Type variables are not in scope of static methods

[peter-ahe-google]

$ cat fisk.dart
class T {
  toString() => "class T";
}

class Foo<T> {
  static m() => new T();
}

main() {
  print(Foo.m());
}

$ dartc_test fisk.dart
fisk.dart:6: cannot access type variable T in static context
     5: class Foo<T> {
     6: static m() => new T();
fisk.dart:6: New expression does not resolve to a constructor
     5: class Foo<T> {
     6: static m() => new T();
Compilation failed with 2 problems.

$ frogsh fisk.dart
We are sorry, but... no constructors on type parameters yet

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
CompilerException: We are sorry, but... no constructors on type parameters yet
    at World._message (frogsh:23264:5)
    at World.internalError (frogsh:23287:8)
    at ParameterType.getConstructor (frogsh:21501:18)
    at ParameterType.getConstructor$1 (frogsh:21525:15)
    at MethodGenerator.visitNewExpression (frogsh:14264:16)
    at lang_NewExpression.visit (frogsh:20744:18)
    at MethodGenerator.visitValue (frogsh:13523:20)
    at MethodGenerator.visitTypedValue (frogsh:13528:15)
    at MethodGenerator.visitReturnStatement (frogsh:13601:22)
    at ReturnStatement.visit (frogsh:20362:18)

$ dart fisk.dart
class T

[DartBot]

This comment was originally written by [email protected]

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Just to make sure I understand, the issue is that T is both a type variable and a top level class. We shouldn't warn about T inside of m() as a type variable because it isn't in scope, and instead should keep looking up the scope tree to resolve the symbol.

[DartBot]

This comment was originally written by [email protected]

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Set owner to [email protected].
Added Started label.

[peter-ahe-google]

Sorry I should have given more details. It is not obvious what I consider a problem here.

The only thing I think is wrong with the errors from dartc is that there are two. One error message should be sufficient.

[peter-ahe-google]

Sorry, I was wrong. The spec says that the type variable isn't in scope.

I think a warning would be nice, though.

[DartBot]

This comment was originally written by [email protected]

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Review for dartc up at http://codereview.chromium.org/9250017/

The following code now runs to completion, printing one warning (already added by Konstantin last week)

$ cat /tmp/fish.dart
class T {
  toString() => "class T";
}

class Foo<T> {
  static m() => new T().toString();
}

main() {
  print(Foo.m());
}

$ dartc_test /tmp/fish.dart
file:/tmp/fish.dart:5: Type variable 'T' is hiding 'CLASS T' at fish.dart::1:7
     4:
     5: class Foo<T> {
class T

If you rename class T to another name, you get:

$ dartc_test /tmp/fish.dart
file:/tmp/fish.dart:6: cannot access type variable T in static context
     5: class Foo<T> {
     6: static m() => new T().toString();
file:/tmp/fish.dart:6: New expression does not resolve to a constructor
     5: class Foo<T> {
     6: static m() => new T().toString();
Compilation failed with 2 problems.

[DartBot]

This comment was originally written by [email protected]

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r3434

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Added Fixed label.

[fsc8000]

Reopened since the corresponding test, after re-enabled, currently fails on the VM, dart2js and dartc.

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cc @peter-ahe-google.
Removed the owner.
Added Triaged label.

[peter-ahe-google]

What is the corresponding test? Shouldn't there be a bug for each area that is failing that test?

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Set owner to @fsc8000.
Added NeedsInfo label.

[fsc8000]

I added the following line to the language.status and language_dart2js.status files:

+type_variable_shadows_class_test: Fail # Issue #643

[fsc8000]

This is working on all platform. The test is invalid since the expected behavior has changed. There is already a negative test for the correct behavior (tests/language/type_variable_static_context_negative_test.dart)

https://code.google.com/p/dart/source/detail?r=15247

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Added Fixed label.