technically yes :)

for example I was looking at some reagent code such as ^{:key id} (if foo? [:div] [:span]), which according to my very limited understanding of metadata is incorrect

it's not incorrect as in, the clojure reader will fail, but the metadata is discarded since if doesn't do anything with it. you should use with-meta here

indeed. But it seems like it's a relatively common mistake to make, I think I've seen it a couple of times because it's easy to assume it applies to the resulting value at runtime (like with-meta). Sure would be nice to notice problems like that without looking at the react warnings in the js/console 😉

but I have no idea is it possible to reliably detect when the metadata is being ignored

in general it's not really something you can detect that is "wrong" since the macro (or special form) might do something with this metadata

but e.g. ^{:foo} 1 is always wrong, since it's a reader error

Let's first discuss if this is a common enough problem to add something for

My case: macro gets a map as a param. I have to get nodes from this map to use with-meta further

can you describe your use case further? example call of the macro for example? why do you need to read from the map?

The codebase I am working now has a lot of macro like:

(macro-that-will-creat-several-functions
  {:get-function "name-of-the-get-fn"
   :set-funtion  "name-of-the-set-fn"
   :this-will-be-used-so-I-need-to-tell-clj-kondo-that-this-value-is-used pool-that-will-be-used-inside})

Maybe better way would be to avoid having a map here and just use keys and values

right

I have a library with some common operations for rewrite-clj nodes here https://github.com/borkdude/rewrite-edn/blob/80f246139b1a43b6f2cbab329521d060ee7c1b7b/src/borkdude/rewrite_edn/impl.cljc#L118

but since clj-kondo nodes don't have whitespace, it's relatively easy to transform them in a map:

(let [children (:children map)
      ks (take-nth 2 children)
      ks (map api/sexpr ks)
      vs (take-nth 2 (rest children))]
  (zipmap ks vs))
  

there you have the key s-expressions to nodes

thank you!