source_parsers should fill Parser.supported attribute to let Sphinx know supported formats

CHANGES

@@ -7,6 +7,9 @@ Dependencies
 Incompatible changes
 --------------------
 
+* Sphinx expects source parser modules to have supported file formats as
+  ``Parser.supported`` attribute
+
 Deprecated
 ----------
 

sphinx/registry.py

@@ -11,12 +11,14 @@
 from __future__ import print_function
 
 import traceback
+import warnings
 
 from pkg_resources import iter_entry_points
 from six import iteritems, itervalues
 
 from sphinx.errors import ExtensionError, SphinxError, VersionRequirementError
 from sphinx.extension import Extension
+from sphinx.deprecation import RemovedInSphinx30Warning
 from sphinx.domains import ObjType
 from sphinx.domains.std import GenericObject, Target
 from sphinx.locale import __
@@ -201,6 +203,12 @@ class SphinxComponentRegistry(object):
         logger.debug('[app] adding search source_parser: %r, %r', suffix, parser)
         if suffix in self.source_parsers:
             raise ExtensionError(__('source_parser for %r is already registered') % suffix)
+
+        if len(parser.supported) == 0:
+            warnings.warn('Old source_parser has been detected. Please fill Parser.supported '
+                          'attribute: %s' % parser.__name__,
+                          RemovedInSphinx30Warning)
+
         self.source_parsers[suffix] = parser
 
     def get_source_parser(self, filename):

tests/roots/test-prolog/prolog_markdown_parser.py

@@ -4,6 +4,8 @@ from docutils.parsers import Parser
 
 
 class DummyMarkdownParser(Parser):
+    supported = ('markdown',)
+
     def parse(self, inputstring, document):
         document.rawsource = inputstring
 

tests/roots/test-root/conf.py

@@ -13,7 +13,6 @@ templates_path = ['_templates']
 
 master_doc = 'contents'
 source_suffix = ['.txt', '.add', '.foo']
-source_parsers = {'.foo': 'parsermod.Parser'}
 
 project = 'Sphinx <Tests>'
 copyright = '2010-2016, Georg Brandl & Team'
@@ -106,9 +105,12 @@ class ClassDirective(Directive):
 
 
 def setup(app):
+    import parsermod
+
     app.add_config_value('value_from_conf_py', 42, False)
     app.add_directive('funcdir', functional_directive, opt=lambda x: x)
     app.add_directive('clsdir', ClassDirective)
     app.add_object_type('userdesc', 'userdescrole', '%s (userdesc)',
                         userdesc_parse, objname='user desc')
     app.add_javascript('file://moo.js')
+    app.add_source_parser('.foo', parsermod.Parser)

tests/roots/test-root/parsermod.py

@@ -3,6 +3,8 @@ from docutils import nodes
 
 
 class Parser(Parser):
+    supported = ('foo',)
+
     def parse(self, input, document):
         section = nodes.section(ids=['id1'])
         section += nodes.title('Generated section', 'Generated section')