diff --git a/sphinx/builders/__init__.py b/sphinx/builders/__init__.py
index 620ff82abe5..e493d11cf59 100644
--- a/sphinx/builders/__init__.py
+++ b/sphinx/builders/__init__.py
@@ -13,7 +13,12 @@
 from docutils import nodes
 from docutils.utils import DependencyList
 
-from sphinx.environment import CONFIG_CHANGED_REASON, CONFIG_OK, BuildEnvironment
+from sphinx.environment import (
+    CONFIG_CHANGED_REASON,
+    CONFIG_OK,
+    BuildEnvironment,
+    _CurrentDocument,
+)
 from sphinx.environment.adapters.asset import ImageAdapter
 from sphinx.errors import SphinxError
 from sphinx.locale import __
@@ -615,7 +620,7 @@ def read_doc(self, docname: str, *, _cache: bool = True) -> None:
         filename = str(self.env.doc2path(docname))
         filetype = get_filetype(self.app.config.source_suffix, filename)
         publisher = self.app.registry.get_publisher(self.app, filetype)
-        self.env.temp_data['_parser'] = publisher.parser
+        self.env.current_document._parser = publisher.parser
         # record_dependencies is mutable even though it is in settings,
         # explicitly re-initialise for each document
         publisher.settings.record_dependencies = DependencyList()
@@ -635,7 +640,7 @@ def read_doc(self, docname: str, *, _cache: bool = True) -> None:
         self.env.all_docs[docname] = time.time_ns() // 1_000
 
         # cleanup
-        self.env.temp_data.clear()
+        self.env.current_document = _CurrentDocument()
         self.env.ref_context.clear()
 
         self.write_doctree(docname, doctree, _cache=_cache)
diff --git a/sphinx/directives/__init__.py b/sphinx/directives/__init__.py
index d92678ab8f2..bad7dbc8f21 100644
--- a/sphinx/directives/__init__.py
+++ b/sphinx/directives/__init__.py
@@ -284,9 +284,9 @@ def run(self) -> list[Node]:
             # needed for association of version{added,changed} directives
             object_name: ObjDescT = self.names[0]
             if isinstance(object_name, tuple):
-                self.env.temp_data['object'] = str(object_name[0])
+                self.env.current_document.obj_desc_name = str(object_name[0])
             else:
-                self.env.temp_data['object'] = str(object_name)
+                self.env.current_document.obj_desc_name = str(object_name)
         self.before_content()
         content_children = self.parse_content_to_nodes(allow_section_headings=True)
         content_node = addnodes.desc_content('', *content_children)
@@ -296,7 +296,7 @@ def run(self) -> list[Node]:
             'object-description-transform', self.domain, self.objtype, content_node
         )
         DocFieldTransformer(self).transform_all(content_node)
-        self.env.temp_data['object'] = ''
+        self.env.temp_data['object'] = None
         self.after_content()
 
         if node['no-typesetting']:
@@ -335,7 +335,7 @@ def run(self) -> list[Node]:
         )
         if role:
             docutils.register_role('', role)  # type: ignore[arg-type]
-            self.env.temp_data['default_role'] = role_name
+            self.env.current_document.default_role = role_name
         else:
             literal_block = nodes.literal_block(self.block_text, self.block_text)
             reporter = self.state.reporter
@@ -362,13 +362,8 @@ class DefaultDomain(SphinxDirective):
 
     def run(self) -> list[Node]:
         domain_name = self.arguments[0].lower()
-        # if domain_name not in env.domains:
-        #     # try searching by label
-        #     for domain in env.domains.sorted():
-        #         if domain.label.lower() == domain_name:
-        #             domain_name = domain.name
-        #             break
-        self.env.temp_data['default_domain'] = self.env.domains.get(domain_name)
+        default_domain = self.env.domains.get(domain_name)
+        self.env.current_document.default_domain = default_domain
         return []
 
 
diff --git a/sphinx/directives/code.py b/sphinx/directives/code.py
index b68f6e1a729..00925debe7d 100644
--- a/sphinx/directives/code.py
+++ b/sphinx/directives/code.py
@@ -48,7 +48,7 @@ def run(self) -> list[Node]:
         linenothreshold = self.options.get('linenothreshold', sys.maxsize)
         force = 'force' in self.options
 
-        self.env.temp_data['highlight_language'] = language
+        self.env.current_document.highlight_language = language
         return [
             addnodes.highlightlang(
                 lang=language, force=force, linenothreshold=linenothreshold
@@ -159,8 +159,9 @@ def run(self) -> list[Node]:
             # no highlight language specified.  Then this directive refers the current
             # highlight setting via ``highlight`` directive or ``highlight_language``
             # configuration.
-            literal['language'] = self.env.temp_data.get(
-                'highlight_language', self.config.highlight_language
+            literal['language'] = (
+                self.env.current_document.highlight_language
+                or self.config.highlight_language
             )
         extra_args = literal['highlight_args'] = {}
         if hl_lines is not None:
diff --git a/sphinx/directives/patches.py b/sphinx/directives/patches.py
index ff2989520d8..9b60bc047a1 100644
--- a/sphinx/directives/patches.py
+++ b/sphinx/directives/patches.py
@@ -115,8 +115,9 @@ def run(self) -> list[Node]:
             # no highlight language specified.  Then this directive refers the current
             # highlight setting via ``highlight`` directive or ``highlight_language``
             # configuration.
-            node['language'] = self.env.temp_data.get(
-                'highlight_language', self.config.highlight_language
+            node['language'] = (
+                self.env.current_document.highlight_language
+                or self.config.highlight_language
             )
 
         if 'number-lines' in self.options:
diff --git a/sphinx/domains/c/__init__.py b/sphinx/domains/c/__init__.py
index 28d77227eee..02996096bac 100644
--- a/sphinx/domains/c/__init__.py
+++ b/sphinx/domains/c/__init__.py
@@ -207,19 +207,19 @@ def describe_signature(self, signode: TextElement, ast: ASTDeclaration,
 
     def run(self) -> list[Node]:
         env = self.state.document.settings.env  # from ObjectDescription.run
-        if 'c:parent_symbol' not in env.temp_data:
+        if 'c:parent_symbol' not in env.current_document:
             root = env.domaindata['c']['root_symbol']
-            env.temp_data['c:parent_symbol'] = root
+            env.current_document['c:parent_symbol'] = root
             env.ref_context['c:parent_key'] = root.get_lookup_key()
 
