From 9bcefb6bca6013e9577b821c4b65c39c7a570027 Mon Sep 17 00:00:00 2001
From: hadley <h.wickham@gmail.com>
Date: Thu, 28 Jun 2018 16:06:17 -0500
Subject: [PATCH] Respect escapes when passing links

Fixes #720
---
 NEWS.md                                 |  3 ++-
 R/markdown.R                            |  2 +-
 tests/testthat/test-rd-markdown-links.R | 12 ++++++++++++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 88c10d5fb..ed92c91d2 100644
--- a/NEWS.md
+++ b/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
 
diff --git a/R/markdown.R b/R/markdown.R
index 01e24d392..7333b7010 100644
--- a/R/markdown.R
+++ b/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 [
diff --git a/tests/testthat/test-rd-markdown-links.R b/tests/testthat/test-rd-markdown-links.R
index c95c70d96..07f0e67b0 100644
--- a/tests/testthat/test-rd-markdown-links.R
+++ b/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",