Respect escapes when passing links

Fixes #720

NEWS.md

@@ -110,7 +110,8 @@
     * `%` in inline code blocks is now automatically escaped (#640).
 
     * Parsing of markdown links has been tweaked to reduce false positives 
-      (#555)
+      (#555). If you still get a false positive, you can now put `\\` in front 
+      of the `[` to avoid it being converted to a link (#720).
 
 # roxygen2 6.0.1
 

R/markdown.R

@@ -278,7 +278,7 @@ add_linkrefs_to_md <- function(text) {
     regex(
       comments = TRUE,
       "
-        (?<=[^\\]]|^)           # must not be preceded by ]
+        (?<=[^\\]\\\\]|^)       # must not be preceded by ] or \
         \\[([^\\]\\[]+)\\]      # match anything inside of []
         (?:\\[([^\\]\\[]+)\\])? # match optional second pair of []
         (?=[^\\[]|$)            # must not be followed by [

tests/testthat/test-rd-markdown-links.R

@@ -31,6 +31,18 @@ test_that("can not have [ inside of link", {
   )
 })
 
+test_that("can escape [ to avoid spurious links", {
+  expect_equal(
+    md_link_html("\\[test\\]"),
+    "<p>[test]</p>\n"
+  )
+
+  expect_equal(
+    md_link_html("\\[ [test] \\]"),
+    "<p>[ <a href=\"R:test\">test</a> ]</p>\n",
+  )
+})
+
 test_that("commonmark picks up the various link references", {
   cases <- list(
     c("foo [func()] bar",