CFE confuses library prefix and a name of a field

[mraleph]

import 'dart:core' as core;

class Foo {
  core.int core = 10;
}

void main() {
  new Foo();
}

pkg/front_end/tool/fasta compile -o /tmp/xxx.dill --strong-mode --platform=$HOME/src/dart/sdk/out/ReleaseX64/vm_platform_strong.dill /tmp/xxx.dart
Unhandled exception:
Crash when compiling file:///tmp/xxx.dart,
at character offset null:
file:///tmp/xxx.dart:5:3: Internal problem: Unsupported operation: 'name'.
  core.int core = 10;
  ^
#0      internalProblem (package:front_end/src/fasta/problems.dart:29:3)
#1      unsupported (package:front_end/src/fasta/problems.dart:55:10)
#2      IncompleteSend&ErrorAccessor.name (package:front_end/src/fasta/kernel/fasta_accessors.dart:266:20)
#3      IncompleteSend&ErrorAccessor.plainNameForRead (package:front_end/src/fasta/kernel/fasta_accessors.dart:269:34)
#4      getNodeName (package:front_end/src/fasta/kernel/body_builder.dart:4186:17)
#5      BodyBuilder.handleType (package:front_end/src/fasta/kernel/body_builder.dart:1860:40)
#6      Parser.parseType.commitType (package:front_end/src/fasta/parser/parser.dart:2424:18)
#7      Parser.parseType (package:front_end/src/fasta/parser/parser.dart:2499:26)
#8      Parser.parseFields (package:front_end/src/fasta/parser/parser.dart:3136:7)
#9      Parser.parseClassMemberImpl (package:front_end/src/fasta/parser/parser.dart:3800:15)
#10     Parser.parseClassMember (package:front_end/src/fasta/parser/parser.dart:3639:12)
#11     DietListener.parseFields (package:front_end/src/fasta/source/diet_listener.dart:734:22)
#12     DietListener.buildFields (package:front_end/src/fasta/source/diet_listener.dart:579:5)
#13     DietListener.endFields (package:front_end/src/fasta/source/diet_listener.dart:226:5)
#14     Parser.parseFields (package:front_end/src/fasta/parser/parser.dart:3163:16)
#15     Parser.parseClassMemberImpl (package:front_end/src/fasta/parser/parser.dart:3800:15)
#16     Parser.parseClassBody (package:front_end/src/fasta/parser/parser.dart:3615:15)
#17     Parser.parseClass (package:front_end/src/fasta/parser/parser.dart:1732:13)
#18     Parser.parseClassOrNamedMixinApplication (package:front_end/src/fasta/parser/parser.dart:1692:14)
#19     Parser.parseTopLevelKeywordDeclaration (package:front_end/src/fasta/parser/parser.dart:526:14)
#20     Parser.parseTopLevelDeclarationImpl (package:front_end/src/fasta/parser/parser.dart:442:14)
#21     Parser.parseUnit (package:front_end/src/fasta/parser/parser.dart:326:15)

[peter-ahe-google]

Proposed fix.

[peter-ahe-google]

FWIW, the front-end is not confusing prefix and field name. But it's crashing as it's attempting to report an error.

[vsmenon]

@lrhn Can you clarify if the code at the top is a static error? If so, we should file an issue on the analyzer to report it. We're seeing the pattern in existing user code.

[lrhn]

@leafpetersen

I'd say that it is a static error in Dart 2. The core in core.int is resolved in a scope where core is a field. That is consistent with Dart having only one lexical scope.
That's also apparently what implementations do in many places, just not all. Some happen to accept core.int as a malformed type that is interpreted as dynamic.

If we change to:

import 'dart:core' as core;
class Foo {
  core.int core() => 10;
}
void main() {
  core.print(new Foo().core.runtimeType);
}

then dart2js prints () => dynamic and the VM prints () => int. So, no agreement.

If we change the code to:

import 'dart:core' as core;

class Foo {
  get core => <core.int>[];  // Returns List<dynamic> or List<int>?
  get core2 => core.int;  // Stack overflow or return Type?
}

void main() {
  core.print(new Foo().core is core.List<core.String>);
  core.print(new Foo().core2);
}

I would like the two getter bodies to treat core.int the same. Currently both dart2js and the VM treats <core.int>[] as a malformed type, and core.int as a getter access. So, not consistent with treating core.int as a type outside the body.

You say that existing code is using this pattern. Any references?