
+    });
+    SyntaxFactory::makeFunctionType(LeftParen,
+                                    TypeList,
+                                    RightParen,
+                                    None,
+                                    Throws,
+                                    Arrow,
+                                    Int)
+      .print(OS);
+    ASSERT_EQ(OS.str().str(), "(x: Int, y: Int) throws -> Int");
+  }
   {
     SmallString<48> Scratch;
     llvm::raw_svector_ostream OS(Scratch);
@@ -515,6 +547,7 @@ TEST(TypeSyntaxTests, FunctionTypeMakeAPIs) {
     SyntaxFactory::makeFunctionType(LeftParen,
                                     TypeList,
                                     RightParen,
+                                    None,
                                     Rethrows,
                                     Arrow,
                                     Int).print(OS);
@@ -529,6 +562,7 @@ TEST(TypeSyntaxTests, FunctionTypeMakeAPIs) {
     SyntaxFactory::makeFunctionType(LeftParen,
                                     TypeList,
                                     RightParen,
+                                    None,
                                     TokenSyntax::missingToken(tok::kw_throws,
                                                               "throws"),
                                     Arrow,

utils/gyb_syntax_support/DeclNodes.py

@@ -72,10 +72,12 @@
          ]),
 
     # function-signature ->
-    #   '(' parameter-list? ')' (throws | rethrows)? '->'? type?
+    #   '(' parameter-list? ')' async? (throws | rethrows)? '->'? type?
     Node('FunctionSignature', kind='Syntax',
          children=[
              Child('Input', kind='ParameterClause'),
+             Child('AsyncKeyword', kind='Token', text_choices=['async'],
+                   is_optional=True),
              Child('ThrowsOrRethrowsKeyword', kind='Token',
                    is_optional=True,
                    token_choices=[

utils/gyb_syntax_support/ExprNodes.py

@@ -179,10 +179,12 @@
              Child('OperatorToken', kind='BinaryOperatorToken'),
          ]),
 
-    # arrow-expr -> 'throws'? '->'
+    # arrow-expr -> 'async'? 'throws'? '->'
     # NOTE: This appears only in SequenceExpr.
     Node('ArrowExpr', kind='Expr',
          children=[
+             Child('AsyncKeyword', kind='Token', text_choices=['async'],
+                   is_optional=True),
              Child('ThrowsToken', kind='ThrowsToken',
                    is_optional=True),
              Child('ArrowToken', kind='ArrowToken'),

utils/gyb_syntax_support/TypeNodes.py

@@ -159,14 +159,16 @@
 
     # throwing-specifier -> 'throws' | 'rethrows'
     # function-type -> attribute-list '(' function-type-argument-list ')'
-    #   throwing-specifier? '->'? type?
+    #   async? throwing-specifier? '->'? type?
     Node('FunctionType', kind='Type',
          traits=['Parenthesized'],
          children=[
              Child('LeftParen', kind='LeftParenToken'),
              Child('Arguments', kind='TupleTypeElementList',
                    collection_element_name='Argument'),
              Child('RightParen', kind='RightParenToken'),
+             Child('AsyncKeyword', kind='Token', text_choices=['async'],
+                   is_optional=True),
              Child('ThrowsOrRethrowsKeyword', kind='Token',
                    is_optional=True,
                    token_choices=[