         # When multiple declarations are made in the same directive
         # they need to know about each other to provide symbol lookup for function parameters.
         # We use last_symbol to store the latest added declaration in a directive.
-        env.temp_data['c:last_symbol'] = None
+        env.current_document['c:last_symbol'] = None
         return super().run()
 
     def handle_signature(self, sig: str, signode: TextElement) -> ASTDeclaration:
-        parentSymbol: Symbol = self.env.temp_data['c:parent_symbol']
+        parentSymbol: Symbol = self.env.current_document['c:parent_symbol']
 
         max_len = (self.env.config.c_maximum_signature_line_length
                    or self.env.config.maximum_signature_line_length
@@ -239,7 +239,7 @@ def handle_signature(self, sig: str, signode: TextElement) -> ASTDeclaration:
             # the possibly inner declarations.
             name = _make_phony_error_name()
             symbol = parentSymbol.add_name(name)
-            self.env.temp_data['c:last_symbol'] = symbol
+            self.env.current_document['c:last_symbol'] = symbol
             raise ValueError from e
 
         try:
@@ -248,15 +248,15 @@ def handle_signature(self, sig: str, signode: TextElement) -> ASTDeclaration:
             # append the new declaration to the sibling list
             assert symbol.siblingAbove is None
             assert symbol.siblingBelow is None
-            symbol.siblingAbove = self.env.temp_data['c:last_symbol']
+            symbol.siblingAbove = self.env.current_document['c:last_symbol']
             if symbol.siblingAbove is not None:
                 assert symbol.siblingAbove.siblingBelow is None
                 symbol.siblingAbove.siblingBelow = symbol
-            self.env.temp_data['c:last_symbol'] = symbol
+            self.env.current_document['c:last_symbol'] = symbol
         except _DuplicateSymbolError as e:
             # Assume we are actually in the old symbol,
             # instead of the newly created duplicate.
-            self.env.temp_data['c:last_symbol'] = e.symbol
+            self.env.current_document['c:last_symbol'] = e.symbol
             msg = __("Duplicate C declaration, also defined at %s:%s.\n"
                      "Declaration is '.. c:%s:: %s'.")
             logger.warning(
@@ -278,15 +278,15 @@ def handle_signature(self, sig: str, signode: TextElement) -> ASTDeclaration:
         return ast
 
     def before_content(self) -> None:
-        lastSymbol: Symbol = self.env.temp_data['c:last_symbol']
+        lastSymbol: Symbol = self.env.current_document['c:last_symbol']
         assert lastSymbol
-        self.oldParentSymbol = self.env.temp_data['c:parent_symbol']
+        self.oldParentSymbol = self.env.current_document['c:parent_symbol']
         self.oldParentKey: LookupKey = self.env.ref_context['c:parent_key']
-        self.env.temp_data['c:parent_symbol'] = lastSymbol
+        self.env.current_document['c:parent_symbol'] = lastSymbol
         self.env.ref_context['c:parent_key'] = lastSymbol.get_lookup_key()
 
     def after_content(self) -> None:
-        self.env.temp_data['c:parent_symbol'] = self.oldParentSymbol
+        self.env.current_document['c:parent_symbol'] = self.oldParentSymbol
         self.env.ref_context['c:parent_key'] = self.oldParentKey
 
 
@@ -375,8 +375,8 @@ def run(self) -> list[Node]:
                 name = _make_phony_error_name()
             symbol = rootSymbol.add_name(name)
             stack = [symbol]
-        self.env.temp_data['c:parent_symbol'] = symbol
-        self.env.temp_data['c:namespace_stack'] = stack
+        self.env.current_document['c:parent_symbol'] = symbol
+        self.env.current_document['c:namespace_stack'] = stack
         self.env.ref_context['c:parent_key'] = symbol.get_lookup_key()
         return []
 
@@ -400,14 +400,14 @@ def run(self) -> list[Node]:
         except DefinitionError as e:
             logger.warning(e, location=self.get_location())
             name = _make_phony_error_name()
-        oldParent = self.env.temp_data.get('c:parent_symbol', None)
+        oldParent = self.env.current_document.get('c:parent_symbol', None)
         if not oldParent:
             oldParent = self.env.domaindata['c']['root_symbol']
         symbol = oldParent.add_name(name)
-        stack = self.env.temp_data.get('c:namespace_stack', [])
+        stack = self.env.current_document.get('c:namespace_stack', [])
         stack.append(symbol)
-        self.env.temp_data['c:parent_symbol'] = symbol
-        self.env.temp_data['c:namespace_stack'] = stack
+        self.env.current_document['c:parent_symbol'] = symbol
+        self.env.current_document['c:namespace_stack'] = stack
         self.env.ref_context['c:parent_key'] = symbol.get_lookup_key()
         return []
 
@@ -420,7 +420,7 @@ class CNamespacePopObject(SphinxDirective):
     option_spec: ClassVar[OptionSpec] = {}
 
     def run(self) -> list[Node]:
-        stack = self.env.temp_data.get('c:namespace_stack', None)
+        stack = self.env.current_document.get('c:namespace_stack', None)
         if not stack or len(stack) == 0:
             logger.warning("C namespace pop on empty stack. Defaulting to global scope.",
                            location=self.get_location())
@@ -431,8 +431,8 @@ def run(self) -> list[Node]:
             symbol = stack[-1]
         else:
             symbol = self.env.domaindata['c']['root_symbol']
-        self.env.temp_data['c:parent_symbol'] = symbol
-        self.env.temp_data['c:namespace_stack'] = stack
+        self.env.current_document['c:parent_symbol'] = symbol
+        self.env.current_document['c:namespace_stack'] = stack
         self.env.ref_context['c:parent_key'] = symbol.get_lookup_key()
         return []
 
