8000 Fix crashes and fails in forward references by ilevkivskyi · Pull Request #3952 · python/mypy · GitHub
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Fix crashes and fails in forward references #3952

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Merged
merged 43 commits into from
Sep 27, 2017
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45e5931
Add basic tests, more details will be added when they will not crash
ilevkivskyi Aug 31, 2017
cb4caa5
Correct tests
ilevkivskyi Sep 1, 2017
1cdc980
Implement ForwardRef type, wrap UnboundType, pass SecondPass to third…
ilevkivskyi Sep 11, 2017
260ef02
Add ForwardRefRemover
ilevkivskyi Sep 11, 2017
a58a217
Add elimination patches
ilevkivskyi Sep 11, 2017
950a022
Fix replacement logic; fix newtype error formatting
ilevkivskyi Sep 11, 2017
411b24d
Fix third pass (need to go deeper)
ilevkivskyi Sep 11, 2017
b9b8528
Implement syntethic replacer
ilevkivskyi Sep 11, 2017
48d6de4
Need to go deeper (as usual)
ilevkivskyi Sep 11, 2017
ec45441
Fix postponed fallback join
ilevkivskyi Sep 11, 2017
ac32ed4
Simplify some code and add annotations
ilevkivskyi Sep 11, 2017
3fb3019
Simplify traversal logic; add loads of tests
ilevkivskyi Sep 12, 2017
f9b1320
Take care about one more special case; add few tests and dcostrings
ilevkivskyi Sep 12, 2017
cf014b8
Unify visitors
ilevkivskyi Sep 12, 2017
665236b
Add some more comments and docstrings
ilevkivskyi Sep 12, 2017
9a318aa
Add recursive type warnings
ilevkivskyi Sep 12, 2017
757fbd9
Fix lint
ilevkivskyi Sep 12, 2017
4502ce2
Also clean-up bases; add more tests and allow some previously skipped
ilevkivskyi Sep 13, 2017
3b39d40
One more TypedDict test
ilevkivskyi Sep 13, 2017
c8b28fe
Add another simple self-referrential NamedTuple test
ilevkivskyi Sep 13, 2017
9f92b0f
Fix type_override; add tests for recursive aliases; fix Callable TODO…
Sep 13, 2017
9779103
Merge branch 'master' into fix-synthetic-crashes
ilevkivskyi Sep 14, 2017
b914bdb
Merge remote-tracking branch 'upstream/master' into fix-synthetic-cra…
ilevkivskyi Sep 19, 2017
3568fdb
Skip the whole ForwardRef dance in unchecked functions
ilevkivskyi Sep 19, 2017
54d9331
Simplify test
ilevkivskyi Sep 19, 2017
b9ddacc
Fix self-check
ilevkivskyi Sep 19, 2017
5bfe9ca
Fix cross-file forward references (+test)
ilevkivskyi Sep 19, 2017
a2912e9
More tests
ilevkivskyi Sep 19, 2017
10c65b8
Merge branch 'master' into fix-synthetic-crashes
ilevkivskyi Sep 20, 2017
21dfbfe
Fix situation when recursive namedtuple appears directly in base clas…
ilevkivskyi Sep 20, 2017
f2ddbcd
Merge branch 'fix-synthetic-crashes' of https://github.com/ilevkivsky…
ilevkivskyi Sep 20, 2017
03597ee
Clean-up PR: Remove unnecesary imports, outdated comment, unnecessary…
ilevkivskyi Sep 20, 2017
649ef32
Add tests for generic classes, enums, with statements and for statements
ilevkivskyi Sep 20, 2017
83f8907
Add processing for for and with statements (+more tests)
ilevkivskyi Sep 20, 2017
13c7176
Add support for generic types with forward references
ilevkivskyi Sep 20, 2017
79b10d6
Prohibit forward refs to type vars and subscripted forward refs to al…
ilevkivskyi Sep 21, 2017
321a809
Refactor code to avoid passing semantic analyzer to type analyzer, on…
ilevkivskyi Sep 21, 2017
076c909
Address the rest of the review comments
ilevkivskyi Sep 22, 2017
c1a63ec
Improve two tests
ilevkivskyi Sep 22, 2017
97e6f47
Add one more test as suggested in #3990
ilevkivskyi Sep 23, 2017
8f52654
Address latest review comments
ilevkivskyi Sep 26, 2017
6edd078
Improve tests; Fix one more crash on NewType MRO
ilevkivskyi Sep 27, 2017
514b8bd
Fix formatting in tests
ilevkivskyi Sep 27, 2017
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Take care about one more special case; add few tests and dcostrings
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ilevkivskyi committed Sep 12, 2017
commit f9b132085d9521d095ade99d44df059dfcba1d9f
20 changes: 20 additions & 0 deletions mypy/semanal.py
Original file line number Diff line number Diff line change
Expand Up @@ -4670,6 +4670,9 @@ def visit_any(self, t: AnyType) -> Type:


