Always complain about invalid varargs and varkwargs (#18207)

Author: hauntsaninja

mypy/checkexpr.py

@@ -2481,6 +2481,17 @@ def check_argument_types(
         check_arg = check_arg or self.check_arg
         # Keep track of consumed tuple *arg items.
         mapper = ArgTypeExpander(self.argument_infer_context())
+
+        for arg_type, arg_kind in zip(arg_types, arg_kinds):
+            arg_type = get_proper_type(arg_type)
+            if arg_kind == nodes.ARG_STAR and not self.is_valid_var_arg(arg_type):
+                self.msg.invalid_var_arg(arg_type, context)
+            if arg_kind == nodes.ARG_STAR2 and not self.is_valid_keyword_var_arg(arg_type):
+                is_mapping = is_subtype(
+                    arg_type, self.chk.named_type("_typeshed.SupportsKeysAndGetItem")
+                )
+                self.msg.invalid_keyword_var_arg(arg_type, is_mapping, context)
+
         for i, actuals in enumerate(formal_to_actual):
             orig_callee_arg_type = get_proper_type(callee.arg_types[i])
 
@@ -2573,15 +2584,6 @@ def check_argument_types(
                 if actual_type is None:
                     continue  # Some kind of error was already reported.
                 # Check that a *arg is valid as varargs.
-                if actual_kind == nodes.ARG_STAR and not self.is_valid_var_arg(actual_type):
-                    self.msg.invalid_var_arg(actual_type, context)
-                if actual_kind == nodes.ARG_STAR2 and not self.is_valid_keyword_var_arg(
-                    actual_type
-                ):
-                    is_mapping = is_subtype(
-                        actual_type, self.chk.named_type("_typeshed.SupportsKeysAndGetItem")
-                    )
-                    self.msg.invalid_keyword_var_arg(actual_type, is_mapping, context)
                 expanded_actual = mapper.expand_actual_type(
                     actual_type,
                     actual_kind,

mypy/messages.py

@@ -1394,7 +1394,7 @@ def could_not_infer_type_arguments(
             self.fail("Cannot infer function type argument", context)
 
     def invalid_var_arg(self, typ: Type, context: Context) -> None:
-        self.fail("List or tuple expected as variadic arguments", context)
+        self.fail("Expected iterable as variadic argument", context)
 
     def invalid_keyword_var_arg(self, typ: Type, is_mapping: bool, context: Context) -> None:
         typ = get_proper_type(typ)

test-data/unit/check-functools.test

@@ -215,14 +215,16 @@ def bar(*a: bytes, **k: int):
     p1("a", d="a", **k)
     p1("a", **k)  # E: Argument 2 to "foo" has incompatible type "**Dict[str, int]"; expected "str"
     p1(**k)  # E: Argument 1 to "foo" has incompatible type "**Dict[str, int]"; expected "str"
-    p1(*a)  # E: List or tuple expected as variadic arguments
+    p1(*a)  # E: Expected iterable as variadic argument
 
 
 def baz(a: int, b: int) -> int: ...
 def test_baz(xs: List[int]):
     p3 = functools.partial(baz, *xs)
     p3()
     p3(1)  # E: Too many arguments for "baz"
+
+
 [builtins fixtures/dict.pyi]
 
 [case testFunctoolsPartialGeneric]

test-data/unit/check-kwargs.test

@@ -358,6 +358,9 @@ f(**d)         # E: Keywords must be strings
 f(**A())       # E: Argument after ** must be a mapping, not "A"
 kwargs: Optional[Any]
 f(**kwargs)    # E: Argument after ** must be a mapping, not "Optional[Any]"
+
+def g(a: int) -> None: pass
+g(a=1, **4)  # E: Argument after ** must be a mapping, not "int"
 [builtins fixtures/dict.pyi]
 
 [case testPassingKeywordVarArgsToNonVarArgsFunction]

test-data/unit/check-varargs.test

@@ -268,17 +268,19 @@ f(a, *(b, cc))
 [builtins fixtures/tuple.pyi]
 
 [case testInvalidVarArg]
-# flags: --no-strict-optional
 def f(a: 'A') -> None:
     pass
 
 class A: pass
 
-a = None # type: A
+a = A()
 
-f(*None)
-f(*a)    # E: List or tuple expected as variadic arguments
+f(*None)  # E: Expected iterable as variadic argument
+f(*a)    # E: Expected iterable as variadic argument
 f(*(a,))
+
+f(*4)  # E: Expected iterable as variadic argument
+f(a, *4)  # E: Expected iterable as variadic argument
 [builtins fixtures/tuple.pyi]
 
 
@@ -543,9 +545,9 @@ if int():
 if int():
     b, b = f(b, b, *aa) # E: Argument 3 to "f" has incompatible type "*List[A]"; expected "B"
 if int():
-    a, b = f(a, *a)  # E: List or tuple expected as variadic arguments
+    a, b = f(a, *a)  # E: Expected iterable as variadic argument
 if int():
-    a, b = f(*a)     # E: List or tuple expected as variadic arguments
+    a, b = f(*a)     # E: Expected iterable as variadic argument
 
 if int():
     a, a = f(*aa)
@@ -737,7 +739,7 @@ bar(*good1)
 bar(*good2)
 bar(*good3)
 bar(*bad1)  # E: Argument 1 to "bar" has incompatible type "*I[str]"; expected "float"
-bar(*bad2)  # E: List or tuple expected as variadic arguments
+bar(*bad2)  # E: Expected iterable as variadic argument
 [builtins fixtures/dict.pyi]
 
 -- Keyword arguments unpacking