[inspections] PY-85120 Do not consider expressions like a: list[int] | None = None a type alias

Target expression should have either explicit `TypeAlias` annotation or valid type expression in assignment without type annotation (to be considered implicit type alias)

(cherry picked from commit 1059a8df2d221bd068eee706139be20c256df549)

GitOrigin-RevId: 8c952138fbc4124f02f717ce8a1784c1f0dc86b2

python/python-psi-impl/src/com/jetbrains/python/psi/PyFileElementType.java

@@ -60,7 +60,7 @@ public class PyFileElementType extends IStubFileElementType<PyFileStub> {
   @Override
   public int getStubVersion() {
     // Don't forget to update versions of indexes that use the updated stub-based elements
-    return 103;
+    return 104;
   }
 
   @Override

python/python-psi-impl/src/com/jetbrains/python/psi/impl/stubs/PyTypingAliasStubType.java

@@ -80,7 +80,7 @@ public final class PyTypingAliasStubType extends CustomTargetExpressionStubType<
       return null;
     }
 
-    if (isExplicitTypeAlias(target) || looksLikeTypeHint(value)) {
+    if (isExplicitTypeAlias(target) || (looksLikeTypeHint(value) && target.getAnnotation() == null)) {
       return value;
     }
     return null;

python/testData/stubs/TypeAliasStubs.py

@@ -22,6 +22,9 @@ bin3_ok = Union[str, bool] | None
 bin4_notOk = str & int
 list_notOk = [int, str]
 
+bin5_notOk: int | str = "foo"
+list_none_notOk: list[int] | None = None
+
 callable_ok = Callable[[int, str], bool]
 
 explicit_alias1_ok: TypeAlias = 'Foo is bar.'

python/testSrc/com/jetbrains/python/inspections/PyTypeHintsInspectionTest.java

@@ -3189,6 +3189,16 @@ public class PyTypeHintsInspectionTest extends PyInspectionTestCase {
                    """);
   }
 
+  // PY-85120
+  public void testTargetExpressionWithAnnotationNotConsideredTypeAlias() {
+    doTestByText("""
+                   a: list[int] | None = None  # Not a type alias
+                   
+                   if a:
+                       _ = a[1]  # No error expected
+                   """);
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {