Better warnings for old coords and new guides

NEWS.md

@@ -1,6 +1,8 @@
 
 # ggplot2 (development version)
 
+* `coord_map()` and `coord_polar()` throw informative warnings when used
+  with the guide system (#5707).
 * When passing a function to `stat_contour(breaks)`, that function is used to
   calculate the breaks even if `bins` and `binwidth` are missing 
   (@teunbrand, #5686).

R/coord-map.R

@@ -235,6 +235,24 @@ CoordMap <- ggproto("CoordMap", Coord,
     details
   },
 
+  setup_panel_guides = function(self, panel_params, guides, params = list()) {
+    guide_names <- intersect(
+      names(guides$guides),
+      c("x", "x.sec", "y", "y.sec", "r", "r.sec", "theta", "theta.sec")
+    )
+    if (length(guide_names) > 0) {
+      cli::cli_warn(
+        "{.fn {snake_class(self)}} cannot render {cli::qty(guide_names)} \\
+        guide{?s} for the aesthetic{?s}: {.and {.field {guide_names}}}."
+      )
+    }
+    panel_params
+  },
+
+  train_panel_guides = function(self, panel_params, layers, params = list()) {
+    panel_params
+  },
+
   render_bg = function(self, panel_params, theme) {
     xrange <- expand_range(panel_params$x.range, 0.2)
     yrange <- expand_range(panel_params$y.range, 0.2)

R/coord-polar.R

@@ -162,6 +162,16 @@ CoordPolar <- ggproto("CoordPolar", Coord,
   },
 
   setup_panel_guides = function(self, panel_params, guides, params = list()) {
+    guide_names <- intersect(
+      names(guides$guides),
+      c("x", "x.sec", "y", "y.sec", "r", "r.sec", "theta", "theta.sec")
+    )
+    if (length(guide_names) > 0) {
+      cli::cli_warn(
+        "{.fn {snake_class(self)}} cannot render {cli::qty(guide_names)} \\
+        guide{?s} for the aesthetic{?s}: {.and {.field {guide_names}}}."
+      )
+    }
     panel_params
   },
 

tests/testthat/_snaps/coord-map.md

@@ -6,3 +6,7 @@
 
     `ylim` must be a vector of length 2, not an integer vector of length 3.
 
+# coord_map throws informative warning about guides
+
+    `coord_map()` cannot render guide for the aesthetic: x.
+

tests/testthat/_snaps/coord-polar.md

@@ -1,3 +1,7 @@
+# coord_polar throws informative warning about guides
+
+    `coord_polar()` cannot render guide for the aesthetic: theta.
+
 # coord_radial warns about axes
 
     `guide_axis()` cannot be used for theta.

tests/testthat/test-coord-map.R

@@ -50,3 +50,9 @@ test_that("coord map throws error when limits are badly specified", {
   # throws error when limit's length is different than two
   expect_snapshot_error(ggplot() + coord_cartesian(ylim=1:3))
 })
+
+test_that("coord_map throws informative warning about guides", {
+  expect_snapshot_warning(
+   ggplot_build(ggplot() + coord_map() + guides(x = guide_axis()))
+  )
+})

tests/testthat/test-coord-polar.R

@@ -98,6 +98,12 @@ test_that("coord_polar can have free scales in facets", {
   expect_equal(sc$y$get_limits(), c(0, 1))
 })
 
+test_that("coord_polar throws informative warning about guides", {
+  expect_snapshot_warning(
+    ggplot_build(ggplot() + coord_polar() + guides(theta = guide_axis()))
+  )
+})
+
 test_that("coord_radial warns about axes", {
 
   p <- ggplot(mtcars, aes(disp, mpg)) +