Changed strictParameterNoneValue to default to true rather than false. This reflects the updated guidance in PEP 484, which indicates that type checkers should not assume that a default argument of None should imply an Optional type.

docs/configuration.md

@@ -48,7 +48,7 @@ The following settings control pyright’s diagnostic output (warnings or errors
 
 **strictSetInference** [boolean]: When inferring the type of a set, use strict type assumptions. For example, the expression `{1, 'a', 3.4}` could be inferred to be of type `Set[Any]` or `Set[Union[int, str, float]]`. If this setting is true, it will use the latter (stricter) type. The default value for this setting is 'false'.
 
-**strictParameterNoneValue** [boolean]: PEP 484 indicates that when a function parameter is assigned a default value of None, its type should implicitly be Optional even if the explicit type is not. When enabled, this rule requires that parameter type annotations use Optional explicitly in this case. The default value for this setting is 'false'.
+**strictParameterNoneValue** [boolean]: PEP 484 indicates that when a function parameter is assigned a default value of None, its type should implicitly be Optional even if the explicit type is not. When enabled, this rule requires that parameter type annotations use Optional explicitly in this case. The default value for this setting is 'true'.
 
 **enableTypeIgnoreComments** [boolean]: PEP 484 defines support for "# type: ignore" comments. This switch enables or disables support for these comments. The default value for this setting is 'true'.
 
@@ -279,7 +279,7 @@ The following table lists the default severity levels for each diagnostic rule w
 | strictListInference                       | false      | false      | true       |
 | strictDictionaryInference                 | false      | false      | true       |
 | strictSetInference                        | false      | false      | true       |
-| strictParameterNoneValue                  | false      | false      | true       |
+| strictParameterNoneValue                  | true       | true       | true       |
 | enableTypeIgnoreComments                  | true       | true       | true       |
 | reportGeneralTypeIssues                   | "none"     | "error"    | "error"    |
 | reportPropertyTypeMismatch                | "none"     | "none"     | "none"     |

packages/pyright-internal/src/common/configOptions.ts

@@ -393,7 +393,7 @@ export function getOffDiagnosticRuleSet(): DiagnosticRuleSet {
         strictListInference: false,
         strictSetInference: false,
         strictDictionaryInference: false,
-        strictParameterNoneValue: false,
+        strictParameterNoneValue: true,
         enableTypeIgnoreComments: true,
         reportGeneralTypeIssues: 'none',
         reportPropertyTypeMismatch: 'none',
@@ -468,7 +468,7 @@ export function getBasicDiagnosticRuleSet(): DiagnosticRuleSet {
         strictListInference: false,
         strictSetInference: false,
         strictDictionaryInference: false,
-        strictParameterNoneValue: false,
+        strictParameterNoneValue: true,
         enableTypeIgnoreComments: true,
         reportGeneralTypeIssues: 'error',
         reportPropertyTypeMismatch: 'none',

packages/pyright-internal/src/tests/samples/classVar1.py

@@ -1,7 +1,7 @@
 # This sample tests the type checker's handling of ClassVar
 # as described in PEP 526.
 
-from typing import Any, ClassVar, Dict
+from typing import Any, ClassVar, Dict, Optional
 
 
 class MyDescriptor:
@@ -18,7 +18,7 @@ class Starship:
     stats: ClassVar[Dict[str, int]] = {}
     desc: ClassVar[MyDescriptor] = MyDescriptor()
 
-    def __init__(self, damage: int, captain: str = None):
+    def __init__(self, damage: int, captain: Optional[str] = None):
         self.damage = damage
         if captain:
             self.captain = captain  # Else keep the default

packages/vscode-pyright/schemas/pyrightconfig.schema.json

@@ -123,7 +123,7 @@
       "$id": "#/properties/strictParameterNoneValue",
       "type": "boolean",
       "title": "Allow implicit Optional when default parameter value is None",
-      "default": false
+      "default": true
     },
     "enableTypeIgnoreComments": {
       "$id": "#/properties/enableTypeIgnoreComments",