Add NULL compat to expr_label() (#1656)

Co-authored-by: Zelos Zhu <[email protected]>
Closes #1655.

NEWS.md

@@ -7,6 +7,8 @@
 
 * `obj_type_friendly()` now only displays the first class of S3 objects (#1622).
 
+* `expr_label()` now has back-compatility with respect to changes made by R version 4.4 and `is.atomic(NULL)` (#1655)
+
 # rlang 1.1.1
 
 * `englue()` now allows omitting `{{`. This is to make it easier to

R/expr.R

@@ -185,7 +185,7 @@ is_symbolic <- function(x) {
 expr_label <- function(expr) {
   if (is.character(expr)) {
     encodeString(expr, quote = '"')
-  } else if (is.atomic(expr)) {
+  } else if (is.null(expr) || is.atomic(expr)) {
     format(expr)
   } else if (is.name(expr)) {
     paste0("`", as.character(expr), "`")

tests/testthat/test-expr.R

@@ -42,6 +42,9 @@ test_that("expr_label() truncates long calls", {
   expect_identical(expr_label(long_call), "`foo(...)`")
 })
 
+test_that("expr_label() NULL values come out as expected", {
+  expect_identical(expr_label(NULL), "NULL")
+})
 
 # expr_name() --------------------------------------------------------