TypeApplications error message doesn't parenthesize infix name

If you compile the following program:

module Bug where

f :: (Int -> Int) -> (Int -> Int) -> (Int -> Int)
f =  (.) @Int

You'll get this error:

$ /opt/ghc/8.4.3/bin/ghc Bug.hs
[1 of 1] Compiling Bug              ( Bug.hs, Bug.o )

Bug.hs:4:6: error:
    Pattern syntax in expression context: .@Int
    Did you mean to enable TypeApplications?
  |
4 | f =  (.) @Int
  |      ^^^^^^^^

I was taken aback by this strange .@ thing before I realized what was actually going on: the error message simply forgot to parenthesize .. This is ppr_expr's fault, since it calls ppr on an RdrName instead of pprPrefixOcc. Patch incoming.

Trac metadata

Trac field	Value
Version	8.4.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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