diff --git a/CHANGES b/CHANGES
index befd9ef75..9899d77a9 100644
--- a/CHANGES
+++ b/CHANGES
@@ -18,6 +18,7 @@ Deprecated
 * ``sphinx.ext.autodoc.importer.MockLoader``
 * ``sphinx.ext.autodoc.importer.mock()``
 * ``sphinx.ext.autosummary.autolink_role()``
+* ``sphinx.util.node.find_source_node()``
 * ``sphinx.util.i18n.find_catalog()``
 * ``sphinx.util.i18n.find_catalog_files()``
 * ``sphinx.util.i18n.find_catalog_source_files()``
@@ -27,6 +28,8 @@ For more details, see :ref:`deprecation APIs list <dev-deprecated-apis>`.
 Features added
 --------------
 
+* Add a helper method ``SphinxDirective.set_source_info()``
+
 Bugs fixed
 ----------
 
diff --git a/doc/extdev/index.rst b/doc/extdev/index.rst
index 44bea4845..a8c016d0f 100644
--- a/doc/extdev/index.rst
+++ b/doc/extdev/index.rst
@@ -259,6 +259,11 @@ The following is a list of deprecated interfaces.
      - 4.0
      - ``sphinx.ext.autosummary.AutoLink``
 
+   * - ``sphinx.util.node.find_source_node()``
+     - 2.1
+     - 4.0
+     - ``sphinx.util.node.get_node_source()``
+
    * - ``sphinx.util.i18n.find_catalog()``
      - 2.1
      - 4.0
diff --git a/sphinx/directives/code.py b/sphinx/directives/code.py
index 73afac4ba..75ab61796 100644
--- a/sphinx/directives/code.py
+++ b/sphinx/directives/code.py
@@ -20,7 +20,6 @@ from sphinx.locale import __
 from sphinx.util import logging
 from sphinx.util import parselinenos
 from sphinx.util.docutils import SphinxDirective
-from sphinx.util.nodes import set_source_info
 
 if False:
     # For type annotation
@@ -173,7 +172,7 @@ class CodeBlock(SphinxDirective):
             extra_args['hl_lines'] = hl_lines
         if 'lineno-start' in self.options:
             extra_args['linenostart'] = self.options['lineno-start']
-        set_source_info(self, literal)
+        self.set_source_info(literal)
 
         caption = self.options.get('caption')
         if caption:
@@ -446,7 +445,7 @@ class LiteralInclude(SphinxDirective):
             text, lines = reader.read(location=location)
 
             retnode = nodes.literal_block(text, text, source=filename)  # type: nodes.Element
-            set_source_info(self, retnode)
+            self.set_source_info(retnode)
             if self.options.get('diff'):  # if diff is set, set udiff
                 retnode['language'] = 'udiff'
             elif 'language' in self.options:
diff --git a/sphinx/directives/other.py b/sphinx/directives/other.py
index 2efca0722..cc2268a41 100644
--- a/sphinx/directives/other.py
+++ b/sphinx/directives/other.py
@@ -21,8 +21,7 @@ from sphinx.locale import _
 from sphinx.util import url_re, docname_join
 from sphinx.util.docutils import SphinxDirective
 from sphinx.util.matching import Matcher, patfilter
-from sphinx.util.nodes import explicit_title_re, set_source_info, \
-    process_index_entry
+from sphinx.util.nodes import explicit_title_re, process_index_entry
 
 if False:
     # For type annotation
@@ -77,7 +76,7 @@ class TocTree(SphinxDirective):
         subnode['includehidden'] = 'includehidden' in self.options
         subnode['numbered'] = self.options.get('numbered', 0)
         subnode['titlesonly'] = 'titlesonly' in self.options
-        set_source_info(self, subnode)
+        self.set_source_info(subnode)
         wrappernode = nodes.compound(classes=['toctree-wrapper'])
         wrappernode.append(subnode)
         self.add_name(wrappernode)
@@ -204,7 +203,7 @@ class Index(SphinxDirective):
         indexnode = addnodes.index()
         indexnode['entries'] = []
         indexnode['inline'] = False
-        set_source_info(self, indexnode)
+        self.set_source_info(indexnode)
         for entry in arguments:
             indexnode['entries'].extend(process_index_entry(entry, targetid))
         return [indexnode, targetnode]
@@ -231,7 +230,7 @@ class TabularColumns(SphinxDirective):
         # type: () -> List[nodes.Node]
         node = addnodes.tabular_col_spec()
         node['spec'] = self.arguments[0]
-        set_source_info(self, node)
+        self.set_source_info(node)
         return [node]
 
