On 21.04, the REPL user prompt disappears after execution

20.04 has 1.10.1, 21.04 is the first version with 1.10.2. Was 20.10 affected?

Can you please include the output and some more info about your system? I know there were also some readline changes that happened recently-ish (e.g. in Debian bullseye, Fedora 34).

I cannot reproduce on Debian bullseye so I assume this is Ubuntu-specific:

ehashman@fedora:~$ clojure
Clojure 1.10.2
(map + [1 2 3])
(1 2 3)
(println "hello world")
hello world
nil
user=>
ehashman@fedora:~$ apt show clojure
Package: clojure
Version: 1.10.2-1
Priority: optional
...
ehashman@fedora:~$ cat /etc/debian_version
11.0

The prompt is replaced with the expression. Upon hitting Enter, first the expression itself gets printed, then the value.

(+ 1 2)
3

1
1
2
2
3
3
user=>

Notice how the prompt is missing after all REPL evaluations, except the most recent one.

This is not happening on 20.10, so this behavior is new.

Retitled bug to better describe the problem and confirmed that this also affects Debian upstream.

Does not affect a REPL launched on Clojure 1.10.2 with Leiningen.

Leiningen appears to launch a 1.10.1 REPL by default.

This appears to be entirely cosmetic so I'm not sure will be fixed in bullseye (has no effect on Clojure core functionality and we are frozen). Thanks for the report.

Okay, it's an issue with the rlwrap script.

System clojure (Debian bullseye):

ehashman@fedora:/tmp/app$ clojure
Clojure 1.10.2
(map inc [0 1 2])
(1 2 3)
user=>

With a copy of the Clojure CLI wrapper script set to use upstream Clojure binaries instead of the system ones:

ehashman@fedora:/tmp/app$ ./clojure
Clojure 1.10.2
(map inc [0 1 2])
(1 2 3)
user=>

Running those upstream ones directly with java:

ehashman@fedora:/tmp/app$ java -cp /home/ehashman/.m2/repository/org/clojure/clojure/1.10.2/clojure-1.10.2.jar:/home/ehashman/.m2/repository/org/clojure/core.specs.alpha/0.2.56/core.specs.alpha-0.2.56.jar:/home/ehashman/.m2/repository/org/clojure/spec.alpha/0.2.194/spec.alpha-0.2.194.jar"$extra_classpath" clojure.main
Clojure 1.10.2
user=> (map inc [0 1 2])
(1 2 3)
user=>

Running Debian's jar directly:

ehashman@fedora:/tmp/app$ java -cp /usr/share/java/clojure.jar clojure.main
Clojure 1.10.2
user=> (map inc [0 1 2])
(1 2 3)
user=>

https://ask.clojure.org/index.php/10025/have-prompts-previous-lines-command-started-disappearing

It's a bug in readline and is affecting clj as well. Won't get fixed until rlwrap 0.44 is available. The readline changes for bracketed paste have thrown a bunch of people, but I didn't think it would affect Clojure too :)