add aspect ratio warning

Author: teunbrand

R/layout.R

@@ -309,6 +309,14 @@ Layout <- ggproto("Layout", NULL,
       return(table)
     }
 
+    if (isTRUE(table$respect)) {
+      args <- !c(is.null(new_widths), is.null(new_heights))
+      args <- c("panel.widths", "panel.heights")[args]
+      cli::cli_warn(
+        "Aspect ratios are overruled by {.arg {args}} theme element{?s}."
+      )
+    }
+
     rows <- panel_rows(table)
     cols <- panel_cols(table)
 

tests/testthat/test-theme.R

@@ -650,6 +650,13 @@ test_that("panel.widths and panel.heights works with free-space panels", {
 
 })
 
+test_that("panel.widths and panel.heights appropriately warn about aspect override", {
+  p <- ggplot(mpg, aes(displ, hwy)) +
+    geom_point() +
+    theme(aspect.ratio = 1, panel.widths = unit(4, "cm"))
+  expect_warning(ggplotGrob(p), "Aspect ratios are overruled")
+})
+
 # Visual tests ------------------------------------------------------------
 
 test_that("aspect ratio is honored", {