Update ResolveLib to 0.4.0

src/pip/_vendor/resolvelib/__init__.py

@@ -11,7 +11,7 @@
     "ResolutionTooDeep",
 ]
 
-__version__ = "0.3.0"
+__version__ = "0.4.0"
 
 
 from .providers import AbstractProvider, AbstractResolver

src/pip/_vendor/resolvelib/compat/collections_abc.py

@@ -0,0 +1,6 @@
+__all__ = ["Sequence"]
+
+try:
+    from collections.abc import Sequence
+except ImportError:
+    from collections import Sequence

src/pip/_vendor/resolvelib/providers.py

@@ -27,7 +27,7 @@ def get_preference(self, resolution, candidates, information):
 
         * `requirement` specifies a requirement contributing to the current
           candidate list
-        * `parent` specifies the candidate that provids (dependend on) the
+        * `parent` specifies the candidate that provides (dependend on) the
           requirement, or `None` to indicate a root requirement.
 
         The preference could depend on a various of issues, including (not
@@ -48,23 +48,28 @@ def get_preference(self, resolution, candidates, information):
         """
         raise NotImplementedError
 
-    def find_matches(self, requirement):
-        """Find all possible candidates that satisfy a requirement.
+    def find_matches(self, requirements):
+        """Find all possible candidates that satisfy the given requirements.
 
-        This should try to get candidates based on the requirement's type.
+        This should try to get candidates based on the requirements' types.
         For VCS, local, and archive requirements, the one-and-only match is
         returned, and for a "named" requirement, the index(es) should be
         consulted to find concrete candidates for this requirement.
 
-        The returned candidates should be sorted by reversed preference, e.g.
-        the most preferred should be LAST. This is done so list-popping can be
-        as efficient as possible.
+        :param requirements: A collection of requirements which all of the the
+            returned candidates must match. All requirements are guaranteed to
+            have the same identifier. The collection is never empty.
+        :returns: An iterable that orders candidates by preference, e.g. the
+            most preferred candidate should come first.
         """
         raise NotImplementedError
 
     def is_satisfied_by(self, requirement, candidate):
         """Whether the given requirement can be satisfied by a candidate.
 
+        The candidate is guarenteed to have been generated from the
+        requirement.
+
         A boolean should be returned to indicate whether `candidate` is a
         viable solution to the requirement.
         """
@@ -92,30 +97,13 @@ def __init__(self, provider, reporter):
     def resolve(self, requirements, **kwargs):
         """Take a collection of constraints, spit out the resolution result.
 
-        Parameters
-        ----------
-        requirements : Collection
-            A collection of constraints
-        kwargs : optional
-            Additional keyword arguments that subclasses may accept.
-
-        Raises
-        ------
-        self.base_exception
-            Any raised exception is guaranteed to be a subclass of
-            self.base_exception. The string representation of an exception
-            should be human readable and provide context for why it occurred.
-
-        Returns
-        -------
-        retval : object
-            A representation of the final resolution state. It can be any object
-            with a `mapping` attribute that is a Mapping. Other attributes can
-            be used to provide resolver-specific information.
-
-            The `mapping` attribute MUST be key-value pair is an identifier of a
-            requirement (as returned by the provider's `identify` method) mapped
-            to the resolved candidate (chosen from the return value of the
-            provider's `find_matches` method).
+        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

src/pip/_vendor/resolvelib/reporters.py

@@ -23,12 +23,18 @@ def ending(self, state):
         """Called before the resolution ends successfully.
         """
 
-    def adding_requirement(self, requirement):
-        """Called when the resolver adds a new requirement into the resolve criteria.
+    def adding_requirement(self, requirement, parent):
+        """Called when adding a new requirement into the resolve criteria.
+
+        :param requirement: The additional requirement to be applied to filter
+            the available candidaites.
+        :param parent: The candidate that requires ``requirement`` as a
+            dependency, or None if ``requirement`` is one of the root
+            requirements passed in from ``Resolver.resolve()``.
         """
 
     def backtracking(self, candidate):
-        """Called when the resolver rejects a candidate during backtracking.
+        """Called when rejecting a candidate during backtracking.
         """
 
     def pinning(self, candidate):

src/pip/_vendor/resolvelib/resolvers.py

@@ -1,5 +1,6 @@
 import collections
 
+from .compat import collections_abc
 from .providers import AbstractResolver
 from .structs import DirectedGraph
 
@@ -68,16 +69,18 @@ def __init__(self, candidates, information, incompatibilities):
 
     def __repr__(self):
         requirements = ", ".join(
-            "{!r} from {!r}".format(req, parent)
+            "({!r}, via={!r})".format(req, parent)
             for req, parent in self.information
         )
-        return "<Criterion {}>".format(requirements)
+        return "Criterion({})".format(requirements)
 
