Inconsistency between `is_call()` + `call_name()` vs `is_call(name = ...)` on quosure

[mgirlich]

I incorrectly used is_call() on a quosure and found this confusing inconsistency:

library(rlang)

x <- quo(desc(x))
is_call(x)
#> [1] TRUE
call_name(x)
#> [1] "desc"
is_call(x, "desc")
#> [1] FALSE

^{Created on 2023-02-03 with reprex v2.0.2}

[lionel-]

I've been meaning to make is_call() return FALSE on quosures but it's been difficult a few years ago and is probably even more difficult now, regarding backwards compatibility.

In general though, is_call() is lower level than call_name() and the invariant you are looking for is not guaranteed. We do have invariants in terms of is_call_simple() though.