Manual scale limits default to present names of values

NEWS.md

@@ -1,5 +1,11 @@
 # ggplot2 (development version)
 
+* `scale_*_manual()` no longer displays extra legend keys, or changes their 
+  order, when a named `values` argument has more items than the data. The 
+  previous behaviour can be replicated by using 
+  `scale_*_manual(values = vals, limits = names(vals))`. (@teunbrand, @banfai, 
+  #4511, #4534, #4556, #4545, #4616)
+
 # ggplot2 3.3.5
 This is a very small release focusing on fixing a couple of untenable issues 
 that surfaced with the 3.3.4 release

R/scale-manual.r

@@ -132,8 +132,8 @@ manual_scale <- function(aesthetic, values = NULL, breaks = waiver(), ..., limit
     force(values)
   }
 
-  if (is.null(limits)) {
-    limits <- names(values)
+  if (is.null(limits) && !is.null(names(values))) {
+    limits <- function(x) {intersect(x, names(values))}
   }
 
   # order values according to breaks