perf: return least complex marker when building intersection

This is analogous to what we do when building the union. Although this means extra work, it pays off if the resulting marker is used in another marker operation.

src/poetry/core/version/markers.py

@@ -1076,7 +1076,24 @@ def dnf(marker: BaseMarker) -> BaseMarker:
 
 
 def intersection(*markers: BaseMarker) -> BaseMarker:
-    return dnf(MultiMarker(*markers))
+    # Sometimes normalization makes it more complicate instead of simple
+    # -> choose candidate with the least complexity
+    unnormalized: BaseMarker = MultiMarker(*markers)
+    while (
+        isinstance(unnormalized, (MultiMarker, MarkerUnion))
+        and len(unnormalized.markers) == 1
+    ):
+        unnormalized = unnormalized.markers[0]
+
+    disjunction = dnf(MultiMarker(*markers))
+    if not isinstance(disjunction, MarkerUnion):
+        return disjunction
+
+    conjunction = cnf(disjunction)
+    if not isinstance(conjunction, MultiMarker):
+        return conjunction
+
+    return min(disjunction, conjunction, unnormalized, key=lambda x: x.complexity)
 
 
 def union(*markers: BaseMarker) -> BaseMarker:

tests/version/test_markers.py

@@ -940,9 +940,8 @@ def test_marker_union_intersect_single_marker() -> None:
 
     intersection = m.intersect(parse_marker('implementation_name == "cpython"'))
     assert (
-        str(intersection)
-        == 'sys_platform == "darwin" and implementation_name == "cpython" '
-        'or python_version < "3.4" and implementation_name == "cpython"'
+        str(intersection) == '(sys_platform == "darwin" or python_version < "3.4")'
+        ' and implementation_name == "cpython"'
     )
 
 
@@ -968,11 +967,8 @@ def test_marker_union_intersect_marker_union() -> None:
         parse_marker('implementation_name == "cpython" or os_name == "Windows"')
     )
     assert (
-        str(intersection)
-        == 'sys_platform == "darwin" and implementation_name == "cpython" '
-        'or sys_platform == "darwin" and os_name == "Windows" or '
-        'python_version < "3.4" and implementation_name == "cpython" or '
-        'python_version < "3.4" and os_name == "Windows"'
+        str(intersection) == '(sys_platform == "darwin" or python_version < "3.4") and '
+        '(implementation_name == "cpython" or os_name == "Windows")'
     )
 
 
@@ -1000,18 +996,16 @@ def test_marker_union_intersect_multi_marker() -> None:
 
     # Intersection isn't _quite_ symmetrical.
     expected1 = (
-        'sys_platform == "darwin" and implementation_name == "cpython" and os_name =='
-        ' "Windows" or python_version < "3.4" and implementation_name == "cpython" and'
-        ' os_name == "Windows"'
+        '(sys_platform == "darwin" or python_version < "3.4")'
+        ' and implementation_name == "cpython" and os_name == "Windows"'
     )
 
     intersection = m1.intersect(m2)
     assert str(intersection) == expected1
 
     expected2 = (
-        'implementation_name == "cpython" and os_name == "Windows" and sys_platform'
-        ' == "darwin" or implementation_name == "cpython" and os_name == "Windows"'
-        ' and python_version < "3.4"'
+        'implementation_name == "cpython" and os_name == "Windows"'
+        ' and (sys_platform == "darwin" or python_version < "3.4")'
     )
 
     intersection = m2.intersect(m1)