Repository: quora/pyanalyze
Pull request #332 (2021-12-10 04:46:02)

make test context more powerful
So these tests more closely reflect real type checking.


Patch:
diff --git a/docs/changelog.md b/docs/changelog.md
index 2710248..3c991f6 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Improve support for complex type aliases in stubs
+  (#331)
 - Limit special case for `Literal` callables to
   functions, not any callable (#329)
 - Support for constants in stubs that do not exist
diff --git a/pyanalyze/annotations.py b/pyanalyze/annotations.py
index d3a734d..6210082 100644
--- a/pyanalyze/annotations.py
+++ b/pyanalyze/annotations.py
@@ -495,137 +495,135 @@ def _type_from_value(value: Value, ctx: Context, is_typeddict: bool = False) ->
     elif isinstance(value, AnnotatedValue):
         return _type_from_value(value.value, ctx)
     elif isinstance(value, _SubscriptedValue):
-        if isinstance(value.root, GenericValue):
-            if len(value.root.args) == len(value.members):
-                return GenericValue(
-                    value.root.typ,
-                    [_type_from_value(member, ctx) for member in value.members],
-                )
-        if isinstance(value.root, _SubscriptedValue):
-            root_type = _type_from_value(value.root, ctx)
-            if isinstance(root_type, GenericValue) and len(root_type.args) == len(
-                value.members
-            ):
-                return GenericValue(
-                    root_type.typ,
-                    [_type_from_value(member, ctx) for member in value.members],
-                )
-        if isinstance(value.root, TypedValue) and isinstance(value.root.typ, str):
+        return _type_from_subscripted_value(
+            value.root, value.members, ctx, is_typeddict=is_typeddict
+        )
+    elif isinstance(value, AnyValue):
+        return value
+    elif isinstance(value, TypedValue) and isinstance(value.typ, str):
+        # Synthetic type
+        return value
+    else:
+        ctx.show_error(f"Unrecognized annotation {value}")
+        return AnyValue(AnySource.error)
+
+
+def _type_from_subscripted_value(
+    root: Optional[Value],
+    members: Sequence[Value],
+    ctx: Context,
+    is_typeddict: bool = False,
+) -> Value:
+    if isinstance(root, GenericValue):
+        if len(root.args) == len(members):
             return GenericValue(
-                value.root.typ, [_type_from_value(elt, ctx) for elt in value.members]
+                root.typ, [_type_from_value(member, ctx) for member in members]
             )
+    if isinstance(root, _SubscriptedValue):
+        root_type = _type_from_value(root, ctx)
+        return _type_from_subscripted_value(root_type, members, ctx)
+    elif isinstance(root, MultiValuedValue):
+        return unite_values(
+            *[
+                _type_from_subscripted_value(subval, members, ctx, is_typeddict)
+                for subval in root.vals
+            ]
+        )
+    if isinstance(root, TypedValue) and isinstance(root.typ, str):
+        return GenericValue(root.typ, [_type_from_value(elt, ctx) for elt in members])
 
