This comment was originally written by @Fox32

I get similar warnings that I suspect to be caused by different imports. The improved message would also be nice for:

'The argument of type A cannot be assigned to the parameter type A'
and
'A value of type A cannot be assigned to a variable of type A'

Fixed in r r31621

Set owner to @sgmitrovic.
Added Fixed label.

This comment was originally written by yu.asakus...@gmail.com

I am afraid that the original issue reported here has not been fixed, although some variant of it may have been fixed.

Dart Editor version 1.2.0.edge_031904
Dart SDK version 1.2.0-edge.31903
obtained from
http://storage.googleapis.com/dart-archive/channels/be/raw/latest/editor/darteditor-windows-x64.zip

Testcase:

=== typeerror/bin/typeerror.dart ===

import 'data.dart';
import '../lib/myclass.dart';
void main() {
  A myVar = myA;
}

=== typerror/bin/data.dart ===

import 'package:typeerror/myclass.dart';
A myA = new A();

=== typeerror/lib/myclass.dart ===

library typeerror.myclass;
class A {}

=== Actual results ===

In the Problems window in Dart Editor:
A value of type 'A' cannot be assigned to a variable of type 'A'
(on line 4 of typeerror.dart)

When executed:
Unhandled exception:
type 'typeerror.myclass.A' is not a subtype of type 'typeerror.myclass.A' of 'myVar'.

Neither message clarifies that the two types mentioned in the message are different. The problem here is that from the compiler’s point of view, the library names such as typeerror.myclass do not uniquely identify a library; in the example above, package:typeerror/myclass.dart and file:///home/user/dart/typeerror/lib/myclass.dart are different libraries which have the same name typeerror.myclass. As far as I know, the only way to uniquely identify a library in Dart is the absolute URI of (the main compilation unit of) the library.

Also note that the two types do not have to have the same name for this issue to arise. It is possible that the programmer intended to assign a value of type D to a variable of its superclass C, where the file defining C and D is imported twice as different libraries.

Added Accepted label.

Removed this from the Later milestone.
Added Oldschool-Milestone-Later label.

Removed Oldschool-Milestone-Later label.

I just hit this issue (the original one that fails on importing the same fila via different schemes as one source).

I'm on Dart 1.21.0. It only happens in checked mode (which is what IntelliJ WebStorm uses when you run a file).

I made a StackOverflow question out of it so that people at least get some information on how to deal with this on their end.

But we really should fix it. It's confusing and looks bad. In case you need a test case, I'll provide it.

Assigning to you, @kevmoo, because you were the last person acting on this bug.

@filiph It's on the VM's hopper – and I'm not going to be able to fix it. 😬

I believe @crelier fixed this at some point.