point out the possibly outdated packages to make it easier for users …

…to know what to do with the deprecation of xfun::isFALSE: yihui/yihui.org#1470 (comment)

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: xfun
 Type: Package
 Title: Supporting Functions for Packages Maintained by 'Yihui Xie'
-Version: 0.41.5
+Version: 0.41.6
 Authors@R: c(
   person("Yihui", "Xie", role = c("aut", "cre", "cph"), email = "[email protected]", comment = c(ORCID = "0000-0003-0645-5666")),
   person("Wush", "Wu", role = "ctb"),

R/utils.R

@@ -140,14 +140,28 @@ in_dir = function(dir, expr) {
 #' @export
 #' @keywords internal
 isFALSE = function(x) {
+  pkgs = tools::dependsOnPkgs('xfun', dependencies = 'all', recursive = FALSE)
+  pkgs = intersect(pkgs, sys.packages())
+  vers = sapply(pkgs, function(p) as.character(packageVersion(p)))
   if ('isFALSE' %in% ls(baseenv())) stop(
     'The function xfun::isFALSE() has been deprecated. Please ',
-    'consider using base::isFALSE(x) or identical(x, FALSE) instead. ',
+    if (length(vers)) {
+      c('update the possibly outdated package(s): ', paste(pkgs, vers, sep = ' ', collapse = ', '), '. ')
+    } else {
+      'consider using base::isFALSE(x) or identical(x, FALSE) instead. '
+    },
     'You may see https://yihui.org/en/2023/02/xfun-isfalse/ for more info.'
   )
   identical(x, FALSE)
 }
 
+# try to get the names of packages for all functions on the call stack
+sys.packages = function() {
+  unique(unlist(lapply(seq_along(sys.calls()), function(i) {
+    environment(sys.function(i))$.packageName
+  })))
+}
+
 #' Parse R code and do not keep the source
 #'
 #' An abbreviation of `parse(keep.source = FALSE)`.