provider: raise error if there are incompatible constraints in the requirements of a package

src/poetry/puzzle/provider.py

@@ -59,6 +59,18 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
+class IncompatibleConstraintsError(Exception):
+    """
+    Exception when there are duplicate dependencies with incompatible constraints.
+    """
+
+    def __init__(self, package: Package, *dependencies: Dependency) -> None:
+        constraints = "\n".join(dep.to_pep_508() for dep in dependencies)
+        super().__init__(
+            f"Incompatible constraints in requirements of {package}:\n{constraints}"
+        )
+
+
 class Indicator(ProgressIndicator):
     CONTEXT: str | None = None
 
@@ -740,7 +752,7 @@ class Provider:
                 f"<warning>Different requirements found for {warnings}.</warning>"
             )
 
-            deps = self._handle_any_marker_dependencies(deps)
+            deps = self._handle_any_marker_dependencies(package, deps)
 
             overrides = []
             overrides_marker_intersection: BaseMarker = AnyMarker()
@@ -975,7 +987,7 @@ class Provider:
         return deps
 
     def _handle_any_marker_dependencies(
-        self, dependencies: list[Dependency]
+        self, package: Package, dependencies: list[Dependency]
     ) -> list[Dependency]:
         """
         We need to check if one of the duplicate dependencies
@@ -999,11 +1011,16 @@ class Provider:
         any_markers_dependencies = [d for d in dependencies if d.marker.is_any()]
         other_markers_dependencies = [d for d in dependencies if not d.marker.is_any()]
 
-        for dep_any in any_markers_dependencies:
+        if any_markers_dependencies:
             for dep_other in other_markers_dependencies:
-                dep_other.constraint = dep_other.constraint.intersect(
-                    dep_any.constraint
-                )
+                new_constraint = dep_other.constraint
+                for dep_any in any_markers_dependencies:
+                    new_constraint = new_constraint.intersect(dep_any.constraint)
+                if new_constraint.is_empty():
+                    raise IncompatibleConstraintsError(
+                        package, dep_other, *any_markers_dependencies
+                    )
+                dep_other.constraint = new_constraint
 
         marker = other_markers_dependencies[0].marker
         for other_dep in other_markers_dependencies[1:]:

tests/puzzle/test_solver.py

 from __future__ import annotations
 
+import re
+
 from pathlib import Path
 from typing import TYPE_CHECKING
 from typing import Any
@@ -19,6 +21,7 @@ from poetry.factory import Factory
 from poetry.packages import DependencyPackage
 from poetry.puzzle import Solver
 from poetry.puzzle.exceptions import SolverProblemError
+from poetry.puzzle.provider import IncompatibleConstraintsError
 from poetry.repositories.repository import Repository
 from poetry.repositories.repository_pool import RepositoryPool
 from poetry.utils.env import MockEnv
@@ -1480,6 +1483,27 @@ def test_solver_duplicate_dependencies_different_constraints_merge_no_markers(
     )
 
 
+def test_solver_duplicate_dependencies_different_constraints_conflict(
+    solver: Solver, repo: Repository, package: ProjectPackage
+) -> None:
+    package.add_dependency(Factory.create_dependency("A", ">=1.1"))
+    package.add_dependency(
+        Factory.create_dependency("A", {"version": "<1.1", "python": "3.10"})
+    )
+
+    repo.add_package(get_package("A", "1.0"))
+    repo.add_package(get_package("A", "1.1"))
+    repo.add_package(get_package("A", "1.2"))
+
+    expectation = (
+        "Incompatible constraints in requirements of root (1.0):\n"
+        'A (<1.1) ; python_version == "3.10"\n'
+        "A (>=1.1)"
+    )
+    with pytest.raises(IncompatibleConstraintsError, match=re.escape(expectation)):
+        solver.solve()
+
+
 def test_solver_duplicate_dependencies_different_constraints_discard_no_markers1(
     solver: Solver, repo: Repository, package: ProjectPackage
 ) -> None: