Give label_bquote() access to calling environment

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* Make sure `label_bquote()` has access to the calling environment when 
+  evaluating the labels (@thomasp85, #4141)
 
 * Fix bug in `annotate_logticks()` that would cause an error when used together
   with `coord_flip()` (@thomasp85, #3954)

R/labeller.r

@@ -205,6 +205,8 @@ label_bquote <- function(rows = NULL, cols = NULL,
   rows_quoted <- substitute(rows)
   has_warned <- FALSE
 
+  call_env <- env_parent()
+
   fun <- function(labels) {
     quoted <- resolve_labeller(rows_quoted, cols_quoted, labels)
     if (is.null(quoted)) {
@@ -225,7 +227,7 @@ label_bquote <- function(rows = NULL, cols = NULL,
         }
         params$x <- params[[1]]
       }
-
+      params <- as_environment(params, call_env)
       eval(substitute(bquote(expr, params), list(expr = quoted)))
     }
     list(do.call("Map", c(list(f = evaluate), labels)))

tests/testthat/test-labellers.R

@@ -0,0 +1,9 @@
+context("Labellers")
+
+test_that("label_bquote has access to functions in the calling environment", {
+  labels <- data.frame(lab = letters[1:2])
+  attr(labels, "facet") <- "wrap"
+  labeller <- label_bquote(rows = .(paste0(lab, ":")))
+  labels_calc <- labeller(labels)
+  expect_equal(labels_calc[[1]][[1]], "a:")
+})