Macroexpand hook with # functions reader macro

[markgdawson]

version

I'm running clj-kondo 2022.08.03 on the JVM in Linux.

problem

I'm used the macroexpand hook to expand the try-let macro. My macro implementation is mostly good enough and is working for me in most cases. But clj-kondo produces errors when there is a function defined by #(...) in the expansion of the macro. It seems to me that clj-kondo is failing to recognise reader macro functions when using the macroexpand hook.

repro

EDIT: here is a minimal project which this repro in runnable form: https://github.com/markgdawson/clj-kondo-reader-macro-repro.
Run with clj -M:clj-kondo.

(ns core
  (:require [try-let :refer [try-let]]))

(try-let [a 10]
         #(+ a 2)
         (catch Throwable e e))

In this case I get clj-kondo error on this macro saying unused-binding a.

For completeness, I use try-let in deps.edn as: try-let/try-let {:mvn/version "1.3.1"}.

The warning goes away with:

(try-let [a 10]
         a
         #(+ a 2)
         (catch Throwable e e))

and with

(try-let [a 10]
         (fn [] (+ a 2))
         (catch Throwable e e))

config
./.clj-kondo/configs/try-let/config.edn

{:hooks
 {:macroexpand {try-let/try-let clj-kondo.try-let.try-let/try-let}}}

./.clj-kondo/configs/try-let/clj_kondo/try_let/try_let.clj

(ns clj-kondo.try-let.try-let)

(defn expression-type [body]
  (if (and (seq? body)
           (#{'catch 'finally} (first body)))
    :catches
    :body))

(defmacro try-let
  [bindings & body]
  (let [{:keys [body catches]} (group-by expression-type body)]
    `(try (let [~@bindings] ~@body)
          ~@catches)))

expected behavior

I expected clj-kondo not to throw errors for valid/correct code expansions which use the # function reader macro.

[borkdude]

I can see the error here locally too, thanks for making such a good repro.