fix considered python constraint for overrides (#10157)

Previously, the Python constraint of the root package has always been used to check for incompatibilities, even if the Python constraint had effectively been restricted by overrides before. This could result in false conflicts à la "The current project's supported Python range is not compatible with some of the required packages Python requirement."

src/poetry/puzzle/provider.py

@@ -125,7 +125,7 @@ def __init__(
         self._direct_origin = DirectOrigin(self._pool.artifact_cache)
         self._io = io
         self._env: Env | None = None
-        self._python_constraint = package.python_constraint
+        self._package_python_constraint = package.python_constraint
         self._is_debugging: bool = self._io.is_debug() or self._io.is_very_verbose()
         self._overrides: dict[Package, dict[str, Dependency]] = {}
         self._deferred_cache: dict[Dependency, Package] = {}
@@ -159,11 +159,29 @@ def pool(self) -> RepositoryPool:
     def use_latest(self) -> Collection[NormalizedName]:
         return self._use_latest
 
+    @functools.cached_property
+    def _overrides_marker_intersection(self) -> BaseMarker:
+        overrides_marker_intersection: BaseMarker = AnyMarker()
+        for dep_overrides in self._overrides.values():
+            for dep in dep_overrides.values():
+                overrides_marker_intersection = overrides_marker_intersection.intersect(
+                    dep.marker
+                )
+        return overrides_marker_intersection
+
+    @functools.cached_property
+    def _python_constraint(self) -> VersionConstraint:
+        return self._package_python_constraint.intersect(
+            get_python_constraint_from_marker(self._overrides_marker_intersection)
+        )
+
     def is_debugging(self) -> bool:
         return self._is_debugging
 
     def set_overrides(self, overrides: dict[Package, dict[str, Dependency]]) -> None:
         self._overrides = overrides
+        self.__dict__.pop("_python_constraint", None)
+        self.__dict__.pop("_overrides_marker_intersection", None)
 
     def load_deferred(self, load_deferred: bool) -> None:
         self._load_deferred = load_deferred
@@ -180,16 +198,18 @@ def use_source_root(self, source_root: Path) -> Iterator[Provider]:
 
     @contextmanager
     def use_environment(self, env: Env) -> Iterator[Provider]:
-        original_python_constraint = self._python_constraint
+        original_python_constraint = self._package_python_constraint
 
         self._env = env
-        self._python_constraint = Version.parse(env.marker_env["python_full_version"])
+        self._package_python_constraint = Version.parse(
+            env.marker_env["python_full_version"]
+        )
 
         try:
             yield self
         finally:
             self._env = None
-            self._python_constraint = original_python_constraint
+            self._package_python_constraint = original_python_constraint
 
     @contextmanager
     def use_latest_for(self, names: Collection[NormalizedName]) -> Iterator[Provider]:
@@ -629,16 +649,12 @@ def complete_package(
                 continue
 
             # Sort out irrelevant requirements
-            overrides_marker_intersection: BaseMarker = AnyMarker()
-            for dep_overrides in self._overrides.values():
-                for dep in dep_overrides.values():
-                    overrides_marker_intersection = (
-                        overrides_marker_intersection.intersect(dep.marker)
-                    )
             deps = [
                 dep
                 for dep in deps
-                if not overrides_marker_intersection.intersect(dep.marker).is_empty()
+                if not self._overrides_marker_intersection.intersect(
+                    dep.marker
+                ).is_empty()
             ]
             if len(deps) < 2:
                 if not deps or (len(deps) == 1 and deps[0].constraint.is_empty()):

tests/puzzle/test_solver.py

@@ -58,7 +58,7 @@
 
 def set_package_python_versions(provider: Provider, python_versions: str) -> None:
     provider._package.python_versions = python_versions
-    provider._python_constraint = provider._package.python_constraint
+    provider._package_python_constraint = provider._package.python_constraint
 
 
 def check_solver_result(
@@ -4445,6 +4445,72 @@ def patched_choose_next(unsatisfied: list[Dependency]) -> Dependency:
     )
 
 
+@pytest.mark.parametrize("numpy_before_pandas", [False, True])
+@pytest.mark.parametrize("conflict", [False, True])
+def test_solver_should_not_raise_errors_for_irrelevant_transitive_python_constraints2(
+    solver: Solver,
+    repo: Repository,
+    package: ProjectPackage,
+    mocker: MockerFixture,
+    numpy_before_pandas: bool,
+    conflict: bool,
+) -> None:
+    """This time with overrides."""
+    package.python_versions = ">=3.6.2, <3.10"
+    set_package_python_versions(solver.provider, ">=3.6.2, <3.10")
+    package.add_dependency(Factory.create_dependency("pandas", ">=1"))
+    package.add_dependency(
+        Factory.create_dependency("numpy", {"version": ">=1.20.0", "python": ">=3.7"})
+    )
+    package.add_dependency(
+        Factory.create_dependency("numpy", {"version": "*", "python": "<3.7"})
+    )
+
+    pandas = get_package("pandas", "1.1.5")
+    pandas.add_dependency(Factory.create_dependency("numpy", ">=1.15"))
+
+    numpy_19 = get_package("numpy", "1.19")
+    numpy_19.python_versions = ">=3.6"
+    numpy_20 = get_package("numpy", "1.20")
+    numpy_20.python_versions = ">=3.8" if conflict else ">=3.7"
+
+    repo.add_package(pandas)
+    repo.add_package(numpy_19)
+    repo.add_package(numpy_20)
+
+    def patched_choose_next(unsatisfied: list[Dependency]) -> Dependency:
+        order = (
+            ("root", "pandas", "numpy")
+            if numpy_before_pandas
+            else ("root", "numpy", "pandas")
+        )
+        for preferred in order:
+            for dep in unsatisfied:
+                if dep.name == preferred:
+                    return dep
+        raise RuntimeError
+
+    mocker.patch(
+        "poetry.mixology.version_solver.VersionSolver._choose_next",
+        side_effect=patched_choose_next,
+    )
+
+    if conflict:
+        with pytest.raises(SolverProblemError):
+            solver.solve()
+    else:
+        transaction = solver.solve()
+
+        check_solver_result(
+            transaction,
+            [
+                {"job": "install", "package": numpy_19},
+                {"job": "install", "package": numpy_20},
+                {"job": "install", "package": pandas},
+            ],
+        )
+
+
 @pytest.mark.parametrize("is_locked", [False, True])
 def test_solver_keeps_multiple_locked_dependencies_for_same_package(
     package: ProjectPackage,