fix reportUnusedParameter false positive on abstract setters

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

@@ -121,6 +121,14 @@ export function clonePropertyWithSetter(
     if (!isProperty(prop)) {
         return prop;
     }
+    // this is safe. see comment on isProperty
+    prop = prop as ClassType;
+
+    // if it's an abstract property, mark the parameter as accessed
+    if (prop.priv?.fgetInfo?.methodType && FunctionType.isAbstractMethod(prop.priv.fgetInfo.methodType)) {
+        // first parameter is self, there should only ever be one other parameter.
+        evaluator.markParamAccessed(errorNode.d.params[1]);
+    }
 
     const classType = prop as ClassType;
     const flagsToClone = classType.shared.flags;

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

@@ -28434,6 +28434,7 @@ export function createTypeEvaluator(
         checkForCancellation,
         printControlFlowGraph,
         typesOverlap,
+        markParamAccessed,
     };
 
     const codeFlowEngine = getCodeFlowEngine(evaluatorInterface, speculativeTypeTracker);

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

@@ -884,4 +884,5 @@ export interface TypeEvaluator {
         logger: ConsoleInterface
     ) => void;
     typesOverlap: (leftType: Type, rightType: Type, checkEq: boolean) => boolean;
+    markParamAccessed: (param: ParameterNode) => void;
 }

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

@@ -1423,7 +1423,8 @@ export function isEllipsisType(type: Type): boolean {
     return isAny(type) && type.priv.isEllipsis;
 }
 
-export function isProperty(type: Type) {
+// type guard commented out due to https://github.com/microsoft/TypeScript/issues/15048
+export function isProperty(type: Type) /* : type is ClassType */ {
     return isClassInstance(type) && ClassType.isPropertyClass(type);
 }
 

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

@@ -1,4 +1,4 @@
-from abc import abstractmethod
+from abc import ABC, abstractmethod
 from typing import override
 
 
@@ -23,4 +23,12 @@ def __baz__(self, asdf: int):  # no error, dunder
     def qux(self, __asdf: int):  # error, unused cringe positional argument
         ...
 
-def bar(_value: int): ...
+def bar(_value: int): ...
+
+class Baz(ABC):
+    @property
+    @abstractmethod
+    def foo(self) -> str:...
+    @foo.setter
+    def foo(self, new_value: str):  # no error, abstract property
+        ...