prefer vctrs::new_data_frame() over tibble(!!!) (#5371)

* prefer vctrs::new_data_frame()

* Let vctrs::rbind() handle vctrs, but keep dealing with lists for now

* using expect_equivalent()

* make it clearer that bare lists are the special case

* make test explicit

R/bind.r

@@ -115,7 +115,13 @@ bind_rows <- function(..., .id = NULL) {
     }
   }
 
-  dots <- map(dots, function(.x) if (is.data.frame(.x)) .x else tibble(!!!.x))
+  dots <- map(dots, function(.x) {
+    if (vec_is_list(.x)) {
+      .x <- new_data_frame(as.list(.x))
+    }
+    .x
+  })
+
   if (is.null(.id)) {
     names(dots) <- NULL
   }

tests/testthat/test-bind.R

@@ -443,10 +443,8 @@ test_that("bind_rows() handles rowwise vectors", {
 
 test_that("bind_rows() accepts lists of dataframe-like lists as first argument", {
   ll <- list(a = 1, b = 2)
-  df <- tibble(a = 1, b = 2)
-
-  expect_equal(bind_rows(list(ll)), df)
-  expect_equal(bind_rows(list(ll, ll)), df[c(1, 1), ])
+  expect_equal(bind_rows(list(ll)), data.frame(a = 1, b = 2))
+  expect_equal(bind_rows(list(ll, ll)), data.frame(a = c(1, 1), b = c(2, 2)))
 })
 
 test_that("bind_rows can handle lists (#1104)", {
@@ -523,7 +521,10 @@ test_that("bind_rows() handles named S3 objects (#4931)", {
 
   expect_identical(
     bind_rows(fct, fct),
-    tibble(x = unname(fct)[c(1, 1)], y = unname(fct)[c(2, 2)])
+    data.frame(
+      x = factor(c("a", "a"), levels = c("a", "b")),
+      y = factor(c("b", "b"), levels = c("a", "b"))
+    )
   )
 })