964fc41b89
Improve suggestion for calling fn-like expr on type mismatch 1.) Suggest calling values of with RPIT types (and probably TAIT) when we expect `Ty` and have `impl Fn() -> Ty` 2.) Suggest calling closures even when they're not assigned to a local variable first 3.) Drive-by fix of a pretty-printing bug (`impl Fn()-> Ty` => `impl Fn() -> Ty`) r? ```@estebank```
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