derive labels even if not specified in scale (#1884)

Author: thomasp85

R/axis-secondary.R

@@ -103,7 +103,7 @@ AxisSecondary <- ggproto("AxisSecondary", NULL,
   init = function(self, scale) {
     if (self$empty()) return()
     if (!is.formula(self$trans)) stop("transformation for secondary axes must be a formula", call. = FALSE)
-    if (is.derived(self$name)) self$name <- scale$name
+    if (is.derived(self$name) && !is.waive(scale$name)) self$name <- scale$name
     if (is.derived(self$breaks)) self$breaks <- scale$breaks
     if (is.derived(self$labels)) self$labels <- scale$labels
   },

R/layout.R

@@ -148,6 +148,7 @@ Layout <- ggproto("Layout", NULL,
     } else {
       self$panel_scales$x[[1]]$sec_name()
     } %|W|% labels$sec.x
+    if (is.derived(secondary)) secondary <- primary
     secondary <- self$panel_scales$x[[1]]$make_sec_title(secondary)
     list(primary = primary, secondary = secondary)[self$panel_scales$x[[1]]$axis_order()]
   },
@@ -160,6 +161,7 @@ Layout <- ggproto("Layout", NULL,
     } else {
       self$panel_scales$y[[1]]$sec_name()
     } %|W|% labels$sec.y
+    if (is.derived(secondary)) secondary <- primary
     secondary <- self$panel_scales$y[[1]]$make_sec_title(secondary)
     list(primary = primary, secondary = secondary)[self$panel_scales$y[[1]]$axis_order()]
   },