Migrated from http://lampsvn.epfl.ch/trac/scala/ticket/2871
Reporter spiros
I found this bug when researching bug #2689 and reported it in a comment because I thought that it was the same bug. #2689 got fixed but this problem still remains.
The general case # we introduce a compilation error in a file

1. we save the file to compile
2. edit and save another file to fix the issue (by adding a method for example)

A concrete example that reproduces the bug:

1. Create and save a file A.scala like the following:

class A
class B

# Create and save a file C.scala like the following:

class C {
  val a: A = new B
}

B does not yet extend A so we correctly get the compilation error type mismatch; found : B required: A. Now if we change B to extend A and save A.scala the error message will get removed from the Problems View but not from the editor.