Add support for the new function-type syntax.

pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart

Index: pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart b/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
index a63af7f9ac69314a36f08e0b54e96eb0793914d4..8b9dd3d5085d95358e817e00f1df813ef7ace9a6 100644
--- a/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
+++ b/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
@@ -439,7 +439,7 @@ class AstBuilder extends ScopeListener {
     push(ast.symbolLiteral(toAnalyzerToken(hashToken), components));
   }
 
-  void endType(Token beginToken, Token endToken) {
+  void handleType(Token beginToken, Token endToken) {
     debugEvent("Type");
     TypeArgumentList arguments = pop();
     Identifier name = pop();
@@ -1097,28 +1097,61 @@ class AstBuilder extends ScopeListener {
     // keyword up to an element?
     handleIdentifier(token);
     handleNoTypeArguments(token);
-    endType(token, token);
+    handleType(token, token);
   }
 
   @override
-  void endFunctionTypeAlias(Token typedefKeyword, Token endToken) {
+  void endFunctionTypeAlias(
+      Token typedefKeyword, Token equals, Token endToken) {
     debugEvent("FunctionTypeAlias");
-    FormalParameterList parameters = pop();
-    TypeParameterList typeParameters = pop();
-    SimpleIdentifier name = pop();
-    TypeAnnotation returnType = pop();
-    List<Annotation> metadata = pop();
-    // TODO(paulberry): capture doc comments.  See dartbug.com/28851.
-    Comment comment = null;
-    push(ast.functionTypeAlias(
-        comment,
-        metadata,
-        toAnalyzerToken(typedefKeyword),
-        returnType,
-        name,
-        typeParameters,
-        parameters,
-        toAnalyzerToken(endToken)));
+    if (equals == null) {
+      FormalParameterList parameters = pop();
+      TypeParameterList typeParameters = pop();
+      SimpleIdentifier name = pop();
+      TypeAnnotation returnType = pop();
+      List<Annotation> metadata = pop();
+      // TODO(paulberry): capture doc comments.  See dartbug.com/28851.
+      Comment comment = null;
+      push(ast.functionTypeAlias(
+          comment,
+          metadata,
+          toAnalyzerToken(typedefKeyword),
+          returnType,
+          name,
+          typeParameters,
+          parameters,
+          toAnalyzerToken(endToken)));
+    } else {
+      Node type = pop();

[Paul Berry, 2017/02/22 18:47:25]

Shouldn't the type of `type` be TypeAnnotation?

[floitsch, 2017/02/22 19:21:39]

Maybe. I wasn't sure.
Changed to TypeAnnotation.

This only happens if it can't parse a function-type, and I don't know how the
error-recovery is implemented, and what type is produced if things go wrong. I'm
not even sure they can go wrong...

+      TypeParameterList templateParameters = pop();
+      SimpleIdentifier name = pop();
+      List<Annotation> metadata = pop();
+

[Paul Berry, 2017/02/22 18:47:25]

Duplicate lines 1113-1114 here.

[floitsch, 2017/02/22 19:21:39]

Done.

+      if (type is! GenericFunctionType) {
+        // TODO(brianwilkerson) Generate an error and recover (better than
+        // this).
+        push(ast.genericTypeAlias(
+            commentAndMetadata.comment,

[Paul Berry, 2017/02/22 18:47:26]

Change to "comment"

[floitsch, 2017/02/22 19:21:40]

Acknowledged.

+            commentAndMetadata.metadata,

[Paul Berry, 2017/02/22 18:47:25]

Change to "metadata"

[floitsch, 2017/02/22 19:21:39]

Acknowledged.

+            keyword,

[Paul Berry, 2017/02/22 18:47:26]

Change to "toAnalyzerToken(typedefKeyword)"

[floitsch, 2017/02/22 19:21:39]

Acknowledged.

+            name,
+            typeParameters,
+            equals,

[Paul Berry, 2017/02/22 18:47:26]

Change to "toAnalyzerToken(equals)"

[floitsch, 2017/02/22 19:21:39]

Acknowledged.

+            null,
+            semicolon));

[Paul Berry, 2017/02/22 18:47:26]

Change to "toAnalyzerToken(endToken)"

[floitsch, 2017/02/22 19:21:39]

Acknowledged.

+      } else {
+        FunctionTypeAnnotation functionType = type;

[Paul Berry, 2017/02/22 18:47:26]

I'm confused by this.  Since the if-test on line 1130 is "if type is!
GenericFunctionType)", the type of `type` is now known to be
GenericFunctionType.  I don't know what FunctionTypeAnnotation is.

Suggestion: rework the if-test to the form:

if (type is Foo) {
  ...
} else if (type is Bar) {
  ...
} else {
  internalError('Unexpected kind of type: ${type.runtimeType}');
}

[floitsch, 2017/02/22 19:21:40]

Changed the whole thing.

+        push(ast.genericTypeAlias(
+            commentAndMetadata.comment,

[Paul Berry, 2017/02/22 18:47:25]

Change to "comment"

[floitsch, 2017/02/22 19:21:39]

Done.

+            commentAndMetadata.metadata,

[Paul Berry, 2017/02/22 18:47:25]

Change to "metadata"

[floitsch, 2017/02/22 19:21:39]

Done.

+            keyword,

[Paul Berry, 2017/02/22 18:47:25]

Change to "toAnalyzerToken(typedefKeyword)"

[floitsch, 2017/02/22 19:21:39]

Done.

+            name,
+            typeParameters,
+            equals,

[Paul Berry, 2017/02/22 18:47:26]

Change to "toAnalyzerToken(equals)"

[floitsch, 2017/02/22 19:21:39]

Done.

+            functionType,
+            semicolon));

[Paul Berry, 2017/02/22 18:47:25]

Change to "toAnalyzerToken(endToken)"

[floitsch, 2017/02/22 19:21:39]

Done.

+      }
+    }
   }
 
   /**