E4034

Multiple possible record types detected, please add more annotation.

Erroneous Example

fn main {
  struct S { x : Int; y : Int }
  struct T { x : Int; y : Int }
  let c = { x: 2, y: 1 }
}

The example above tries to assign a record with fields x and y to a variable c, but this field combination matches both S and T types, giving the following error on line 4:

Multiple possible record types detected: T, S, please add more annotation.

Suggestion

Disambiguate the record type by adding a type annotation:

fn main {
  struct S { x : Int; y : Int }
  struct T { x : Int; y : Int }
  let c : S = { x: 2, y: 1 }
  let c2 = S::{ x : 2, y : 1 }
}