diff --git a/docs/html/topics/more-dependency-resolution.md b/docs/html/topics/more-dependency-resolution.md
index b955e2ec114..21520528781 100644
--- a/docs/html/topics/more-dependency-resolution.md
+++ b/docs/html/topics/more-dependency-resolution.md
@@ -160,8 +160,6 @@ follows:
     explicit URL.
 * If equal, prefer if any requirement is "pinned", i.e. contains
     operator ``===`` or ``==``.
-* If equal, calculate an approximate "depth" and resolve requirements
-    closer to the user-specified requirements first.
 * Order user-specified requirements by the order they are specified.
 * If equal, prefers "non-free" requirements, i.e. contains at least one
     operator, such as ``>=`` or ``<``.
diff --git a/news/13001.bugfix.rst b/news/13001.bugfix.rst
new file mode 100644
index 00000000000..3d9888d8d1d
--- /dev/null
+++ b/news/13001.bugfix.rst
@@ -0,0 +1,4 @@
+Resolvelib 1.1.0 fixes a known issue where pip would report a
+ResolutionImpossible error even though there is a valid solution.
+However, some very complex dependency resolutions that previously
+resolved may resolve slower or fail with an ResolutionTooDeep error.
diff --git a/news/resolvelib.vendor.rst b/news/resolvelib.vendor.rst
new file mode 100644
index 00000000000..09a40292332
--- /dev/null
+++ b/news/resolvelib.vendor.rst
@@ -0,0 +1 @@
+Upgrade resolvelib to 1.1.0.
diff --git a/src/pip/_internal/resolution/resolvelib/factory.py b/src/pip/_internal/resolution/resolvelib/factory.py
index 6c273eb88db..55c11b29158 100644
--- a/src/pip/_internal/resolution/resolvelib/factory.py
+++ b/src/pip/_internal/resolution/resolvelib/factory.py
@@ -748,7 +748,7 @@ def get_installation_error(
         # The simplest case is when we have *one* cause that can't be
         # satisfied. We just report that case.
         if len(e.causes) == 1:
-            req, parent = e.causes[0]
+            req, parent = next(iter(e.causes))
             if req.name not in constraints:
                 return self._report_single_requirement_conflict(req, parent)
 
diff --git a/src/pip/_internal/resolution/resolvelib/provider.py b/src/pip/_internal/resolution/resolvelib/provider.py
index fb0dd85f112..74cdb9d80f9 100644
--- a/src/pip/_internal/resolution/resolvelib/provider.py
+++ b/src/pip/_internal/resolution/resolvelib/provider.py
@@ -1,4 +1,3 @@
-import collections
 import math
 from functools import lru_cache
 from typing import (
@@ -100,7 +99,6 @@ def __init__(
         self._ignore_dependencies = ignore_dependencies
         self._upgrade_strategy = upgrade_strategy
         self._user_requested = user_requested
-        self._known_depths: Dict[str, float] = collections.defaultdict(lambda: math.inf)
 
     def identify(self, requirement_or_candidate: Union[Requirement, Candidate]) -> str:
         return requirement_or_candidate.name
@@ -124,10 +122,6 @@ def get_preference(
           explicit URL.
         * If equal, prefer if any requirement is "pinned", i.e. contains
           operator ``===`` or ``==``.
-        * If equal, calculate an approximate "depth" and resolve requirements
-          closer to the user-specified requirements first. If the depth cannot
-          by determined (eg: due to no matching parents), it is considered
-          infinite.
         * Order user-specified requirements by the order they are specified.
         * If equal, prefers "non-free" requirements, i.e. contains at least one
           operator, such as ``>=`` or ``<``.
@@ -157,23 +151,6 @@ def get_preference(
         direct = candidate is not None
         pinned = any(op[:2] == "==" for op in operators)
         unfree = bool(operators)
-
-        try:
-            requested_order: Union[int, float] = self._user_requested[identifier]
-        except KeyError:
-            requested_order = math.inf
-            if has_information:
-                parent_depths = (
-                    self._known_depths[parent.name] if parent is not None else 0.0
-                    for _, parent in information[identifier]
-                )
-                inferred_depth = min(d for d in parent_depths) + 1.0
-            else:
-                inferred_depth = math.inf
-        else:
-            inferred_depth = 1.0
-        self._known_depths[identifier] = inferred_depth
-
         requested_order = self._user_requested.get(identifier, math.inf)
 
         # Requires-Python has only one candidate and the check is basically
@@ -190,7 +167,6 @@ def get_preference(
             not direct,
             not pinned,
             not backtrack_cause,
-            inferred_depth,
             requested_order,
             not unfree,
             identifier,
diff --git a/src/pip/_internal/resolution/resolvelib/reporter.py b/src/pip/_internal/resolution/resolvelib/reporter.py
index 0594569d850..f8ad815fe9f 100644
--- a/src/pip/_internal/resolution/resolvelib/reporter.py
+++ b/src/pip/_internal/resolution/resolvelib/reporter.py
@@ -1,6 +1,6 @@
 from collections import defaultdict
 from logging import getLogger
-from typing import Any, DefaultDict
+from typing import Any, DefaultDict, Optional
 
 from pip._vendor.resolvelib.reporters import BaseReporter
 
@@ -9,7 +9,7 @@
 logger = getLogger(__name__)
 
 
-class PipReporter(BaseReporter):
+class PipReporter(BaseReporter[Requirement, Candidate, str]):
     def __init__(self) -> None:
         self.reject_count_by_package: DefaultDict[str, int] = defaultdict(int)
 
@@ -55,7 +55,7 @@ def rejecting_candidate(self, criterion: Any, candidate: Candidate) -> None:
         logger.debug(msg)
 
 
-class PipDebuggingReporter(BaseReporter):
+class PipDebuggingReporter(BaseReporter[Requirement, Candidate, str]):
     """A reporter that does an info log for every event it sees."""
 
     def starting(self) -> None:
@@ -71,7 +71,9 @@ def ending_round(self, index: int, state: Any) -> None:
     def ending(self, state: Any) -> None:
         logger.info("Reporter.ending(%r)", state)
 
-    def adding_requirement(self, requirement: Requirement, parent: Candidate) -> None:
+    def adding_requirement(
+        self, requirement: Requirement, parent: Optional[Candidate]
+    ) -> None:
         logger.info("Reporter.adding_requirement(%r, %r)", requirement, parent)
 
     def rejecting_candidate(self, criterion: Any, candidate: Candidate) -> None:
diff --git a/src/pip/_internal/resolution/resolvelib/resolver.py b/src/pip/_internal/resolution/resolvelib/resolver.py
index c12beef0b2a..e6d5f303740 100644
--- a/src/pip/_internal/resolution/resolvelib/resolver.py
+++ b/src/pip/_internal/resolution/resolvelib/resolver.py
@@ -82,7 +82,7 @@ def resolve(
             user_requested=collected.user_requested,
         )
         if "PIP_RESOLVER_DEBUG" in os.environ:
-            reporter: BaseReporter = PipDebuggingReporter()
+            reporter: BaseReporter[Requirement, Candidate, str] = PipDebuggingReporter()
         else:
             reporter = PipReporter()
         resolver: RLResolver[Requirement, Candidate, str] = RLResolver(
diff --git a/src/pip/_vendor/resolvelib/__init__.py b/src/pip/_vendor/resolvelib/__init__.py
index d92acc7bedf..c655c597c6f 100644
--- a/src/pip/_vendor/resolvelib/__init__.py
+++ b/src/pip/_vendor/resolvelib/__init__.py
@@ -11,12 +11,13 @@
     "ResolutionTooDeep",
 ]
 
-__version__ = "1.0.1"
+__version__ = "1.1.0"
 
