Overview

This repo demonstrates a bug I found in ClojureScript where macros are not loaded from preloads whose namespace has only a single part, e.g. macro-repl-bug.

Setup

0. build.edn contains a basic CLJS build with macro-repl-bug configured in :preload and app.main configured as the entry.
1. src/macro_repl_bug.cljc contains two vars: a function foo and a macro bar defined only in the :clj branch. The ns :require-macros itself.

To run the project, you'll need both Java and Clojure installed on your system.

Reproduction

0. Start a CLJS REPL, e.g. clj -M -m cljs.main -co build.edn -v -c -r
1. In the REPL, evaluate (macro-repl-bug/foo)
2. Then, evaluate (macro-repl-bug/bar)

Expected behavior

Both foo and bar are executed from the namespace loaded via preloads

cljs.user=> (macro-repl-bug/foo)
:foo
cljs.user=> (macro-repl-bug/bar)
:bar

Actual behavior

The macro bar is not found.

cljs.user=> (macro-repl-bug/foo)
WARNING: Use of undeclared Var macro-repl-bug/foo at line 1 <cljs repl>
:foo
cljs.user=> (macro-repl-bug/bar)
WARNING: Use of undeclared Var macro-repl-bug/bar at line 1 <cljs repl>
Execution error (TypeError) at (<cljs repl>:1).
macro_repl_bug.bar is not a function

Additional findings

Namespaces with two or more parts, e.g. macro-repl.works, do work as expected.

cljs.user=> (macro-repl.works/foo)
:foo
cljs.user=> (macro-repl.works/bar)
:bar

Requiring the namespace explicitly from the REPL does allow it to be executed:

cljs.user=> (require '[macro-repl-bug])
nil
cljs.user=> (macro-repl-bug/bar)
:bar

However, in a more complex project with shadow-cljs, this only lasts until the next hot reload of the preloaded namespace. I have not figured out a simple repro for this yet.