     @classmethod
     def from_requirement(cls, provider, requirement, parent):
         """Build an instance from a requirement.
         """
-        candidates = provider.find_matches(requirement)
+        candidates = provider.find_matches([requirement])
+        if not isinstance(candidates, collections_abc.Sequence):
+            candidates = list(candidates)
         criterion = cls(
             candidates=candidates,
             information=[RequirementInformation(requirement, parent)],
@@ -98,11 +101,9 @@ def merged_with(self, provider, requirement, parent):
         """
         infos = list(self.information)
         infos.append(RequirementInformation(requirement, parent))
-        candidates = [
-            c
-            for c in self.candidates
-            if provider.is_satisfied_by(requirement, c)
-        ]
+        candidates = provider.find_matches([r for r, _ in infos])
+        if not isinstance(candidates, collections_abc.Sequence):
+            candidates = list(candidates)
         criterion = type(self)(candidates, infos, list(self.incompatibilities))
         if not candidates:
             raise RequirementsConflicted(criterion)
@@ -179,7 +180,7 @@ def _push_new_state(self):
         self._states.append(state)
 
     def _merge_into_criterion(self, requirement, parent):
-        self._r.adding_requirement(requirement)
+        self._r.adding_requirement(requirement, parent)
         name = self._p.identify(requirement)
         try:
             crit = self.state.criteria[name]
@@ -218,51 +219,64 @@ def _get_criteria_to_update(self, candidate):
 
     def _attempt_to_pin_criterion(self, name, criterion):
         causes = []
-        for candidate in reversed(criterion.candidates):
+        for candidate in criterion.candidates:
             try:
                 criteria = self._get_criteria_to_update(candidate)
             except RequirementsConflicted as e:
                 causes.append(e.criterion)
                 continue
 
+            # Check the newly-pinned candidate actually works. This should
+            # always pass under normal circumstances, but in the case of a
+            # faulty provider, we will raise an error to notify the implementer
+            # to fix find_matches() and/or is_satisfied_by().
+            satisfied = all(
+                self._p.is_satisfied_by(r, candidate)
+                for r in criterion.iter_requirement()
+            )
+            if not satisfied:
+                raise InconsistentCandidate(candidate, criterion)
+
             # Put newly-pinned candidate at the end. This is essential because
             # backtracking looks at this mapping to get the last pin.
             self._r.pinning(candidate)
             self.state.mapping.pop(name, None)
             self.state.mapping[name] = candidate
             self.state.criteria.update(criteria)
 
-            # Check the newly-pinned candidate actually works. This should
-            # always pass under normal circumstances, but in the case of a
-            # faulty provider, we will raise an error to notify the implementer
-            # to fix find_matches() and/or is_satisfied_by().
-            if not self._is_current_pin_satisfying(name, criterion):
-                raise InconsistentCandidate(candidate, criterion)
-
             return []
 
         # All candidates tried, nothing works. This criterion is a dead
         # end, signal for backtracking.
         return causes
 
     def _backtrack(self):
-        # We need at least 3 states here:
-        # (a) One known not working, to drop.
-        # (b) One to backtrack to.
-        # (c) One to restore state (b) to its state prior to candidate-pinning,
+        # Drop the current state, it's known not to work.
+        del self._states[-1]
+
+        # We need at least 2 states here:
+        # (a) One to backtrack to.
+        # (b) One to restore state (a) to its state prior to candidate-pinning,
         #     so we can pin another one instead.
-        while len(self._states) >= 3:
-            del self._states[-1]
 
-            # Retract the last candidate pin, and create a new (b).
-            name, candidate = self._states.pop().mapping.popitem()
+        while len(self._states) >= 2:
+            # Retract the last candidate pin.
+            prev_state = self._states.pop()
+            try:
+                name, candidate = prev_state.mapping.popitem()
+            except KeyError:
+                continue
             self._r.backtracking(candidate)
+
+            # Create a new state to work on, with the newly known not-working
+            # candidate excluded.
             self._push_new_state()
 
             # Mark the retracted candidate as incompatible.
             criterion = self.state.criteria[name].excluded_of(candidate)
             if criterion is None:
                 # This state still does not work. Try the still previous state.
+                del self._states[-1]
                 continue
             self.state.criteria[name] = criterion
 

src/pip/_vendor/vendor.txt

@@ -16,7 +16,7 @@ requests==2.23.0
     chardet==3.0.4
     idna==2.9
     urllib3==1.25.8
-resolvelib==0.3.0
+resolvelib==0.4.0
 retrying==1.3.3
 setuptools==44.0.0
 six==1.14.0