Preserve type of y in nest_join()

Fixes #6295

NEWS.md

@@ -1,5 +1,7 @@
 # dplyr (development version)
 
+* `nest_join()` now preserves the type of `y` (#6295).
+
 * `*_join()` now error if you supply them with additional arguments that
   aren't used (#6228).
 

R/join.r

@@ -513,7 +513,7 @@ nest_join.data.frame <- function(x,
   # changing the key vars because of the cast
   new_cols <- vec_cast(out[names(x_key)], vec_ptype2(x_key, y_key))
 
-  y_out <- set_names(y_in[vars$y$out], names(vars$y$out))
+  y_out <- set_names(y[vars$y$out], names(vars$y$out))
   new_cols[[name_var]] <- map(y_loc, vec_slice, x = y_out)
 
   out <- dplyr_col_modify(out, new_cols)

tests/testthat/test-join.r

@@ -261,6 +261,15 @@ test_that("nest_join returns list of tibbles (#3570)",{
   expect_s3_class(out$df2[[1]], "tbl_df")
 })
 
+test_that("nest_join respects types of y",{
+  df1 <- tibble(x = c(1, 2), y = c(2, 3))
+  df2 <- rowwise(tibble(x = c(1, 1), z = c(2, 3)))
+  out <- nest_join(df1, df2, by = "x", multiple = "all")
+
+  expect_s3_class(out$df2[[1]], "rowwise_df")
+})
+
+
 test_that("nest_join computes common columns", {
   df1 <- tibble(x = c(1, 2), y = c(2, 3))
   df2 <- tibble(x = c(1, 3), z = c(2, 3))
@@ -319,7 +328,7 @@ test_that("joins preserve groups", {
 
   # See comment in nest_join
   i <- count_regroups(out <- nest_join(gf1, gf2, by = "a", multiple = "all"))
-  expect_equal(i, 1L)
+  expect_equal(i, 4L)
   expect_equal(group_vars(out), "a")
 })