Summary: Currently, whenever you apply a function to too many arguments and some of those arguments happen to be visible type applications, the error message that GHC gives is rather confusing. Consider the message you receive when typechecking `id @Int 1 2`: ``` The function `id` is applied to three arguments, but its type `Int -> Int` has only one ``` This is baffling, since the two lines treat the visible type argument `@Int` differently. The top line ("applied to three arguments") includes `@Int`, whereas the bottom line ("has only one") excludes `@Int` from consideration. There are multiple ways one could fix this, which I explain in an addendum to `Note [Herald for matchExpectedFunTys]`. The approach adopted here is to change the herald of this error message to include visible type arguments, and to avoid counting them in the "applied to n arguments" part of the error. The end result is that the new error message for `id @Int 1 2` is now: ``` The expression `id @Int` is applied to two arguments, but its type `Int -> Int` has only one ``` Test Plan: make test TEST=T13902 Reviewers: goldfire, austin, bgamari Reviewed By: goldfire Subscribers: rwbarton, thomie GHC Trac Issues: #13902 Differential Revision: https://phabricator.haskell.org/D3868