 
-from .providers import AbstractProvider, AbstractResolver
+from .providers import AbstractProvider
 from .reporters import BaseReporter
 from .resolvers import (
+    AbstractResolver,
     InconsistentCandidate,
     RequirementsConflicted,
     ResolutionError,
diff --git a/src/pip/_vendor/resolvelib/__init__.pyi b/src/pip/_vendor/resolvelib/__init__.pyi
deleted file mode 100644
index d64c52ced00..00000000000
--- a/src/pip/_vendor/resolvelib/__init__.pyi
+++ /dev/null
@@ -1,11 +0,0 @@
-__version__: str
-
-from .providers import AbstractProvider as AbstractProvider
-from .providers import AbstractResolver as AbstractResolver
-from .reporters import BaseReporter as BaseReporter
-from .resolvers import InconsistentCandidate as InconsistentCandidate
-from .resolvers import RequirementsConflicted as RequirementsConflicted
-from .resolvers import ResolutionError as ResolutionError
-from .resolvers import ResolutionImpossible as ResolutionImpossible
-from .resolvers import ResolutionTooDeep as ResolutionTooDeep
-from .resolvers import Resolver as Resolver
diff --git a/src/pip/_vendor/resolvelib/compat/__init__.py b/src/pip/_vendor/resolvelib/compat/__init__.py
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/src/pip/_vendor/resolvelib/compat/collections_abc.py b/src/pip/_vendor/resolvelib/compat/collections_abc.py
deleted file mode 100644
index 1becc5093c5..00000000000
--- a/src/pip/_vendor/resolvelib/compat/collections_abc.py
+++ /dev/null
@@ -1,6 +0,0 @@
-__all__ = ["Mapping", "Sequence"]
-
-try:
-    from collections.abc import Mapping, Sequence
-except ImportError:
-    from collections import Mapping, Sequence
diff --git a/src/pip/_vendor/resolvelib/compat/collections_abc.pyi b/src/pip/_vendor/resolvelib/compat/collections_abc.pyi
deleted file mode 100644
index 2a088b19a93..00000000000
--- a/src/pip/_vendor/resolvelib/compat/collections_abc.pyi
+++ /dev/null
@@ -1 +0,0 @@
-from collections.abc import Mapping, Sequence
diff --git a/src/pip/_vendor/resolvelib/providers.py b/src/pip/_vendor/resolvelib/providers.py
index e99d87ee75f..524e3d83272 100644
--- a/src/pip/_vendor/resolvelib/providers.py
+++ b/src/pip/_vendor/resolvelib/providers.py
@@ -1,30 +1,58 @@
-class AbstractProvider(object):
+from __future__ import annotations
+
+from typing import (
+    TYPE_CHECKING,
+    Generic,
+    Iterable,
+    Iterator,
+    Mapping,
+    Sequence,
+)
+
+from .structs import CT, KT, RT, Matches, RequirementInformation
+
+if TYPE_CHECKING:
+    from typing import Any, Protocol
+
+    class Preference(Protocol):
+        def __lt__(self, __other: Any) -> bool: ...
+
+
+class AbstractProvider(Generic[RT, CT, KT]):
     """Delegate class to provide the required interface for the resolver."""
 
-    def identify(self, requirement_or_candidate):
-        """Given a requirement, return an identifier for it.
+    def identify(self, requirement_or_candidate: RT | CT) -> KT:
+        """Given a requirement or candidate, return an identifier for it.
 
-        This is used to identify a requirement, e.g. whether two requirements
-        should have their specifier parts merged.
+        This is used to identify, e.g. whether two requirements
+        should have their specifier parts merged or a candidate matches a
+        requirement via ``find_matches()``.
         """
         raise NotImplementedError
 
     def get_preference(
         self,
-        identifier,
-        resolutions,
-        candidates,
-        information,
-        backtrack_causes,
-    ):
+        identifier: KT,
+        resolutions: Mapping[KT, CT],
+        candidates: Mapping[KT, Iterator[CT]],
+        information: Mapping[KT, Iterator[RequirementInformation[RT, CT]]],
+        backtrack_causes: Sequence[RequirementInformation[RT, CT]],
+    ) -> Preference:
         """Produce a sort key for given requirement based on preference.
 
+        As this is a sort key it will be called O(n) times per backtrack
+        step, where n is the number of `identifier`s, if you have a check
+        which is expensive in some sense. E.g. It needs to make O(n) checks
+        per call or takes significant wall clock time, consider using
+        `narrow_requirement_selection` to filter the `identifier`s, which
+        is applied before this sort key is called.
+
         The preference is defined as "I think this requirement should be
         resolved first". The lower the return value is, the more preferred
         this group of arguments is.
 
         :param identifier: An identifier as returned by ``identify()``. This
-            identifies the dependency matches which should be returned.
+            identifies the requirement being considered.
         :param resolutions: Mapping of candidates currently pinned by the
             resolver. Each key is an identifier, and the value is a candidate.
             The candidate may conflict with requirements from ``information``.
@@ -32,8 +60,9 @@ def get_preference(
             Each value is an iterator of candidates.
         :param information: Mapping of requirement information of each package.
             Each value is an iterator of *requirement information*.
-        :param backtrack_causes: Sequence of requirement information that were
-            the requirements that caused the resolver to most recently backtrack.
+        :param backtrack_causes: Sequence of *requirement information* that are
+            the requirements that caused the resolver to most recently
+            backtrack.
 
         A *requirement information* instance is a named tuple with two members:
 
@@ -60,15 +89,21 @@ def get_preference(
         """
         raise NotImplementedError
 
-    def find_matches(self, identifier, requirements, incompatibilities):
+    def find_matches(
+        self,
+        identifier: KT,
+        requirements: Mapping[KT, Iterator[RT]],
+        incompatibilities: Mapping[KT, Iterator[CT]],
+    ) -> Matches[CT]:
         """Find all possible candidates that satisfy the given constraints.
 
-        :param identifier: An identifier as returned by ``identify()``. This
-            identifies the dependency matches of which should be returned.
+        :param identifier: An identifier as returned by ``identify()``. All
+            candidates returned by this method should produce the same
+            identifier.
         :param requirements: A mapping of requirements that all returned
             candidates must satisfy. Each key is an identifier, and the value
             an iterator of requirements for that dependency.
-        :param incompatibilities: A mapping of known incompatibilities of
+        :param incompatibilities: A mapping of known incompatibile candidates of
             each dependency. Each key is an identifier, and the value an
             iterator of incompatibilities known to the resolver. All
             incompatibilities *must* be excluded from the return value.
@@ -89,7 +124,7 @@ def find_matches(self, identifier, requirements, incompatibilities):
         """
         raise NotImplementedError
 
-    def is_satisfied_by(self, requirement, candidate):
+    def is_satisfied_by(self, requirement: RT, candidate: CT) -> bool:
         """Whether the given requirement can be satisfied by a candidate.
 
         The candidate is guaranteed to have been generated from the
@@ -100,7 +135,7 @@ def is_satisfied_by(self, requirement, candidate):
         """
         raise NotImplementedError
 
-    def get_dependencies(self, candidate):
+    def get_dependencies(self, candidate: CT) -> Iterable[RT]:
         """Get dependencies of a candidate.
 
         This should return a collection of requirements that `candidate`
@@ -108,26 +143,54 @@ def get_dependencies(self, candidate):
         """
         raise NotImplementedError
 
+    def narrow_requirement_selection(
+        self,
+        identifiers: Iterable[KT],
+        resolutions: Mapping[KT, CT],
+        candidates: Mapping[KT, Iterator[CT]],
+        information: Mapping[KT, Iterator[RequirementInformation[RT, CT]]],
+        backtrack_causes: Sequence[RequirementInformation[RT, CT]],
+    ) -> Iterable[KT]:
+        """
+        An optional method to narrow the selection of requirements being
+        considered during resolution. This method is called O(1) time per
+        backtrack step.
+
+        :param identifiers: An iterable of `identifiers` as returned by
+            ``identify()``. These identify all requirements currently being
+            considered.
+        :param resolutions: A mapping of candidates currently pinned by the
+            resolver. Each key is an identifier, and the value is a candidate
+            that may conflict with requirements from ``information``.
+        :param candidates: A mapping of each dependency's possible candidates.
+            Each value is an iterator of candidates.
+        :param information: A mapping of requirement information for each package.
+            Each value is an iterator of *requirement information*.
+        :param backtrack_causes: A sequence of *requirement information* that are
+            the requirements causing the resolver to most recently
+            backtrack.
 
