Deduplicate isinstance() checks

Author: sterliakov

mypy/plugins/functools.py

@@ -346,7 +346,7 @@ def partial_call_callback(ctx: mypy.plugin.MethodContext) -> Type:
             actual_arg_kinds.append(ctx.arg_kinds[i][j])
             actual_arg_names.append(ctx.arg_names[i][j])
 
-    result, inf = ctx.api.expr_checker.check_call(
+    result, _ = ctx.api.expr_checker.check_call(
         callee=partial_type,
         args=actual_args,
         arg_kinds=actual_arg_kinds,
@@ -359,27 +359,22 @@ def partial_call_callback(ctx: mypy.plugin.MethodContext) -> Type:
     args_bound = "__mypy_partial_paramspec_args_bound" in extra_attrs.immutable
     kwargs_bound = "__mypy_partial_paramspec_kwargs_bound" in extra_attrs.immutable
 
-    # ensure *args: P.args
-    args_passed = any(
-        isinstance(arg, NameExpr)
+    passed_paramspec_parts = [
+        arg.node.type
+        for arg in actual_args
+        if isinstance(arg, NameExpr)
         and isinstance(arg.node, Var)
         and isinstance(arg.node.type, ParamSpecType)
-        and arg.node.type.flavor == ParamSpecFlavor.ARGS
-        for arg in actual_args
-    )
+    ]
+    # ensure *args: P.args
+    args_passed = any(part.flavor == ParamSpecFlavor.ARGS for part in passed_paramspec_parts)
     if not args_bound and not args_passed:
         ctx.api.expr_checker.msg.too_few_arguments(partial_type, ctx.context, actual_arg_names)
     elif args_bound and args_passed:
         ctx.api.expr_checker.msg.too_many_arguments(partial_type, ctx.context)
 
     # ensure **kwargs: P.kwargs
-    kwargs_passed = any(
-        isinstance(arg, NameExpr)
-        and isinstance(arg.node, Var)
-        and isinstance(arg.node.type, ParamSpecType)
-        and arg.node.type.flavor == ParamSpecFlavor.KWARGS
-        for arg in actual_args
-    )
+    kwargs_passed = any(part.flavor == ParamSpecFlavor.KWARGS for part in passed_paramspec_parts)
     if not kwargs_bound and not kwargs_passed:
         ctx.api.expr_checker.msg.too_few_arguments(partial_type, ctx.context, actual_arg_names)