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Jul 1, 2019
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New semantic analyzer: fix recursive type aliases #7091

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6f7cd9f
New semantic analyzer: fix recursive type aliases
JukkaL Jun 27, 2019
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Add TODO comment
JukkaL Jul 1, 2019
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12 changes: 7 additions & 5 deletions mypy/newsemanal/semanal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2347,7 +2347,9 @@ def check_and_set_up_type_alias(self, s: AssignmentStmt) -> bool:
self.analyze_alias(rvalue, allow_placeholder=True)
if not res:
return False
if self.found_incomplete_ref(tag) or isinstance(res, PlaceholderType):
# TODO: Maybe we only need to reject top-level placeholders, similar
# to base classes.
if self.found_incomplete_ref(tag) or has_placeholder(res):
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Please add a comment that we should only prohibit top-level placeholders as in base classes and NewTypes in long term, and this is a temporary measure.

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Added a comment.

# Since we have got here, we know this must be a type alias (incomplete refs
# may appear in nested positions), therefore use becomes_typeinfo=True.
placeholder = PlaceholderNode(self.qualified_name(lvalue.name),
Expand Down Expand Up @@ -2381,9 +2383,6 @@ def check_and_set_up_type_alias(self, s: AssignmentStmt) -> bool:
alias_tvars=alias_tvars, no_args=no_args)
if existing:
# An alias gets updated.
if self.final_iteration:
self.cannot_resolve_name(lvalue.name, 'name', s)
return True
updated = False
if isinstance(existing.node, TypeAlias):
if existing.node.target != res:
Expand All @@ -2397,7 +2396,10 @@ def check_and_set_up_type_alias(self, s: AssignmentStmt) -> bool:
# Otherwise just replace existing placeholder with type alias.
existing.node = alias_node
updated = True
if updated:
if self.final_iteration:
self.cannot_resolve_name(lvalue.name, 'name', s)
return True
elif updated:
self.progress = True
# We need to defer so that this change can get propagated to base classes.
self.defer()
Expand Down
15 changes: 6 additions & 9 deletions test-data/unit/check-incremental.test
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Expand Up @@ -2469,10 +2469,10 @@ x: int = C()[0][0]
from typing import List, Generic, TypeVar, NamedTuple
T = TypeVar('T')

class C(A, B): #type: ignore
class C(A, B): # type: ignore
pass
class G(Generic[T]): pass
A = G[C]
A = G[C] # type: ignore
class B(NamedTuple):
x: int

Expand All @@ -2482,7 +2482,7 @@ C(1)[0]
[out]

[case testSerializeRecursiveAliases1]
# flags: --no-new-semantic-analyzer
# flags: --new-semantic-analyzer
from typing import Type, Callable, Union

A = Union[A, int] # type: ignore
Expand All @@ -2491,7 +2491,7 @@ C = Type[C] # type: ignore
[out]

[case testSerializeRecursiveAliases2]
# flags: --no-new-semantic-analyzer
# flags: --new-semantic-analyzer
from typing import Type, Callable, Union

A = Union[B, int] # type: ignore
Expand All @@ -2500,7 +2500,7 @@ C = Type[A] # type: ignore
[out]

[case testSerializeRecursiveAliases3]
# flags: --no-new-semantic-analyzer
# flags: --new-semantic-analyzer
from typing import Type, Callable, Union, NamedTuple

A = Union[B, int] # type: ignore
Expand Down Expand Up @@ -4514,15 +4514,12 @@ from lib import A
B = List[A]
[builtins fixtures/list.pyi]
[out]
tmp/other.pyi:2: error: Module 'lib' has no attribute 'A'
tmp/other.pyi:3: error: Cannot resolve name "B" (possible cyclic definition)
tmp/lib.pyi:2: error: Module 'other' has no attribute 'B'
[out2]
tmp/other.pyi:2: error: Module 'lib' has no attribute 'A'
tmp/other.pyi:3: error: Cannot resolve name "B" (possible cyclic definition)
tmp/lib.pyi:2: error: Module 'other' has no attribute 'B'
tmp/a.py:2: error: Cannot resolve name "lib.A" (possible cyclic definition)
tmp/a.py:3: note: Revealed type is 'Any'
tmp/a.py:3: note: Revealed type is 'builtins.list[Any]'

[case testRecursiveNamedTupleTypedDict]
# flags: --no-new-semantic-analyzer
Expand Down
31 changes: 24 additions & 7 deletions test-data/unit/check-newsemanal.test
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Expand Up @@ -1383,9 +1383,15 @@ x: B
B = List[C]
class C(B): pass

reveal_type(x) # N: Revealed type is 'builtins.list[__main__.C]'
reveal_type(x[0][0]) # N: Revealed type is '__main__.C*'
reveal_type(x)
reveal_type(x[0][0])
[builtins fixtures/list.pyi]
[out]
main:3: error: Cannot resolve name "B" (possible cyclic definition)
main:4: error: Cannot resolve name "B" (possible cyclic definition)
main:4: error: Cannot resolve name "C" (possible cyclic definition)
main:7: note: Revealed type is 'Any'
main:8: note: Revealed type is 'Any'
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It looks like all new failures in this file are because of the problem with nested placeholders. Please add a comment in the existing issue mentioning this, and add links to the issue in these tests.