 
@@ -330,7 +329,7 @@ class Only(SphinxDirective):
         # type: () -> List[nodes.Node]
         node = addnodes.only()
         node.document = self.state.document
-        set_source_info(self, node)
+        self.set_source_info(node)
         node['expr'] = self.arguments[0]
 
         # Same as util.nested_parse_with_titles but try to handle nested
diff --git a/sphinx/directives/patches.py b/sphinx/directives/patches.py
index 3c31571ac..0f6883609 100644
--- a/sphinx/directives/patches.py
+++ b/sphinx/directives/patches.py
@@ -132,7 +132,7 @@ class MathDirective(SphinxDirective):
                                 label=self.options.get('label'),
                                 nowrap='nowrap' in self.options)
         ret = [node]  # type: List[nodes.Node]
-        set_source_info(self, node)
+        self.set_source_info(node)
         self.add_target(ret)
         return ret
 
diff --git a/sphinx/domains/changeset.py b/sphinx/domains/changeset.py
index 030d88ad3..aeea645c1 100644
--- a/sphinx/domains/changeset.py
+++ b/sphinx/domains/changeset.py
@@ -19,7 +19,6 @@ from sphinx.deprecation import DeprecatedDict, RemovedInSphinx30Warning
 from sphinx.domains import Domain
 from sphinx.locale import _
 from sphinx.util.docutils import SphinxDirective
-from sphinx.util.nodes import set_source_info
 
 
 if False:
@@ -68,7 +67,7 @@ class VersionChange(SphinxDirective):
         # type: () -> List[nodes.Node]
         node = addnodes.versionmodified()
         node.document = self.state.document
-        set_source_info(self, node)
+        self.set_source_info(node)
         node['type'] = self.name
         node['version'] = self.arguments[0]
         text = versionlabels[self.name] % self.arguments[0]
@@ -76,7 +75,7 @@ class VersionChange(SphinxDirective):
             inodes, messages = self.state.inline_text(self.arguments[1],
                                                       self.lineno + 1)
             para = nodes.paragraph(self.arguments[1], '', *inodes, translatable=False)
-            set_source_info(self, para)
+            self.set_source_info(para)
             node.append(para)
         else:
             messages = []
diff --git a/sphinx/ext/doctest.py b/sphinx/ext/doctest.py
index a47d05b55..d7a18ba17 100644
--- a/sphinx/ext/doctest.py
+++ b/sphinx/ext/doctest.py
@@ -29,7 +29,6 @@ from sphinx.locale import __
 from sphinx.util import logging
 from sphinx.util.console import bold  # type: ignore
 from sphinx.util.docutils import SphinxDirective
-from sphinx.util.nodes import set_source_info
 from sphinx.util.osutil import relpath
 
 if False:
@@ -104,7 +103,7 @@ class TestDirective(SphinxDirective):
         else:
             groups = ['default']
         node = nodetype(code, code, testnodetype=self.name, groups=groups)
-        set_source_info(self, node)
+        self.set_source_info(node)
         if test is not None:
             # only save if it differs from code
             node['test'] = test
diff --git a/sphinx/ext/ifconfig.py b/sphinx/ext/ifconfig.py
index 4fd5fa391..04653ebc4 100644
--- a/sphinx/ext/ifconfig.py
+++ b/sphinx/ext/ifconfig.py
@@ -23,7 +23,6 @@ from docutils import nodes
 
 import sphinx
 from sphinx.util.docutils import SphinxDirective
-from sphinx.util.nodes import set_source_info
 
