Release 21.1.2

AUTHORS.txt

@@ -61,6 +61,7 @@ AraHaan
 Arindam Choudhury
 Armin Ronacher
 Artem
+Arun Babu Neelicattu
 Ashley Manton
 Ashwin Ramaswami
 atse
@@ -182,6 +183,7 @@ Desetude
 Devesh Kumar Singh
 Diego Caraballo
 DiegoCaraballo
+Dimitri Merejkowsky
 Dmitry Gladkov
 Domen Kožar
 Dominic Davis-Foster
@@ -408,6 +410,7 @@ Nathaniel J. Smith
 Nehal J Wani
 Neil Botelho
 Nguyễn Gia Phong
+Nicholas Serra
 Nick Coghlan
 Nick Stenning
 Nick Timkovich

NEWS.rst

@@ -9,6 +9,21 @@
 
 .. towncrier release notes start
 
+21.1.2 (2021-05-23)
+===================
+
+Bug Fixes
+---------
+
+- New resolver: Correctly exclude an already installed package if its version is
+  known to be incompatible to stop the dependency resolution process with a clear
+  error message. (`#9841 <https://github.com/pypa/pip/issues/9841>`_)
+- Allow ZIP to archive files with timestamps earlier than 1980. (`#9910 <https://github.com/pypa/pip/issues/9910>`_)
+- Emit clearer error message when a project root does not contain either
+  ``pyproject.toml``, ``setup.py`` or ``setup.cfg``. (`#9944 <https://github.com/pypa/pip/issues/9944>`_)
+- Fix detection of existing standalone pip instance for PEP 517 builds. (`#9953 <https://github.com/pypa/pip/issues/9953>`_)
+
+
 21.1.1 (2021-04-30)
 ===================
 
@@ -18,7 +33,7 @@ Deprecations and Removals
 - Temporarily set the new "Value for ... does not match" location warnings level
   to *DEBUG*, to hide them from casual users. This prepares pip 21.1 for CPython
   inclusion, while pip maintainers digest the first intake of location mismatch
-  issues for the ``distutils``-``sysconfig`` trasition. (`#9912 <https://github.com/pypa/pip/issues/9912>`_)
+  issues for the ``distutils``-``sysconfig`` transition. (`#9912 <https://github.com/pypa/pip/issues/9912>`_)
 
 Bug Fixes
 ---------

src/pip/_internal/build_env.py

@@ -50,15 +50,18 @@ def _create_standalone_pip() -> Iterator[str]:
     """
     source = pathlib.Path(pip_location).resolve().parent
 
-    # Return the current instance if it is already a zip file. This can happen
-    # if a PEP 517 requirement is an sdist itself.
-    if not source.is_dir() and source.parent.name == "__env_pip__.zip":
+    # Return the current instance if `source` is not a directory. We can't build
+    # a zip from this, and it likely means the instance is already standalone.
+    if not source.is_dir():
         yield str(source)
         return
 
     with TempDirectory(kind="standalone-pip") as tmp_dir:
         pip_zip = os.path.join(tmp_dir.path, "__env_pip__.zip")
-        with zipfile.ZipFile(pip_zip, "w") as zf:
+        kwargs = {}
+        if sys.version_info >= (3, 8):
+            kwargs["strict_timestamps"] = False
+        with zipfile.ZipFile(pip_zip, "w", **kwargs) as zf:
             for child in source.rglob("*"):
                 zf.write(child, child.relative_to(source.parent).as_posix())
         yield os.path.join(pip_zip, "pip")

src/pip/_internal/req/req_install.py

@@ -509,13 +509,32 @@ def load_pyproject_toml(self):
             self.unpacked_source_directory, backend, backend_path=backend_path,
         )
 
+    def _check_setup_py_or_cfg_exists(self) -> bool:
+        """Check if the requirement actually has a setuptools build file.
+
+        If setup.py does not exist, we also check setup.cfg in the same
+        directory and allow the directory if that exists.
+        """
+        if os.path.exists(self.setup_py_path):
+            return True
+        stem, ext = os.path.splitext(self.setup_py_path)
+        if ext == ".py" and os.path.exists(f"{stem}.cfg"):
+            return True
+        return False
+
     def _generate_metadata(self):
         # type: () -> str
         """Invokes metadata generator functions, with the required arguments.
         """
         if not self.use_pep517:
             assert self.unpacked_source_directory
 
+            if not self._check_setup_py_or_cfg_exists():
+                raise InstallationError(
+                    f'File "setup.py" or "setup.cfg" not found for legacy '
+                    f'project {self}.'
+                )
+
             return generate_metadata_legacy(
                 build_env=self.build_env,
                 setup_py_path=self.setup_py_path,

