fix transitive_marker handling

Without this fix, `test_solver_should_not_raise_errors_for_irrelevant_transitive_python_constraints` wrongly chooses the later `importlib-resources` version even though it is not compatible with the project's python constraint depending on which is resolved first, `virtualenv` or `pre-commit`, because the transitive marker of the other's dependency on `importlib-resources` is ignored.

src/poetry/mixology/term.py

@@ -95,7 +95,13 @@ def _relation(self, other: Term) -> str:
                     return SetRelation.SUBSET
 
                 # foo ^1.5.0 is disjoint with not foo ^1.0.0
-                if other_constraint.allows_all(self.constraint):
+                if (
+                    other_constraint.allows_all(self.constraint)
+                    # if transitive markers are not equal we have to handle it
+                    # as overlapping so that markers are merged later
+                    and self.dependency.transitive_marker
+                    == other.dependency.transitive_marker
+                ):
                     return SetRelation.DISJOINT
 
                 # foo ^1.0.0 overlaps not foo ^1.5.0
@@ -177,7 +183,12 @@ def _non_empty_term(
             and other.dependency.is_direct_origin()
             else self.dependency
         )
-        return Term(dependency.with_constraint(constraint), is_positive)
+        new_dep = dependency.with_constraint(constraint)
+        if is_positive and other.is_positive():
+            new_dep.transitive_marker = self.dependency.transitive_marker.union(
+                other.dependency.transitive_marker
+            )
+        return Term(new_dep, is_positive)
 
     def __str__(self) -> str:
         prefix = "not " if not self.is_positive() else ""

src/poetry/mixology/version_solver.py

@@ -514,6 +514,8 @@ def _choose_package_version(self) -> str | None:
 
                 complete_name = dependency.complete_name
                 return complete_name
+
+            package.dependency.transitive_marker = dependency.transitive_marker
         else:
             package = locked
 

tests/puzzle/test_solver.py

@@ -4329,8 +4329,13 @@ def test_solver_can_resolve_python_restricted_package_dependencies(
     )
 
 
+@pytest.mark.parametrize("virtualenv_before_pre_commit", [False, True])
 def test_solver_should_not_raise_errors_for_irrelevant_transitive_python_constraints(
-    solver: Solver, repo: Repository, package: ProjectPackage
+    solver: Solver,
+    repo: Repository,
+    package: ProjectPackage,
+    mocker: MockerFixture,
+    virtualenv_before_pre_commit: bool,
 ) -> None:
     package.python_versions = "~2.7 || ^3.5"
     set_package_python_versions(solver.provider, "~2.7 || ^3.5")
@@ -4367,6 +4372,24 @@ def test_solver_should_not_raise_errors_for_irrelevant_transitive_python_constra
     repo.add_package(pre_commit)
     repo.add_package(importlib_resources)
     repo.add_package(importlib_resources_3_2_1)
+
+    def patched_choose_next(unsatisfied: list[Dependency]) -> Dependency:
+        order = (
+            ("root", "virtualenv", "pre-commit", "importlib-resources")
+            if virtualenv_before_pre_commit
+            else ("root", "pre-commit", "virtualenv", "importlib-resources")
+        )
+        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,
+    )
+
     transaction = solver.solve()
 
     check_solver_result(