fix Type::cycle_normalized

crates/ty_python_semantic/resources/corpus/divergent.py

@@ -70,3 +70,24 @@ def descent(x: int, y: int):
 
 def count_set_bits(n):
     return 1 + count_set_bits(n & n - 1) if n else 0
+
+class Literal:
+    def __invert__(self):
+        return Literal()
+
+class OR:
+    def __invert__(self):
+        return AND()
+
+class AND:
+    def __invert__(self):
+        return OR()
+
+def to_NNF(cond):
+    if cond:
+        return ~to_NNF(cond)
+    if cond:
+        return OR()
+    if cond:
+        return AND()
+    return Literal()

crates/ty_python_semantic/resources/mdtest/function/return_type.md

@@ -429,7 +429,7 @@ def list_int(x: int):
         return list1(x)
 
 # TODO: should be `list[int]`
-reveal_type(list_int(1))  # revealed: list[Divergent] | list[int] | list[Divergent]
+reveal_type(list_int(1))  # revealed: list[Divergent] | list[Divergent] | list[int]
 
 def tuple_obj(cond: bool):
     if cond:

crates/ty_python_semantic/src/types.rs

@@ -966,7 +966,8 @@ impl<'db> Type<'db> {
                 if has_divergent_type_in_cycle(previous) && !has_divergent_type_in_cycle(self) {
                     self
                 } else {
-                    UnionType::from_elements_cycle_recovery(db, [self, previous])
+                    // The current type is unioned to the previous type. Unioning in the reverse order can cause the fixed-point iterations to converge slowly or even fail.
+                    UnionType::from_elements_cycle_recovery(db, [previous, self])
                 }
             }
         }