do not modify PATH under Mac; use kpsewhich() to find kpsewhich

NEWS.md

@@ -1,3 +1,9 @@
+# CHANGES IN knitr VERSION 1.5
+
+## MINOR CHANGES
+
+- `knitr:::.onLoad()` no longer modifies the `PATH` variable when `/usr/texbin` is not in `PATH` under Mac OS
+
 # CHANGES IN knitr VERSION 1.4
 
 ## NOTE

R/utils.R

@@ -239,7 +239,7 @@ isFALSE = function(x) identical(x, FALSE)
 
 ## check latex packages; if not exist, copy them over to ./
 test_latex_pkg = function(name, path) {
-  res = try(system(sprintf('kpsewhich %s.sty', name), intern = TRUE), silent = TRUE)
+  res = try(system(sprintf('%s %s.sty', kpsewhich(), name), intern = TRUE), silent = TRUE)
   if (inherits(res, 'try-error') || !length(res)) {
     warning("unable to find LaTeX package '", name, "'; will use a copy from knitr")
     file.copy(path, '.')
@@ -518,3 +518,10 @@ set_html_dev = function() {
     png(tempfile()); dev.off()
   }, silent = TRUE), 'try-error')) 'svg' else 'png')
 }
+
+# locate kpsewhich especially for Mac OS because /usr/texbin may not be in PATH
+kpsewhich = function() {
+  if (Sys.info()['sysname'] != 'Darwin' || !file.exists(x <- '/usr/texbin/kpsewhich')
+      || nzchar(Sys.which('kpsewhich')))
+    'kpsewhich' else x
+}

R/zzz.R

@@ -1,9 +1,3 @@
 .onLoad = function(lib, pkg) {
   register_vignette_engines(pkg)
-  # add /usr/texbin to PATH for Mac OS
-  if (Sys.info()['sysname'] != 'Darwin') return()
-  if (!file_test('-d', texbin <- '/usr/texbin')) return()
-  path = strsplit(Sys.getenv('PATH'), ':')[[1L]]
-  if (texbin %in% path) return()
-  Sys.setenv(PATH = paste(c(path, texbin), collapse = ':'))
 }