drop translator-specific unknown_visit calls

Removes the need for various translators from raising a
`NotImplementedError` exception when missing support for a specific node
type. docutils will already raise [1][2] a `NotImplementedError`
exception for these cases. This help reduce the implementation inside
Sphinx as well as prevents the possible undesired replication of
unknown-node handling with third-party extensions [3].

In most cases, generating a warning message for an unsupported node type
can be preferred. Providing an indication that a node is not supported
can be easier for a user of Sphinx to understand a limitation of a
builder over a generic "not implemented" exception. This commit takes
the logging call which is already used by `texinfo` and applies it to
the `SphinxTranslator` base class -- which any Sphinx translator
implementation can use.

[1]: https://repo.or.cz/docutils.git/blob/d169015ee0f412cffd69b33654d8a119d99bc0f3:/docutils/nodes.py#l2048
[2]: https://repo.or.cz/docutils.git/blob/53716a13b48128af6045139d3cd2909f61e7ed8e:/docutils/nodes.py#l1897
[3]: https://github.com/sphinx-doc/sphinx/issues/9921

Signed-off-by: James Knight <james.d.knight@live.com>

sphinx/util/docutils.py

@@ -28,7 +28,7 @@ from docutils.utils import Reporter, unescape
 from packaging import version
 
 from sphinx.errors import SphinxError
-from sphinx.locale import _
+from sphinx.locale import _, __
 from sphinx.util import logging
 from sphinx.util.typing import RoleFunction
 
@@ -496,6 +496,9 @@ class SphinxTranslator(nodes.NodeVisitor):
         else:
             super().dispatch_departure(node)
 
+    def unknown_visit(self, node: Node) -> None:
+        logger.warning(__('unknown node type: %r'), node, location=node)
+
 
 # cache a vanilla instance of nodes.document
 # Used in new_document() function

sphinx/writers/html.py

@@ -876,9 +876,6 @@ class HTMLTranslator(SphinxTranslator, BaseTranslator):
         if depart:
             depart(self, node)
 
-    def unknown_visit(self, node: Node) -> None:
-        raise NotImplementedError('Unknown node: ' + node.__class__.__name__)
-
     @property
     def permalink_text(self) -> str:
         warnings.warn('HTMLTranslator.permalink_text is deprecated.',

sphinx/writers/html5.py

@@ -811,9 +811,6 @@ class HTML5Translator(SphinxTranslator, BaseTranslator):
         if depart:
             depart(self, node)
 
-    def unknown_visit(self, node: Node) -> None:
-        raise NotImplementedError('Unknown node: ' + node.__class__.__name__)
-
     @property
     def permalink_text(self) -> str:
         warnings.warn('HTMLTranslator.permalink_text is deprecated.',

sphinx/writers/latex.py

@@ -2079,9 +2079,6 @@ class LaTeXTranslator(SphinxTranslator):
     def depart_math_reference(self, node: Element) -> None:
         pass
 
-    def unknown_visit(self, node: Node) -> None:
-        raise NotImplementedError('Unknown node: ' + node.__class__.__name__)
-
 
 # FIXME: Workaround to avoid circular import
 # refs: https://github.com/sphinx-doc/sphinx/issues/5433

sphinx/writers/manpage.py

@@ -462,6 +462,3 @@ class ManualPageTranslator(SphinxTranslator, BaseTranslator):
 
     def depart_math_block(self, node: Element) -> None:
         self.depart_centered(node)
-
-    def unknown_visit(self, node: Node) -> None:
-        raise NotImplementedError('Unknown node: ' + node.__class__.__name__)

sphinx/writers/texinfo.py

@@ -1265,10 +1265,6 @@ class TexinfoTranslator(SphinxTranslator):
         logger.warning(__("unimplemented node type: %r"), node,
                        location=node)
 
-    def unknown_visit(self, node: Node) -> None:
-        logger.warning(__("unknown node type: %r"), node,
-                       location=node)
-
     def unknown_departure(self, node: Node) -> None:
         pass
 

sphinx/writers/text.py

@@ -1189,6 +1189,3 @@ class TextTranslator(SphinxTranslator):
 
     def depart_math_block(self, node: Element) -> None:
         self.end_state()
-
-    def unknown_visit(self, node: Node) -> None:
-        raise NotImplementedError('Unknown node: ' + node.__class__.__name__)