Empty record update [GHC-20825]

Record update syntax, in which only certain fields are replaced in a record, requires that at least one field update be specified.

Examples

No fields updated

Message

NoFields.hs:7:6: error: [GHC-20825]
    Empty record update
  |
7 | r2 = r1 {}
  |      ^^^^^

Explanation

No fields were provided in the update to r1. Provide a field to fix the error.

NoFields.hs
Before
module NoFields where

data Record = Record {a :: Int}

r1 = Record {a = 5}

r2 = r1 {}
After
module NoFields where

data Record = Record {a :: Int}

r1 = Record {a = 5}

r2 = r1 {a = 7}