Fixed error message when checking against a Union[..., Literal[...]]

Fixes #113.

docs/versionhistory.rst

@@ -9,6 +9,7 @@ This library adheres to `Semantic Versioning 2.0 <https://semver.org/#semantic-v
 - 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
+- Fixed error message when checking against a ``Union`` containing a ``Literal``
 
 **2.7.1** (2019-12-27)
 

tests/test_typeguard_py38.py

@@ -1,4 +1,4 @@
-from typing import Literal, TypedDict
+from typing import Literal, TypedDict, Union
 
 import pytest
 
@@ -14,6 +14,16 @@ def foo(a: Literal[1, 6, 8]):
     pytest.raises(TypeError, foo, 4).match(r'must be one of \(1, 6, 8\); got 4 instead$')
 
 
+def test_literal_union():
+    @typechecked
+    def foo(a: Union[str, Literal[1, 6, 8]]):
+        pass
+
+    foo(6)
+    pytest.raises(TypeError, foo, 4).\
+        match(r'must be one of \(str, typing.Literal\[1, 6, 8\]\); got int instead$')
+
+
 @pytest.mark.parametrize('value, total, error_re', [
     ({'x': 6, 'y': 'foo'}, True, None),
     ({'y': 'foo'}, True, r'required key\(s\) \("x"\) missing from argument "arg"'),

typeguard/__init__.py

@@ -164,7 +164,7 @@ def resolve_forwardref(maybe_ref, memo: _CallMemo):
 
 def get_type_name(type_):
     # typing.* types don't have a __name__ on Python 3.7+
-    return getattr(type_, '__name__', None) or type_._name
+    return getattr(type_, '__name__', None) or type_._name or str(type_)
 
 
 def find_function(frame) -> Optional[Callable]: