row_number is hybridifyed on empty indices set. closes #3454

tidyverse · Mar 26, 2018 · 71b8b54 · 71b8b54
1 parent da8d54e
commit 71b8b54
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/src/hybrid_window.cpp b/src/hybrid_window.cpp
@@ -35,10 +35,10 @@ Result* row_number(const RObject& data, const bool ascending) {
 }
 
 Result* row_number_prototype(SEXP call, const ILazySubsets& subsets, int nargs) {
-  if (nargs > 1 || subsets.size() == 0) return 0;
-
   if (nargs == 0) return new RowNumber_0();
 
+  if (nargs > 1) return 0;
+
   RObject data(CADR(call));
   bool ascending = true;
   if (TYPEOF(data) == LANGSXP && CAR(data) == Rf_install("desc")) {

diff --git a/tests/testthat/test-filter.r b/tests/testthat/test-filter.r
@@ -220,6 +220,13 @@ test_that("row_number does not segfault with example from #781", {
   expect_equal(nrow(res), 0L)
 })
 
+test_that("row_number works on 0 length columns (#3454)", {
+  expect_identical(
+    mutate( tibble(), a = row_number()),
+    tibble(a=integer())
+  )
+})
+
 test_that("filter does not alter expression (#971)", {
   my_filter <- ~ am == 1
   expect_equal(my_filter[[2]][[2]], as.name("am"))