-        if not isinstance(value.root, KnownValue):
-            ctx.show_error(f"Cannot resolve subscripted annotation: {value.root}")
+    if not isinstance(root, KnownValue):
+        ctx.show_error(f"Cannot resolve subscripted annotation: {root}")
+        return AnyValue(AnySource.error)
+    root = root.val
+    if root is typing.Union:
+        return unite_values(*[_type_from_value(elt, ctx) for elt in members])
+    elif is_typing_name(root, "Literal"):
+        # Note that in Python 3.8, the way typing's internal cache works means that
+        # Literal[1] and Literal[True] are cached to the same value, so if you use
+        # both, you'll get whichever one was used first in later calls. There's nothing
+        # we can do about that.
+        if all(isinstance(elt, KnownValue) for elt in members):
+            return unite_values(*members)
+        else:
+            ctx.show_error(f"Arguments to Literal[] must be literals, not {members}")
             return AnyValue(AnySource.error)
-        root = value.root.val
-        if root is typing.Union:
-            return unite_values(*[_type_from_value(elt, ctx) for elt in value.members])
-        elif is_typing_name(root, "Literal"):
-            # Note that in Python 3.8, the way typing's internal cache works means that
-            # Literal[1] and Literal[True] are cached to the same value, so if you use
-            # both, you'll get whichever one was used first in later calls. There's nothing
-            # we can do about that.
-            if all(isinstance(elt, KnownValue) for elt in value.members):
-                return unite_values(*value.members)
-            else:
-                ctx.show_error(
-                    f"Arguments to Literal[] must be literals, not {value.members}"
-                )
-                return AnyValue(AnySource.error)
-        elif root is typing.Tuple or root is tuple:
-            if len(value.members) == 2 and value.members[1] == KnownValue(Ellipsis):
-                return GenericValue(tuple, [_type_from_value(value.members[0], ctx)])
-            elif len(value.members) == 1 and value.members[0] == KnownValue(()):
-                return SequenceIncompleteValue(tuple, [])
-            else:
-                return SequenceIncompleteValue(
-                    tuple, [_type_from_value(arg, ctx) for arg in value.members]
-                )
-        elif root is typing.Optional:
-            if len(value.members) != 1:
-                ctx.show_error("Optional[] takes only one argument")
-                return AnyValue(AnySource.error)
-            return unite_values(
-                KnownValue(None), _type_from_value(value.members[0], ctx)
-            )
-        elif root is typing.Type or root is type:
-            if len(value.members) != 1:
-                ctx.show_error("Type[] takes only one argument")
-                return AnyValue(AnySource.error)
-            argument = _type_from_value(value.members[0], ctx)
-            return SubclassValue.make(argument)
-        elif is_typing_name(root, "Annotated"):
-            origin, *metadata = value.members
-            return _make_annotated(_type_from_value(origin, ctx), metadata, ctx)
-        elif is_typing_name(root, "TypeGuard"):
-            if len(value.members) != 1:
-                ctx.show_error("TypeGuard requires a single argument")
-                return AnyValue(AnySource.error)
-            return AnnotatedValue(
-                TypedValue(bool),
-                [TypeGuardExtension(_type_from_value(value.members[0], ctx))],
+    elif root is typing.Tuple or root is tuple:
+        if len(members) == 2 and members[1] == KnownValue(Ellipsis):
+            return GenericValue(tuple, [_type_from_value(members[0], ctx)])
+        elif len(members) == 1 and members[0] == KnownValue(()):
+            return SequenceIncompleteValue(tuple, [])
+        else:
+            return SequenceIncompleteValue(
+                tuple, [_type_from_value(arg, ctx) for arg in members]
             )
-        elif is_typing_name(root, "Required"):
-            if not is_typeddict:
-                ctx.show_error("Required[] used in unsupported context")
-                return AnyValue(AnySource.error)
-            if len(value.members) != 1:
-                ctx.show_error("Required[] requires a single argument")
-                return AnyValue(AnySource.error)
-            return _Pep655Value(True, _type_from_value(value.members[0], ctx))
-        elif is_typing_name(root, "NotRequired"):
-            if not is_typeddict:
-                ctx.show_error("NotRequired[] used in unsupported context")
-                return AnyValue(AnySource.error)
-            if len(value.members) != 1:
-                ctx.show_error("NotRequired[] requires a single argument")
-                return AnyValue(AnySource.error)
-            return _Pep655Value(False, _type_from_value(value.members[0], ctx))
-        elif root is Callable or root is typing.Callable:
-            if len(value.members) == 2:
-                args, return_value = value.members
-                return _make_callable_from_value(args, return_value, ctx)
