Fix graphviz: workaround for wrong map ID which graphviz generates

CHANGES

@@ -25,6 +25,7 @@ Bugs fixed
 * #4449: apidoc: include "empty" packages that contain modules
 * #3917: citation labels are tranformed to ellipsis
 * #4501: graphviz: epub3 validation error caused if graph is not clickable
+* #4514: graphviz: workaround for wrong map ID which graphviz generates
 
 Testing
 --------

sphinx/ext/graphviz.py

@@ -47,22 +47,29 @@ class ClickableMapDefinition(object):
     maptag_re = re.compile('<map id="(.*?)"')
     href_re = re.compile('href=".*?"')
 
-    def __init__(self, filename, content):
-        # type: (unicode, unicode) -> None
+    def __init__(self, filename, content, dot=''):
+        # type: (unicode, unicode, unicode) -> None
         self.id = None
         self.filename = filename
         self.content = content.splitlines()
         self.clickable = []  # type: List[unicode]
 
-        self.parse()
+        self.parse(dot=dot)
 
-    def parse(self):
-        # type: () -> None
+    def parse(self, dot=None):
+        # type: (None) -> None
         matched = self.maptag_re.match(self.content[0])   # type: ignore
         if not matched:
             raise GraphvizError('Invalid clickable map file found: %s' % self.filename)
 
         self.id = matched.group(1)
+        if self.id == '%3':
+            # graphviz generates wrong ID if graph name not specified
+            # https://gitlab.com/graphviz/graphviz/issues/1327
+            hashed = sha1(dot.encode('utf-8')).hexdigest()
+            self.id = 'grapviz%s' % hashed[-10:]
+            self.content[0] = self.content[0].replace('%3', self.id)
+
         for line in self.content:
             if self.href_re.search(line):
                 self.clickable.append(line)
@@ -289,7 +296,7 @@ def render_dot_html(self, node, code, options, prefix='graphviz',
             self.body.append(svgtag)
         else:
             with codecs.open(outfn + '.map', 'r', encoding='utf-8') as mapfile:
-                imgmap = ClickableMapDefinition(outfn + '.map', mapfile.read())
+                imgmap = ClickableMapDefinition(outfn + '.map', mapfile.read(), dot=code)
                 if imgmap.clickable:
                     # has a map
                     self.body.append('<img src="%s" alt="%s" usemap="#%s" %s/>\n' %

tests/test_ext_graphviz.py

@@ -118,30 +118,32 @@ def test_graphviz_i18n(app, status, warning):
 
 
 def test_graphviz_parse_mapfile():
-    # digraph {
-    # }
+    # empty graph
+    code = ('# digraph {\n'
+            '# }\n')
     content = ('<map id="%3" name="%3">\n'
                '</map>')
-    cmap = ClickableMapDefinition('dummy.map', content)
+    cmap = ClickableMapDefinition('dummy.map', content, code)
     assert cmap.filename == 'dummy.map'
-    assert cmap.id == '%3'
+    assert cmap.id == 'grapvizb08107169e'
     assert len(cmap.clickable) == 0
     assert cmap.generate_clickable_map() == ''
 
-    # digraph {
-    #   foo [href="http://www.google.com/"];
-    #   foo -> bar;
-    # }
+    # normal graph
+    code = ('digraph {\n'
+            '  foo [href="http://www.google.com/"];\n'
+            '  foo -> bar;\n'
+            '}\n')
     content = ('<map id="%3" name="%3">\n'
                '<area shape="poly" id="node1" href="http://www.google.com/" title="foo" alt=""'
                ' coords="77,29,76,22,70,15,62,10,52,7,41,5,30,7,20,10,12,15,7,22,5,29,7,37,12,'
                '43,20,49,30,52,41,53,52,52,62,49,70,43,76,37"/>\n'
                '</map>')
-    cmap = ClickableMapDefinition('dummy.map', content)
+    cmap = ClickableMapDefinition('dummy.map', content, code)
     assert cmap.filename == 'dummy.map'
-    assert cmap.id == '%3'
+    assert cmap.id == 'grapviza4ccdd48ce'
     assert len(cmap.clickable) == 1
-    assert cmap.generate_clickable_map() == content
+    assert cmap.generate_clickable_map() == content.replace('%3', cmap.id)
 
     # inheritance-diagram:: sphinx.builders.html
     content = (
@@ -168,7 +170,7 @@ def test_graphviz_parse_mapfile():
         ' alt="" coords="11,3,141,19"/>\n'
         '</map>'
     )
-    cmap = ClickableMapDefinition('dummy.map', content)
+    cmap = ClickableMapDefinition('dummy.map', content, 'dummy_code')
     assert cmap.filename == 'dummy.map'
     assert cmap.id == 'inheritance66ff5471b9'
     assert len(cmap.clickable) == 0