Fixed checking against bound type variables with check_type() without…

… a call memo

Fixes #122.

docs/versionhistory.rst

@@ -8,6 +8,7 @@ This library adheres to `Semantic Versioning 2.0 <https://semver.org/#semantic-v
 - Added support for the ``Mock`` and ``MagicMock`` types (PR by prescod)
 - Added support for ``typing_extensions.Literal`` (PR by Ryan Rowe)
 - Fixed unintended wrapping of untyped generators (PR by prescod)
+- Fixed checking against bound type variables with ``check_type()`` without a call memo
 
 **2.7.1** (2019-12-27)
 

tests/test_typeguard.py

@@ -7,7 +7,7 @@
 from unittest.mock import Mock, MagicMock
 from typing import (
     Any, Callable, Dict, List, Set, Tuple, Union, TypeVar, Sequence, NamedTuple, Iterable,
-    Container, Generic, BinaryIO, TextIO, Generator, Iterator, SupportsInt, AbstractSet)
+    Container, Generic, BinaryIO, TextIO, Generator, Iterator, SupportsInt, AbstractSet, AnyStr)
 
 import pytest
 
@@ -66,6 +66,16 @@ def test_check_type_no_memo_fail():
         match(r'type of foo\[0\] must be int; got str instead')
 
 
+@pytest.mark.parametrize('value', ['bar', b'bar'], ids=['str', 'bytes'])
+def test_check_type_anystr(value):
+    check_type('foo', value, AnyStr)
+
+
+def test_check_type_anystr_fail():
+    pytest.raises(TypeError, check_type, 'foo', int, AnyStr).\
+        match(r'type of foo must be one of \(bytes, str\); got type instead')
+
+
 def test_check_return_type():
     def foo() -> int:
         assert check_return_type(0)

typeguard/__init__.py

@@ -433,10 +433,10 @@ def check_class(argname: str, value, expected_type, memo: Optional[_CallMemo]) -
 
 def check_typevar(argname: str, value, typevar: TypeVar, memo: Optional[_CallMemo],
                   subclass_check: bool = False) -> None:
-    if memo is None:
-        raise TypeError('encountered a TypeVar but a call memo was not provided')
+    bound_type = None
+    if memo is not None:
+        bound_type = resolve_forwardref(memo.typevars.get(typevar, typevar.__bound__), memo)
 
-    bound_type = resolve_forwardref(memo.typevars.get(typevar, typevar.__bound__), memo)
     value_type = value if subclass_check else type(value)
     subject = argname if subclass_check else 'type of ' + argname
     if bound_type is None:
@@ -464,7 +464,7 @@ def check_typevar(argname: str, value, typevar: TypeVar, memo: Optional[_CallMem
                 '{} must be exactly {}; got {} instead'.
                 format(subject, qualified_name(bound_type), qualified_name(value_type)))
 
-    if typevar not in memo.typevars:
+    if memo is not None and typevar not in memo.typevars:
         # Bind the type variable to a concrete type
         memo.typevars[typevar] = value_type