D-Programming-Language/dmd — pull request #1200 by AndrejMitrovic (2012-10-21 00:00:07+00:00)
Title: Fix Issue 7420 - Duplicate "cannot be read at compile time" error messages 

In one example `VarExp::optimize` was calling `fromConstInitializer`, followed by `CmpExp::optimize` calling it again which caused duplicate error messages. Returning `ErrorExp` fixes this.