Ambiguous parsing

[egormkn]

Problem
I found a bug in lama parser, that is somehow connected to ambiguous grammar rules for case expression and infix operators.

Example code

infix | at ++ (lhs, rhs) {
  lhs ++ rhs
}

infix -> at ++ (lhs, rhs) {
  lhs ++ rhs
}

(* Prints "WAT" *)
printf ("%s\n", 
  case "?" of
    "?" -> "W" 
  | "A" -> "T"
  esac.string
);

(* Prints W *)
printf ("%s\n", 
  case "?" of
    "?" -> "W" 
  | "A" -> "T"
  esac
)

Expected behaviour
Both outputs are quite reasonable but they should be the same for both expressions.

Environment

• lamac: v1.0 (Version master, e4b34a3, Sat Mar 21 13:05:14 2020 +0300)
• ostap: v0.4 (dboulytchev/ostap@6565c87)

[dboulytchev]

#5 (comment)