From 7762ab38887e5977400480c4d1b6eddec1c939ee Mon Sep 17 00:00:00 2001
From: "Kenneth Benzie (Benie)" <k.benzie@codeplay.com>
Date: Thu, 2 Nov 2017 15:55:46 +0000
Subject: [PATCH] Fix hard error on cross-linking markdown document

Sphinx 1.6.5 with tip recommonmark hard errors when a markdown document
contains a cross-reference to another local markdown document as it
unconditionally access the `refdomain` of a `pending_xref`. This was
fixed [elsewhere](https://github.com/ignatenkobrain/sphinxcontrib-issuetracker/pull/13/files#diff-61beda6e59ec3020dbf0c2826dbb64c4R161)
by setting it to `None`. This patch uses the same approach which no
longer causes the Sphinx build to fail on cross-linking a markdown
document however the generated link is not correctly rendered producing
broken links in the generated html.

Addressing the broken links, the `mdnode.destination` is stripped of its
file extension if that extension is supported by `CommonMarkParser`
however this will only work for markdown documents, not ReStructuedText
or any other extended file type parsers.

Fixes #89.
---
 recommonmark/parser.py | 17 ++++++++++++++---
 tests/test_basic.py    | 10 +++++-----
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/recommonmark/parser.py b/recommonmark/parser.py
index e54fdf4..0c4924b 100644
--- a/recommonmark/parser.py
+++ b/recommonmark/parser.py
@@ -1,6 +1,7 @@
 """Docutils CommonMark parser"""
 
 import sys
+from os.path import splitext
 
 from docutils import parsers, nodes
 from sphinx import addnodes
@@ -126,7 +127,16 @@ class CommonMarkParser(parsers.Parser):
 
     def visit_link(self, mdnode):
         ref_node = nodes.reference()
-        ref_node['refuri'] = mdnode.destination
+        # Check destination is supported for cross-linking and remove extension
+        destination = mdnode.destination
+        _, ext = splitext(destination)
+        # TODO check for other supported extensions, such as those specified in
+        # the Sphinx conf.py file but how to access this information?
+        # TODO this should probably only remove the extension for local paths,
+        # i.e. not uri's starting with http or other external prefix.
+        if ext.replace('.', '') in self.supported:
+            destination = destination.replace(ext, '')
+        ref_node['refuri'] = destination
         # TODO okay, so this is acutally not always the right line number, but
         # these mdnodes won't have sourcepos on them for whatever reason. This
         # is better than 0 though.
@@ -136,11 +146,12 @@ class CommonMarkParser(parsers.Parser):
             ref_node['title'] = mdnode.title
         next_node = ref_node
 
-        url_check = urlparse(mdnode.destination)
+        url_check = urlparse(destination)
         if not url_check.scheme and not url_check.fragment:
             wrap_node = addnodes.pending_xref(
-                reftarget=mdnode.destination,
+                reftarget=destination,
                 reftype='any',
+                refdomain=None,  # Added to enable cross-linking
                 refexplicit=True,
                 refwarn=True
             )
diff --git a/tests/test_basic.py b/tests/test_basic.py
index 0e703dc..1111c5d 100644
--- a/tests/test_basic.py
+++ b/tests/test_basic.py
@@ -183,7 +183,7 @@ class TestParsing(unittest.TestCase):
             <?xml version="1.0" ?>
             <document source="&lt;string&gt;">
               <paragraph>
-                <pending_xref refexplicit="True" reftarget="/foo" reftype="any" refwarn="True">
+                <pending_xref refdomain="None" refexplicit="True" reftarget="/foo" reftype="any" refwarn="True">
                   <reference refuri="/foo">link</reference>
                 </pending_xref>
               </paragraph>
@@ -198,7 +198,7 @@ class TestParsing(unittest.TestCase):
             <?xml version="1.0" ?>
             <document source="&lt;string&gt;">
               <paragraph>
-                <pending_xref refexplicit="True" reftarget="foo" reftype="any" refwarn="True">
+                <pending_xref refdomain="None" refexplicit="True" reftarget="foo" reftype="any" refwarn="True">
                   <reference refuri="foo">link</reference>
                 </pending_xref>
               </paragraph>
@@ -274,21 +274,21 @@ class TestParsing(unittest.TestCase):
               <bullet_list>
                 <list_item>
                   <paragraph>
-                    <pending_xref refexplicit="True" reftarget="/1" reftype="any" refwarn="True">
+                    <pending_xref refdomain="None" refexplicit="True" reftarget="/1" reftype="any" refwarn="True">
                       <reference refuri="/1">List item 1</reference>
                     </pending_xref>
                   </paragraph>
                 </list_item>
                 <list_item>
                   <paragraph>
-                    <pending_xref refexplicit="True" reftarget="/2" reftype="any" refwarn="True">
+                    <pending_xref refdomain="None" refexplicit="True" reftarget="/2" reftype="any" refwarn="True">
                       <reference refuri="/2">List item 2</reference>
                     </pending_xref>
                   </paragraph>
                 </list_item>
                 <list_item>
                   <paragraph>
-                    <pending_xref refexplicit="True" reftarget="/3" reftype="any" refwarn="True">
+                    <pending_xref refdomain="None" refexplicit="True" reftarget="/3" reftype="any" refwarn="True">
                       <reference refuri="/3">List item 3</reference>
                     </pending_xref>
                   </paragraph>