[R] Column order after group_by(foo) |> select(...) is different from dplyr

[eitsupi]

Describe the bug, including details regarding any error messages, version, and platform.

Related to #35473

I corrected the column order after mutate and transmute in #35473, but it seems that it needs to be corrected in select as well.

The columns used for groups should to be moved to the left.

mtcars |> dplyr::group_by(cyl) |> dplyr::select(mpg)
#> Adding missing grouping variables: `cyl`
#> # A tibble: 32 × 2
#> # Groups:   cyl [3]
#>      cyl   mpg
#>    <dbl> <dbl>
#>  1     6  21
#>  2     6  21
#>  3     4  22.8
#>  4     6  21.4
#>  5     8  18.7
#>  6     6  18.1
#>  7     8  14.3
#>  8     4  24.4
#>  9     4  22.8
#> 10     6  19.2
#> # … with 22 more rows
mtcars |> arrow::arrow_table() |> dplyr::group_by(cyl) |> dplyr::select(mpg) |> dplyr::collect()
#> # A tibble: 32 × 2
#> # Groups:   cyl [3]
#>      mpg   cyl
#>    <dbl> <dbl>
#>  1  21       6
#>  2  21       6
#>  3  22.8     4
#>  4  21.4     6
#>  5  18.7     8
#>  6  18.1     6
#>  7  14.3     8
#>  8  24.4     4
#>  9  22.8     4
#> 10  19.2     6
#> # … with 22 more rows

^{Created on 2023-05-10 with reprex v2.0.2}

Component(s)

R

[nealrichardson]

Thanks. This would be in ensure_group_vars(), and it looks like we might also want to mimic the Adding missing grouping variables message to be explicit when this happens.