 if False:
     # For type annotation
@@ -47,7 +46,7 @@ class IfConfig(SphinxDirective):
         # type: () -> List[nodes.Node]
         node = ifconfig()
         node.document = self.state.document
-        set_source_info(self, node)
+        self.set_source_info(node)
         node['expr'] = self.arguments[0]
         self.state.nested_parse(self.content, self.content_offset,
                                 node, match_titles=True)
diff --git a/sphinx/ext/todo.py b/sphinx/ext/todo.py
index 8f4144142..3939f8ff8 100644
--- a/sphinx/ext/todo.py
+++ b/sphinx/ext/todo.py
@@ -22,7 +22,6 @@ from sphinx.errors import NoUri
 from sphinx.locale import _, __
 from sphinx.util import logging
 from sphinx.util.docutils import SphinxDirective
-from sphinx.util.nodes import set_source_info
 from sphinx.util.texescape import tex_escape_map
 
 if False:
@@ -68,7 +67,7 @@ class Todo(BaseAdmonition, SphinxDirective):
             return [todo]
         elif isinstance(todo, todo_node):
             todo.insert(0, nodes.title(text=_('Todo')))
-            set_source_info(self, todo)
+            self.set_source_info(todo)
 
             targetid = 'index-%s' % self.env.new_serialno('index')
             # Stash the target to be retrieved later in latex_visit_todo_node.
diff --git a/sphinx/util/docutils.py b/sphinx/util/docutils.py
index 393f97abf..6a580d1ae 100644
--- a/sphinx/util/docutils.py
+++ b/sphinx/util/docutils.py
@@ -383,6 +383,11 @@ class SphinxDirective(Directive):
         """Reference to the :class:`.Config` object."""
         return self.env.config
 
+    def set_source_info(self, node):
+        # type: (nodes.Node) -> None
+        """Set source and line number to the node."""
+        node.source, node.line = self.state_machine.get_source_and_line(self.lineno)
+
 
 class SphinxRole:
     """A base class for Sphinx roles.
diff --git a/sphinx/util/nodes.py b/sphinx/util/nodes.py
index b0dd13b38..3e83c218d 100644
--- a/sphinx/util/nodes.py
+++ b/sphinx/util/nodes.py
@@ -9,11 +9,13 @@
 """
 
 import re
+import warnings
 from typing import Any, cast
 
 from docutils import nodes
 
 from sphinx import addnodes
+from sphinx.deprecation import RemovedInSphinx40Warning
 from sphinx.locale import __
 from sphinx.util import logging
 
@@ -152,7 +154,7 @@ def apply_source_workaround(node):
 
     # workaround: literal_block under bullet list (#4913)
     if isinstance(node, nodes.literal_block) and node.source is None:
-        node.source = find_source_node(node)
+        node.source = get_node_source(node)
 
     # workaround: recommonmark-0.2.0 doesn't set rawsource attribute
     if not node.rawsource:
@@ -170,7 +172,7 @@ def apply_source_workaround(node):
     ))):
         logger.debug('[i18n] PATCH: %r to have source and line: %s',
                      get_full_module_name(node), repr_domxml(node))
-        node.source = find_source_node(node)
+        node.source = get_node_source(node)
         node.line = 0  # need fix docutils to get `node.line`
         return
 
@@ -278,6 +280,13 @@ def extract_messages(doctree):
 
 
 def find_source_node(node):
+    # type: (nodes.Element) -> str
+    warnings.warn('find_source_node() is deprecated.',
+                  RemovedInSphinx40Warning)
+    return get_node_source(node)
+
+
+def get_node_source(node):
     # type: (nodes.Element) -> str
     for pnode in traverse_parent(node):
         if pnode.source:
@@ -467,6 +476,12 @@ def set_role_source_info(inliner, lineno, node):
     node.source, node.line = inliner.reporter.get_source_and_line(lineno)  # type: ignore
 
 
+def copy_source_info(src, dst):
+    # type: (nodes.Element, nodes.Element) -> None
+    dst.source = get_node_source(src)
+    dst.line = get_node_line(src)
+
+
 NON_SMARTQUOTABLE_PARENT_NODES = (
     nodes.FixedTextElement,
     nodes.literal,