-            ctx.show_error("Callable requires exactly two arguments")
+    elif root is typing.Optional:
+        if len(members) != 1:
+            ctx.show_error("Optional[] takes only one argument")
             return AnyValue(AnySource.error)
-        elif root is AsynqCallable:
-            if len(value.members) == 2:
-                args, return_value = value.members
-                return _make_callable_from_value(args, return_value, ctx, is_asynq=True)
-            ctx.show_error("AsynqCallable requires exactly two arguments")
+        return unite_values(KnownValue(None), _type_from_value(members[0], ctx))
+    elif root is typing.Type or root is type:
+        if len(members) != 1:
+            ctx.show_error("Type[] takes only one argument")
             return AnyValue(AnySource.error)
-        elif typing_inspect.is_generic_type(root):
-            origin = typing_inspect.get_origin(root)
-            if origin is None:
-                # On Python 3.9 at least, get_origin() of a class that inherits
-                # from Generic[T] is None.
-                origin = root
-            if getattr(origin, "__extra__", None) is not None:
-                origin = origin.__extra__
-            return GenericValue(
-                origin, [_type_from_value(elt, ctx) for elt in value.members]
-            )
-        elif isinstance(root, type):
-            return GenericValue(
-                root, [_type_from_value(elt, ctx) for elt in value.members]
-            )
-        else:
-            # In Python 3.9, generics are implemented differently and typing.get_origin
-            # can help.
-            origin = get_origin(root)
-            if isinstance(origin, type):
-                return GenericValue(
-                    origin, [_type_from_value(elt, ctx) for elt in value.members]
-                )
-            ctx.show_error(f"Unrecognized subscripted annotation: {root}")
+        argument = _type_from_value(members[0], ctx)
+        return SubclassValue.make(argument)
+    elif is_typing_name(root, "Annotated"):
+        origin, *metadata = members
+        return _make_annotated(_type_from_value(origin, ctx), metadata, ctx)
+    elif is_typing_name(root, "TypeGuard"):
+        if len(members) != 1:
+            ctx.show_error("TypeGuard requires a single argument")
             return AnyValue(AnySource.error)
-    elif isinstance(value, AnyValue):
-        return value
-    elif isinstance(value, TypedValue) and isinstance(value.typ, str):
-        # Synthetic type
-        return value
+        return AnnotatedValue(
+            TypedValue(bool), [TypeGuardExtension(_type_from_value(members[0], ctx))]
+        )
+    elif is_typing_name(root, "Required"):
+        if not is_typeddict:
+            ctx.show_error("Required[] used in unsupported context")
+            return AnyValue(AnySource.error)
+        if len(members) != 1:
+            ctx.show_error("Required[] requires a single argument")
+            return AnyValue(AnySource.error)
+        return _Pep655Value(True, _type_from_value(members[0], ctx))
+    elif is_typing_name(root, "NotRequired"):
+        if not is_typeddict:
+            ctx.show_error("NotRequired[] used in unsupported context")
+            return AnyValue(AnySource.error)
+        if len(members) != 1:
+            ctx.show_error("NotRequired[] requires a single argument")
+            return AnyValue(AnySource.error)
+        return _Pep655Value(False, _type_from_value(members[0], ctx))
+    elif root is Callable or root is typing.Callable:
+        if len(members) == 2:
+            args, return_value = members
+            return _make_callable_from_value(args, return_value, ctx)
+        ctx.show_error("Callable requires exactly two arguments")
+        return AnyValue(AnySource.error)
+    elif root is AsynqCallable:
+        if len(members) == 2:
+            args, return_value = members
+            return _make_callable_from_value(args, return_value, ctx, is_asynq=True)
+        ctx.show_error("AsynqCallable requires exactly two arguments")
+        return AnyValue(AnySource.error)
+    elif typing_inspect.is_generic_type(root):
+        origin = typing_inspect.get_origin(root)
+        if origin is None:
+            # On Python 3.9 at least, get_origin() of a class that inherits
+            # from Generic[T] is None.
+            origin = root
+        if getattr(origin, "__extra__", None) is not None:
+            origin = origin.__extra__
+        return GenericValue(origin, [_type_from_value(elt, ctx) for elt in members])
+    elif isinstance(root, type):
+        return GenericValue(root, [_type_from_value(elt, ctx) for elt in members])
     else:
-        ctx.show_error(f"Unrecognized annotation {value}")
+        # In Python 3.9, generics are implemented differently and typing.get_origin
+        # can help.
+        origin = get_origin(root)
+        if isinstance(origin, type):
+            return GenericValue(origin, [_type_from_value(elt, ctx) for elt in members])
+        ctx.show_error(f"Unrecognized subscripted annotation: {root}")
         return AnyValue(AnySource.error)
 