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

@@ -240,18 +240,29 @@ def _iter_found_candidates(
             hashes &= ireq.hashes(trust_internet=False)
             extras |= frozenset(ireq.extras)
 
-        # Get the installed version, if it matches, unless the user
-        # specified `--force-reinstall`, when we want the version from
-        # the index instead.
-        installed_candidate = None
-        if not self._force_reinstall and name in self._installed_dists:
-            installed_dist = self._installed_dists[name]
-            if specifier.contains(installed_dist.version, prereleases=True):
-                installed_candidate = self._make_candidate_from_dist(
-                    dist=installed_dist,
-                    extras=extras,
-                    template=template,
-                )
+        def _get_installed_candidate() -> Optional[Candidate]:
+            """Get the candidate for the currently-installed version."""
+            # If --force-reinstall is set, we want the version from the index
+            # instead, so we "pretend" there is nothing installed.
+            if self._force_reinstall:
+                return None
+            try:
+                installed_dist = self._installed_dists[name]
+            except KeyError:
+                return None
+            # Don't use the installed distribution if its version does not fit
+            # the current dependency graph.
+            if not specifier.contains(installed_dist.version, prereleases=True):
+                return None
+            candidate = self._make_candidate_from_dist(
+                dist=installed_dist,
+                extras=extras,
+                template=template,
+            )
+            # The candidate is a known incompatiblity. Don't use it.
+            if id(candidate) in incompatible_ids:
+                return None
+            return candidate
 
         def iter_index_candidate_infos():
             # type: () -> Iterator[IndexCandidateInfo]
@@ -283,7 +294,7 @@ def iter_index_candidate_infos():
 
         return FoundCandidates(
             iter_index_candidate_infos,
-            installed_candidate,
+            _get_installed_candidate(),
             prefers_installed,
             incompatible_ids,
         )

src/pip/_internal/utils/misc.py

@@ -269,18 +269,14 @@ def tabulate(rows):
     return table, sizes
 
 
-def is_installable_dir(path):
-    # type: (str) -> bool
-    """Is path is a directory containing setup.py or pyproject.toml?"""
+def is_installable_dir(path: str) -> bool:
+    """Is path is a directory containing pyproject.toml, setup.cfg or setup.py?"""
     if not os.path.isdir(path):
         return False
-    setup_py = os.path.join(path, "setup.py")
-    if os.path.isfile(setup_py):
-        return True
-    pyproject_toml = os.path.join(path, "pyproject.toml")
-    if os.path.isfile(pyproject_toml):
-        return True
-    return False
+    return any(
+        os.path.isfile(os.path.join(path, signifier))
+        for signifier in ("pyproject.toml", "setup.cfg", "setup.py")
+    )
 
 
 def read_chunks(file, size=io.DEFAULT_BUFFER_SIZE):

tests/functional/test_new_resolver.py

@@ -1827,3 +1827,33 @@ def test_new_resolver_direct_url_with_extras(tmp_path, script):
     assert not get_created_direct_url(result, "pkg1")
     assert get_created_direct_url(result, "pkg2")
     assert not get_created_direct_url(result, "pkg3")
+
+
+def test_new_resolver_modifies_installed_incompatible(script):
+    create_basic_wheel_for_package(script, name="a", version="1")
+    create_basic_wheel_for_package(script, name="a", version="2")
+    create_basic_wheel_for_package(script, name="a", version="3")
+    create_basic_wheel_for_package(script, name="b", version="1", depends=["a==1"])
+    create_basic_wheel_for_package(script, name="b", version="2", depends=["a==2"])
+    create_basic_wheel_for_package(script, name="c", version="1", depends=["a!=1"])
+    create_basic_wheel_for_package(script, name="c", version="2", depends=["a!=1"])
+    create_basic_wheel_for_package(script, name="d", version="1", depends=["b", "c"])
+
+    script.pip(
+        "install",
+        "--no-cache-dir", "--no-index",
+        "--find-links", script.scratch_path,
+        "b==1",
+    )
+
+    # d-1 depends on b and c. b-1 is already installed and therefore first
+    # pinned, but later found to be incompatible since the "a==1" dependency
+    # makes all c versions impossible to satisfy. The resolver should be able to
+    # discard b-1 and backtrack, so b-2 is selected instead.
+    script.pip(
+        "install",
+        "--no-cache-dir", "--no-index",
+        "--find-links", script.scratch_path,
+        "d==1",
+    )
+    assert_installed(script, d="1", c="2", b="2", a="2")

tools/news/template.rst

@@ -1,6 +1,6 @@
 {% set underline = "=" %}
-{{ top_line }}
-{{ underline * top_line|length }}
+
+{{ underline * ((top_line)|length) }}
 {% for section in sections %}
 {% set underline = "-" %}
 {% if section %}