-class AbstractResolver(object):
-    """The thing that performs the actual resolution work."""
-
-    base_exception = Exception
-
-    def __init__(self, provider, reporter):
-        self.provider = provider
-        self.reporter = reporter
-
-    def resolve(self, requirements, **kwargs):
-        """Take a collection of constraints, spit out the resolution result.
-
-        This returns a representation of the final resolution state, with one
-        guarenteed attribute ``mapping`` that contains resolved candidates as
-        values. The keys are their respective identifiers.
-
-        :param requirements: A collection of constraints.
-        :param kwargs: Additional keyword arguments that subclasses may accept.
+        A *requirement information* instance is a named tuple with two members:
 
-        :raises: ``self.base_exception`` or its subclass.
+        * ``requirement`` specifies a requirement contributing to the current
+          list of candidates.
+        * ``parent`` specifies the candidate that provides (is depended on for)
+          the requirement, or ``None`` to indicate a root requirement.
+
+        Must return a non-empty subset of `identifiers`, with the default
+        implementation being to return `identifiers` unchanged. Those `identifiers`
+        will then be passed to the sort key `get_preference` to pick the most
+        prefered requirement to attempt to pin, unless `narrow_requirement_selection`
+        returns only 1 requirement, in which case that will be used without
+        calling the sort key `get_preference`.
+
+        This method is designed to be used by the provider to optimize the
+        dependency resolution, e.g. if a check cost is O(m) and it can be done
+        against all identifiers at once then filtering the requirement selection
+        here will cost O(m) but making it part of the sort key in `get_preference`
+        will cost O(m*n), where n is the number of `identifiers`.
+
+        Returns:
+            Iterable[KT]: A non-empty subset of `identifiers`.
         """
-        raise NotImplementedError
+        return identifiers
diff --git a/src/pip/_vendor/resolvelib/providers.pyi b/src/pip/_vendor/resolvelib/providers.pyi
deleted file mode 100644
index ec054194ee3..00000000000
--- a/src/pip/_vendor/resolvelib/providers.pyi
+++ /dev/null
@@ -1,44 +0,0 @@
-from typing import (
-    Any,
-    Generic,
-    Iterable,
-    Iterator,
-    Mapping,
-    Protocol,
-    Sequence,
-    Union,
-)
-
-from .reporters import BaseReporter
-from .resolvers import RequirementInformation
-from .structs import CT, KT, RT, Matches
-
-class Preference(Protocol):
-    def __lt__(self, __other: Any) -> bool: ...
-
-class AbstractProvider(Generic[RT, CT, KT]):
-    def identify(self, requirement_or_candidate: Union[RT, CT]) -> KT: ...
-    def get_preference(
-        self,
-        identifier: KT,
-        resolutions: Mapping[KT, CT],
-        candidates: Mapping[KT, Iterator[CT]],
-        information: Mapping[KT, Iterator[RequirementInformation[RT, CT]]],
-        backtrack_causes: Sequence[RequirementInformation[RT, CT]],
-    ) -> Preference: ...
-    def find_matches(
-        self,
-        identifier: KT,
-        requirements: Mapping[KT, Iterator[RT]],
-        incompatibilities: Mapping[KT, Iterator[CT]],
-    ) -> Matches: ...
-    def is_satisfied_by(self, requirement: RT, candidate: CT) -> bool: ...
-    def get_dependencies(self, candidate: CT) -> Iterable[RT]: ...
-
-class AbstractResolver(Generic[RT, CT, KT]):
-    base_exception = Exception
-    provider: AbstractProvider[RT, CT, KT]
-    reporter: BaseReporter
-    def __init__(
-        self, provider: AbstractProvider[RT, CT, KT], reporter: BaseReporter
-    ): ...
diff --git a/src/pip/_vendor/resolvelib/reporters.py b/src/pip/_vendor/resolvelib/reporters.py
index 688b5e10d86..26c9f6e6f92 100644
--- a/src/pip/_vendor/resolvelib/reporters.py
+++ b/src/pip/_vendor/resolvelib/reporters.py
@@ -1,26 +1,36 @@
-class BaseReporter(object):
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Collection, Generic
+
+from .structs import CT, KT, RT, RequirementInformation, State
+
+if TYPE_CHECKING:
+    from .resolvers import Criterion
+
+
+class BaseReporter(Generic[RT, CT, KT]):
     """Delegate class to provider progress reporting for the resolver."""
 
-    def starting(self):
+    def starting(self) -> None:
         """Called before the resolution actually starts."""
 
-    def starting_round(self, index):
+    def starting_round(self, index: int) -> None:
         """Called before each round of resolution starts.
 
         The index is zero-based.
         """
 
-    def ending_round(self, index, state):
+    def ending_round(self, index: int, state: State[RT, CT, KT]) -> None:
         """Called before each round of resolution ends.
 
         This is NOT called if the resolution ends at this round. Use `ending`
         if you want to report finalization. The index is zero-based.
         """
 
-    def ending(self, state):
+    def ending(self, state: State[RT, CT, KT]) -> None:
         """Called before the resolution ends successfully."""
 
-    def adding_requirement(self, requirement, parent):
+    def adding_requirement(self, requirement: RT, parent: CT | None) -> None:
         """Called when adding a new requirement into the resolve criteria.
 
         :param requirement: The additional requirement to be applied to filter
@@ -30,14 +40,16 @@ def adding_requirement(self, requirement, parent):
             requirements passed in from ``Resolver.resolve()``.
         """
 
-    def resolving_conflicts(self, causes):
+    def resolving_conflicts(
+        self, causes: Collection[RequirementInformation[RT, CT]]
+    ) -> None:
         """Called when starting to attempt requirement conflict resolution.
 
         :param causes: The information on the collision that caused the backtracking.
         """
 
-    def rejecting_candidate(self, criterion, candidate):
+    def rejecting_candidate(self, criterion: Criterion[RT, CT], candidate: CT) -> None:
         """Called when rejecting a candidate during backtracking."""
 