@@ -451,9 +451,9 @@ def __init__(
         self.aliasOptions = aliasOptions
         self.document = document
         if env is not None:
-            if 'c:parent_symbol' not in env.temp_data:
+            if 'c:parent_symbol' not in env.current_document:
                 root = env.domaindata['c']['root_symbol']
-                env.temp_data['c:parent_symbol'] = root
+                env.current_document['c:parent_symbol'] = root
                 env.ref_context['c:parent_key'] = root.get_lookup_key()
             self.parentKey = env.ref_context['c:parent_key']
         else:
@@ -659,7 +659,7 @@ def run(self) -> tuple[list[Node], list[system_message]]:
                            location=self.get_location())
             # see below
             return [addnodes.desc_inline('c', text, text, classes=[self.class_type])], []
-        parentSymbol = self.env.temp_data.get('c:parent_symbol', None)
+        parentSymbol = self.env.current_document.get('c:parent_symbol', None)
         if parentSymbol is None:
             parentSymbol = self.env.domaindata['c']['root_symbol']
         # ...most if not all of these classes should really apply to the individual references,
diff --git a/sphinx/domains/changeset.py b/sphinx/domains/changeset.py
index abf622d5bb8..25f8f8e5b16 100644
--- a/sphinx/domains/changeset.py
+++ b/sphinx/domains/changeset.py
@@ -123,7 +123,7 @@ def changesets(self) -> dict[str, list[ChangeSet]]:
     def note_changeset(self, node: addnodes.versionmodified) -> None:
         version = node['version']
         module = self.env.ref_context.get('py:module')
-        objname = self.env.temp_data.get('object', '')
+        objname = self.env.current_document.obj_desc_name
         changeset = ChangeSet(node['type'], self.env.docname, node.line,  # type: ignore[arg-type]
                               module, objname, node.astext())
         self.changesets.setdefault(version, []).append(changeset)
diff --git a/sphinx/domains/cpp/__init__.py b/sphinx/domains/cpp/__init__.py
index 743aa0d1018..2c737814e6c 100644
--- a/sphinx/domains/cpp/__init__.py
+++ b/sphinx/domains/cpp/__init__.py
@@ -285,9 +285,9 @@ def describe_signature(self, signode: desc_signature,
 
     def run(self) -> list[Node]:
         env = self.state.document.settings.env  # from ObjectDescription.run
-        if 'cpp:parent_symbol' not in env.temp_data:
+        if 'cpp:parent_symbol' not in env.current_document:
             root = env.domaindata['cpp']['root_symbol']
-            env.temp_data['cpp:parent_symbol'] = root
+            env.current_document['cpp:parent_symbol'] = root
             env.ref_context['cpp:parent_key'] = root.get_lookup_key()
 
         # The lookup keys assume that no nested scopes exists inside overloaded functions.
@@ -301,7 +301,7 @@ def run(self) -> list[Node]:
         #       :cpp:any:`boom`
         #
         # So we disallow any signatures inside functions.
-        parentSymbol = env.temp_data['cpp:parent_symbol']
+        parentSymbol = env.current_document['cpp:parent_symbol']
         parentDecl = parentSymbol.declaration
         if parentDecl is not None and parentDecl.objectType == 'function':
             msg = ("C++ declarations inside functions are not supported. "
@@ -310,16 +310,16 @@ def run(self) -> list[Node]:
             logger.warning(msg, location=self.get_location())
             name = _make_phony_error_name()
             symbol = parentSymbol.add_name(name)
-            env.temp_data['cpp:last_symbol'] = symbol
+            env.current_document['cpp:last_symbol'] = symbol
             return []
         # When multiple declarations are made in the same directive
         # they need to know about each other to provide symbol lookup for function parameters.
         # We use last_symbol to store the latest added declaration in a directive.
-        env.temp_data['cpp:last_symbol'] = None
+        env.current_document['cpp:last_symbol'] = None
         return super().run()
 
     def handle_signature(self, sig: str, signode: desc_signature) -> ASTDeclaration:
-        parentSymbol: Symbol = self.env.temp_data['cpp:parent_symbol']
+        parentSymbol: Symbol = self.env.current_document['cpp:parent_symbol']
 
         max_len = (self.env.config.cpp_maximum_signature_line_length
                    or self.env.config.maximum_signature_line_length
@@ -339,7 +339,7 @@ def handle_signature(self, sig: str, signode: desc_signature) -> ASTDeclaration:
             # the possibly inner declarations.
             name = _make_phony_error_name()
             symbol = parentSymbol.add_name(name)
-            self.env.temp_data['cpp:last_symbol'] = symbol
+            self.env.current_document['cpp:last_symbol'] = symbol
             raise ValueError from e
 
         try:
@@ -348,15 +348,15 @@ def handle_signature(self, sig: str, signode: desc_signature) -> ASTDeclaration:
             # append the new declaration to the sibling list
             assert symbol.siblingAbove is None
             assert symbol.siblingBelow is None
-            symbol.siblingAbove = self.env.temp_data['cpp:last_symbol']
+            symbol.siblingAbove = self.env.current_document['cpp:last_symbol']
             if symbol.siblingAbove is not None:
                 assert symbol.siblingAbove.siblingBelow is None
                 symbol.siblingAbove.siblingBelow = symbol
-            self.env.temp_data['cpp:last_symbol'] = symbol
+            self.env.current_document['cpp:last_symbol'] = symbol
         except _DuplicateSymbolError as e:
             # Assume we are actually in the old symbol,
             # instead of the newly created duplicate.
-            self.env.temp_data['cpp:last_symbol'] = e.symbol
+            self.env.current_document['cpp:last_symbol'] = e.symbol
             msg = __("Duplicate C++ declaration, also defined at %s:%s.\n"
                      "Declaration is '.. cpp:%s:: %s'.")
             logger.warning(
@@ -379,25 +379,26 @@ def handle_signature(self, sig: str, signode: desc_signature) -> ASTDeclaration:
         return ast
 
