Further improve type annotations, reduce mypy whitelist (#10770)

Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>

3 files changed, 25 insertions, 14 deletions

diff --git a/sphinx/environment/__init__.py b/sphinx/environment/__init__.py
index df82c5a8a..430e03358 100644
--- a/sphinx/environment/__init__.py
+++ b/sphinx/environment/__init__.py
@@ -91,7 +91,7 @@ class BuildEnvironment:
 
     # --------- ENVIRONMENT INITIALIZATION -------------------------------------
 
-    def __init__(self, app: "Sphinx" = None):
+    def __init__(self, app: Optional["Sphinx"] = None):
         self.app: Sphinx = None
         self.doctreedir: str = None
         self.srcdir: str = None
@@ -327,7 +327,7 @@ class BuildEnvironment:
         """
         return self.project.doc2path(docname, base)
 
-    def relfn2path(self, filename: str, docname: str = None) -> Tuple[str, str]:
+    def relfn2path(self, filename: str, docname: Optional[str] = None) -> Tuple[str, str]:
         """Return paths to a file referenced from a document, relative to
         documentation root and absolute.
 
@@ -340,7 +340,7 @@ class BuildEnvironment:
             rel_fn = filename[1:]
         else:
             docdir = path.dirname(self.doc2path(docname or self.docname,
-                                                base=None))
+                                                base=False))
             rel_fn = path.join(docdir, filename)
 
         return (canon_path(path.normpath(rel_fn)),
@@ -488,7 +488,9 @@ class BuildEnvironment:
 
         *filename* should be absolute or relative to the source directory.
         """
-        self.included[self.docname].add(self.path2doc(filename))
+        doc = self.path2doc(filename)
+        if doc:
+            self.included[self.docname].add(doc)
 
     def note_reread(self) -> None:
         """Add the current document to the list of documents that will
@@ -517,9 +519,14 @@ class BuildEnvironment:
         doctree.reporter = LoggingReporter(self.doc2path(docname))
         return doctree
 
-    def get_and_resolve_doctree(self, docname: str, builder: "Builder",
-                                doctree: nodes.document = None, prune_toctrees: bool = True,
-                                includehidden: bool = False) -> nodes.document:
+    def get_and_resolve_doctree(
+        self,
+        docname: str,
+        builder: "Builder",
+        doctree: Optional[nodes.document] = None,
+        prune_toctrees: bool = True,
+        includehidden: bool = False
+    ) -> nodes.document:
         """Read the doctree from the pickle, resolve cross-references and
         toctrees and return it.
         """
@@ -543,7 +550,7 @@ class BuildEnvironment:
 
     def resolve_toctree(self, docname: str, builder: "Builder", toctree: addnodes.toctree,
                         prune: bool = True, maxdepth: int = 0, titles_only: bool = False,
-                        collapse: bool = False, includehidden: bool = False) -> Node:
+                        collapse: bool = False, includehidden: bool = False) -> Optional[Node]:
         """Resolve a *toctree* node into individual bullet lists with titles
         as items, returning None (if no containing titles are found) or
         a new node.
@@ -583,7 +590,9 @@ class BuildEnvironment:
     def collect_relations(self) -> Dict[str, List[Optional[str]]]:
         traversed = set()
 
-        def traverse_toctree(parent: str, docname: str) -> Iterator[Tuple[str, str]]:
+        def traverse_toctree(
+            parent: Optional[str], docname: str
+        ) -> Iterator[Tuple[Optional[str], str]]:
             if parent == docname:
                 logger.warning(__('self referenced toctree found. Ignored.'),
                                location=docname, type='toc',
diff --git a/sphinx/environment/adapters/indexentries.py b/sphinx/environment/adapters/indexentries.py
index 364331286..b651acae0 100644
--- a/sphinx/environment/adapters/indexentries.py
+++ b/sphinx/environment/adapters/indexentries.py
@@ -25,7 +25,7 @@ class IndexEntries:
         """Create the real index from the collected index entries."""
         new: Dict[str, List] = {}
 
-        def add_entry(word: str, subword: str, main: str, link: bool = True,
+        def add_entry(word: str, subword: str, main: Optional[str], link: bool = True,
                       dic: Dict[str, List] = new, key: Optional[str] = None) -> None:
             # Force the word to be unicode if it's a ASCII bytestring.
             # This will solve problems with unicode normalization later.
diff --git a/sphinx/environment/collectors/toctree.py b/sphinx/environment/collectors/toctree.py
index 507c83e97..52a8fd8d1 100644
--- a/sphinx/environment/collectors/toctree.py
+++ b/sphinx/environment/collectors/toctree.py
@@ -1,6 +1,6 @@
 """Toctree collector for sphinx.environment."""
 
-from typing import Any, Dict, List, Set, Tuple, Type, TypeVar, cast
+from typing import Any, Dict, List, Optional, Set, Tuple, Type, TypeVar, cast
 
 from docutils import nodes
 from docutils.nodes import Element, Node
@@ -66,7 +66,7 @@ class TocTreeCollector(EnvironmentCollector):
                     result.extend(traverse_in_section(child, cls))
             return result
 
-        def build_toc(node: Element, depth: int = 1) -> nodes.bullet_list:
+        def build_toc(node: Element, depth: int = 1) -> Optional[nodes.bullet_list]:
             entries: List[Element] = []
             for sectionnode in node:
                 # find all toctree nodes in this section and add them
@@ -132,7 +132,9 @@ class TocTreeCollector(EnvironmentCollector):
         old_secnumbers = env.toc_secnumbers
         env.toc_secnumbers = {}
 
-        def _walk_toc(node: Element, secnums: Dict, depth: int, titlenode: nodes.title = None) -> None:  # NOQA
+        def _walk_toc(
+            node: Element, secnums: Dict, depth: int, titlenode: Optional[nodes.title] = None
+        ) -> None:
             # titlenode is the title of the document, it will get assigned a
             # secnumber too, so that it shows up in next/prev/parent rellinks
             for subnode in node.children:
@@ -207,7 +209,7 @@ class TocTreeCollector(EnvironmentCollector):
         env.toc_fignumbers = {}
         fignum_counter: Dict[str, Dict[Tuple[int, ...], int]] = {}
 
-        def get_figtype(node: Node) -> str:
+        def get_figtype(node: Node) -> Optional[str]:
             for domain in env.domains.values():
                 figtype = domain.get_enumerable_node_type(node)
                 if domain.name == 'std' and not domain.get_numfig_title(node):  # type: ignore