-    def pinning(self, candidate):
+    def pinning(self, candidate: CT) -> None:
         """Called when adding a candidate to the potential solution."""
diff --git a/src/pip/_vendor/resolvelib/reporters.pyi b/src/pip/_vendor/resolvelib/reporters.pyi
deleted file mode 100644
index b2ad286ba06..00000000000
--- a/src/pip/_vendor/resolvelib/reporters.pyi
+++ /dev/null
@@ -1,11 +0,0 @@
-from typing import Any
-
-class BaseReporter:
-    def starting(self) -> Any: ...
-    def starting_round(self, index: int) -> Any: ...
-    def ending_round(self, index: int, state: Any) -> Any: ...
-    def ending(self, state: Any) -> Any: ...
-    def adding_requirement(self, requirement: Any, parent: Any) -> Any: ...
-    def rejecting_candidate(self, criterion: Any, candidate: Any) -> Any: ...
-    def resolving_conflicts(self, causes: Any) -> Any: ...
-    def pinning(self, candidate: Any) -> Any: ...
diff --git a/src/pip/_vendor/resolvelib/resolvers.pyi b/src/pip/_vendor/resolvelib/resolvers.pyi
deleted file mode 100644
index 528a1a259af..00000000000
--- a/src/pip/_vendor/resolvelib/resolvers.pyi
+++ /dev/null
@@ -1,79 +0,0 @@
-from typing import (
-    Collection,
-    Generic,
-    Iterable,
-    Iterator,
-    List,
-    Mapping,
-    Optional,
-)
-
-from .providers import AbstractProvider, AbstractResolver
-from .structs import CT, KT, RT, DirectedGraph, IterableView
-
-# This should be a NamedTuple, but Python 3.6 has a bug that prevents it.
-# https://stackoverflow.com/a/50531189/1376863
-class RequirementInformation(tuple, Generic[RT, CT]):
-    requirement: RT
-    parent: Optional[CT]
-
-class Criterion(Generic[RT, CT, KT]):
-    candidates: IterableView[CT]
-    information: Collection[RequirementInformation[RT, CT]]
-    incompatibilities: List[CT]
-    @classmethod
-    def from_requirement(
-        cls,
-        provider: AbstractProvider[RT, CT, KT],
-        requirement: RT,
-        parent: Optional[CT],
-    ) -> Criterion[RT, CT, KT]: ...
-    def iter_requirement(self) -> Iterator[RT]: ...
-    def iter_parent(self) -> Iterator[Optional[CT]]: ...
-    def merged_with(
-        self,
-        provider: AbstractProvider[RT, CT, KT],
-        requirement: RT,
-        parent: Optional[CT],
-    ) -> Criterion[RT, CT, KT]: ...
-    def excluded_of(self, candidates: List[CT]) -> Criterion[RT, CT, KT]: ...
-
-class ResolverException(Exception): ...
-
-class RequirementsConflicted(ResolverException, Generic[RT, CT, KT]):
-    criterion: Criterion[RT, CT, KT]
-
-class ResolutionError(ResolverException): ...
-
-class InconsistentCandidate(ResolverException, Generic[RT, CT, KT]):
-    candidate: CT
-    criterion: Criterion[RT, CT, KT]
-
-class ResolutionImpossible(ResolutionError, Generic[RT, CT]):
-    causes: List[RequirementInformation[RT, CT]]
-
-class ResolutionTooDeep(ResolutionError):
-    round_count: int
-
-# This should be a NamedTuple, but Python 3.6 has a bug that prevents it.
-# https://stackoverflow.com/a/50531189/1376863
-class State(tuple, Generic[RT, CT, KT]):
-    mapping: Mapping[KT, CT]
-    criteria: Mapping[KT, Criterion[RT, CT, KT]]
-    backtrack_causes: Collection[RequirementInformation[RT, CT]]
-
-class Resolution(Generic[RT, CT, KT]):
-    def resolve(
-        self, requirements: Iterable[RT], max_rounds: int
-    ) -> State[RT, CT, KT]: ...
-
-class Result(Generic[RT, CT, KT]):
-    mapping: Mapping[KT, CT]
-    graph: DirectedGraph[Optional[KT]]
-    criteria: Mapping[KT, Criterion[RT, CT, KT]]
-
-class Resolver(AbstractResolver, Generic[RT, CT, KT]):
-    base_exception = ResolverException
-    def resolve(
-        self, requirements: Iterable[RT], max_rounds: int = 100
-    ) -> Result[RT, CT, KT]: ...
diff --git a/src/pip/_vendor/resolvelib/resolvers/__init__.py b/src/pip/_vendor/resolvelib/resolvers/__init__.py
new file mode 100644
index 00000000000..7b2c5d597eb
--- /dev/null
+++ b/src/pip/_vendor/resolvelib/resolvers/__init__.py
@@ -0,0 +1,27 @@
+from ..structs import RequirementInformation
+from .abstract import AbstractResolver, Result
+from .criterion import Criterion
+from .exceptions import (
+    InconsistentCandidate,
+    RequirementsConflicted,
+    ResolutionError,
+    ResolutionImpossible,
+    ResolutionTooDeep,
+    ResolverException,
+)
+from .resolution import Resolution, Resolver
+
+__all__ = [
+    "AbstractResolver",
+    "InconsistentCandidate",
+    "Resolver",
+    "Resolution",
+    "RequirementsConflicted",
+    "ResolutionError",
+    "ResolutionImpossible",
+    "ResolutionTooDeep",
+    "RequirementInformation",
+    "ResolverException",
+    "Result",
+    "Criterion",
+]
diff --git a/src/pip/_vendor/resolvelib/resolvers/abstract.py b/src/pip/_vendor/resolvelib/resolvers/abstract.py
new file mode 100644
index 00000000000..f9b5a7aa1fa
--- /dev/null
+++ b/src/pip/_vendor/resolvelib/resolvers/abstract.py
@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import collections
+from typing import TYPE_CHECKING, Any, Generic, Iterable, Mapping, NamedTuple
+
+from ..structs import CT, KT, RT, DirectedGraph
+
+if TYPE_CHECKING:
+    from ..providers import AbstractProvider
+    from ..reporters import BaseReporter
+    from .criterion import Criterion
+
+    class Result(NamedTuple, Generic[RT, CT, KT]):
+        mapping: Mapping[KT, CT]
+        graph: DirectedGraph[KT | None]
+        criteria: Mapping[KT, Criterion[RT, CT]]
+
+else:
+    Result = collections.namedtuple("Result", ["mapping", "graph", "criteria"])
+
+
+class AbstractResolver(Generic[RT, CT, KT]):
+    """The thing that performs the actual resolution work."""
+
+    base_exception = Exception
+
+    def __init__(
+        self,
+        provider: AbstractProvider[RT, CT, KT],
+        reporter: BaseReporter[RT, CT, KT],
+    ) -> None:
+        self.provider = provider
+        self.reporter = reporter
+
+    def resolve(self, requirements: Iterable[RT], **kwargs: Any) -> Result[RT, CT, KT]:
+        """Take a collection of constraints, spit out the resolution result.
+
+        This returns a representation of the final resolution state, with one
+        guarenteed attribute ``mapping`` that contains resolved candidates as
+        values. The keys are their respective identifiers.
+
+        :param requirements: A collection of constraints.
+        :param kwargs: Additional keyword arguments that subclasses may accept.
+
+        :raises: ``self.base_exception`` or its subclass.
+        """
+        raise NotImplementedError
diff --git a/src/pip/_vendor/resolvelib/resolvers/criterion.py b/src/pip/_vendor/resolvelib/resolvers/criterion.py
new file mode 100644
index 00000000000..ee5019ccd03
--- /dev/null
+++ b/src/pip/_vendor/resolvelib/resolvers/criterion.py
@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+from typing import Collection, Generic, Iterable, Iterator
+
+from ..structs import CT, RT, RequirementInformation
+
+
+class Criterion(Generic[RT, CT]):
+    """Representation of possible resolution results of a package.
+
+    This holds three attributes:
+
+    * `information` is a collection of `RequirementInformation` pairs.
+      Each pair is a requirement contributing to this criterion, and the
+      candidate that provides the requirement.
+    * `incompatibilities` is a collection of all known not-to-work candidates
+      to exclude from consideration.
+    * `candidates` is a collection containing all possible candidates deducted
+      from the union of contributing requirements and known incompatibilities.
+      It should never be empty, except when the criterion is an attribute of a
+      raised `RequirementsConflicted` (in which case it is always empty).
+
+    .. note::
+        This class is intended to be externally immutable. **Do not** mutate
+        any of its attribute containers.
+    """
+
+    def __init__(
+        self,
+        candidates: Iterable[CT],
+        information: Collection[RequirementInformation[RT, CT]],
+        incompatibilities: Collection[CT],
+    ) -> None:
+        self.candidates = candidates
+        self.information = information
+        self.incompatibilities = incompatibilities
+
+    def __repr__(self) -> str:
+        requirements = ", ".join(
+            f"({req!r}, via={parent!r})" for req, parent in self.information
+        )
+        return f"Criterion({requirements})"
+
+    def iter_requirement(self) -> Iterator[RT]:
+        return (i.requirement for i in self.information)
+
+    def iter_parent(self) -> Iterator[CT | None]:
+        return (i.parent for i in self.information)
diff --git a/src/pip/_vendor/resolvelib/resolvers/exceptions.py b/src/pip/_vendor/resolvelib/resolvers/exceptions.py
new file mode 100644
index 00000000000..35e275576f7
--- /dev/null
+++ b/src/pip/_vendor/resolvelib/resolvers/exceptions.py
@@ -0,0 +1,57 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Collection, Generic
+
+from ..structs import CT, RT, RequirementInformation
+
+if TYPE_CHECKING:
+    from .criterion import Criterion
+
+
+class ResolverException(Exception):
+    """A base class for all exceptions raised by this module.
+
+    Exceptions derived by this class should all be handled in this module. Any
+    bubbling pass the resolver should be treated as a bug.
+    """
+
+
+class RequirementsConflicted(ResolverException, Generic[RT, CT]):
+    def __init__(self, criterion: Criterion[RT, CT]) -> None:
+        super().__init__(criterion)
+        self.criterion = criterion
+
+    def __str__(self) -> str:
+        return "Requirements conflict: {}".format(
+            ", ".join(repr(r) for r in self.criterion.iter_requirement()),
+        )
+
+
+class InconsistentCandidate(ResolverException, Generic[RT, CT]):
+    def __init__(self, candidate: CT, criterion: Criterion[RT, CT]):
+        super().__init__(candidate, criterion)
+        self.candidate = candidate
+        self.criterion = criterion
+
+    def __str__(self) -> str:
+        return "Provided candidate {!r} does not satisfy {}".format(
+            self.candidate,
+            ", ".join(repr(r) for r in self.criterion.iter_requirement()),
+        )
+
+
+class ResolutionError(ResolverException):
+    pass
+
+
+class ResolutionImpossible(ResolutionError, Generic[RT, CT]):
+    def __init__(self, causes: Collection[RequirementInformation[RT, CT]]):
+        super().__init__(causes)
+        # causes is a list of RequirementInformation objects
+        self.causes = causes
+
+
+class ResolutionTooDeep(ResolutionError):
+    def __init__(self, round_count: int) -> None:
+        super().__init__(round_count)
+        self.round_count = round_count
diff --git a/src/pip/_vendor/resolvelib/resolvers.py b/src/pip/_vendor/resolvelib/resolvers/resolution.py
similarity index 67%
rename from src/pip/_vendor/resolvelib/resolvers.py
rename to src/pip/_vendor/resolvelib/resolvers/resolution.py
index 2c3d0e306f9..da3c66e2ab7 100644
--- a/src/pip/_vendor/resolvelib/resolvers.py
+++ b/src/pip/_vendor/resolvelib/resolvers/resolution.py
@@ -1,127 +1,90 @@
+from __future__ import annotations
+
 import collections
 import itertools
 import operator
-
-from .providers import AbstractResolver
-from .structs import DirectedGraph, IteratorMapping, build_iter_view
-
-RequirementInformation = collections.namedtuple(
-    "RequirementInformation", ["requirement", "parent"]
+from typing import TYPE_CHECKING, Collection, Generic, Iterable, Mapping
+
+from ..structs import (
+    CT,
+    KT,
+    RT,
+    DirectedGraph,
+    IterableView,
+    IteratorMapping,
+    RequirementInformation,
+    State,
+    build_iter_view,
+)
+from .abstract import AbstractResolver, Result
+from .criterion import Criterion
+from .exceptions import (
+    InconsistentCandidate,
+    RequirementsConflicted,
+    ResolutionImpossible,
+    ResolutionTooDeep,
+    ResolverException,
 )
 
