Added support for an unpacked tuple assignment within an instance met…

…hod when the source of the assignment is the `self` parameter.

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

@@ -2494,6 +2494,8 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
         // entries at that location.
         const unpackIndex = target.expressions.findIndex((expr) => expr.nodeType === ParseNodeType.Unpack);
 
+        type = makeTopLevelTypeVarsConcrete(type);
+
         doForEachSubtype(type, (subtype) => {
             // Is this subtype a tuple?
             const tupleType = getSpecializedTupleType(subtype);

packages/pyright-internal/src/tests/samples/namedTuples5.py

@@ -0,0 +1,15 @@
+# This sample tests the case where a NamedTuple object is referenced
+# through a `self` parameter.
+
+from typing import Literal, NamedTuple
+
+
+class Fruit(NamedTuple):
+    name: str
+    cost: float
+
+    def new_cost(self, new_cost: float):
+        my_name, my_cost = self
+        t1: Literal["str"] = reveal_type(my_name)
+        t2: Literal["float"] = reveal_type(my_cost)
+        return Fruit(my_name, new_cost)

packages/pyright-internal/src/tests/typeEvaluator1.test.ts

@@ -1013,6 +1013,12 @@ test('NamedTuples4', () => {
     TestUtils.validateResults(analysisResults, 0);
 });
 
+test('NamedTuples5', () => {
+    const analysisResults = TestUtils.typeAnalyzeSampleFiles(['namedTuples5.py']);
+
+    TestUtils.validateResults(analysisResults, 0);
+});
+
 test('Slots1', () => {
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['slots1.py']);