 


Test patch:
diff --git a/pyanalyze/test_annotations.py b/pyanalyze/test_annotations.py
index f1540a3..cf1fd0a 100644
--- a/pyanalyze/test_annotations.py
+++ b/pyanalyze/test_annotations.py
@@ -326,7 +326,7 @@ class TestAnnotations(TestNameCheckVisitorBase):
             assert_is_value(empty, SequenceIncompleteValue(tuple, []))
 
     @assert_passes()
-    def test_strinigified_tuples(self):
+    def test_stringified_tuples(self):
         from typing import Tuple, Union
 
         def capybara(
@@ -526,6 +526,21 @@ def f(x: int, y: List[str]):
             assert_is_value(x, TypedValue(int) | TypedValue(str))
             assert_is_value(y, KnownValue(-1))
 
+    @assert_passes()
+    def test_double_subscript(self):
+        from typing import Union, List, Set, TypeVar
+
+        T = TypeVar("T")
+
+        # A bit weird but we hit this kind of case with generic
+        # aliases in typeshed.
+        def capybara(x: "Union[List[T], Set[T]][int]"):
+            assert_is_value(
+                x,
+                GenericValue(list, [TypedValue(int)])
+                | GenericValue(set, [TypedValue(int)]),
+            )
+
     @skip_before((3, 8))
     @assert_fails(ErrorCode.incompatible_argument)
     def test_initvar(self):
diff --git a/pyanalyze/test_value.py b/pyanalyze/test_value.py
index 2e8348f..dbf087c 100644
--- a/pyanalyze/test_value.py
+++ b/pyanalyze/test_value.py
@@ -3,7 +3,7 @@ import collections.abc
 import enum
 import io
 import pickle
-from typing import NewType, Sequence, Union
+from typing import NewType
 from typing_extensions import Protocol, runtime_checkable
 import typing
 import types
@@ -14,17 +14,15 @@ from . import tests
 from . import value
 from .checker import Checker
 from .name_check_visitor import NameCheckVisitor
-from .signature import Signature, MaybeSignature
+from .signature import Signature
 from .stacked_scopes import Composite
 from .test_config import TestConfig
-from .type_object import TypeObject
 from .value import (
     AnnotatedValue,
     AnySource,
     AnyValue,
     CallableValue,
     CanAssignError,
-    GenericBases,
     KVPair,
     Value,
     GenericValue,
@@ -32,34 +30,13 @@ from .value import (
     TypedValue,
     MultiValuedValue,
     SubclassValue,
-    CanAssignContext,
     SequenceIncompleteValue,
     TypeVarMap,
     concrete_values_from_iterable,
 )
 
-
-class Context(CanAssignContext):
-    def __init__(self) -> None:
-        self.checker = Checker(TestConfig())
-        self.visitor = NameCheckVisitor("", "", ast.parse(""), checker=self.checker)
-
-    def make_type_object(self, typ: Union[type, super]) -> TypeObject:
-        return self.checker.make_type_object(typ)
-
-    def get_generic_bases(
-        self, typ: Union[type, str], generic_args: Sequence[Value] = ()
-    ) -> GenericBases:
-        return self.checker.arg_spec_cache.get_generic_bases(typ, generic_args)
-
-    def signature_from_value(self, value: Value) -> MaybeSignature:
-        return self.visitor.signature_from_value(value)
-
-    def get_attribute_from_value(self, root_value: Value, attribute: str) -> Value:
-        return self.visitor.get_attribute(Composite(root_value), attribute)
-
-
-CTX = Context()
+_checker = Checker(TestConfig())
+CTX = NameCheckVisitor("", "", ast.parse(""), checker=_checker)
 
 
 def assert_cannot_assign(left: Value, right: Value) -> None: