[R] Support tidyselect where() selection helper in dplyr verbs

[asfimport]

Since we can now determine the data type of an unevaluated array expression (ARROW-12291) I think we should be able to support the where() selection helper.

This is already done for the relocate() verb (in ARROW-12781 ) but not for any other verbs. 

Steps required to do this:

1. ARROW-12781 
2. ARROW-12105
3. Remove the check_select_helpers() function definition and remove all the calls to it
4. Modify any remaining the expect_error() tests that test where() and check for the error message "Unsupported selection helper"

Reporter: Ian Cook / @ianmcook
Assignee: Nicola Crane / @thisisnic

Related issues:

• [R] Implement use of where() inside `across() (is related to)
• [R] Replace vars_select, vars_rename with eval_select, eval_rename (depends upon)
• [R] Determine the type of an unevaluated expression (depends upon)
• [R] Implement is.type() functions for dplyr (depends upon)

_{Note: This issue was originally created as ARROW-12778. Please see the migration documentation for further details.}

[asfimport]

Dewey Dunnington / @paleolimbot:
I think the missing piece is something like simulate_data_frame() (which is what dbplyr and the substrait R package use to support where():

library(arrow, warn.conflicts = FALSE)
#> Some features are not enabled in this build of Arrow. Run `arrow_info()` for more information.

simulate_data_frame <- function(schema) {
  arrays <- lapply(schema$fields, function(field) concat_arrays(type = field$type))
  vectors <- lapply(
    arrays,
    function(array) tryCatch(
      as.vector(array), 
      error = function(...) vctrs::unspecified()
    )
  )
  
  names(vectors) <- names(schema)
  tibble::new_tibble(vectors, nrow = 0)
}

simulate_data_frame(schema(col1 = int32(), col2 = string()))
#> # A tibble: 0 × 2
#> # … with 2 variables: col1 <int>, col2 <chr>

In substrait R, for example, @thisisnic implemented where() support with only a few lines! https://github.com/voltrondata/substrait-r/blob/ed6f4057b90c91275bcce5a125b0836e60ab4e8d/R/pkg-dplyr.R#L242

[asfimport]

Kirill Müller:
I wonder if we could also offer native type checks, such as is_int32() or is_decimal(), to do the selection the other way around.

[asfimport]

Nicola Crane / @thisisnic:
I've opened ARROW-17896 re native type checking

[asfimport]

Neal Richardson / @nealrichardson:
Is this issue resolved by ARROW-12105, or is there more to do?

[asfimport]

Nicola Crane / @thisisnic:
Nope, this is done now, will close! :D