     def before_content(self) -> None:
-        lastSymbol: Symbol = self.env.temp_data['cpp:last_symbol']
+        lastSymbol: Symbol = self.env.current_document['cpp:last_symbol']
         assert lastSymbol
-        self.oldParentSymbol = self.env.temp_data['cpp:parent_symbol']
+        self.oldParentSymbol = self.env.current_document['cpp:parent_symbol']
         self.oldParentKey: LookupKey = self.env.ref_context['cpp:parent_key']
-        self.env.temp_data['cpp:parent_symbol'] = lastSymbol
+        self.env.current_document['cpp:parent_symbol'] = lastSymbol
         self.env.ref_context['cpp:parent_key'] = lastSymbol.get_lookup_key()
-        self.env.temp_data['cpp:domain_name'] = (
-            *self.env.temp_data.get('cpp:domain_name', ()),
+        self.env.current_document['cpp:domain_name'] = (
+            *self.env.current_document.get('cpp:domain_name', ()),
             lastSymbol.identOrOp._stringify(str),
         )
 
     def after_content(self) -> None:
-        self.env.temp_data['cpp:parent_symbol'] = self.oldParentSymbol
+        self.env.current_document['cpp:parent_symbol'] = self.oldParentSymbol
         self.env.ref_context['cpp:parent_key'] = self.oldParentKey
-        self.env.temp_data['cpp:domain_name'] = self.env.temp_data['cpp:domain_name'][:-1]
+        old_cpp_domain_name = self.env.current_document['cpp:domain_name'][:-1]
+        self.env.current_document['cpp:domain_name'] = old_cpp_domain_name
 
     def _object_hierarchy_parts(self, sig_node: desc_signature) -> tuple[str, ...]:
         return tuple(s.identOrOp._stringify(str) for s in
-                     self.env.temp_data['cpp:last_symbol'].get_full_nested_name().names)
+                     self.env.current_document['cpp:last_symbol'].get_full_nested_name().names)
 
     def _toc_entry_name(self, sig_node: desc_signature) -> str:
         if not sig_node.get('_toc_parts'):
@@ -411,7 +412,9 @@ def _toc_entry_name(self, sig_node: desc_signature) -> str:
             parens = ''
         *parents, name = sig_node['_toc_parts']
         if config.toc_object_entries_show_parents == 'domain':
-            return '::'.join((*self.env.temp_data.get('cpp:domain_name', ()), name + parens))
+            return '::'.join(
+                (*self.env.current_document.get('cpp:domain_name', ()), name + parens)
+            )
         if config.toc_object_entries_show_parents == 'hide':
             return name + parens
         if config.toc_object_entries_show_parents == 'all':
@@ -511,8 +514,8 @@ def run(self) -> list[Node]:
                 ast = ASTNamespace(name, None)
             symbol = rootSymbol.add_name(ast.nestedName, ast.templatePrefix)
             stack = [symbol]
-        self.env.temp_data['cpp:parent_symbol'] = symbol
-        self.env.temp_data['cpp:namespace_stack'] = stack
+        self.env.current_document['cpp:parent_symbol'] = symbol
+        self.env.current_document['cpp:namespace_stack'] = stack
         self.env.ref_context['cpp:parent_key'] = symbol.get_lookup_key()
         return []
 
@@ -537,14 +540,14 @@ def run(self) -> list[Node]:
             logger.warning(e, location=self.get_location())
             name = _make_phony_error_name()
             ast = ASTNamespace(name, None)
-        oldParent = self.env.temp_data.get('cpp:parent_symbol', None)
+        oldParent = self.env.current_document.get('cpp:parent_symbol', None)
         if not oldParent:
             oldParent = self.env.domaindata['cpp']['root_symbol']
         symbol = oldParent.add_name(ast.nestedName, ast.templatePrefix)
-        stack = self.env.temp_data.get('cpp:namespace_stack', [])
+        stack = self.env.current_document.get('cpp:namespace_stack', [])
         stack.append(symbol)
-        self.env.temp_data['cpp:parent_symbol'] = symbol
-        self.env.temp_data['cpp:namespace_stack'] = stack
+        self.env.current_document['cpp:parent_symbol'] = symbol
+        self.env.current_document['cpp:namespace_stack'] = stack
         self.env.ref_context['cpp:parent_key'] = symbol.get_lookup_key()
         return []
 
@@ -557,7 +560,7 @@ class CPPNamespacePopObject(SphinxDirective):
     option_spec: ClassVar[OptionSpec] = {}
 
     def run(self) -> list[Node]:
-        stack = self.env.temp_data.get('cpp:namespace_stack', None)
+        stack = self.env.current_document.get('cpp:namespace_stack', None)
         if not stack or len(stack) == 0:
             logger.warning("C++ namespace pop on empty stack. Defaulting to global scope.",
                            location=self.get_location())
@@ -568,8 +571,8 @@ def run(self) -> list[Node]:
             symbol = stack[-1]
         else:
             symbol = self.env.domaindata['cpp']['root_symbol']
-        self.env.temp_data['cpp:parent_symbol'] = symbol
-        self.env.temp_data['cpp:namespace_stack'] = stack
+        self.env.current_document['cpp:parent_symbol'] = symbol
+        self.env.current_document['cpp:namespace_stack'] = stack
         self.env.ref_context['cpp:parent_key'] = symbol.get_lookup_key()
         return []
 
@@ -582,9 +585,9 @@ def __init__(self, sig: str, aliasOptions: dict,
         self.sig = sig
         self.aliasOptions = aliasOptions
         if env is not None:
-            if 'cpp:parent_symbol' not in env.temp_data:
+            if 'cpp:parent_symbol' not in env.current_document:
                 root = env.domaindata['cpp']['root_symbol']
-                env.temp_data['cpp:parent_symbol'] = root
+                env.current_document['cpp:parent_symbol'] = root
                 env.ref_context['cpp:parent_key'] = root.get_lookup_key()
             self.parentKey = env.ref_context['cpp:parent_key']
         else:
@@ -771,7 +774,7 @@ def run(self) -> list[Node]:
         self.before_content()
         content_node = addnodes.desc_content('', *self.parse_content_to_nodes())
         node.append(content_node)
-        self.env.temp_data['object'] = None
+        self.env.current_document.obj_desc_name = ''
         self.after_content()
         return [node]
 
