Use strict optional checking in req_install.py

src/pip/_internal/req/req_install.py

@@ -1,6 +1,3 @@
-# The following comment should be removed at some point in the future.
-# mypy: strict-optional=False
-
 import functools
 import logging
 import os
@@ -244,6 +241,7 @@ def supports_pyproject_editable(self) -> bool:
 
     @property
     def specifier(self) -> SpecifierSet:
+        assert self.req is not None
         return self.req.specifier
 
     @property
@@ -257,7 +255,8 @@ def is_pinned(self) -> bool:
 
         For example, some-package==1.2 is pinned; some-package>1.2 is not.
         """
-        specifiers = self.specifier
+        assert self.req is not None
+        specifiers = self.req.specifier
         return len(specifiers) == 1 and next(iter(specifiers)).operator in {"==", "==="}
 
     def match_markers(self, extras_requested: Optional[Iterable[str]] = None) -> bool:
@@ -305,6 +304,7 @@ def hashes(self, trust_internet: bool = True) -> Hashes:
         else:
             link = None
         if link and link.hash:
+            assert link.hash_name is not None
             good_hashes.setdefault(link.hash_name, []).append(link.hash)
         return Hashes(good_hashes)
 
@@ -314,6 +314,7 @@ def from_path(self) -> Optional[str]:
             return None
         s = str(self.req)
         if self.comes_from:
+            comes_from: Optional[str]
             if isinstance(self.comes_from, str):
                 comes_from = self.comes_from
             else:
@@ -345,7 +346,7 @@ def ensure_build_location(
 
         # When parallel builds are enabled, add a UUID to the build directory
         # name so multiple builds do not interfere with each other.
-        dir_name: str = canonicalize_name(self.name)
+        dir_name: str = canonicalize_name(self.req.name)
         if parallel_builds:
             dir_name = f"{dir_name}_{uuid.uuid4().hex}"
 
@@ -388,6 +389,7 @@ def _set_requirement(self) -> None:
         )
 
     def warn_on_mismatching_name(self) -> None:
+        assert self.req is not None
         metadata_name = canonicalize_name(self.metadata["Name"])
         if canonicalize_name(self.req.name) == metadata_name:
             # Everything is fine.
@@ -457,6 +459,7 @@ def is_wheel_from_cache(self) -> bool:
     # Things valid for sdists
     @property
     def unpacked_source_directory(self) -> str:
+        assert self.source_dir, f"No source dir for {self}"
         return os.path.join(
             self.source_dir, self.link and self.link.subdirectory_fragment or ""
         )
@@ -543,7 +546,7 @@ def prepare_metadata(self) -> None:
         Under PEP 517 and PEP 660, call the backend hook to prepare the metadata.
         Under legacy processing, call setup.py egg-info.
         """
-        assert self.source_dir
+        assert self.source_dir, f"No source dir for {self}"
         details = self.name or f"from {self.link}"
 
         if self.use_pep517:
@@ -592,18 +595,20 @@ def get_dist(self) -> BaseDistribution:
         if self.metadata_directory:
             return get_directory_distribution(self.metadata_directory)
         elif self.local_file_path and self.is_wheel:
+            assert self.req is not None
             return get_wheel_distribution(
-                FilesystemWheel(self.local_file_path), canonicalize_name(self.name)
+                FilesystemWheel(self.local_file_path),
+                canonicalize_name(self.req.name),
             )
         raise AssertionError(
             f"InstallRequirement {self} has no metadata directory and no wheel: "
             f"can't make a distribution."
         )
 
     def assert_source_matches_version(self) -> None:
-        assert self.source_dir
+        assert self.source_dir, f"No source dir for {self}"
         version = self.metadata["version"]
-        if self.req.specifier and version not in self.req.specifier:
+        if self.req and self.req.specifier and version not in self.req.specifier:
             logger.warning(
                 "Requested %s, but installing version %s",
                 self,
@@ -696,9 +701,10 @@ def _clean_zip_name(name: str, prefix: str) -> str:
             name = name.replace(os.path.sep, "/")
             return name
 
+        assert self.req is not None
         path = os.path.join(parentdir, path)
         name = _clean_zip_name(path, rootdir)
-        return self.name + "/" + name
+        return self.req.name + "/" + name
 
     def archive(self, build_dir: Optional[str]) -> None:
         """Saves archive to provided build_dir.
@@ -777,8 +783,9 @@ def install(
         use_user_site: bool = False,
         pycompile: bool = True,
     ) -> None:
+        assert self.req is not None
         scheme = get_scheme(
-            self.name,
+            self.req.name,
             user=use_user_site,
             home=home,
             root=root,
@@ -792,7 +799,7 @@ def install(
                 prefix=prefix,
                 home=home,
                 use_user_site=use_user_site,
-                name=self.name,
+                name=self.req.name,
                 setup_py_path=self.setup_py_path,
                 isolated=self.isolated,
                 build_env=self.build_env,
@@ -805,7 +812,7 @@ def install(
         assert self.local_file_path
 
         install_wheel(
-            self.name,
+            self.req.name,
             self.local_file_path,
             scheme=scheme,
             req_description=str(self.req),