docs/html/index.rst

@@ -17,7 +17,7 @@ Please take a look at our documentation for how to install and use pip:
    ux_research_design
    news
 
-In 2020, we're working on improvements to the heart of pip. Please `learn more and take our survey`_ to help us do it right.
+In 2020, we're working on improvements to the heart of pip: :ref:`Resolver changes 2020`. Please `learn more and take our survey`_ to help us do it right, and `join our user experience surveys pool`_.
 
 If you find bugs, need help, or want to talk to the developers, please use our mailing lists or chat rooms:
 
@@ -40,6 +40,7 @@ rooms, and mailing lists is expected to follow the `PSF Code of Conduct`_.
 
 .. _package installer: https://packaging.python.org/guides/tool-recommendations/
 .. _Python Package Index: https://pypi.org
+.. _join our user experience surveys pool: ux_research_design
 .. _learn more and take our survey: https://pyfound.blogspot.com/2020/03/new-pip-resolver-to-roll-out-this-year.html
 .. _Installation: https://pip.pypa.io/en/stable/installing.html
 .. _Documentation: https://pip.pypa.io/en/stable/

news/8924.feature

@@ -0,0 +1,2 @@
+New resolver: Tweak resolution logic to improve user experience when
+user-supplied requirements conflict.

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

@@ -117,6 +117,6 @@ def __bool__(self):
         # type: () -> bool
         if self._prefers_installed and self._installed:
             return True
-        return any(1 for _ in self)
+        return any(self)
 
     __nonzero__ = __bool__  # XXX: Python 2.

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

@@ -43,7 +43,7 @@ def __init__(
         self._constraints = constraints
         self._ignore_dependencies = ignore_dependencies
         self._upgrade_strategy = upgrade_strategy
-        self.user_requested = user_requested
+        self._user_requested = user_requested
 
     def identify(self, dependency):
         # type: (Union[Requirement, Candidate]) -> str
@@ -56,7 +56,8 @@ def get_preference(
         information  # type: Sequence[Tuple[Requirement, Candidate]]
     ):
         # type: (...) -> Any
-        return bool(candidates)
+        transitive = all(parent is not None for _, parent in information)
+        return (transitive, bool(candidates))
 
     def find_matches(self, requirements):
         # type: (Sequence[Requirement]) -> Iterable[Candidate]
@@ -79,7 +80,7 @@ def _eligible_for_upgrade(name):
             if self._upgrade_strategy == "eager":
                 return True
             elif self._upgrade_strategy == "only-if-needed":
-                return (name in self.user_requested)
+                return (name in self._user_requested)
             return False
 
         return self._factory.find_candidates(

tools/requirements/tests.txt

@@ -5,7 +5,7 @@ enum34; python_version < '3.4'
 freezegun
 mock
 pretend
-pytest<6.1.0 # Until https://github.com/pytest-dev/pytest-rerunfailures/issues/128 is fixed
+pytest
 pytest-cov
 pytest-rerunfailures
 pytest-timeout