stop importing xfun::isFALSE() and define isFALSE() only for R < 3.5.0

yihui/xfun#67

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: knitr
 Type: Package
 Title: A General-Purpose Package for Dynamic Report Generation in R
-Version: 1.41.1
+Version: 1.41.2
 Authors@R: c(
     person("Yihui", "Xie", role = c("aut", "cre"), email = "[email protected]", comment = c(ORCID = "0000-0003-0645-5666")),
     person("Abhraneel", "Sarma", role = "ctb"),

NAMESPACE

@@ -159,7 +159,6 @@ import(utils)
 importFrom(xfun,attr)
 importFrom(xfun,file_ext)
 importFrom(xfun,file_string)
-importFrom(xfun,isFALSE)
 importFrom(xfun,is_R_CMD_check)
 importFrom(xfun,is_abs_path)
 importFrom(xfun,is_windows)

R/block.R

@@ -364,7 +364,7 @@ purge_cache = function(options) {
 
 cache_globals = function(option, code) {
   if (is.character(option)) option else {
-    (if (xfun::isFALSE(option)) find_symbols else find_globals)(code)
+    (if (isFALSE(option)) find_symbols else find_globals)(code)
   }
 }
 

R/package.R

@@ -25,7 +25,7 @@
 #'   \code{knit} + \code{R} (while \code{Sweave} = \code{S} + \code{weave}).
 #' @references Full documentation and demos: \url{https://yihui.org/knitr/};
 #'   FAQ's: \url{https://yihui.org/knitr/faq/}
-#' @importFrom xfun attr file_ext isFALSE is_windows loadable parse_only
+#' @importFrom xfun attr file_ext is_windows loadable parse_only
 #'   sans_ext try_silent with_ext read_utf8 write_utf8 file_string
 #'   is_R_CMD_check is_abs_path
 NULL

R/utils.R

@@ -44,6 +44,9 @@ comment_to_var = function(x, varname, pattern, envir) {
   FALSE
 }
 
+# TODO: remove this when we don't support R < 3.5.0
+if (getRversion() < '3.5.0') isFALSE = function(x) identical(x, FALSE)
+
 is_blank = function(x) {
   if (length(x)) all(grepl('^\\s*$', x)) else TRUE
 }