stubtest: fix literal type construction (python#11931)

Co-authored-by: hauntsaninja <>

mypy/fastparse.py

@@ -40,6 +40,7 @@
 from mypy.errors import Errors
 from mypy.options import Options
 from mypy.reachability import mark_block_unreachable
+from mypy.util import bytes_to_human_readable_repr
 
 try:
     # pull this into a final variable to make mypyc be quiet about the
@@ -1638,17 +1639,3 @@ def stringify_name(n: AST) -> Optional[str]:
         if sv is not None:
             return "{}.{}".format(sv, n.attr)
     return None  # Can't do it.
-
-
-def bytes_to_human_readable_repr(b: bytes) -> str:
-    """Converts bytes into some human-readable representation. Unprintable
-    bytes such as the nul byte are escaped. For example:
-
-        >>> b = bytes([102, 111, 111, 10, 0])
-        >>> s = bytes_to_human_readable_repr(b)
-        >>> print(s)
-        foo\n\x00
-        >>> print(repr(s))
-        'foo\\n\\x00'
-    """
-    return repr(b)[2:-1]

mypy/fastparse2.py

@@ -47,10 +47,11 @@
 from mypy import message_registry, errorcodes as codes
 from mypy.errors import Errors
 from mypy.fastparse import (
-    TypeConverter, parse_type_comment, bytes_to_human_readable_repr, parse_type_ignore_tag,
+    TypeConverter, parse_type_comment, parse_type_ignore_tag,
     TYPE_IGNORE_PATTERN, INVALID_TYPE_IGNORE
 )
 from mypy.options import Options
+from mypy.util import bytes_to_human_readable_repr
 from mypy.reachability import mark_block_unreachable
 
 try:

mypy/stubtest.py

@@ -25,7 +25,7 @@
 from mypy import nodes
 from mypy.config_parser import parse_config_file
 from mypy.options import Options
-from mypy.util import FancyFormatter
+from mypy.util import FancyFormatter, bytes_to_human_readable_repr
 
 
 class Missing:
@@ -942,6 +942,7 @@ def is_subtype_helper(left: mypy.types.Type, right: mypy.types.Type) -> bool:
     ):
         # Pretend Literal[0, 1] is a subtype of bool to avoid unhelpful errors.
         return True
+
     with mypy.state.strict_optional_set(True):
         return mypy.subtypes.is_subtype(left, right)
 
@@ -1029,17 +1030,19 @@ def anytype() -> mypy.types.AnyType:
         return mypy.types.TupleType(items, fallback)
 
     fallback = mypy.types.Instance(type_info, [anytype() for _ in type_info.type_vars])
-    try:
-        # Literals are supposed to be only bool, int, str, bytes or enums, but this seems to work
-        # well (when not using mypyc, for which bytes and enums are also problematic).
-        return mypy.types.LiteralType(
-            value=runtime,
-            fallback=fallback,
-        )
-    except TypeError:
-        # Ask for forgiveness if we're using mypyc.
+
+    value: Union[bool, int, str]
+    if isinstance(runtime, bytes):
+        value = bytes_to_human_readable_repr(runtime)
+    elif isinstance(runtime, enum.Enum):
+        value = runtime.name
+    elif isinstance(runtime, (bool, int, str)):
+        value = runtime
+    else:
         return fallback
 
+    return mypy.types.LiteralType(value=value, fallback=fallback)
+
 
 _all_stubs: Dict[str, nodes.MypyFile] = {}
 

mypy/test/teststubtest.py

@@ -750,6 +750,84 @@ def __init__(self, x): pass
             error="X.__init__"
         )
 
+    @collect_cases
+    def test_good_literal(self) -> Iterator[Case]:
+        yield Case(
+            stub=r"""
+            from typing_extensions import Literal
+
+            import enum
+            class Color(enum.Enum):
+                RED: int
+
+            NUM: Literal[1]
+            CHAR: Literal['a']
+            FLAG: Literal[True]
+            NON: Literal[None]
+            BYT1: Literal[b'abc']
+            BYT2: Literal[b'\x90']
+            ENUM: Literal[Color.RED]
+            """,
+            runtime=r"""
+            import enum
+            class Color(enum.Enum):
+                RED = 3
+
+            NUM = 1
+            CHAR = 'a'
+            NON = None
+            FLAG = True
+            BYT1 = b"abc"
+            BYT2 = b'\x90'
+            ENUM = Color.RED
+            """,
+            error=None,
+        )
+
+    @collect_cases
+    def test_bad_literal(self) -> Iterator[Case]:
+        yield Case("from typing_extensions import Literal", "", None)  # dummy case
+        yield Case(
+            stub="INT_FLOAT_MISMATCH: Literal[1]",
+            runtime="INT_FLOAT_MISMATCH = 1.0",
+            error="INT_FLOAT_MISMATCH",
+        )
+        yield Case(
+            stub="WRONG_INT: Literal[1]",
+            runtime="WRONG_INT = 2",
+            error="WRONG_INT",
+        )
+        yield Case(
+            stub="WRONG_STR: Literal['a']",
+            runtime="WRONG_STR = 'b'",
+            error="WRONG_STR",
+        )
+        yield Case(
+            stub="BYTES_STR_MISMATCH: Literal[b'value']",
+            runtime="BYTES_STR_MISMATCH = 'value'",
+            error="BYTES_STR_MISMATCH",
+        )
+        yield Case(
+            stub="STR_BYTES_MISMATCH: Literal['value']",
+            runtime="STR_BYTES_MISMATCH = b'value'",
+            error="STR_BYTES_MISMATCH",
+        )
+        yield Case(
+            stub="WRONG_BYTES: Literal[b'abc']",
+            runtime="WRONG_BYTES = b'xyz'",
+            error="WRONG_BYTES",
+        )
+        yield Case(
+            stub="WRONG_BOOL_1: Literal[True]",
+            runtime="WRONG_BOOL_1 = False",
+            error='WRONG_BOOL_1',
+        )
+        yield Case(
+            stub="WRONG_BOOL_2: Literal[False]",
+            runtime="WRONG_BOOL_2 = True",
+            error='WRONG_BOOL_2',
+        )
+
 
 def remove_color_code(s: str) -> str:
     return re.sub("\\x1b.*?m", "", s)  # this works!

mypy/util.py

@@ -105,6 +105,20 @@ def find_python_encoding(text: bytes, pyversion: Tuple[int, int]) -> Tuple[str,
         return default_encoding, -1
 
 
+def bytes_to_human_readable_repr(b: bytes) -> str:
+    """Converts bytes into some human-readable representation. Unprintable
+    bytes such as the nul byte are escaped. For example:
+
+        >>> b = bytes([102, 111, 111, 10, 0])
+        >>> s = bytes_to_human_readable_repr(b)
+        >>> print(s)
+        foo\n\x00
+        >>> print(repr(s))
+        'foo\\n\\x00'
+    """
+    return repr(b)[2:-1]
+
+
 class DecodeError(Exception):
     """Exception raised when a file cannot be decoded due to an unknown encoding type.