Fix partial ungrouping (#6607)

* Fix partial ungrouping

* Disallow renaming during partial ungrouping

R/group-by.R

@@ -159,7 +159,12 @@ ungroup.grouped_df <- function(x, ...) {
     as_tibble(x)
   } else {
     old_groups <- group_vars(x)
-    to_remove <- tidyselect::eval_select(expr(c(...)), x)
+    to_remove <- tidyselect::eval_select(
+      expr = expr(c(...)),
+      data = x,
+      allow_rename = FALSE
+    )
+    to_remove <- names(to_remove)
 
     new_groups <- setdiff(old_groups, to_remove)
     group_by(x, !!!syms(new_groups))

tests/testthat/_snaps/group-by.md

@@ -1,3 +1,11 @@
+# can't rename while partially `ungroup()`-ing (#6606)
+
+    Code
+      ungroup(gdf, g2 = g)
+    Condition
+      Error in `ungroup()`:
+      ! Can't rename variables in this context.
+
 # select(group_by(.)) implicitely adds grouping variables (#170)
 
     Code

tests/testthat/test-group-by.R

@@ -72,6 +72,23 @@ test_that("grouping by constant adds column (#410)", {
   expect_equal(nrow(grouped), 1L)
 })
 
+test_that("can partially `ungroup()` (#6606)", {
+  df <- tibble(g1 = 1:2, g2 = 3:4, x = 5:6)
+  gdf <- group_by(df, g1, g2)
+
+  expect_identical(ungroup(gdf, g1), group_by(df, g2))
+  expect_identical(ungroup(gdf, g1, g2), df)
+})
+
+test_that("can't rename while partially `ungroup()`-ing (#6606)", {
+  df <- tibble(g = 1:2, x = 3:4)
+  gdf <- group_by(df, g)
+
+  expect_snapshot(error = TRUE, {
+    ungroup(gdf, g2 = g)
+  })
+})
+
 test_that(".dots is soft deprecated", {
   rlang::local_options(lifecycle_verbosity = "warning")