@@ -828,7 +831,7 @@ def run(self) -> tuple[list[Node], list[system_message]]:
                            location=self.get_location())
             # see below
             return [addnodes.desc_inline('cpp', text, text, classes=[self.class_type])], []
-        parentSymbol = self.env.temp_data.get('cpp:parent_symbol', None)
+        parentSymbol = self.env.current_document.get('cpp:parent_symbol', None)
         if parentSymbol is None:
             parentSymbol = self.env.domaindata['cpp']['root_symbol']
         # ...most if not all of these classes should really apply to the individual references,
diff --git a/sphinx/environment/__init__.py b/sphinx/environment/__init__.py
index b17c1ee453b..1e53abff3d5 100644
--- a/sphinx/environment/__init__.py
+++ b/sphinx/environment/__init__.py
@@ -6,7 +6,7 @@
 import os
 import pickle
 from collections import defaultdict
-from copy import copy
+from copy import deepcopy
 from typing import TYPE_CHECKING
 
 from sphinx import addnodes
@@ -192,10 +192,10 @@ def __init__(self, app: Sphinx) -> None:
         self.original_image_uri: dict[_StrPath, str] = {}
 
         # temporary data storage while reading a document
-        self.temp_data: dict[str, Any] = {}
+        self.current_document: _CurrentDocument = _CurrentDocument()
         # context for cross-references (e.g. current module or class)
-        # this is similar to temp_data, but will for example be copied to
-        # attributes of "any" cross references
+        # this is similar to ``self.current_document``,
+        # but will for example be copied to attributes of "any" cross references
         self.ref_context: dict[str, Any] = {}
 
         # search index data
@@ -422,7 +422,13 @@ def relfn2path(self, filename: str, docname: str | None = None) -> tuple[str, st
         if filename.startswith('/'):
             abs_fn = (self.srcdir / filename[1:]).resolve()
         else:
-            doc_dir = self.doc2path(docname or self.docname, base=False).parent
+            if not docname:
+                if self.docname:
+                    docname = self.docname
+                else:
+                    msg = 'docname'
+                    raise KeyError(msg)
+            doc_dir = self.doc2path(docname, base=False).parent
             abs_fn = (self.srcdir / doc_dir / filename).resolve()
 
         rel_fn = _relative_path(abs_fn, self.srcdir)
@@ -554,32 +560,42 @@ def check_dependents(self, app: Sphinx, already: set[str]) -> Iterator[str]:
 
     def prepare_settings(self, docname: str) -> None:
         """Prepare to set up environment for reading."""
-        self.temp_data['docname'] = docname
-        # defaults to the global default, but can be re-set in a document
-        self.temp_data['default_role'] = self.config.default_role
-        self.temp_data['default_domain'] = self.domains.get(self.config.primary_domain)
+        self.current_document = _CurrentDocument(
+            docname=docname,
+            # defaults to the global default, but can be re-set in a document
+            default_role=self.config.default_role,
+            default_domain=self.domains.get(self.config.primary_domain),
+        )
 
     # utilities to use while reading a document
 
+    @property
+    def temp_data(self) -> _CurrentDocument:
+        """Returns the temporary data storage for the current document.
+
+        Kept for backwards compatibility.
+        """
+        return self.current_document
+
     @property
     def docname(self) -> str:
         """Returns the docname of the document currently being parsed."""
-        return self.temp_data['docname']
+        return self.current_document.docname
 
     @property
     def parser(self) -> Parser:
         """Returns the parser being used for to parse the current document."""
-        return self.temp_data['_parser']
+        if (parser := self.current_document._parser) is not None:
+            return parser
+        msg = 'parser'
+        raise KeyError(msg)
 
     def new_serialno(self, category: str = '') -> int:
         """Return a serial number, e.g. for index entry targets.
 
         The number is guaranteed to be unique in the current document.
         """
-        key = category + 'serialno'
-        cur = self.temp_data.get(key, 0)
-        self.temp_data[key] = cur + 1
-        return cur
+        return self.current_document.new_serial_number(category)
 
     def note_dependency(
         self, filename: str | os.PathLike[str], *, docname: str | None = None
@@ -722,17 +738,19 @@ def resolve_references(
 
     def apply_post_transforms(self, doctree: nodes.document, docname: str) -> None:
         """Apply all post-transforms."""
+        backup = self.current_document
+        new = deepcopy(backup)
+        new.docname = docname
         try:
             # set env.docname during applying post-transforms
-            backup = copy(self.temp_data)
-            self.temp_data['docname'] = docname
+            self.current_document = new
 
             transformer = SphinxTransformer(doctree)
             transformer.set_environment(self)
             transformer.add_transforms(self.app.registry.get_post_transforms())
             transformer.apply_transforms()
         finally:
-            self.temp_data = backup
+            self.current_document = backup
 
