Remove unneeded arg_match()

[krlmlr]

With UI tests.

Makes vec_as_location2() quite a bit faster, realistically we need to remove that tryCatch() and perhaps rewrite in C to make performance comparable with base.

vctrs main

library(vctrs)
library(magrittr)

bench::mark(
  vec_as_location2("x", 1L, "x", missing = "propagate", arg = "x"),
  iterations = 1000
) %>%
  dplyr::select(-expression)
#> # A tibble: 1 x 5
#>        min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1   78.7µs   88.8µs     9451.     322KB     18.9

^{Created on 2020-06-14 by the reprex package (v0.3.0)}

This PR

library(vctrs)
library(magrittr)

bench::mark(
  vec_as_location2("x", 1L, "x", missing = "propagate", arg = "x"),
  iterations = 10000
) %>%
  dplyr::select(-expression)
#> # A tibble: 1 x 5
#>        min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1   24.8µs   28.1µs    32548.     174KB     16.3

^{Created on 2020-06-14 by the reprex package (v0.3.0)}

[lionel-]

This becomes a length > 1 vector so we need to match?

[lionel-]

Let's just use arg_match0()? I'm going to focus on rlang and vctrs releases today and tomorrow.

[krlmlr]

Sure, once rlang > 0.4.6 is on CRAN we can use that.

[krlmlr]

UI tests integrated in #1146.