From 33a9a0247184f8495f0e1fd2329934192a04d342 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Wed, 5 Feb 2025 09:09:36 +0100
Subject: [PATCH 1/3] swap x/y when using `coord_flip()`

---
 R/guides-grid.R | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/R/guides-grid.R b/R/guides-grid.R
index 6b8f116a24..1b2f1a4a99 100644
--- a/R/guides-grid.R
+++ b/R/guides-grid.R
@@ -12,7 +12,11 @@ guide_grid <- function(theme, panel_params, coord, square = TRUE) {
   y_minor <- setdiff(panel_params$y$mapped_breaks_minor(), y_major)
 
   transform <- if (isTRUE(square)) {
-    function(x) coord$transform(x, panel_params)
+    if (inherits(coord, "CoordFlip")) {
+      function(x) coord$transform(flip_axis_labels(x), panel_params)
+    } else {
+      function(x) coord$transform(x, panel_params)
+    }
   } else {
     function(x) coord_munch(coord, x, panel_params)
   }

From f48baf3347b324e9671be1e085f2493f0fc51bfc Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Wed, 5 Feb 2025 09:16:14 +0100
Subject: [PATCH 2/3] include grid in snapshot

---
 .../turning-off-secondary-title-with-coord-flip.svg   | 11 +++++++++++
 tests/testthat/test-coord-flip.R                      |  7 ++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/tests/testthat/_snaps/coord-flip/turning-off-secondary-title-with-coord-flip.svg b/tests/testthat/_snaps/coord-flip/turning-off-secondary-title-with-coord-flip.svg
index ffb66ff639..207bd13c34 100644
--- a/tests/testthat/_snaps/coord-flip/turning-off-secondary-title-with-coord-flip.svg
+++ b/tests/testthat/_snaps/coord-flip/turning-off-secondary-title-with-coord-flip.svg
@@ -27,6 +27,17 @@
 </defs>
 <g clip-path='url(#cpMzIuNzl8Njk5LjgwfDIyLjc4fDU0NS4xMQ==)'>
 <rect x='32.79' y='22.78' width='667.01' height='522.33' style='stroke-width: 1.07; stroke: none; fill: #FFFFFF;' />
+<polyline points='32.79,529.45 699.80,529.45 ' style='stroke-width: 1.07; stroke: #CCCCCC; stroke-linecap: butt;' />
+<polyline points='32.79,428.42 699.80,428.42 ' style='stroke-width: 1.07; stroke: #CCCCCC; stroke-linecap: butt;' />
+<polyline points='32.79,327.39 699.80,327.39 ' style='stroke-width: 1.07; stroke: #CCCCCC; stroke-linecap: butt;' />
+<polyline points='32.79,226.36 699.80,226.36 ' style='stroke-width: 1.07; stroke: #CCCCCC; stroke-linecap: butt;' />
+<polyline points='32.79,125.33 699.80,125.33 ' style='stroke-width: 1.07; stroke: #CCCCCC; stroke-linecap: butt;' />
+<polyline points='32.79,24.30 699.80,24.30 ' style='stroke-width: 1.07; stroke: #CCCCCC; stroke-linecap: butt;' />
+<polyline points='63.11,545.11 63.11,22.78 ' style='stroke-width: 1.07; stroke: #E5E5E5; stroke-linecap: butt;' />
+<polyline points='214.70,545.11 214.70,22.78 ' style='stroke-width: 1.07; stroke: #E5E5E5; stroke-linecap: butt;' />
+<polyline points='366.30,545.11 366.30,22.78 ' style='stroke-width: 1.07; stroke: #E5E5E5; stroke-linecap: butt;' />
+<polyline points='517.89,545.11 517.89,22.78 ' style='stroke-width: 1.07; stroke: #E5E5E5; stroke-linecap: butt;' />
+<polyline points='669.48,545.11 669.48,22.78 ' style='stroke-width: 1.07; stroke: #E5E5E5; stroke-linecap: butt;' />
 <circle cx='366.30' cy='307.19' r='1.95' style='stroke-width: 0.71; fill: #000000;' />
 <circle cx='366.30' cy='307.19' r='1.95' style='stroke-width: 0.71; fill: #000000;' />
 <circle cx='63.11' cy='270.81' r='1.95' style='stroke-width: 0.71; fill: #000000;' />
diff --git a/tests/testthat/test-coord-flip.R b/tests/testthat/test-coord-flip.R
index 0a346ebb24..fc63748418 100644
--- a/tests/testthat/test-coord-flip.R
+++ b/tests/testthat/test-coord-flip.R
@@ -4,7 +4,12 @@ test_that("secondary labels are correctly turned off", {
     ggplot(mtcars, aes(x = mpg, y = cyl)) +
       geom_point() +
       scale_x_continuous(sec.axis = dup_axis(guide = guide_axis(title = NULL))) +
-      coord_flip()
+      coord_flip() +
+      theme_test() +
+      theme(
+        panel.grid.major.y = element_line(colour = "grey80"),
+        panel.grid.major.x = element_line(colour = "grey90")
+      )
   )
 })
 

From ca430003be9a557673586f050eba25bae57a3bc9 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Wed, 5 Feb 2025 09:17:18 +0100
Subject: [PATCH 3/3] add news bullet

---
 NEWS.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/NEWS.md b/NEWS.md
index 74b049ace5..16a835452e 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* Fixed regression with incorrectly drawn gridlines when using `coord_flip()` 
+  (@teunbrand, #6293).
 * New parameters for `geom_label()` (@teunbrand and @steveharoz, #5365):
   * The `linewidth` aesthetic is now applied and replaces the `label.size` 
     argument.