NPE during visit of misconstructed AST structure

[bwilkerson]

The following input (between the dotted lines):

---

class test {
  factory test<X extneds List>(){}
}
//
typedef Map Fox<T1 extends Map>(List input);
class HashMapImplementation<K extends Hashable, V> implements HashMap<K, V> {}
//
class Fooa {
  final Bara<Fooa> bar = const Bara/* <Fooa> Workaround bug #­322 */();
}

class Bara<T extends Fooa> {
  const Bara();
}

main1() {
  print(new Fooa());
}
/*********/
class C1<Q> {
  Q x;
  C1(Q x) { this.x = x; }
}

class C2<Q> {
  Q x;
  C2(this.x) {}
}

main2() {
  C1<int> c1 = new C1<int>(0);
  C2<int> c2 = new C2<int>(1);
}
/*********/
class Foo {
  final Bar<Foo> bar = const Bar<Foo>();
}

class Bar<T extends Foo> {
  const Bar();
}

main3() {
  print(new Foo());
}
/*********/

class X {
  static final num MAX = 0;
  num yc,xc;
  mth() {
    xc = yc = MAX;
    xc.abs();
    num f = MAX;
  }
}
class Y {
  String x="hi";
  mth() {
    x.length;
    int n = 0;
    x.charCodeAt(n);
  }
}
class Z {
  Map m = const Map();
  mth() {
    var x = new List.from(['a']);
  }
}
class A {
  int x;
  mth() {
    int y = this.x;
  }
}
class B1 {
  B1();
  x(){}
}
class B2 extends B1 {
  B2() { super.x();}
}
class C {
  mth(Map x, q) {}
  mtf(q, Map x) {}
  m() { for (int i = 0; i < 5; i++); A x;}
}
class D {
  f(){} g(){f(/f/);}
}
class E {
  int x; mth() {var y = x;}
}
class F {
  var x = false;
}

---

will cause the parser to produce an AST structure containing a DartBinaryExpression whose arg1 is null. Obviously this AST structure should never be produced. Below is the stack trace from the NPE in case it's useful.

---

!ENTRY com.google.dart.tools.ui 4 2 2011-11-04 08:40:43.130
!MESSAGE Problems occurred when invoking code from plug-in: "com.google.dart.tools.ui".
!STACK 0
java.lang.NullPointerException
    at com.google.dart.compiler.ast.DartBinaryExpression.visitChildren(DartBinaryExpression.java:66)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitExpression(DartNodeTraverser.java:67)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitBinaryExpression(DartNodeTraverser.java:111)
    at com.google.dart.compiler.ast.DartBinaryExpression.accept(DartBinaryExpression.java:72)
    at com.google.dart.compiler.ast.DartMapLiteralEntry.visitChildren(DartMapLiteralEntry.java:39)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitMapLiteralEntry(DartNodeTraverser.java:271)
    at com.google.dart.compiler.ast.DartMapLiteralEntry.accept(DartMapLiteralEntry.java:45)
    at com.google.dart.compiler.ast.DartNodeTraverser.visit(DartNodeTraverser.java:413)
    at com.google.dart.compiler.ast.DartMapLiteral.visitChildren(DartMapLiteral.java:38)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitExpression(DartNodeTraverser.java:67)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitMapLiteral(DartNodeTraverser.java:266)
    at com.google.dart.compiler.ast.DartMapLiteral.accept(DartMapLiteral.java:43)
    at com.google.dart.compiler.ast.DartMapLiteralEntry.visitChildren(DartMapLiteralEntry.java:39)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitMapLiteralEntry(DartNodeTraverser.java:271)
    at com.google.dart.compiler.ast.DartMapLiteralEntry.accept(DartMapLiteralEntry.java:45)
    at com.google.dart.compiler.ast.DartNodeTraverser.visit(DartNodeTraverser.java:413)
    at com.google.dart.compiler.ast.DartMapLiteral.visitChildren(DartMapLiteral.java:38)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitExpression(DartNodeTraverser.java:67)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitMapLiteral(DartNodeTraverser.java:266)
    at com.google.dart.compiler.ast.DartMapLiteral.accept(DartMapLiteral.java:43)
    at com.google.dart.compiler.ast.DartBinaryExpression.visitChildren(DartBinaryExpression.java:67)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitExpression(DartNodeTraverser.java:67)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitBinaryExpression(DartNodeTraverser.java:111)
    at com.google.dart.compiler.ast.DartBinaryExpression.accept(DartBinaryExpression.java:72)
    at com.google.dart.compiler.ast.DartExprStmt.visitChildren(DartExprStmt.java:31)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitStatement(DartNodeTraverser.java:71)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitExprStmt(DartNodeTraverser.java:191)
    at com.google.dart.compiler.ast.DartExprStmt.accept(DartExprStmt.java:36)
    at com.google.dart.compiler.ast.DartNodeTraverser.visit(DartNodeTraverser.java:413)
    at com.google.dart.compiler.ast.DartBlock.visitChildren(DartBlock.java:44)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitStatement(DartNodeTraverser.java:71)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitBlock(DartNodeTraverser.java:116)
    at com.google.dart.compiler.ast.DartBlock.accept(DartBlock.java:49)
    at com.google.dart.compiler.ast.DartFunction.visitChildren(DartFunction.java:57)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitFunction(DartNodeTraverser.java:216)
    at com.google.dart.compiler.ast.DartFunction.accept(DartFunction.java:66)
    at com.google.dart.compiler.ast.DartMethodDefinition.visitChildren(DartMethodDefinition.java:85)
    at com.google.dart.compiler.ast.DartMethodDefinition$DartMethodWithInitializersDefinition.visitChildren(DartMethodDefinition.java:121)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitDeclaration(DartNodeTraverser.java:87)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitClassMember(DartNodeTraverser.java:91)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitMethodDefinition(DartNodeTraverser.java:276)
    at com.google.dart.compiler.ast.DartMethodDefinition.accept(DartMethodDefinition.java:90)
    at com.google.dart.tools.core.internal.model.CompilationUnitImpl$CompilationUnitStructureBuilder.visitClass(CompilationUnitImpl.java:189)
    at com.google.dart.tools.core.internal.model.CompilationUnitImpl$CompilationUnitStructureBuilder.visitClass(CompilationUnitImpl.java:1)
    at com.google.dart.compiler.ast.DartClass.accept(DartClass.java:175)
    at com.google.dart.compiler.ast.DartNodeTraverser.visit(DartNodeTraverser.java:413)
    at com.google.dart.compiler.ast.DartUnit.visitChildren(DartUnit.java:99)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitNode(DartNodeTraverser.java:54)
    at com.google.dart.compiler.ast.DartNodeTraverser.visitUnit(DartNodeTraverser.java:391)
    at com.google.dart.tools.core.internal.model.CompilationUnitImpl$CompilationUnitStructureBuilder.visitUnit(CompilationUnitImpl.java:338)
    at com.google.dart.tools.core.internal.model.CompilationUnitImpl$CompilationUnitStructureBuilder.visitUnit(CompilationUnitImpl.java:1)
    at com.google.dart.compiler.ast.DartUnit.accept(DartUnit.java:107)
    at com.google.dart.tools.core.internal.model.CompilationUnitImpl.buildStructure(CompilationUnitImpl.java:1449)

[scheglov]

http://codereview.chromium.org/8576007/

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Set owner to @scheglov.
Added Fixed label.