Dubious use of `isDeadEndId` in Core.Utils:diffExpr
diffExpr we have:
-- The error message of failed pattern matches will contain -- generated names, which are allowed to differ. diffExpr _ _ (App (App (Var absent) _) _) (App (App (Var absent2) _) _) | isDeadEndId absent && isDeadEndId absent2 = 
But that seems a bit sketchy. For example one might be a call to error and one a call to undefined which should probably not considered the same.
Checking their dmd sigs agree might be better. But I think we only use this for linting so not a high priority and perhaps ok for linting purposes.