From 9a809d4d01f1a9cba4401e98d95cccf8a0ec7e75 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Fri, 17 Apr 2020 22:42:21 -0700
Subject: Markdown writer: avoid unnecessary escapes before intraword `_`

when `intraword_underscores` extension is enabled.
Closes #6296.
---
 src/Text/Pandoc/Writers/Markdown.hs |  7 ++++++-
 test/command/6296.md                | 14 ++++++++++++++
 test/writer.markdown                |  2 +-
 3 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 test/command/6296.md

diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index 7a11e3c16..fb9888b24 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -313,7 +313,12 @@ escapeText opts =
               case cs of
                    '.':'.':rest -> '\\':'.':'.':'.':go rest
                    _            -> '.':go cs
-       _   -> c : go cs
+       _   -> case cs of
+                '_':x:xs
+                  | isEnabled Ext_intraword_underscores opts
+                  , isAlphaNum c
+                  , isAlphaNum x -> c : '_' : x : go xs
+                _                -> c : go cs
 
 attrsToMarkdown :: Attr -> Doc Text
 attrsToMarkdown attribs = braces $ hsep [attribId, attribClasses, attribKeys]
diff --git a/test/command/6296.md b/test/command/6296.md
new file mode 100644
index 000000000..f4ce6b6d5
--- /dev/null
+++ b/test/command/6296.md
@@ -0,0 +1,14 @@
+```
+% pandoc -f native -t markdown
+[Str "_hi_there"]
+^D
+\_hi_there
+```
+
+```
+% pandoc -f native -t markdown-intraword_underscores
+[Str "_hi_there"]
+^D
+\_hi\_there
+```
+
diff --git a/test/writer.markdown b/test/writer.markdown
index 7393ee18e..ec867fa47 100644
--- a/test/writer.markdown
+++ b/test/writer.markdown
@@ -683,7 +683,7 @@ Just a [URL](/url/).
 
 [URL and title](/url/ "title with single quotes")
 
-[with\_underscore](/url/with_underscore)
+[with_underscore](/url/with_underscore)
 
 [Email link](mailto:nobody@nowhere.net)
 
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