Allow calling a function with name '_'

mypy/checkexpr.py

@@ -1,6 +1,5 @@
 """Expression type checker. This file is conceptually part of TypeChecker."""
 
-from mypy.util import unnamed_function
 from mypy.backports import OrderedDict, nullcontext
 from contextlib import contextmanager
 import itertools
@@ -347,12 +346,6 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
                 and callee_type.implicit):
             self.msg.untyped_function_call(callee_type, e)
 
-        if (isinstance(callee_type, CallableType)
-                and not callee_type.is_type_obj()
-                and unnamed_function(callee_type.name)):
-            self.msg.underscore_function_call(e)
-            return AnyType(TypeOfAny.from_error)
-
         # Figure out the full name of the callee for plugin lookup.
         object_type = None
         member = None

test-data/unit/check-functions.test

@@ -2230,6 +2230,12 @@ reveal_type(h) # N: Revealed type is "builtins.function"
 h(7) # E: Cannot call function of unknown type
 [builtins fixtures/bool.pyi]
 
+[case testFunctionWithNameUnderscore]
+def _(x: int) -> None: pass
+
+_(1)
+_('x')  # E: Argument 1 to "_" has incompatible type "str"; expected "int"
+
 -- Positional-only arguments
 -- -------------------------
 

test-data/unit/check-redefine.test

@@ -498,7 +498,8 @@ def _(arg: str):
 def _(arg: int) -> int:
     return 'a' # E: Incompatible return value type (got "str", expected "int")
 
-[case testCallingUnderscoreFunctionIsNotAllowed]
+[case testCallingUnderscoreFunctionIsNotAllowed-skip]
+# Skipped because of https://github.com/python/mypy/issues/11774
 def _(arg: str) -> None:
     pass