Metadata isn't being preserved on conj

[djblue]

In jank:

% ./build/jank repl
Bottom of clojure.core
clojure.core=> (meta ^:meta {})
{:meta true}
clojure.core=> (meta (conj ^:meta {} [:k :v]))
nil
clojure.core=> 

In clj:

% clj
Clojure 1.12.0
user=> (meta ^:meta {})
{:meta true}
user=> (meta (conj ^:meta {} [:k :v]))
{:meta true}
user=> 

I haven't investigated further, but this might apply to other operations and collection types.

[jeaye]

Yep, you're right about this. Meta preservation is likely missing in a lot of places, since metadata was implemented pretty late. We do have all of the behaviors for it now, though. Just need to identify where it's needed.

[shantanu-sardesai]

@jeaye Should this one be closed?

user=> (meta (conj ^:meta {} [:k :v]))
{:meta true}

And I see Chris already worked on it in one of his previous PR.

[shantanu-sardesai]

I suppose this also could do with a few new test cases in the test suite?

[jeaye]

Yes, we should make sure that meta preservation is tested as well. This is something we're lacking, for coverage.

[shantanu-sardesai]

It looks like this still requires some work after all:

user=> (let [meta-data {:foo 42} \
user=>...    apply-meta #(-> % (with-meta meta-data) (conj [:k :v]) meta)] \
user=>... (apply-meta '()))
nil