From a5cac0a0c401b0d5c901ac734c877f6a32bddb40 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Mon, 15 Dec 2014 10:50:10 -0800
Subject: [PATCH] Don't treat a citation as a reference link label.

Closes #1763.
---
 README                              | 4 +++-
 src/Text/Pandoc/Readers/Markdown.hs | 7 ++++---
 tests/markdown-reader-more.native   | 2 ++
 tests/markdown-reader-more.txt      | 7 +++++++
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/README b/README
index 0bb55877a..933509c91 100644
--- a/README
+++ b/README
@@ -2400,7 +2400,9 @@ The link consists of link text in square brackets, followed by a label in
 square brackets. (There can be space between the two.) The link definition
 consists of the bracketed label, followed by a colon and a space, followed by
 the URL, and optionally (after a space) a link title either in quotes or in
-parentheses.
+parentheses.  The label must not be parseable as a citation (assuming
+the `citations` extension is enabled):  citations take precedence over
+link labels.
 
 Here are some examples:
 
diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index 2ca3b0eb6..187b479c3 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/src/Text/Pandoc/Readers/Markdown.hs
@@ -1675,9 +1675,10 @@ referenceLink :: (String -> String -> Inlines -> Inlines)
               -> (F Inlines, String) -> MarkdownParser (F Inlines)
 referenceLink constructor (lab, raw) = do
   sp <- (True <$ lookAhead (char ' ')) <|> return False
-  (ref,raw') <- try
-           (skipSpaces >> optional (newline >> skipSpaces) >> reference)
-           <|> return (mempty, "")
+  (ref,raw') <- option (mempty, "") $
+      lookAhead (try (spnl >> normalCite >> return (mempty, "")))
+      <|>
+      try (spnl >> reference)
   let labIsRef = raw' == "" || raw' == "[]"
   let key = toKey $ if labIsRef then raw else raw'
   parsedRaw <- parseFromString (mconcat <$> many inline) raw'
diff --git a/tests/markdown-reader-more.native b/tests/markdown-reader-more.native
index 00313a0ac..3f4bb5740 100644
--- a/tests/markdown-reader-more.native
+++ b/tests/markdown-reader-more.native
@@ -152,6 +152,8 @@
 ,Para [Link [Str "linky"] ("hi_(there_(nested))","")]
 ,Header 2 ("reference-link-fallbacks",[],[]) [Str "Reference",Space,Str "link",Space,Str "fallbacks"]
 ,Para [Str "[",Emph [Str "not",Space,Str "a",Space,Str "link"],Str "]",Space,Str "[",Emph [Str "nope"],Str "]\8230"]
+,Header 2 ("reference-link-followed-by-a-citation",[],[]) [Str "Reference",Space,Str "link",Space,Str "followed",Space,Str "by",Space,Str "a",Space,Str "citation"]
+,Para [Str "MapReduce",Space,Str "is",Space,Str "a",Space,Str "paradigm",Space,Str "popularized",Space,Str "by",Space,Link [Str "Google"] ("http://google.com",""),Space,Cite [Citation {citationId = "mapreduce", citationPrefix = [], citationSuffix = [], citationMode = NormalCitation, citationNoteNum = 0, citationHash = 0}] [Str "[@mapreduce]"],Space,Str "as",Space,Str "its",Space,Str "most",Space,Str "vocal",Space,Str "proponent."]
 ,Header 2 ("empty-reference-links",[],[]) [Str "Empty",Space,Str "reference",Space,Str "links"]
 ,Para [Str "bar"]
 ,Para [Link [Str "foo2"] ("","")]]
diff --git a/tests/markdown-reader-more.txt b/tests/markdown-reader-more.txt
index ea4fc9cad..d7439f6cb 100644
--- a/tests/markdown-reader-more.txt
+++ b/tests/markdown-reader-more.txt
@@ -262,6 +262,13 @@ Empty cells
 
 [*not a link*] [*nope*]...
 
+## Reference link followed by a citation
+
+MapReduce is a paradigm popularized by [Google] [@mapreduce] as its
+most vocal proponent.
+
+[Google]: http://google.com
+
 ## Empty reference links
 
 [foo2]: