review comment: subclass instead of constructor flag

src/pip/_internal/resolution/resolvelib/factory.py

@@ -1,5 +1,4 @@
 import contextlib
-import itertools
 import functools
 import logging
 from typing import (
@@ -63,6 +62,7 @@
     ExplicitRequirement,
     RequiresPythonRequirement,
     SpecifierRequirement,
+    SpecifierWithoutExtrasRequirement,
     UnsatisfiableRequirement,
 )
 
@@ -467,7 +467,7 @@ def _make_requirements_from_install_req(
             yield from ()
         elif not ireq.link:
             if ireq.extras and ireq.req is not None and ireq.req.specifier:
-                yield SpecifierRequirement(ireq, drop_extras=True),
+                yield SpecifierWithoutExtrasRequirement(ireq),
             yield SpecifierRequirement(ireq)
         else:
             self._fail_if_link_is_unsupported_wheel(ireq.link)

src/pip/_internal/resolution/resolvelib/requirements.py

@@ -41,18 +41,9 @@ def is_satisfied_by(self, candidate: Candidate) -> bool:
 
 
 class SpecifierRequirement(Requirement):
-    def __init__(
-        self,
-        ireq: InstallRequirement,
-        *,
-        drop_extras: bool = False,
-    ) -> None:
-        """
-        :param drop_extras: Ignore any extras that are part of the install requirement,
-            making this a requirement on the base only.
-        """
+    def __init__(self, ireq: InstallRequirement) -> None:
         assert ireq.link is None, "This is a link, not a specifier"
-        self._ireq = ireq if not drop_extras else install_req_drop_extras(ireq)
+        self._ireq = ireq
         self._extras = frozenset(self._ireq.extras)
 
     def __str__(self) -> str:
@@ -102,6 +93,17 @@ def is_satisfied_by(self, candidate: Candidate) -> bool:
         return spec.contains(candidate.version, prereleases=True)
 
 
+class SpecifierWithoutExtrasRequirement(SpecifierRequirement):
+    """
+    Requirement backed by an install requirement on a base package. Trims extras from its install requirement if there are any.
+    """
+
+    def __init__(self, ireq: InstallRequirement) -> None:
+        assert ireq.link is None, "This is a link, not a specifier"
+        self._ireq = install_req_drop_extras(ireq)
+        self._extras = frozenset(self._ireq.extras)
+
+
 class RequiresPythonRequirement(Requirement):
     """A requirement representing Requires-Python metadata."""