Formatter breaks :refer-clojure :exclude with platform-specific reader conditionals

[jetmind]

When a .cljc file has separate per-platform :refer-clojure forms wrapped in #?, the formatter merges them into a single :refer-clojure with #?@ splicing inside :exclude. This breaks compilation because #?@ splices the vector contents, so :exclude receives bare symbols instead of a vector.

Minimal reproduction

Create repro.cljc:

(ns repro
  #?(:cljs (:refer-clojure :exclude [juxt])
     :clj  (:refer-clojure :exclude [juxt format])))

Run fix:

$ standard-clj fix repro.cljc
standard-clj fix v0.27.0

F /repro.cljc [2.94ms]

1 file formatted with Standard Clojure Style 👍 [9.27ms]

Result in repro.cljc:

(ns repro
  (:refer-clojure
    :exclude #?@(:clj [format juxt]
                 :cljs [juxt])))

Fails to compile:

$ clojure -M -e '(load-file "repro.cljc")'
Syntax error macroexpanding clojure.core/ns at (repro.cljc:1:1).
((:refer-clojure :exclude format juxt)) - failed: Extra input spec: :clojure.core.specs.alpha/ns-form

#?@ splices the vector contents, so Clojure sees :exclude format juxt instead of :exclude [format juxt].

Expected behavior

Either leave the two separate #?-wrapped :refer-clojure forms as-is, or use #? (without @) to preserve the vector: :exclude #?(:clj [format juxt] :cljs [juxt]).

Version

$ standard-clj --version
v0.27.0 [dc54207]

[oakmac]

Thank you for this excellent bug report 👍

Looking at the tests, I can see a bunch of FIXME comments about how I never tested this output 🙃

I am leaning toward changing how this works entirely and simply printing each :refer-clojure on it's own line (ie: one per platform). I think most uses of :refer-clojure keep the symbol list small and this is likely the most readable output when there are reader conditionals.