Parse try-catch statements with Fasta.

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

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library fasta.analyzer.ast_builder;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast_factory.dart' show AstFactory;
 import 'package:analyzer/dart/ast/standard_ast_factory.dart' as standard;
 import 'package:analyzer/dart/ast/token.dart' as analyzer show Token;
@@ skipping 752 matching lines @@
         toAnalyzerToken(beginToken),
         parameters,
         toAnalyzerToken(leftDelimiter),
         toAnalyzerToken(rightDelimiter),
         toAnalyzerToken(endToken)));
   }
 
   void handleCatchBlock(Token onKeyword, Token catchKeyword) {
     debugEvent("CatchBlock");
     Block body = pop();
-    FormalParameterList catchParameters = popIfNotNull(catchKeyword);
-    if (catchKeyword != null) {
-      exitLocalScope();

[Paul Berry, 2017/03/14 19:30:06]

It's not obvious to me why it's safe to drop the call to exitLocalScope().  Did
you remove this by mistake?

[scheglov, 2017/03/14 19:34:42]

No, this is an intentional change.
There is no corresponding enterLocalScope() invocation for catch clauses.

[Paul Berry, 2017/03/14 19:39:01]

Ok, thanks for clarifying.

-    }
+    FormalParameterList catchParameterList = popIfNotNull(catchKeyword);
     TypeAnnotation type = popIfNotNull(onKeyword);
     SimpleIdentifier exception;
     SimpleIdentifier stackTrace;
-    if (catchParameters != null) {
+    if (catchParameterList != null) {
+      List<FormalParameter> catchParameters = catchParameterList.parameters;
       if (catchParameters.length > 0) {
-        exception = catchParameters.parameters[0].identifier;
+        exception = catchParameters[0].identifier;
       }
       if (catchParameters.length > 1) {
-        stackTrace = catchParameters.parameters[1].identifier;
+        stackTrace = catchParameters[1].identifier;
       }
     }
-    BeginGroupToken leftParenthesis = catchKeyword.next;
     push(ast.catchClause(
         toAnalyzerToken(onKeyword),
         type,
         toAnalyzerToken(catchKeyword),
-        toAnalyzerToken(leftParenthesis),
+        catchParameterList?.leftParenthesis,
         exception,
         null,
         stackTrace,
-        toAnalyzerToken(leftParenthesis.endGroup),
+        catchParameterList?.rightParenthesis,
         body));
   }
 
+  @override
+  void handleFinallyBlock(Token finallyKeyword) {
+    debugEvent("FinallyBlock");
+    // The finally block is popped in "endTryStatement".
+  }
+
   void endTryStatement(int catchCount, Token tryKeyword, Token finallyKeyword) {
     Block finallyBlock = popIfNotNull(finallyKeyword);
     List<CatchClause> catchClauses = popList(catchCount);
     Block body = pop();
     push(ast.tryStatement(toAnalyzerToken(tryKeyword), body, catchClauses,
         toAnalyzerToken(finallyKeyword), finallyBlock));
   }
 
   void handleNoExpression(Token token) {
     debugEvent("NoExpression");
@@ skipping 799 matching lines @@
       } else if (identical('static', s)) {
         staticKeyword = token;
       } else if (identical('var', s)) {
         finalConstOrVarKeyword = token;
       } else {
         internalError('Unhandled modifier: $s');
       }
     }
   }
 }