Fix epp:open call for OTP 24

The arity of epp:open has changed and in order for xref
and dialyzer to be happy with both version we need to hide
it behind a version macro.

apps/els_core/src/els_escript.erl

@@ -149,17 +149,7 @@ parse_source(S, File, Fd, StartLine, HeaderSz) ->
  _ = io:get_line(Fd, ''),
  Encoding = epp:set_encoding(Fd),
  {ok, _} = file:position(Fd, HeaderSz),
- {ok, Epp} =
- case erlang:function_exported(epp, open, 5) of
- true ->
- %% Pre OTP-24 function to call for escripts
- %% Done via apply in order to silence dialyzer
- apply(epp, open, [File, Fd, StartLine,
- IncludePath, PreDefMacros]);
- false ->
- epp:open([{fd, Fd}, {name, File}, {location, StartLine},
- {includes, IncludePath}, {macros, PreDefMacros}])
- end,
+ {ok, Epp} = epp_open(File, Fd, StartLine, IncludePath, PreDefMacros),
  _ = [io:setopts(Fd, [{encoding, Encoding}]) || Encoding =/= none],
  {ok, FileForm} = epp:parse_erl_form(Epp),
  OptModRes = epp:parse_erl_form(Epp),
@@ -181,6 +171,31 @@ parse_source(S, File, Fd, StartLine, HeaderSz) ->
  ok = file:close(Fd),
  check_source(S2).
 
+-spec epp_open(_, _, pos_integer(), _, _) -> {ok, term()}.
+-if(?OTP_RELEASE < 24).
+%% If the environment used to compile is < 24 we should test
+%% if the eep:open/5 function is available, and if it is we use that.
+%% We to the check as we want the a version compiled with 23 to
+%% work with 24.
+epp_open(File, Fd, StartLine, IncludePath, PreDefMacros) ->
+ case erlang:function_exported(epp, open, 5) of
+ true ->
+ epp:open(File, Fd, StartLine, IncludePath, PreDefMacros);
+ false ->
+ epp:open([{fd, Fd}, {name, File}, {location, StartLine},
+ {includes, IncludePath}, {macros, PreDefMacros}])
+ end.
+-else.
+%% This is compiled with 24 or later, so has no chance of working
+%% with earlier releases that 24 so we can just use the new way of
+%% opening an escript.
+epp_open(File, Fd, StartLine, IncludePath, PreDefMacros) ->
+ epp:open([{fd, Fd}, {name, File}, {location, StartLine},
+ {includes, IncludePath}, {macros, PreDefMacros}]).
+-endif.
+
+
+
 -spec check_source(state()) -> state().
 check_source(S) ->
  case S of