Fixed recent regression that affected unannotated __call__ methods in a metaclass. This change aligns pyright's behavior to the typing spec. It addresses #7717. (#7746)

packages/pyright-internal/src/analyzer/constructors.ts

@@ -674,28 +674,31 @@ function validateMetaclassCall(
 ): CallResult | undefined {
     const metaclassCallMethodInfo = getBoundCallMethod(evaluator, errorNode, type);
 
-    if (metaclassCallMethodInfo) {
+    if (!metaclassCallMethodInfo) {
-        const callResult = evaluator.validateCallArguments(
+        return undefined;
-            errorNode,
-            argList,
-            metaclassCallMethodInfo,
-            /* typeVarContext */ undefined,
-            skipUnknownArgCheck,
-            inferenceContext
-        );
-
-        if (!callResult.returnType || isUnknown(callResult.returnType)) {
-            // The return result isn't known. We'll assume in this case that
-            // the metaclass __call__ method allocated a new instance of the
-            // requested class.
-            const typeVarContext = new TypeVarContext(getTypeVarScopeId(type));
-            callResult.returnType = applyExpectedTypeForConstructor(evaluator, type, inferenceContext, typeVarContext);
-        }
-
-        return callResult;
     }
 
-    return undefined;
+    const callResult = evaluator.validateCallArguments(
+        errorNode,
+        argList,
+        metaclassCallMethodInfo,
+        /* typeVarContext */ undefined,
+        skipUnknownArgCheck,
+        inferenceContext
+    );
+
+    // If the return type is unannotated, don't use the inferred return type.
+    const callType = metaclassCallMethodInfo.type;
+    if (isFunction(callType) && !callType.details.declaredReturnType) {
+        return undefined;
+    }
+
+    // If the return type is unknown, ignore it.
+    if (callResult.returnType && isUnknown(callResult.returnType)) {
+        return undefined;
+    }
+
+    return callResult;
 }
 
 function applyExpectedSubtypeForConstructor(

packages/pyright-internal/src/tests/samples/metaclass7.py

@@ -5,6 +5,9 @@
 # pyright: reportIncompatibleMethodOverride=false
 
 
+from typing import Any, Self
+
+
 class MetaClass1(type):
     def __call__(cls, **kwargs):
         return object.__new__(**kwargs)
@@ -33,7 +36,7 @@ reveal_type(v2, expected_text="NoReturn")
 
 
 class MetaClass3(type):
-    def __call__(cls, *args, **kwargs):
+    def __call__(cls, *args, **kwargs) -> Any:
         return super().__call__(*args, **kwargs)
 
 
@@ -44,3 +47,17 @@ class Class3(metaclass=MetaClass3):
 
 v3 = Class3()
 reveal_type(v3, expected_text="Any")
+
+
+class MetaClass4(type):
+    def __call__(cls, *args, **kwargs):
+        return super().__call__(*args, **kwargs)
+
+
+class Class4(metaclass=MetaClass4):
+    def __new__(cls, *args, **kwargs) -> Self:
+        return super().__new__(cls, *args, **kwargs)
+
+
+v4 = Class4()
+reveal_type(v4, expected_text="Class4")