         # allow custom references to be resolved
         self.events.emit('doctree-resolved', doctree, docname)
@@ -842,3 +860,208 @@ def _check_toc_parents(toctree_includes: dict[str, list[str]]) -> None:
                 type='toc',
                 subtype='multiple_toc_parents',
             )
+
+
+class _CurrentDocument:
+    """Temporary data storage while reading a document."""
+
+    __slots__ = (
+        '_parser',
+        '_serial_numbers',
+        '_ext_props',
+        'autodoc_annotations',
+        'autodoc_class',
+        'autodoc_module',
+        'default_domain',
+        'default_role',
+        'docname',
+        'highlight_language',
+        'obj_desc_name',
+        'reading_started_at',
+    )
+
+    def __init__(
+        self,
+        *,
+        docname: str = '',
+        default_role: str = '',
+        default_domain: Domain | None = None,
+    ) -> None:
+        #: The docname of the document currently being parsed.
+        self.docname = docname
+
+        #: The default role for the current document.
+        #: Set by the ``.. default-role::`` directive.
+        self.default_role: str = default_role
+
+        #: The default domain for the current document.
+        #: Set by the ``.. default-domain::`` directive.
+        self.default_domain: Domain | None = default_domain
+
+        #: The parser being used to parse the current document.
+        self._parser: Parser | None = None
+
+        #: The default language for syntax highlighting.
+        #: Set by the ``.. highlight::`` directive to override
+        #: the ``highlight_language`` config value.
+        self.highlight_language: str = ''
+
+        #: The current object's name.
+        #: Used in the Changes builder.
+        self.obj_desc_name: str = ''
+
+        #: Records type hints of Python objects in the current document.
+        #: Used in ``sphinx.ext.autodoc.typehints``.
+        #: Maps object names to maps of attribute names -> type hints.
+        self.autodoc_annotations: dict[str, dict[str, str]] = {}
+
+        #: The current Python class name.
+        #: Used in ``sphinx.ext.autodoc``.
+        self.autodoc_class: str = ''
+
+        #: The current Python module name.
+        #: Used in ``sphinx.ext.autodoc``.
+        self.autodoc_module: str = ''
+
+        #: Records the time when reading begain for the current document.
+        #: Used in ``sphinx.ext.duration``.
+        self.reading_started_at: float = 0.0
+
+        # Used for generating unique serial numbers.
+        self._serial_numbers: dict[str, int] = {}
+
+        # Stores properties relating to the current document set by extensions.
+        self._ext_props: dict[str, Any] = {}
+
+    def new_serial_number(self, category: str = '', /) -> int:
+        """Return a serial number, e.g. for index entry targets.
+
+        The number is guaranteed to be unique in the current document.
+        """
+        current = self._serial_numbers.get(category, 0)
+        self._serial_numbers[category] = current + 1
+        return current
+
+    # Mapping interface:
+
+    def __getitem__(self, item: str) -> Any:
+        if item == 'annotations':
+            return self.autodoc_annotations
+        if item == 'autodoc:class':
+            return self.autodoc_class
+        if item == 'autodoc:module':
+            return self.autodoc_module
+        if item == 'object':
+            return self.obj_desc_name
+        if item == 'started_at':
+            return self.reading_started_at
+        if item in {
+            '_parser',
+            'autodoc_annotations',
+            'default_domain',
+            'default_role',
+            'docname',
+            'highlight_language',
+            'obj_desc_name',
+            'reading_started_at',
+        }:
+            return getattr(self, item)
+        return self._ext_props[item]
+
+    def __setitem__(self, key: str, value: Any) -> None:
+        if key == 'annotations':
+            self.autodoc_annotations = value
+        elif key == 'autodoc:class':
+            self.autodoc_class = value
+        elif key == 'autodoc:module':
+            self.autodoc_module = value
+        elif key == 'object':
+            self.obj_desc_name = value
+        elif key == 'started_at':
+            self.reading_started_at = value
+        elif key in {
+            '_parser',
+            'autodoc_annotations',
+            'default_domain',
+            'default_role',
+            'docname',
+            'highlight_language',
+            'obj_desc_name',
+            'reading_started_at',
+        }:
+            setattr(self, key, value)
+        else:
+            self._ext_props[key] = value
+
+    def __delitem__(self, key: str) -> None:
+        del self._ext_props[key]
+
+    def __contains__(self, item: str) -> bool:
+        if item in {
+            'annotations',
+            'autodoc:class',
+            'autodoc:module',
+            'object',
+            'started_at',
+        }:
+            return True
+        if item in {
+            '_parser',
+            '_serial_numbers',
+            '_ext_props',
+            'autodoc_annotations',
+            'autodoc_class',
+            'autodoc_module',
+            'default_domain',
+            'default_role',
+            'docname',
+            'highlight_language',
+            'obj_desc_name',
+            'reading_started_at',
+        }:
+            return True
+        return item in self._ext_props
+
+    def get(self, key: str, default: Any | None = None) -> Any | None:
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def pop(self, key: str, default: Any | None = None) -> Any | None:
+        if key == 'annotations':
+            key = 'autodoc_annotations'
+        if key == 'autodoc:class':
+            key = 'autodoc_class'
+        if key == 'autodoc:module':
+            key = 'autodoc_module'
+        elif key == 'object':
+            key = 'obj_desc_name'
+        elif key == 'started_at':
+            key = 'reading_started_at'
+        try:
+            blank: str | float | dict[str, dict[str, str]] | None = {
+                '_parser': None,
+                'autodoc_annotations': {},
+                'autodoc_class': '',
+                'autodoc_module': '',
+                'default_domain': None,
+                'default_role': '',
+                'docname': '',
+                'highlight_language': '',
+                'obj_desc_name': '',
+                'reading_started_at': 0.0,
+            }[key]
+        except KeyError:
+            pass
+        else:
+            value = getattr(self, key)
+            setattr(self, key, blank)
+            return value
+        return self._ext_props.pop(key, default)
+
+    def setdefault(self, key: str, default: Any | None = None) -> Any | None:
+        return self._ext_props.setdefault(key, default)
+
+    def clear(self) -> None:
+        _CurrentDocument.__init__(self)  # NoQA: PLC2801
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 60c31e2542e..9f6b9e25d16 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -821,9 +821,9 @@ def document_members(self, all_members: bool = False) -> None:
         *self.options.members*.
         """
         # set current namespace for finding members
-        self.env.temp_data['autodoc:module'] = self.modname
+        self.env.current_document.autodoc_module = self.modname
         if self.objpath:
-            self.env.temp_data['autodoc:class'] = self.objpath[0]
+            self.env.current_document.autodoc_class = self.objpath[0]
 
         want_all = (all_members or
                     self.options.inherited_members or
@@ -856,8 +856,8 @@ def document_members(self, all_members: bool = False) -> None:
                 check_module=members_check_module and not isattr)
 
         # reset current objects
-        self.env.temp_data['autodoc:module'] = None
-        self.env.temp_data['autodoc:class'] = None
+        self.env.current_document.autodoc_module = ''
+        self.env.current_document.autodoc_class = ''
 
     def sort_members(self, documenters: list[tuple[Documenter, bool]],
                      order: str) -> list[tuple[Documenter, bool]]:
@@ -1159,7 +1159,7 @@ def resolve_name(self, modname: str | None, parents: Any, path: str, base: str,
 
