PY-22730 Don't render Optional[Any] as Union[None, Any]

Specifically, handle "weak" union type only after checking that a
union can be displayed as Optional.

python/src/com/jetbrains/python/documentation/PyTypeModelBuilder.java

@@ -17,6 +17,7 @@ package com.jetbrains.python.documentation;
 
 import com.google.common.collect.Collections2;
 import com.google.common.collect.Maps;
+import com.intellij.openapi.util.Ref;
 import com.intellij.psi.PsiElement;
 import com.intellij.util.containers.ContainerUtil;
 import com.jetbrains.python.PyNames;
@@ -268,7 +269,11 @@ public class PyTypeModelBuilder {
     else if (type instanceof PyUnionType && allowUnions) {
       final PyUnionType unionType = (PyUnionType)type;
       final Collection<PyType> unionMembers = unionType.getMembers();
-      if (type instanceof PyDynamicallyEvaluatedType || PyTypeChecker.isUnknown(type, false)) {
+      final Ref<PyType> optionalType = getOptionalType(unionType);
+      if (optionalType != null) {
+        result = new OptionalType(build(optionalType.get(), true));
+      }
+      else if (type instanceof PyDynamicallyEvaluatedType || PyTypeChecker.isUnknown(type, false)) {
         result = new UnknownType(build(unionType.excludeNull(myContext), true));
       }
       else if (unionMembers.stream().allMatch(t -> t instanceof PyClassType && ((PyClassType)t).isDefinition())) {
@@ -276,10 +281,7 @@ public class PyTypeModelBuilder {
         result = new ClassObjectType(new OneOf(instanceTypes));
       }
       else {
-        result = Optional
-          .ofNullable(getOptionalType(unionType))
-          .<TypeModel>map(optionalType -> new OptionalType(build(optionalType, true)))
-          .orElseGet(() -> new OneOf(Collections2.transform(unionMembers, t -> build(t, false))));
+        result = new OneOf(Collections2.transform(unionMembers, t -> build(t, false)));
       }
     }
     else if (type instanceof PyCallableType && !(type instanceof PyClassLikeType)) {
@@ -318,7 +320,7 @@ public class PyTypeModelBuilder {
   }
 
   @Nullable
-  private static PyType getOptionalType(@NotNull PyUnionType type) {
+  private static Ref<PyType> getOptionalType(@NotNull PyUnionType type) {
     final Collection<PyType> members = type.getMembers();
     if (members.size() == 2) {
       boolean foundNone = false;
@@ -332,7 +334,7 @@ public class PyTypeModelBuilder {
         }
       }
       if (foundNone) {
-        return optional;
+        return Ref.create(optional);
       }
     }
     return null;

python/testData/inspections/PyTypeCheckerInspection/ClassObjectType.py

@@ -31,6 +31,6 @@ def expects_myclass_descendant_or_none(x: Optional[Type[T2]]):
     pass
     
 expects_myclass_descendant_or_none(MyClass)
-expects_myclass_descendant_or_none(<weak_warning descr="Expected type 'Union[None, Any]' (matched generic type 'Optional[Type[TypeVar('T2', MyClass)]]'), got 'MyClass' instead">MyClass()</weak_warning>)
-expects_myclass_descendant_or_none(<weak_warning descr="Expected type 'Union[None, Any]' (matched generic type 'Optional[Type[TypeVar('T2', MyClass)]]'), got 'Type[object]' instead">object</weak_warning>)
-expects_myclass_descendant_or_none(<weak_warning descr="Expected type 'Union[None, Any]' (matched generic type 'Optional[Type[TypeVar('T2', MyClass)]]'), got 'object' instead">object()</weak_warning>)
+expects_myclass_descendant_or_none(<weak_warning descr="Expected type 'Optional[Any]' (matched generic type 'Optional[Type[TypeVar('T2', MyClass)]]'), got 'MyClass' instead">MyClass()</weak_warning>)
+expects_myclass_descendant_or_none(<weak_warning descr="Expected type 'Optional[Any]' (matched generic type 'Optional[Type[TypeVar('T2', MyClass)]]'), got 'Type[object]' instead">object</weak_warning>)
+expects_myclass_descendant_or_none(<weak_warning descr="Expected type 'Optional[Any]' (matched generic type 'Optional[Type[TypeVar('T2', MyClass)]]'), got 'object' instead">object()</weak_warning>)

python/testData/inspections/PyTypeCheckerInspection/OptionalOfBoundTypeVarInWarnings.py

@@ -0,0 +1,11 @@
+from typing import Optional, TypeVar
+
+
+T = TypeVar('T', int)
+
+
+def expects_int_subclass_or_none(x: Optional[T]):
+    pass
+
+
+expects_int_subclass_or_none(<weak_warning descr="Expected type 'Optional[Any]' (matched generic type 'Optional[TypeVar('T', int)]'), got 'str' instead">'foo'</weak_warning>)

python/testSrc/com/jetbrains/python/Py3TypeTest.java

@@ -450,7 +450,7 @@ public class Py3TypeTest extends PyTestCase {
 
   // PY-20757
   public void testMinElseNone() {
-    doTest("Union[None, Any]",
+    doTest("Optional[Any]",
            "def get_value(v):\n" +
            "    if v:\n" +
            "        return min(v)\n" +

python/testSrc/com/jetbrains/python/PyTypeTest.java

@@ -1496,14 +1496,14 @@ public class PyTypeTest extends PyTestCase {
 
   // PY-20409
   public void testGetFromDictWithDefaultNoneValue() {
-    doTest("Union[None, Any]",
+    doTest("Optional[Any]",
            "d = {}\n" +
            "expr = d.get(\"abc\", None)");
   }
 
   // PY-20757
   public void testMinOrNone() {
-    doTest("Union[None, Any]",
+    doTest("Optional[Any]",
            "def get_value(v):\n" +
            "    if v:\n" +
            "        return min(v)\n" +

python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java

@@ -213,4 +213,9 @@ public class Py3TypeCheckerInspectionTest extends PyTestCase {
   public void testClassObjectTypeWithUnion() {
     doTest();
   }
+
+  // PY-22730
+  public void testOptionalOfBoundTypeVarInWarnings() {
+    doTest();
+  }
 }