+if TYPE_CHECKING:
+    from ..providers import AbstractProvider, Preference
+    from ..reporters import BaseReporter
 
-class ResolverException(Exception):
-    """A base class for all exceptions raised by this module.
-
-    Exceptions derived by this class should all be handled in this module. Any
-    bubbling pass the resolver should be treated as a bug.
-    """
-
-
-class RequirementsConflicted(ResolverException):
-    def __init__(self, criterion):
-        super(RequirementsConflicted, self).__init__(criterion)
-        self.criterion = criterion
-
-    def __str__(self):
-        return "Requirements conflict: {}".format(
-            ", ".join(repr(r) for r in self.criterion.iter_requirement()),
-        )
-
-
-class InconsistentCandidate(ResolverException):
-    def __init__(self, candidate, criterion):
-        super(InconsistentCandidate, self).__init__(candidate, criterion)
-        self.candidate = candidate
-        self.criterion = criterion
-
-    def __str__(self):
-        return "Provided candidate {!r} does not satisfy {}".format(
-            self.candidate,
-            ", ".join(repr(r) for r in self.criterion.iter_requirement()),
-        )
-
-
-class Criterion(object):
-    """Representation of possible resolution results of a package.
-
-    This holds three attributes:
-
-    * `information` is a collection of `RequirementInformation` pairs.
-      Each pair is a requirement contributing to this criterion, and the
-      candidate that provides the requirement.
-    * `incompatibilities` is a collection of all known not-to-work candidates
-      to exclude from consideration.
-    * `candidates` is a collection containing all possible candidates deducted
-      from the union of contributing requirements and known incompatibilities.
-      It should never be empty, except when the criterion is an attribute of a
-      raised `RequirementsConflicted` (in which case it is always empty).
-
-    .. note::
-        This class is intended to be externally immutable. **Do not** mutate
-        any of its attribute containers.
-    """
-
-    def __init__(self, candidates, information, incompatibilities):
-        self.candidates = candidates
-        self.information = information
-        self.incompatibilities = incompatibilities
-
-    def __repr__(self):
-        requirements = ", ".join(
-            "({!r}, via={!r})".format(req, parent)
-            for req, parent in self.information
-        )
-        return "Criterion({})".format(requirements)
-
-    def iter_requirement(self):
-        return (i.requirement for i in self.information)
-
-    def iter_parent(self):
-        return (i.parent for i in self.information)
-
-
-class ResolutionError(ResolverException):
-    pass
-
-
-class ResolutionImpossible(ResolutionError):
-    def __init__(self, causes):
-        super(ResolutionImpossible, self).__init__(causes)
-        # causes is a list of RequirementInformation objects
-        self.causes = causes
 
+def _build_result(state: State[RT, CT, KT]) -> Result[RT, CT, KT]:
+    mapping = state.mapping
+    all_keys: dict[int, KT | None] = {id(v): k for k, v in mapping.items()}
+    all_keys[id(None)] = None
 
-class ResolutionTooDeep(ResolutionError):
-    def __init__(self, round_count):
-        super(ResolutionTooDeep, self).__init__(round_count)
-        self.round_count = round_count
+    graph: DirectedGraph[KT | None] = DirectedGraph()
+    graph.add(None)  # Sentinel as root dependencies' parent.
 
+    connected: set[KT | None] = {None}
+    for key, criterion in state.criteria.items():
+        if not _has_route_to_root(state.criteria, key, all_keys, connected):
+            continue
+        if key not in graph:
+            graph.add(key)
+        for p in criterion.iter_parent():
+            try:
+                pkey = all_keys[id(p)]
+            except KeyError:
+                continue
+            if pkey not in graph:
+                graph.add(pkey)
+            graph.connect(pkey, key)
 
-# Resolution state in a round.
-State = collections.namedtuple("State", "mapping criteria backtrack_causes")
+    return Result(
+        mapping={k: v for k, v in mapping.items() if k in connected},
+        graph=graph,
+        criteria=state.criteria,
+    )
 
 
-class Resolution(object):
+class Resolution(Generic[RT, CT, KT]):
     """Stateful resolution object.
 
     This is designed as a one-off object that holds information to kick start
     the resolution process, and holds the results afterwards.
     """
 
-    def __init__(self, provider, reporter):
+    def __init__(
+        self,
+        provider: AbstractProvider[RT, CT, KT],
+        reporter: BaseReporter[RT, CT, KT],
+    ) -> None:
         self._p = provider
         self._r = reporter
-        self._states = []
+        self._states: list[State[RT, CT, KT]] = []
 
     @property
-    def state(self):
+    def state(self) -> State[RT, CT, KT]:
         try:
             return self._states[-1]
-        except IndexError:
-            raise AttributeError("state")
+        except IndexError as e:
+            raise AttributeError("state") from e
 
-    def _push_new_state(self):
+    def _push_new_state(self) -> None:
         """Push a new state into history.
 
         This new state will be used to hold resolution results of the next
@@ -135,7 +98,12 @@ def _push_new_state(self):
         )
         self._states.append(state)
 
-    def _add_to_criteria(self, criteria, requirement, parent):
+    def _add_to_criteria(
+        self,
+        criteria: dict[KT, Criterion[RT, CT]],
+        requirement: RT,
+        parent: CT | None,
+    ) -> None:
         self._r.adding_requirement(requirement=requirement, parent=parent)
 
         identifier = self._p.identify(requirement_or_candidate=requirement)
@@ -174,7 +142,9 @@ def _add_to_criteria(self, criteria, requirement, parent):
             raise RequirementsConflicted(criterion)
         criteria[identifier] = criterion
 
-    def _remove_information_from_criteria(self, criteria, parents):
+    def _remove_information_from_criteria(
+        self, criteria: dict[KT, Criterion[RT, CT]], parents: Collection[KT]
+    ) -> None:
         """Remove information from parents of criteria.
 
         Concretely, removes all values from each criterion's ``information``
@@ -199,7 +169,7 @@ def _remove_information_from_criteria(self, criteria, parents):
                 criterion.incompatibilities,
             )
 
-    def _get_preference(self, name):
+    def _get_preference(self, name: KT) -> Preference:
         return self._p.get_preference(
             identifier=name,
             resolutions=self.state.mapping,
@@ -214,7 +184,9 @@ def _get_preference(self, name):
             backtrack_causes=self.state.backtrack_causes,
         )
 
-    def _is_current_pin_satisfying(self, name, criterion):
+    def _is_current_pin_satisfying(
+        self, name: KT, criterion: Criterion[RT, CT]
+    ) -> bool:
         try:
             current_pin = self.state.mapping[name]
         except KeyError:
@@ -224,16 +196,16 @@ def _is_current_pin_satisfying(self, name, criterion):
             for r in criterion.iter_requirement()
         )
 
-    def _get_updated_criteria(self, candidate):
+    def _get_updated_criteria(self, candidate: CT) -> dict[KT, Criterion[RT, CT]]:
         criteria = self.state.criteria.copy()
         for requirement in self._p.get_dependencies(candidate=candidate):
             self._add_to_criteria(criteria, requirement, parent=candidate)
         return criteria
 
-    def _attempt_to_pin_criterion(self, name):
+    def _attempt_to_pin_criterion(self, name: KT) -> list[Criterion[RT, CT]]:
         criterion = self.state.criteria[name]
 
