Reject ParamSpec-typed callables calls with insufficient arguments

Author: sterliakov

mypy/checkexpr.py

@@ -1745,7 +1745,11 @@ def check_callable_call(
                 )
 
         param_spec = callee.param_spec()
-        if param_spec is not None and arg_kinds == [ARG_STAR, ARG_STAR2]:
+        if (
+            param_spec is not None
+            and arg_kinds == [ARG_STAR, ARG_STAR2]
+            and len(formal_to_actual) == 2
+        ):
             arg1 = self.accept(args[0])
             arg2 = self.accept(args[1])
             if (
@@ -2351,6 +2355,10 @@ def check_argument_count(
                 # Positional argument when expecting a keyword argument.
                 self.msg.too_many_positional_arguments(callee, context)
                 ok = False
+            elif callee.param_spec() is not None:
+                if not formal_to_actual[i]:
+                    self.msg.too_few_arguments(callee, context, actual_names)
+                    ok = False
         return ok
 
     def check_for_extra_actual_arguments(

test-data/unit/check-parameter-specification.test

@@ -2204,3 +2204,54 @@ parametrize(_test, Case(1, b=2), Case(3, b=4))
 parametrize(_test, Case(1, 2), Case(3))
 parametrize(_test, Case(1, 2), Case(3, b=4))
 [builtins fixtures/paramspec.pyi]
+
+[case testRunParamSpecInsufficientArgs]
+from typing_extensions import ParamSpec, Concatenate
+from typing import Callable
+
+_P = ParamSpec("_P")
+
+def run(predicate: Callable[_P, str], *args: _P.args, **kwargs: _P.kwargs) -> None:
+    predicate()  # E: Too few arguments
+    predicate(*args)  # E: Too few arguments
+    predicate(**kwargs)  # E: Too few arguments
+    predicate(*args, **kwargs)
+
+[builtins fixtures/paramspec.pyi]
+
+[case testRunParamSpecConcatenateInsufficientArgs]
+from typing_extensions import ParamSpec, Concatenate
+from typing import Callable
+
+_P = ParamSpec("_P")
+
+def run(predicate: Callable[Concatenate[int, _P], str], *args: _P.args, **kwargs: _P.kwargs) -> None:
+    predicate()  # E: Too few arguments
+    predicate(1)  # E: Too few arguments
+    predicate(1, *args)  # E: Too few arguments
+    predicate(1, *args)  # E: Too few arguments
+    predicate(1, **kwargs)  # E: Too few arguments
+    predicate(*args, **kwargs)  # E: Argument 1 has incompatible type "*_P.args"; expected "int"
+    predicate(1, *args, **kwargs)
+
+[builtins fixtures/paramspec.pyi]
+
+[case testRunParamSpecConcatenateInsufficientArgsInDecorator]
+from typing_extensions import ParamSpec, Concatenate
+from typing import Callable
+
+P = ParamSpec("P")
+
+def decorator(fn: Callable[Concatenate[str, P], None]) -> Callable[P, None]:
+    def inner(*args: P.args, **kwargs: P.kwargs) -> None:
+        fn("value")  # E: Too few arguments
+        fn("value", *args)  # E: Too few arguments
+        fn("value", **kwargs)  # E: Too few arguments
+        fn(*args, **kwargs)  # E: Argument 1 has incompatible type "*P.args"; expected "str"
+        fn("value", *args, **kwargs)
+    return inner
+
+@decorator
+def foo(s: str, s2: str) -> None: ...
+
+[builtins fixtures/paramspec.pyi]