         # if documenting a toplevel object without explicit module,
         # it can be contained in another auto directive ...
-        modname = self.env.temp_data.get('autodoc:module')
+        modname = self.env.current_document.autodoc_module
         # ... or in the scope of a module directive
         if not modname:
             modname = self.env.ref_context.get('py:module')
@@ -1184,19 +1184,18 @@ def resolve_name(self, modname: str | None, parents: Any, path: str, base: str,
             # if documenting a class-level object without path,
             # there must be a current class, either from a parent
             # auto directive ...
-            mod_cls_ = self.env.temp_data.get('autodoc:class')
+            mod_cls = self.env.current_document.autodoc_class
             # ... or from a class directive
-            if mod_cls_ is None:
-                mod_cls_ = self.env.ref_context.get('py:class')
-                # ... if still None, there's no way to know
-                if mod_cls_ is None:
+            if not mod_cls:
+                mod_cls = self.env.ref_context.get('py:class', '')
+                # ... if still falsy, there's no way to know
+                if not mod_cls:
                     return None, []
-            mod_cls = mod_cls_
         modname, sep, cls = mod_cls.rpartition('.')
         parents = [cls]
         # if the module name is still missing, get it like above
         if not modname:
-            modname = self.env.temp_data.get('autodoc:module')
+            modname = self.env.current_document.autodoc_module
         if not modname:
             modname = self.env.ref_context.get('py:module')
         # ... else, it stays None, which means invalid
diff --git a/sphinx/ext/autodoc/typehints.py b/sphinx/ext/autodoc/typehints.py
index a2b05aac705..faf08d2971a 100644
--- a/sphinx/ext/autodoc/typehints.py
+++ b/sphinx/ext/autodoc/typehints.py
@@ -30,8 +30,7 @@ def record_typehints(app: Sphinx, objtype: str, name: str, obj: Any,
 
     try:
         if callable(obj):
-            annotations = app.env.temp_data.setdefault('annotations', {})
-            annotation = annotations.setdefault(name, {})
+            annotation = app.env.current_document.autodoc_annotations.setdefault(name, {})
             sig = inspect.signature(obj, type_aliases=app.config.autodoc_type_aliases)
             for param in sig.parameters.values():
                 if param.annotation is not param.empty:
@@ -58,7 +57,7 @@ def merge_typehints(app: Sphinx, domain: str, objtype: str, contentnode: Element
         # signature node does not have valid context info for the target object
         return
 
-    annotations = app.env.temp_data.get('annotations', {})
+    annotations = app.env.current_document.autodoc_annotations
     if annotations.get(fullname, {}):
         field_lists = [n for n in contentnode if isinstance(n, nodes.field_list)]
         if field_lists == []:
diff --git a/sphinx/ext/duration.py b/sphinx/ext/duration.py
index 6739f676ff9..cc21cb6afef 100644
--- a/sphinx/ext/duration.py
+++ b/sphinx/ext/duration.py
@@ -63,13 +63,12 @@ def on_builder_inited(app: Sphinx) -> None:
 
 def on_source_read(app: Sphinx, docname: str, content: list[str]) -> None:
     """Start to measure reading duration."""
-    app.env.temp_data['started_at'] = time.monotonic()
+    app.env.current_document.reading_started_at = time.monotonic()
 
 
 def on_doctree_read(app: Sphinx, doctree: nodes.document) -> None:
     """Record a reading duration."""
-    started_at = app.env.temp_data['started_at']
-    duration = time.monotonic() - started_at
+    duration = time.monotonic() - app.env.current_document.reading_started_at
     domain = app.env.domains['duration']
     domain.note_reading_duration(duration)
 
diff --git a/sphinx/ext/intersphinx/_resolve.py b/sphinx/ext/intersphinx/_resolve.py
index 0dbab63dc69..474de8428e5 100644
--- a/sphinx/ext/intersphinx/_resolve.py
+++ b/sphinx/ext/intersphinx/_resolve.py
@@ -398,7 +398,7 @@ def run(self) -> tuple[list[Node], list[system_message]]:
             # the user did not specify a domain,
             # so we check first the default (if available) then standard domains
             domains: list[Domain] = []
-            if default_domain := self.env.temp_data.get('default_domain'):
+            if default_domain := self.env.current_document.default_domain:
                 domains.append(default_domain)
             if (
                 std_domain := self.env.domains.standard_domain
@@ -505,7 +505,7 @@ def get_role_name(self, name: str) -> tuple[str, str] | None:
         names = name.split(':')
         if len(names) == 1:
             # role
-            default_domain = self.env.temp_data.get('default_domain')
+            default_domain = self.env.current_document.default_domain
             domain = default_domain.name if default_domain else None
             role = names[0]
         elif len(names) == 2:
diff --git a/sphinx/testing/restructuredtext.py b/sphinx/testing/restructuredtext.py
index 620e8483492..a4e89719d0f 100644
--- a/sphinx/testing/restructuredtext.py
+++ b/sphinx/testing/restructuredtext.py
@@ -10,7 +10,7 @@
 def parse(app: Sphinx, text: str, docname: str = 'index') -> nodes.document:
     """Parse a string as reStructuredText with Sphinx application."""
     try:
-        app.env.temp_data['docname'] = docname
+        app.env.current_document.docname = docname
         reader = SphinxStandaloneReader()
         reader.setup(app)
         parser = RSTParser()
@@ -30,4 +30,4 @@ def parse(app: Sphinx, text: str, docname: str = 'index') -> nodes.document:
                 },
             )
     finally:
-        app.env.temp_data.pop('docname', None)
+        app.env.current_document.docname = ''
diff --git a/sphinx/util/docutils.py b/sphinx/util/docutils.py
index f8fa00f4316..58a575f30ba 100644
--- a/sphinx/util/docutils.py
+++ b/sphinx/util/docutils.py
@@ -285,7 +285,7 @@ def lookup_domain_element(self, type: str, name: str) -> Any:
                 )
         # else look in the default domain
         else:
-            def_domain = self.env.temp_data.get('default_domain')
+            def_domain = self.env.current_document.default_domain
             if def_domain is not None:
                 element = getattr(def_domain, type)(name)
                 if element is not None:
@@ -587,7 +587,7 @@ def __call__(
         if name:
             self.name = name.lower()
         else:
-            self.name = self.env.temp_data.get('default_role', '')
+            self.name = self.env.current_document.default_role
             if not self.name:
                 self.name = self.env.config.default_role
             if not self.name:
diff --git a/tests/test_environment/test_environment.py b/tests/test_environment/test_environment.py
index 05427faf56f..d762fa55670 100644
--- a/tests/test_environment/test_environment.py
+++ b/tests/test_environment/test_environment.py
@@ -183,13 +183,13 @@ def test_env_relfn2path(app):
     assert absfn == str(app.srcdir / 'logo.jpg')
 