-        causes = []
+        causes: list[Criterion[RT, CT]] = []
         for candidate in criterion.candidates:
             try:
                 criteria = self._get_updated_criteria(candidate)
@@ -267,7 +239,42 @@ def _attempt_to_pin_criterion(self, name):
         # end, signal for backtracking.
         return causes
 
-    def _backjump(self, causes):
+    def _patch_criteria(
+        self, incompatibilities_from_broken: list[tuple[KT, list[CT]]]
+    ) -> bool:
+        # Create a new state from the last known-to-work one, and apply
+        # the previously gathered incompatibility information.
+        for k, incompatibilities in incompatibilities_from_broken:
+            if not incompatibilities:
+                continue
+            try:
+                criterion = self.state.criteria[k]
+            except KeyError:
+                continue
+            matches = self._p.find_matches(
+                identifier=k,
+                requirements=IteratorMapping(
+                    self.state.criteria,
+                    operator.methodcaller("iter_requirement"),
+                ),
+                incompatibilities=IteratorMapping(
+                    self.state.criteria,
+                    operator.attrgetter("incompatibilities"),
+                    {k: incompatibilities},
+                ),
+            )
+            candidates: IterableView[CT] = build_iter_view(matches)
+            if not candidates:
+                return False
+            incompatibilities.extend(criterion.incompatibilities)
+            self.state.criteria[k] = Criterion(
+                candidates=candidates,
+                information=list(criterion.information),
+                incompatibilities=incompatibilities,
+            )
+        return True
+
+    def _backjump(self, causes: list[RequirementInformation[RT, CT]]) -> bool:
         """Perform backjumping.
 
         When we enter here, the stack is like this::
@@ -298,7 +305,7 @@ def _backjump(self, causes):
             the new Z and go back to step 2.
         5b. If the incompatibilities apply cleanly, end backtracking.
         """
-        incompatible_reqs = itertools.chain(
+        incompatible_reqs: Iterable[CT | RT] = itertools.chain(
             (c.parent for c in causes if c.parent is not None),
             (c.requirement for c in causes),
         )
@@ -307,66 +314,44 @@ def _backjump(self, causes):
             # Remove the state that triggered backtracking.
             del self._states[-1]
 
-            # Ensure to backtrack to a state that caused the incompatibility
-            incompatible_state = False
-            while not incompatible_state:
+            # Optimistically backtrack to a state that caused the incompatibility
+            broken_state = self.state
+            while True:
                 # Retrieve the last candidate pin and known incompatibilities.
                 try:
                     broken_state = self._states.pop()
                     name, candidate = broken_state.mapping.popitem()
                 except (IndexError, KeyError):
-                    raise ResolutionImpossible(causes)
+                    raise ResolutionImpossible(causes) from None
+
+                # Only backjump if the current broken state is
+                # an incompatible dependency
+                if name not in incompatible_deps:
+                    break
+
+                # If the current dependencies and the incompatible dependencies
+                # are overlapping then we have found a cause of the incompatibility
                 current_dependencies = {
-                    self._p.identify(d)
-                    for d in self._p.get_dependencies(candidate)
+                    self._p.identify(d) for d in self._p.get_dependencies(candidate)
                 }
-                incompatible_state = not current_dependencies.isdisjoint(
-                    incompatible_deps
-                )
+                if not current_dependencies.isdisjoint(incompatible_deps):
+                    break
+
+                # Fallback: We should not backtrack to the point where
+                # broken_state.mapping is empty, so stop backtracking for
+                # a chance for the resolution to recover
+                if not broken_state.mapping:
+                    break
 
             incompatibilities_from_broken = [
-                (k, list(v.incompatibilities))
-                for k, v in broken_state.criteria.items()
+                (k, list(v.incompatibilities)) for k, v in broken_state.criteria.items()
             ]
 
             # Also mark the newly known incompatibility.
             incompatibilities_from_broken.append((name, [candidate]))
 
-            # Create a new state from the last known-to-work one, and apply
-            # the previously gathered incompatibility information.
-            def _patch_criteria():
-                for k, incompatibilities in incompatibilities_from_broken:
-                    if not incompatibilities:
-                        continue
-                    try:
-                        criterion = self.state.criteria[k]
-                    except KeyError:
-                        continue
-                    matches = self._p.find_matches(
-                        identifier=k,
-                        requirements=IteratorMapping(
-                            self.state.criteria,
-                            operator.methodcaller("iter_requirement"),
-                        ),
-                        incompatibilities=IteratorMapping(
-                            self.state.criteria,
-                            operator.attrgetter("incompatibilities"),
-                            {k: incompatibilities},
-                        ),
-                    )
-                    candidates = build_iter_view(matches)
-                    if not candidates:
-                        return False
-                    incompatibilities.extend(criterion.incompatibilities)
-                    self.state.criteria[k] = Criterion(
-                        candidates=candidates,
-                        information=list(criterion.information),
-                        incompatibilities=incompatibilities,
-                    )
-                return True
-
             self._push_new_state()
-            success = _patch_criteria()
+            success = self._patch_criteria(incompatibilities_from_broken)
 
             # It works! Let's work on this new state.
             if success:
@@ -378,7 +363,13 @@ def _patch_criteria():
         # No way to backtrack anymore.
         return False
 
-    def resolve(self, requirements, max_rounds):
+    def _extract_causes(
+        self, criteron: list[Criterion[RT, CT]]
+    ) -> list[RequirementInformation[RT, CT]]:
+        """Extract causes from list of criterion and deduplicate"""
+        return list({id(i): i for c in criteron for i in c.information}.values())
+
+    def resolve(self, requirements: Iterable[RT], max_rounds: int) -> State[RT, CT, KT]:
         if self._states:
             raise RuntimeError("already resolved")
 
@@ -396,7 +387,7 @@ def resolve(self, requirements, max_rounds):
             try:
                 self._add_to_criteria(self.state.criteria, r, parent=None)
             except RequirementsConflicted as e:
-                raise ResolutionImpossible(e.criterion.information)
+                raise ResolutionImpossible(e.criterion.information) from e
 
         # The root state is saved as a sentinel so the first ever pin can have
         # something to backtrack to if it fails. The root state is basically
@@ -418,16 +409,42 @@ def resolve(self, requirements, max_rounds):
                 return self.state
 
             # keep track of satisfied names to calculate diff after pinning
-            satisfied_names = set(self.state.criteria.keys()) - set(
-                unsatisfied_names
-            )
+            satisfied_names = set(self.state.criteria.keys()) - set(unsatisfied_names)
+
+            if len(unsatisfied_names) > 1:
+                narrowed_unstatisfied_names = list(
+                    self._p.narrow_requirement_selection(
+                        identifiers=unsatisfied_names,
+                        resolutions=self.state.mapping,
+                        candidates=IteratorMapping(
+                            self.state.criteria,
+                            operator.attrgetter("candidates"),
+                        ),
+                        information=IteratorMapping(
+                            self.state.criteria,
+                            operator.attrgetter("information"),
+                        ),
+                        backtrack_causes=self.state.backtrack_causes,
+                    )
+                )
+            else:
+                narrowed_unstatisfied_names = unsatisfied_names
+
+            # If there are no unsatisfied names use unsatisfied names
+            if not narrowed_unstatisfied_names:
+                raise RuntimeError("narrow_requirement_selection returned 0 names")
 
-            # Choose the most preferred unpinned criterion to try.
-            name = min(unsatisfied_names, key=self._get_preference)
-            failure_causes = self._attempt_to_pin_criterion(name)
+            # If there is only 1 unsatisfied name skip calling self._get_preference
+            if len(narrowed_unstatisfied_names) > 1:
+                # Choose the most preferred unpinned criterion to try.
+                name = min(narrowed_unstatisfied_names, key=self._get_preference)
+            else:
+                name = narrowed_unstatisfied_names[0]
 
-            if failure_causes:
-                causes = [i for c in failure_causes for i in c.information]
+            failure_criterion = self._attempt_to_pin_criterion(name)
+
+            if failure_criterion:
+                causes = self._extract_causes(failure_criterion)
                 # Backjump if pinning fails. The backjump process puts us in
                 # an unpinned state, so we can work on it in the next round.
                 self._r.resolving_conflicts(causes=causes)
@@ -457,64 +474,16 @@ def resolve(self, requirements, max_rounds):
         raise ResolutionTooDeep(max_rounds)
 
