From a2475fda8ec687f9c63ca037e63b113c87f926a6 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Wed, 21 May 2025 16:13:01 +0200
Subject: [PATCH 1/2] convert `check_labeller()` to `validate_labeller()`

---
 R/facet-grid-.R | 2 +-
 R/facet-wrap.R  | 2 +-
 R/labeller.R    | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/R/facet-grid-.R b/R/facet-grid-.R
index 0c0df60bb0..244ccc69f7 100644
--- a/R/facet-grid-.R
+++ b/R/facet-grid-.R
@@ -187,7 +187,7 @@ facet_grid <- function(rows = NULL, cols = NULL, scales = "fixed",
   facets_list <- grid_as_facets_list(rows, cols)
 
   # Check for deprecated labellers
-  check_labeller(labeller)
+  labeller <- validate_labeller(labeller)
 
   ggproto(NULL, FacetGrid,
     shrink = shrink,
diff --git a/R/facet-wrap.R b/R/facet-wrap.R
index 310745e9dd..2481bb5e6a 100644
--- a/R/facet-wrap.R
+++ b/R/facet-wrap.R
@@ -188,7 +188,7 @@ facet_wrap <- function(facets, nrow = NULL, ncol = NULL, scales = "fixed",
   )
 
   # Check for deprecated labellers
-  check_labeller(labeller)
+  labeller <- validate_labeller(labeller)
 
   # Flatten all facets dimensions into a single one
   facets <- compact_facets(facets)
diff --git a/R/labeller.R b/R/labeller.R
index ad57a4f283..9a80fca9ea 100644
--- a/R/labeller.R
+++ b/R/labeller.R
@@ -578,13 +578,13 @@ assemble_strips <- function(grobs, theme, horizontal = TRUE, clip) {
 }
 
 # Reject old school labeller
-check_labeller <- function(labeller) {
+validate_labeller <- function(labeller) {
 
   labeller <- match.fun(labeller)
   is_deprecated <- all(c("variable", "value") %in% names(formals(labeller)))
 
   if (!is_deprecated) {
-    return(invisible())
+    return(labeller)
   }
 
   lifecycle::deprecate_stop(

From 047d58b82ab957c82d7eb41c625e411de957eeb7 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Wed, 21 May 2025 16:14:54 +0200
Subject: [PATCH 2/2] add small test

---
 tests/testthat/test-labellers.R | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tests/testthat/test-labellers.R b/tests/testthat/test-labellers.R
index 460349e960..7cc6ad0df3 100644
--- a/tests/testthat/test-labellers.R
+++ b/tests/testthat/test-labellers.R
@@ -1,3 +1,11 @@
+test_that("facets convert labeller to function", {
+  f <- facet_grid(foo ~ bar, labeller = "label_both")
+  expect_type(f$params$labeller, "closure")
+
+  f <- facet_wrap(foo ~ bar, labeller = "label_value")
+  expect_type(f$params$labeller, "closure")
+})
+
 test_that("label_bquote has access to functions in the calling environment", {
   labels <- data.frame(lab = letters[1:2])
   attr(labels, "facet") <- "wrap"