This comment was originally written by @mhausner

Import name conflicts in types make the type malformed and is thus mapped to dynamic. You are trying to allocate an object of a malformed type. The fact that it's malformed because of a name clash is coincidence.

We had better error messages in the past but then the language was changed, turning compilation errors to runtime errors. If you want better error messages, lobby for compile time errors :-)

would it be possible to add more details in dynamic errors though? For example, maybe we can tag why a type is malformed, so then the error could hint how to debug/fix the issue:

  Unhandled exception:
  'a.dart': Error: line 4 pos 7: type 'Foo' is not loaded
    new Foo();
        ^
  malformed type used. Found two conflicting definitions.

You could also elect to run the other half of the compilation system and analyze your sources. It should nicely complain about this problem.

Added this to the Later milestone.
Removed Priority-Unassigned label.
Added Priority-Low label.

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

Removed Oldschool-Milestone-Later label.

This comment was originally written by @mhausner

Removed Type-Defect label.
Added Type-Enhancement label.

This comment was originally written by @mhausner

Issue #20471 has been merged into this issue.

This comment was originally written by @mhausner

Issue #19571 has been merged into this issue.

This comment was originally written by @kaendfinger

This definitely seems like a good idea. Even though the analyzer will tell you, we should not leave a user scratching their head when they wrote a quick script and don't even know the analyzer exists.

The error will be coming from CFE now. Closing this.