 
-def _has_route_to_root(criteria, key, all_keys, connected):
-    if key in connected:
-        return True
-    if key not in criteria:
-        return False
-    for p in criteria[key].iter_parent():
-        try:
-            pkey = all_keys[id(p)]
-        except KeyError:
-            continue
-        if pkey in connected:
-            connected.add(key)
-            return True
-        if _has_route_to_root(criteria, pkey, all_keys, connected):
-            connected.add(key)
-            return True
-    return False
-
-
-Result = collections.namedtuple("Result", "mapping graph criteria")
-
-
-def _build_result(state):
-    mapping = state.mapping
-    all_keys = {id(v): k for k, v in mapping.items()}
-    all_keys[id(None)] = None
-
-    graph = DirectedGraph()
-    graph.add(None)  # Sentinel as root dependencies' parent.
-
-    connected = {None}
-    for key, criterion in state.criteria.items():
-        if not _has_route_to_root(state.criteria, key, all_keys, connected):
-            continue
-        if key not in graph:
-            graph.add(key)
-        for p in criterion.iter_parent():
-            try:
-                pkey = all_keys[id(p)]
-            except KeyError:
-                continue
-            if pkey not in graph:
-                graph.add(pkey)
-            graph.connect(pkey, key)
-
-    return Result(
-        mapping={k: v for k, v in mapping.items() if k in connected},
-        graph=graph,
-        criteria=state.criteria,
-    )
-
-
-class Resolver(AbstractResolver):
+class Resolver(AbstractResolver[RT, CT, KT]):
     """The thing that performs the actual resolution work."""
 
     base_exception = ResolverException
 
-    def resolve(self, requirements, max_rounds=100):
+    def resolve(  # type: ignore[override]
+        self,
+        requirements: Iterable[RT],
+        max_rounds: int = 100,
+    ) -> Result[RT, CT, KT]:
         """Take a collection of constraints, spit out the resolution result.
 
         The return value is a representation to the final resolution result. It
@@ -545,3 +514,28 @@ def resolve(self, requirements, max_rounds=100):
         resolution = Resolution(self.provider, self.reporter)
         state = resolution.resolve(requirements, max_rounds=max_rounds)
         return _build_result(state)
+
+
+def _has_route_to_root(
+    criteria: Mapping[KT, Criterion[RT, CT]],
+    key: KT | None,
+    all_keys: dict[int, KT | None],
+    connected: set[KT | None],
+) -> bool:
+    if key in connected:
+        return True
+    if key not in criteria:
+        return False
+    assert key is not None
+    for p in criteria[key].iter_parent():
+        try:
+            pkey = all_keys[id(p)]
+        except KeyError:
+            continue
+        if pkey in connected:
+            connected.add(key)
+            return True
+        if _has_route_to_root(criteria, pkey, all_keys, connected):
+            connected.add(key)
+            return True
+    return False
diff --git a/src/pip/_vendor/resolvelib/structs.py b/src/pip/_vendor/resolvelib/structs.py
index 359a34f6018..18c74d41548 100644
--- a/src/pip/_vendor/resolvelib/structs.py
+++ b/src/pip/_vendor/resolvelib/structs.py
@@ -1,34 +1,73 @@
-import itertools
-
-from .compat import collections_abc
-
+from __future__ import annotations
 
-class DirectedGraph(object):
+import itertools
+from collections import namedtuple
+from typing import (
+    TYPE_CHECKING,
+    Callable,
+    Generic,
+    Iterable,
+    Iterator,
+    Mapping,
+    NamedTuple,
+    Sequence,
+    TypeVar,
+    Union,
+)
+
+KT = TypeVar("KT")  # Identifier.
+RT = TypeVar("RT")  # Requirement.
+CT = TypeVar("CT")  # Candidate.
+
+Matches = Union[Iterable[CT], Callable[[], Iterable[CT]]]
+
+if TYPE_CHECKING:
+    from .resolvers.criterion import Criterion
+
+    class RequirementInformation(NamedTuple, Generic[RT, CT]):
+        requirement: RT
+        parent: CT | None
+
+    class State(NamedTuple, Generic[RT, CT, KT]):
+        """Resolution state in a round."""
+
+        mapping: dict[KT, CT]
+        criteria: dict[KT, Criterion[RT, CT]]
+        backtrack_causes: list[RequirementInformation[RT, CT]]
+
+else:
+    RequirementInformation = namedtuple(
+        "RequirementInformation", ["requirement", "parent"]
+    )
+    State = namedtuple("State", ["mapping", "criteria", "backtrack_causes"])
+
+
+class DirectedGraph(Generic[KT]):
     """A graph structure with directed edges."""
 
-    def __init__(self):
-        self._vertices = set()
-        self._forwards = {}  # <key> -> Set[<key>]
-        self._backwards = {}  # <key> -> Set[<key>]
+    def __init__(self) -> None:
+        self._vertices: set[KT] = set()
+        self._forwards: dict[KT, set[KT]] = {}  # <key> -> Set[<key>]
+        self._backwards: dict[KT, set[KT]] = {}  # <key> -> Set[<key>]
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[KT]:
         return iter(self._vertices)
 
-    def __len__(self):
+    def __len__(self) -> int:
         return len(self._vertices)
 
-    def __contains__(self, key):
+    def __contains__(self, key: KT) -> bool:
         return key in self._vertices
 
-    def copy(self):
+    def copy(self) -> DirectedGraph[KT]:
         """Return a shallow copy of this graph."""
-        other = DirectedGraph()
+        other = type(self)()
         other._vertices = set(self._vertices)
         other._forwards = {k: set(v) for k, v in self._forwards.items()}
         other._backwards = {k: set(v) for k, v in self._backwards.items()}
         return other
 
-    def add(self, key):
+    def add(self, key: KT) -> None:
         """Add a new vertex to the graph."""
         if key in self._vertices:
             raise ValueError("vertex exists")
@@ -36,7 +75,7 @@ def add(self, key):
         self._forwards[key] = set()
         self._backwards[key] = set()
 
-    def remove(self, key):
+    def remove(self, key: KT) -> None:
         """Remove a vertex from the graph, disconnecting all edges from/to it."""
         self._vertices.remove(key)
         for f in self._forwards.pop(key):
@@ -44,10 +83,10 @@ def remove(self, key):
         for t in self._backwards.pop(key):
             self._forwards[t].remove(key)
 
-    def connected(self, f, t):
+    def connected(self, f: KT, t: KT) -> bool:
         return f in self._backwards[t] and t in self._forwards[f]
 
-    def connect(self, f, t):
+    def connect(self, f: KT, t: KT) -> None:
         """Connect two existing vertices.
 
         Nothing happens if the vertices are already connected.
@@ -57,56 +96,59 @@ def connect(self, f, t):
         self._forwards[f].add(t)
         self._backwards[t].add(f)
 
-    def iter_edges(self):
+    def iter_edges(self) -> Iterator[tuple[KT, KT]]:
         for f, children in self._forwards.items():
             for t in children:
                 yield f, t
 
-    def iter_children(self, key):
+    def iter_children(self, key: KT) -> Iterator[KT]:
         return iter(self._forwards[key])
 
-    def iter_parents(self, key):
+    def iter_parents(self, key: KT) -> Iterator[KT]:
         return iter(self._backwards[key])
 
 
-class IteratorMapping(collections_abc.Mapping):
-    def __init__(self, mapping, accessor, appends=None):
+class IteratorMapping(Mapping[KT, Iterator[CT]], Generic[RT, CT, KT]):
+    def __init__(
+        self,
+        mapping: Mapping[KT, RT],
+        accessor: Callable[[RT], Iterable[CT]],
+        appends: Mapping[KT, Iterable[CT]] | None = None,
+    ) -> None:
         self._mapping = mapping
         self._accessor = accessor
-        self._appends = appends or {}
+        self._appends: Mapping[KT, Iterable[CT]] = appends or {}
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "IteratorMapping({!r}, {!r}, {!r})".format(
             self._mapping,
             self._accessor,
             self._appends,
         )
 
-    def __bool__(self):
+    def __bool__(self) -> bool:
         return bool(self._mapping or self._appends)
 
-    __nonzero__ = __bool__  # XXX: Python 2.
-
-    def __contains__(self, key):
+    def __contains__(self, key: object) -> bool:
         return key in self._mapping or key in self._appends
 
-    def __getitem__(self, k):
+    def __getitem__(self, k: KT) -> Iterator[CT]:
         try:
             v = self._mapping[k]
         except KeyError:
             return iter(self._appends[k])
         return itertools.chain(self._accessor(v), self._appends.get(k, ()))
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[KT]:
         more = (k for k in self._appends if k not in self._mapping)
         return itertools.chain(self._mapping, more)
 
-    def __len__(self):
+    def __len__(self) -> int:
         more = sum(1 for k in self._appends if k not in self._mapping)
         return len(self._mapping) + more
 
 
-class _FactoryIterableView(object):
+class _FactoryIterableView(Iterable[RT]):
     """Wrap an iterator factory returned by `find_matches()`.
 
