Revert "Don't allow casting to non-bare data frames"

This reverts commit b4f1c40.

R/cast.R

@@ -209,13 +209,12 @@ vec_default_cast <- function(x,
       return(out)
     }
 
-    if (is_bare_df(to)) {
-      # Bare-class fallback for data frames
-      if (inherits(to, "tbl_df")) {
-        out <- df_as_tibble(out)
-      }
-      return(out)
+    # Bare-class fallback for data frames.
+    # FIXME: Should we only allow it when target is a bare df?
+    if (inherits(to, "tbl_df")) {
+      out <- df_as_tibble(out)
     }
+    return(out)
   }
 
   if (is_same_type(x, to)) {

tests/testthat/_snaps/cast.md

@@ -62,15 +62,6 @@
       Error:
       ! Can't combine `..1$a$b` <factor<c1562>> and `..2$a$b` <double>.
 
-# vec_cast() only falls back when casting to base type
-
-    Code
-      (expect_error(vec_cast(mtcars, foobar(mtcars))))
-    Output
-      <error/vctrs_error_cast>
-      Error:
-      ! Can't convert `mtcars` <data.frame> to <vctrs_foobar>.
-
 # vec_cast() only attempts to fall back if `to` is a data frame (#1568)
 
     Code

tests/testthat/_snaps/type-misc.md

@@ -1,12 +1,3 @@
-# data.table and tibble do not have a common type
-
-    Code
-      (expect_error(vec_cast(tibble(y = 2), data.table(x = TRUE, y = 1L))))
-    Output
-      <error/vctrs_error_cast>
-      Error:
-      ! Can't convert `tibble(y = 2)` <tibble> to <data.table>.
-
 # data table has formatting methods
 
     Code

tests/testthat/test-cast.R

@@ -92,11 +92,9 @@ test_that("unspecified can be cast to shaped vectors", {
   expect_identical(out, exp)
 })
 
-test_that("vec_cast() only falls back when casting to base type", {
+test_that("vec_cast() falls back to base class even when casting to non-base type", {
   expect_equal(vec_cast(foobar(mtcars), mtcars), mtcars)
-  expect_snapshot({
-    (expect_error(vec_cast(mtcars, foobar(mtcars))))
-  })
+  expect_equal(vec_cast(mtcars, foobar(mtcars)), mtcars)
 })
 
 test_that("vec_cast() only attempts to fall back if `to` is a data frame (#1568)", {
@@ -284,3 +282,20 @@ test_that("df-fallback for cast is not sensitive to attributes order", {
 
   expect_identical(vec_cast(x, ptype), x)
 })
+
+test_that("bare-type fallback for df-cast works", {
+  # NOTE: Not sure why this was necessary. The cubble and yamlet
+  # packages fail without this.
+  local_methods(
+    c.vctrs_foobaz = function(...) quux(NextMethod())
+  )
+
+  df <- data_frame(x = 1, y = foobaz("foo"))
+  gdf <- dplyr::new_grouped_df(
+    df,
+    data_frame(x = 1, .rows = list(1L)),
+    class = "vctrs_foobar"
+  )
+
+  expect_error(vec_rbind(gdf, gdf), NA)
+})

tests/testthat/test-type-misc.R

@@ -77,10 +77,10 @@ test_that("data.table and tibble do not have a common type", {
     vec_cast(data.table(y = 2), tibble(x = TRUE, y = 1L)),
     tibble(x = lgl(NA), y = 2L)
   )
-
-  expect_snapshot({
-    (expect_error(vec_cast(tibble(y = 2), data.table(x = TRUE, y = 1L))))
-  })
+  expect_identical(
+    vec_cast(tibble(y = 2), data.table(x = TRUE, y = 1L)),
+    data_frame(x = lgl(NA), y = 2L)
+  )
 })
 
 test_that("data table has formatting methods", {