Fill in missing se parameter (#5700)

* fill in missing `se`

* account for flipped aesthetics

* add news bullet

Author: teunbrand

NEWS.md

@@ -1,5 +1,9 @@
 # ggplot2 (development version)
 
+* The default `se` parameter in layers with `geom = "smooth"` will be `TRUE` 
+  when the data has `ymin` and `ymax` parameters and `FALSE` if these are 
+  absent. Note that this does not affect the default of `geom_smooth()` or
+  `stat_smooth()` (@teunbrand, #5572).
 * The bounded density option in `stat_density()` uses a wider range to
   prevent discontinuities (#5641).
 * `geom_raster()` now falls back to rendering as `geom_rect()` when coordinates

R/geom-smooth.R

@@ -125,6 +125,13 @@ geom_smooth <- function(mapping = NULL, data = NULL,
 GeomSmooth <- ggproto("GeomSmooth", Geom,
   setup_params = function(data, params) {
     params$flipped_aes <- has_flipped_aes(data, params, range_is_orthogonal = TRUE, ambiguous = TRUE)
+    params$se <- params$se %||%
+      if (params$flipped_aes) {
+        all(c("xmin", "xmax") %in% names(data))
+      } else {
+        all(c("ymin", "ymax") %in% names(data))
+      }
+
     params
   },