wrap-out middleware should qualify symbols that rely on later runtime resolve calls

[mrrodriguez]

In cider.nrepl.middleware.out/print-stream
the proxy OutputStream for the PrintWriter later bound to System/setOut ends up doing this

(resolve '*out*)

(same goes for *err*)

The point is that this is an unqualified reference to *out*, instead of clojure.core/*out*. This can cause issues if System/out is being called from *ns*'s that do not automatically have clojure.core/*out* mapped to the ns-interns.

In particular, I saw this come up in a CLJS macroexpansion situation, where System/out was called and the *ns* was bound to cljs.main during the CLJS compiler's analysis stage.

I believe a solution to this issue may be to fully-qualify these symbols so that the macro doesn't implicitly rely on what *ns* is bound to when these PrintStream.write methods are called.

Expected behavior

wrap-out to work transparently when System/out called in application.

Actual behavior

wrap-out can sometimes cause NullPointerException if the caller calls System/out with a *ns* bound that cannot resolve the bare, unqualified symbol *out* or *err*.

This comes up in CLJS if there is a macro that calls something like (.println System/out s) during macroexansion with the *ns* bound to the cljs.main ns.

Steps to reproduce the problem

I believe all you need to show it is

(ns fail-wrap-out-middleware
  (:refer-clojure :exclude [*out*]))

(.println System/out "10")

A real-world example is vvvvalvalval/scope-capture#24 (comment)

Environment & Version information

cider-nrepl version

0.17.0

but this is still in master and is in older versions as well.

Java version

1.8, 1.9 etc