     # omit docname (w/ current docname)
-    app.env.temp_data['docname'] = 'subdir/document'
+    app.env.current_document.docname = 'subdir/document'
     relfn, absfn = app.env.relfn2path('images/logo.jpg')
     assert Path(relfn) == Path('subdir/images/logo.jpg')
     assert absfn == str(app.srcdir / 'subdir' / 'images' / 'logo.jpg')
 
     # omit docname (w/o current docname)
-    app.env.temp_data.clear()
+    app.env.current_document.clear()
     with pytest.raises(KeyError, match=r"^'docname'$"):
         app.env.relfn2path('images/logo.jpg')
 
diff --git a/tests/test_extensions/autodoc_util.py b/tests/test_extensions/autodoc_util.py
index 7c4da07970e..3d08c739300 100644
--- a/tests/test_extensions/autodoc_util.py
+++ b/tests/test_extensions/autodoc_util.py
@@ -22,7 +22,8 @@ def do_autodoc(
     options: dict[str, Any] | None = None,
 ) -> StringList:
     options = {} if options is None else options.copy()
-    app.env.temp_data.setdefault('docname', 'index')  # set dummy docname
+    if not app.env.current_document.docname:
+        app.env.current_document.docname = 'index'  # set dummy docname
     doccls = app.registry.documenters[objtype]
     docoptions = process_documenter_options(doccls, app.config, options)
     state = Mock()
diff --git a/tests/test_extensions/test_ext_autodoc.py b/tests/test_extensions/test_ext_autodoc.py
index eb775aba081..89d8d037269 100644
--- a/tests/test_extensions/test_ext_autodoc.py
+++ b/tests/test_extensions/test_ext_autodoc.py
@@ -95,9 +95,10 @@ def verify(objtype, name, result):
         'test_ext_autodoc.raises(exc) -> None',
         ('test_ext_autodoc', ['raises'], 'exc', 'None'),
     )
-    directive.env.temp_data['autodoc:module'] = 'test_ext_autodoc'
+    directive.env.current_document.autodoc_module = 'test_ext_autodoc'
     verify('function', 'raises', ('test_ext_autodoc', ['raises'], None, None))
-    del directive.env.temp_data['autodoc:module']
+    directive.env.current_document.autodoc_module = ''
+
     directive.env.ref_context['py:module'] = 'test_ext_autodoc'
     verify('function', 'raises', ('test_ext_autodoc', ['raises'], None, None))
     verify('class', 'Base', ('test_ext_autodoc', ['Base'], None, None))
@@ -111,7 +112,7 @@ def verify(objtype, name, result):
     )
     directive.env.ref_context['py:module'] = 'sphinx.testing.util'
     directive.env.ref_context['py:class'] = 'Foo'
-    directive.env.temp_data['autodoc:class'] = 'SphinxTestApp'
+    directive.env.current_document.autodoc_class = 'SphinxTestApp'
     verify(
         'method',
         'cleanup',
@@ -526,7 +527,7 @@ def test_autodoc_exception(app):
 
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_autodoc_warnings(app):
-    app.env.temp_data['docname'] = 'dummy'
+    app.env.current_document.docname = 'dummy'
 
     # can't import module
     do_autodoc(app, 'module', 'unknown')
@@ -1299,7 +1300,7 @@ def test_autodoc_module_member_order(app):
 
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_autodoc_module_scope(app):
-    app.env.temp_data['autodoc:module'] = 'target'
+    app.env.current_document.autodoc_module = 'target'
     actual = do_autodoc(app, 'attribute', 'Class.mdocattr')
     assert list(actual) == [
         '',
@@ -1314,8 +1315,8 @@ def test_autodoc_module_scope(app):
 
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_autodoc_class_scope(app):
-    app.env.temp_data['autodoc:module'] = 'target'
-    app.env.temp_data['autodoc:class'] = 'Class'
+    app.env.current_document.autodoc_module = 'target'
+    app.env.current_document.autodoc_class = 'Class'
     actual = do_autodoc(app, 'attribute', 'mdocattr')
     assert list(actual) == [
         '',
diff --git a/tests/test_markup/test_markup.py b/tests/test_markup/test_markup.py
index 9eb0b83fa89..2af8227a2e2 100644
--- a/tests/test_markup/test_markup.py
+++ b/tests/test_markup/test_markup.py
@@ -36,7 +36,7 @@ def settings(app):
     settings = optparser.get_default_values()
     settings.smart_quotes = True
     settings.env = app.builder.env
-    settings.env.temp_data['docname'] = 'dummy'
+    settings.env.current_document.docname = 'dummy'
     settings.contentsname = 'dummy'
     domain_context = sphinx_domains(settings.env)
     domain_context.enable()
diff --git a/tests/test_util/test_util_i18n.py b/tests/test_util/test_util_i18n.py
index 95d0909f90a..9018936cc5c 100644
--- a/tests/test_util/test_util_i18n.py
+++ b/tests/test_util/test_util_i18n.py
@@ -117,7 +117,7 @@ def test_format_date_timezone():
 @pytest.mark.sphinx('html', testroot='root')
 def test_get_filename_for_language(app):
     get_filename = i18n.get_image_filename_for_language
-    app.env.temp_data['docname'] = 'index'
+    app.env.current_document.docname = 'index'
 
     # language is en
     app.env.config.language = 'en'
@@ -156,7 +156,7 @@ def test_get_filename_for_language(app):
     assert get_filename('foo.png', app.env) == '/en/foo.png'
 
     # docpath (for a document in the sub directory)
-    app.env.temp_data['docname'] = 'subdir/index'
+    app.env.current_document.docname = 'subdir/index'
     assert get_filename('foo.png', app.env) == '/subdir/en/foo.png'