fix: use "constraints and a bound" in TypeVar error message

PEP 484 uses "constraints" for the positional arguments of TypeVar
(e.g. TypeVar("T", int, str)) and "bound" for the keyword argument.
The existing message "cannot have both values and an upper bound" used
neither term correctly.  Updated to:

  TypeVar cannot have both constraints and a bound

Closes #20973

Made-with: Cursor

Author: Leo Ji

mypy/semanal.py

@@ -4936,7 +4936,7 @@ def process_typevar_parameters(
                     return None
             elif param_name == "bound":
                 if has_values:
-                    self.fail("TypeVar cannot have both values and an upper bound", context)
+                    self.fail("TypeVar cannot have both constraints and a bound", context)
                     return None
                 tv_arg = self.get_typevarlike_argument("TypeVar", param_name, param_value, context)
                 if tv_arg is None:

test-data/unit/semanal-errors.test

@@ -1062,7 +1062,7 @@ k = TypeVar('k', contravariant=1) # E: TypeVar "contravariant" may only be a lit
 
 [case testMoreInvalidTypevarArguments]
 from typing import TypeVar
-T = TypeVar('T', int, str, bound=bool) # E: TypeVar cannot have both values and an upper bound
+T = TypeVar('T', int, str, bound=bool) # E: TypeVar cannot have both constraints and a bound
 S = TypeVar('S', covariant=True, contravariant=True) \
     # E: TypeVar cannot be both covariant and contravariant
 [builtins fixtures/bool.pyi]