[erl-frontend] Validate association kind in map pattern

Summary: Associations in map patterns should only be exact (`:=`). We did not validate this previously (D28832961 (65884018dc)), because we didn't have certain AST transformation passes that would eliminate some special functions that allowed invalid association kinds (later removed by transformation). However, with D29103633 (25711189a8), we get the AST from a different source and these invalid cases are removed, so the check is added.

Reviewed By: mmarescotti

Differential Revision: D29162325

fbshipit-source-id: a47d9f05d

infer/src/erlang/ErlangAstValidator.ml

@@ -29,8 +29,7 @@ let rec validate_pattern (p : Ast.expression) =
       true
   | Map {map; updates} ->
       let validate_assoc (a : Ast.association) =
-        validate_pattern a.key && validate_pattern a.value
-        (* TODO: a.kind must be Exact, except inside ets:fun2ms or dbg:fun2ms *)
+        match a.kind with Exact -> validate_pattern a.key && validate_pattern a.value | _ -> false
       in
       is_none map && List.for_all ~f:validate_assoc updates
   | Match {pattern; body} ->