Fix dependency resolution for children of conditional dependencies

poetry/console/commands/debug/resolve.py

@@ -48,9 +48,9 @@ class DebugResolveCommand(Command):
                 for ex in extras:
                     dep.extras.append(ex)
 
-            package.python_versions = self.option("python") or (
-                self.poetry.package.python_versions
-            )
+        package.python_versions = self.option("python") or (
+            self.poetry.package.python_versions
+        )
 
         pool = self.poetry.pool
 

poetry/mixology/term.py

@@ -14,7 +14,7 @@ class Term(object):
     See https://github.com/dart-lang/pub/tree/master/doc/solver.md#term.
     """
 
-    def __init__(self, dependency, is_positive):  # type: Dependency  # type: bool
+    def __init__(self, dependency, is_positive):  # type: (Dependency, bool)  -> None
         self._dependency = dependency
         self._positive = is_positive
 
@@ -158,7 +158,10 @@ class Term(object):
         if constraint.is_empty():
             return
 
-        return Term(Dependency(self.dependency.name, constraint), is_positive)
+        dep = Dependency(self.dependency.name, constraint)
+        dep.python_versions = str(self.dependency.python_versions)
+
+        return Term(dep, is_positive)
 
     def __str__(self):
         return "{}{}".format("not " if not self.is_positive() else "", self._dependency)

poetry/packages/dependency.py

@@ -10,7 +10,6 @@ from poetry.version.markers import AnyMarker
 from poetry.version.markers import parse_marker
 
 from .constraints import parse_constraint as parse_generic_constraint
-from .constraints.any_constraint import AnyConstraint
 from .constraints.constraint import Constraint
 from .constraints.multi_constraint import MultiConstraint
 from .constraints.union_constraint import UnionConstraint
@@ -49,6 +48,8 @@ class Dependency(object):
 
         self._python_versions = "*"
         self._python_constraint = parse_constraint("*")
+        self._transitive_python_versions = None
+        self._transitive_python_constraint = None
 
         self._extras = []
         self._in_extras = []
@@ -96,10 +97,29 @@ class Dependency(object):
             )
 
     @property
+    def transitive_python_versions(self):
+        if self._transitive_python_versions is None:
+            return self._python_versions
+
+        return self._transitive_python_versions
+
+    @transitive_python_versions.setter
+    def transitive_python_versions(self, value):
+        self._transitive_python_versions = value
+        self._transitive_python_constraint = parse_constraint(value)
+
+    @property
     def python_constraint(self):
         return self._python_constraint
 
     @property
+    def transitive_python_constraint(self):
+        if self._transitive_python_constraint is None:
+            return self._python_constraint
+
+        return self._transitive_python_constraint
+
+    @property
     def extras(self):  # type: () -> list
         return self._extras
 

poetry/puzzle/provider.py

@@ -317,7 +317,7 @@ class Provider:
 
     def incompatibilities_for(
         self, package
-    ):  # type: (Package) -> List[Incompatibility]
+    ):  # type: (DependencyPackage) -> List[Incompatibility]
         """
         Returns incompatibilities that encapsulate a given package's dependencies,
         or that it can't be safely selected.
@@ -335,14 +335,19 @@ class Provider:
             if not package.python_constraint.allows_all(
                 self._package.python_constraint
             ):
+                intersection = package.python_constraint.intersect(
+                    package.dependency.transitive_python_constraint
+                )
+                difference = package.dependency.transitive_python_constraint.difference(
+                    intersection
+                )
                 if (
-                    package.dependency.python_constraint.is_any()
-                    or not self._package.python_constraint.allows_all(
-                        package.dependency.python_constraint
-                    )
-                    or not package.python_constraint.allows_all(
+                    package.dependency.transitive_python_constraint.is_any()
+                    or self._package.python_constraint.intersect(
                         package.dependency.python_constraint
-                    )
+                    ).is_empty()
+                    or intersection.is_empty()
+                    or not difference.is_empty()
                 ):
                     return [
                         Incompatibility(
@@ -368,7 +373,9 @@ class Provider:
             for dep in dependencies
         ]
 
-    def complete_package(self, package):  # type: (str, Version) -> Package
+    def complete_package(
+        self, package
+    ):  # type: (DependencyPackage) -> DependencyPackage
         if package.is_root():
             return package
 
@@ -518,6 +525,14 @@ class Provider:
                 )
                 raise CompatibilityError(*python_constraints)
 
+        if not package.dependency.python_constraint.is_any():
+            for dep in dependencies:
+                dep.transitive_python_versions = str(
+                    dep.python_constraint.intersect(
+                        package.dependency.python_constraint
+                    )
+                )
+
         package.requires = dependencies
 
         return package

poetry/version/markers.py

@@ -432,9 +432,6 @@ class MultiMarker(BaseMarker):
         if other.is_empty():
             return other
 
-        if other in self._markers:
-            return other
-
         new_markers = self._markers + [other]
 
         return MultiMarker.of(*new_markers)

tests/puzzle/test_solver.py

@@ -962,6 +962,39 @@ def test_solver_does_not_trigger_conflict_for_python_constraint_if_python_requir
     )
 
 
+def test_solver_does_not_trigger_conflict_for_python_constraint_if_python_requirement_is_compatible_multiple(
+    solver, repo, package
+):
+    package.python_versions = "~2.7 || ^3.4"
+    package.add_dependency("A", {"version": "^1.0", "python": "^3.6"})
+    package.add_dependency("B", {"version": "^1.0", "python": "^3.5.3"})
+
+    package_a = get_package("A", "1.0.0")
+    package_a.python_versions = ">=3.6"
+    package_a.add_dependency("B", "^1.0")
+
+    package_b = get_package("B", "1.0.0")
+    package_b.python_versions = ">=3.5.3"
+
+    repo.add_package(package_a)
+    repo.add_package(package_b)
+
+    ops = solver.solve()
+
+    check_solver_result(
+        ops,
+        [
+            {"job": "install", "package": package_b},
+            {"job": "install", "package": package_a},
+        ],
+    )
+
+    assert str(ops[0].package.marker) == (
+        'python_version >= "3.6" and python_version < "4.0" '
+        'or python_version >= "3.5.3" and python_version < "4.0.0"'
+    )
+
+
 def test_solver_triggers_conflict_for_dependency_python_not_fully_compatible_with_package_python(
     solver, repo, package
 ):

tests/version/test_markers.py

@@ -70,6 +70,15 @@ def test_single_marker_intersect_with_multi():
     )
 
 
+def test_single_marker_intersect_with_multi_with_duplicate():
+    m = parse_marker('python_version < "4.0"')
+
+    intersection = m.intersect(
+        parse_marker('sys_platform == "darwin" and python_version < "4.0"')
+    )
+    assert str(intersection) == 'sys_platform == "darwin" and python_version < "4.0"'
+
+
 def test_single_marker_intersect_with_multi_compacts_constraint():
     m = parse_marker('python_version < "3.6"')