     Calling `iter()` on this class would invoke the underlying iterator
@@ -115,56 +157,53 @@ class _FactoryIterableView(object):
     built-in Python sequence types.
     """
 
-    def __init__(self, factory):
+    def __init__(self, factory: Callable[[], Iterable[RT]]) -> None:
         self._factory = factory
-        self._iterable = None
+        self._iterable: Iterable[RT] | None = None
 
-    def __repr__(self):
-        return "{}({})".format(type(self).__name__, list(self))
+    def __repr__(self) -> str:
+        return f"{type(self).__name__}({list(self)})"
 
-    def __bool__(self):
+    def __bool__(self) -> bool:
         try:
             next(iter(self))
         except StopIteration:
             return False
         return True
 
-    __nonzero__ = __bool__  # XXX: Python 2.
-
-    def __iter__(self):
-        iterable = (
-            self._factory() if self._iterable is None else self._iterable
-        )
+    def __iter__(self) -> Iterator[RT]:
+        iterable = self._factory() if self._iterable is None else self._iterable
         self._iterable, current = itertools.tee(iterable)
         return current
 
 
-class _SequenceIterableView(object):
+class _SequenceIterableView(Iterable[RT]):
     """Wrap an iterable returned by find_matches().
 
     This is essentially just a proxy to the underlying sequence that provides
     the same interface as `_FactoryIterableView`.
     """
 
-    def __init__(self, sequence):
+    def __init__(self, sequence: Sequence[RT]):
         self._sequence = sequence
 
-    def __repr__(self):
-        return "{}({})".format(type(self).__name__, self._sequence)
+    def __repr__(self) -> str:
+        return f"{type(self).__name__}({self._sequence})"
 
-    def __bool__(self):
+    def __bool__(self) -> bool:
         return bool(self._sequence)
 
-    __nonzero__ = __bool__  # XXX: Python 2.
-
-    def __iter__(self):
+    def __iter__(self) -> Iterator[RT]:
         return iter(self._sequence)
 
 
-def build_iter_view(matches):
+def build_iter_view(matches: Matches[CT]) -> Iterable[CT]:
     """Build an iterable view from the value returned by `find_matches()`."""
     if callable(matches):
         return _FactoryIterableView(matches)
-    if not isinstance(matches, collections_abc.Sequence):
+    if not isinstance(matches, Sequence):
         matches = list(matches)
     return _SequenceIterableView(matches)
+
+
+IterableView = Iterable
diff --git a/src/pip/_vendor/resolvelib/structs.pyi b/src/pip/_vendor/resolvelib/structs.pyi
deleted file mode 100644
index 0ac59f0f00a..00000000000
--- a/src/pip/_vendor/resolvelib/structs.pyi
+++ /dev/null
@@ -1,40 +0,0 @@
-from abc import ABCMeta
-from typing import (
-    Callable,
-    Container,
-    Generic,
-    Iterable,
-    Iterator,
-    Mapping,
-    Tuple,
-    TypeVar,
-    Union,
-)
-
-KT = TypeVar("KT")  # Identifier.
-RT = TypeVar("RT")  # Requirement.
-CT = TypeVar("CT")  # Candidate.
-_T = TypeVar("_T")
-
-Matches = Union[Iterable[CT], Callable[[], Iterable[CT]]]
-
-class IteratorMapping(Mapping[KT, _T], metaclass=ABCMeta):
-    pass
-
-class IterableView(Container[CT], Iterable[CT], metaclass=ABCMeta):
-    pass
-
-class DirectedGraph(Generic[KT]):
-    def __iter__(self) -> Iterator[KT]: ...
-    def __len__(self) -> int: ...
-    def __contains__(self, key: KT) -> bool: ...
-    def copy(self) -> "DirectedGraph[KT]": ...
-    def add(self, key: KT) -> None: ...
-    def remove(self, key: KT) -> None: ...
-    def connected(self, f: KT, t: KT) -> bool: ...
-    def connect(self, f: KT, t: KT) -> None: ...
-    def iter_edges(self) -> Iterable[Tuple[KT, KT]]: ...
-    def iter_children(self, key: KT) -> Iterable[KT]: ...
-    def iter_parents(self, key: KT) -> Iterable[KT]: ...
-
-def build_iter_view(matches: Matches) -> IterableView[CT]: ...
diff --git a/src/pip/_vendor/vendor.txt b/src/pip/_vendor/vendor.txt
index f04a9c1e73c..7e5f614e845 100644
--- a/src/pip/_vendor/vendor.txt
+++ b/src/pip/_vendor/vendor.txt
@@ -12,7 +12,7 @@ requests==2.32.3
 rich==13.9.4
     pygments==2.18.0
     typing_extensions==4.12.2
-resolvelib==1.0.1
+resolvelib==1.1.0
 setuptools==70.3.0
 tomli==2.2.1
 truststore==0.10.0
diff --git a/tests/unit/resolution_resolvelib/test_provider.py b/tests/unit/resolution_resolvelib/test_provider.py
deleted file mode 100644
index 5f30e2bc1dd..00000000000
--- a/tests/unit/resolution_resolvelib/test_provider.py
+++ /dev/null
@@ -1,78 +0,0 @@
-from typing import TYPE_CHECKING, List, Optional
-
-from pip._vendor.resolvelib.resolvers import RequirementInformation
-
-from pip._internal.models.candidate import InstallationCandidate
-from pip._internal.models.link import Link
-from pip._internal.req.constructors import install_req_from_req_string
-from pip._internal.resolution.resolvelib.factory import Factory
-from pip._internal.resolution.resolvelib.provider import PipProvider
-from pip._internal.resolution.resolvelib.requirements import SpecifierRequirement
-
-if TYPE_CHECKING:
-    from pip._internal.resolution.resolvelib.provider import PreferenceInformation
-
-
-def build_requirement_information(
-    name: str, parent: Optional[InstallationCandidate]
-) -> List["PreferenceInformation"]:
-    install_requirement = install_req_from_req_string(name)
-    # RequirementInformation is typed as a tuple, but it is a namedtupled.
-    # https://github.com/sarugaku/resolvelib/blob/7bc025aa2a4e979597c438ad7b17d2e8a08a364e/src/resolvelib/resolvers.pyi#L20-L22
-    requirement_information: PreferenceInformation = RequirementInformation(
-        requirement=SpecifierRequirement(install_requirement),  # type: ignore[call-arg]
-        parent=parent,
-    )
-    return [requirement_information]
-
-
-def test_provider_known_depths(factory: Factory) -> None:
-    # Root requirement is specified by the user
-    # therefore has an inferred depth of 1
-    root_requirement_name = "my-package"
-    provider = PipProvider(
-        factory=factory,
-        constraints={},
-        ignore_dependencies=False,
-        upgrade_strategy="to-satisfy-only",
-        user_requested={root_requirement_name: 0},
-    )
-
-    root_requirement_information = build_requirement_information(
-        name=root_requirement_name, parent=None
-    )
-    provider.get_preference(
-        identifier=root_requirement_name,
-        resolutions={},
-        candidates={},
-        information={root_requirement_name: root_requirement_information},
-        backtrack_causes=[],
-    )
-    assert provider._known_depths == {root_requirement_name: 1.0}
-
-    # Transitive requirement is a dependency of root requirement
-    # theforefore has an inferred depth of 2
-    root_package_candidate = InstallationCandidate(
-        root_requirement_name,
-        "1.0",
-        Link("https://{root_requirement_name}.com"),
-    )
-    transitive_requirement_name = "my-transitive-package"
-
-    transitive_package_information = build_requirement_information(
-        name=transitive_requirement_name, parent=root_package_candidate
-    )
-    provider.get_preference(
-        identifier=transitive_requirement_name,
-        resolutions={},
-        candidates={},
-        information={
-            root_requirement_name: root_requirement_information,
-            transitive_requirement_name: transitive_package_information,
-        },
-        backtrack_causes=[],
-    )
-    assert provider._known_depths == {
-        transitive_requirement_name: 2.0,
-        root_requirement_name: 1.0,
-    }