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Added new issues about this: #7111


[case testNewAnalyzerAliasToNotReadyTwoDeferralsFunction]
import a
Expand All @@ -1410,14 +1416,18 @@ from typing import List
from b import D

def f(x: B) -> List[B]: ...
B = List[C]
B = List[C] # E
class C(B): pass

[file b.py]
from a import f
class D: ...
reveal_type(f) # N: Revealed type is 'def (x: builtins.list[a.C]) -> builtins.list[builtins.list[a.C]]'
reveal_type(f) # N
[builtins fixtures/list.pyi]
[out]
tmp/b.py:3: note: Revealed type is 'def (x: builtins.list[Any]) -> builtins.list[builtins.list[Any]]'
tmp/a.py:5: error: Cannot resolve name "B" (possible cyclic definition)
tmp/a.py:5: error: Cannot resolve name "C" (possible cyclic definition)

[case testNewAnalyzerAliasToNotReadyMixed]
from typing import List, Union
Expand Down Expand Up @@ -1947,14 +1957,21 @@ class B(List[C]):
from typing import NewType, List

x: D
reveal_type(x[0][0]) # N: Revealed type is '__main__.C*'
reveal_type(x[0][0])

D = List[C]
C = NewType('C', B)

class B(D):
pass
[builtins fixtures/list.pyi]
[out]
main:3: error: Cannot resolve name "D" (possible cyclic definition)
main:4: note: Revealed type is 'Any'
main:6: error: Cannot resolve name "D" (possible cyclic definition)
main:6: error: Cannot resolve name "C" (possible cyclic definition)
main:7: error: Argument 2 to NewType(...) must be a valid type
main:7: error: Cannot resolve name "B" (possible cyclic definition)

-- Copied from check-classes.test (tricky corner cases).
[case testNewAnalyzerNoCrashForwardRefToBrokenDoubleNewTypeClass]
Expand All @@ -1974,10 +1991,10 @@ class C:
from typing import List, Generic, TypeVar, NamedTuple
T = TypeVar('T')

class C(A, B):
class C(A, B): # E: Cannot resolve name "A" (possible cyclic definition)
pass
class G(Generic[T]): pass
A = G[C]
A = G[C] # E: Cannot resolve name "A" (possible cyclic definition)
class B(NamedTuple):
x: int

Expand Down
33 changes: 17 additions & 16 deletions test-data/unit/check-type-aliases.test
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Expand Up @@ -178,30 +178,31 @@ Alias = Tuple[int, T]
[out]

[case testRecursiveAliasesErrors1]
# flags: --no-new-semantic-analyzer
# flags: --new-semantic-analyzer
# Recursive aliases are not supported yet.
from typing import Type, Callable, Union

A = Union[A, int]
B = Callable[[B], int]
C = Type[C]
[out]
main:5: error: Recursive types not fully supported yet, nested types replaced with "Any"
main:6: error: Recursive types not fully supported yet, nested types replaced with "Any"
main:7: error: Recursive types not fully supported yet, nested types replaced with "Any"
A = Union[A, int] # E: Cannot resolve name "A" (possible cyclic definition)
B = Callable[[B], int] # E: Cannot resolve name "B" (possible cyclic definition)
C = Type[C] # E: Cannot resolve name "C" (possible cyclic definition)

[case testRecursiveAliasesErrors2]
# flags: --no-new-semantic-analyzer
# flags: --new-semantic-analyzer
# Recursive aliases are not supported yet.
from typing import Type, Callable, Union

A = Union[B, int]
B = Callable[[C], int]
C = Type[A]
x: A
reveal_type(x)
[out]
main:5: error: Recursive types not fully supported yet, nested types replaced with "Any"
main:6: error: Recursive types not fully supported yet, nested types replaced with "Any"
main:7: error: Recursive types not fully supported yet, nested types replaced with "Any"
main:5: error: Cannot resolve name "A" (possible cyclic definition)
main:5: error: Cannot resolve name "B" (possible cyclic definition)
main:6: error: Cannot resolve name "B" (possible cyclic definition)
main:6: error: Cannot resolve name "C" (possible cyclic definition)
main:7: error: Cannot resolve name "C" (possible cyclic definition)
main:9: note: Revealed type is 'Union[Any, builtins.int]'

[case testDoubleForwardAlias]
from typing import List
Expand All @@ -223,12 +224,12 @@ reveal_type(x[0].x) # N: Revealed type is 'builtins.str'
[out]

[case testJSONAliasApproximation]
# flags: --no-new-semantic-analyzer
# flags: --new-semantic-analyzer
# Recursive aliases are not supported yet.
from typing import List, Union, Dict
x: JSON
JSON = Union[int, str, List[JSON], Dict[str, JSON]] # type: ignore
reveal_type(x) # N: Revealed type is 'Union[builtins.int, builtins.str, builtins.list[Any], builtins.dict[builtins.str, Any]]'
x: JSON # E: Cannot resolve name "JSON" (possible cyclic definition)
JSON = Union[int, str, List[JSON], Dict[str, JSON]] # E: Cannot resolve name "JSON" (possible cyclic definition)
reveal_type(x) # N: Revealed type is 'Any'
if isinstance(x, list):
reveal_type(x) # N: Revealed type is 'builtins.list[Any]'
[builtins fixtures/isinstancelist.pyi]
Expand Down