Missing sub-expression variable declaration

[barkmadley]

I ended up writing something like this expression at some point, and I'm not sure if I had hit a documented problem, or if bucklescript is missing some Javascript semantics:

let _ =
  Js.Undefined.to_opt (Js.Undefined.return "") = Some ""

This produces a runtime error regarding an undefined variable v, because of the generated Javascript:

// Generated by BUCKLESCRIPT VERSION 1.3.0 , PLEASE EDIT WITH CARE
'use strict';

var Caml_obj = require("bs-platform/lib/js/caml_obj");

Caml_obj.caml_equal((v = "", v === undefined ? /* None */0 : [v]), /* Some */[""]);

/*  Not a pure module */

It is simple enough to work-around by explicitly binding the Js.Undefined.return "" expression to a name, but it does seem like the bucklescript compiler should be able to declare new variables for any free ones it needs to create inside sub-expressions.

bsc.exe -v output:

The OCaml compiler, version BuckleScript 1.3.0 (Using OCaml4.02.3+BS )
Standard library directory: /home/bark/projects/bs-connect3/node_modules/bs-platform/lib/ocaml

Actually bs-platform is at version 1.3.1. I guess the -v output also needs to be updated.

[bobzhang]

Thanks for reporting the bug. @barkmadley I am travelling, will fix this when I come back

[bobzhang]

fixed in #982