class TypeReplacer(TypeTranslator):
"""This is very similar TypeTranslator but tracks visited nodes to avoid
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Maybe rename to ForwardReferenceResolver or something? The current name doesn't quite capture what this does. The docstring could mention that this does two things:

  • Resolves/fixes forward references.
  • Generates errors for unsupported type recursion and breaks recursion by resolving recursive back references to Any types. (Recursive type references can be thought of as a subset of forward references.)

Style nit: I prefer multi-line docstrings to be formatted like this:

"""Single-line summary of what this does.

Continue description here if it doesn't fit on a single
line ...
"""

infinite recursion on potentially circular (self- or mutually-referential) types.
"""
def __init__(self):
self.seen = [] # type: List[Type]
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You could use a Set[int] containing id()s of Type objects for better performance with large types, but the practical impact is slightly minor.

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This actually does not work, I get some weird failures, when I change this to a set. I am not sure why, but my guess is that Python reuses ids for deleted objects.


Expand Down Expand Up @@ -4736,13 +4739,30 @@ def visit_type_type(self, t: TypeType) -> Type:


class ForwardRefRemover(TypeReplacer):
"""This visitor tracks situations like this:

x: A # this type is not yet known and therefore wrapped in ForwardRef
# it's content is updated in ThirdPass, now we need to unwrap this type.
A = NewType('A', int)
"""
def visit_forwardref_type(self, t: ForwardRef) -> Type:
return t.link.accept(self)


class SyntheticReplacer(ForwardRefRemover):
"""This visitor tracks situations like this:

x: A # when analyzing this type we will get an Instance from FirstPass
# now we need to update this to actual analyzed TupleType.
class A(NamedTuple):
attr: str
"""
def visit_instance(self, t: Instance) -> Type:
info = t.type
# Special case, analyzed bases transformed the type into TupleType.
if info.tuple_type and not self.seen:
return info.tuple_type.copy_modified(fallback=Instance(info, []))
# Update forward Instance's to corresponding analyzed types.
if info.replaced and info.replaced.tuple_type:
tp = info.replaced.tuple_type
if any((s is tp) or (s is t) for s in self.seen):
Expand Down
2 changes: 1 addition & 1 deletion mypy/typeanal.py
Original file line number Diff line number Diff line change
Expand Up @@ -605,7 +605,7 @@ def __init__(self,

def visit_instance(self, t: Instance) -> None:
info = t.type
if info.replaced:
if info.replaced or info.tuple_type:
self.indicator['synthetic'] = True
# Check type argument count.
if len(t.args) != len(info.type_vars):
Expand Down
10 changes: 10 additions & 0 deletions test-data/unit/check-classes.test
Original file line number Diff line number Diff line change
Expand Up @@ -3385,6 +3385,16 @@ D = TypeVar('D')
def mkdict(dict_type: Type[D]) -> D: ...
reveal_type(mkdict(ExampleDict)) # E: Revealed type is '__main__.ExampleDict*[Any, Any]'

[case testTupleForwardBase]
from m import a
a[0]() # E: "int" not callable

[file m.py]
from typing import Tuple
a = None # type: A
class A(Tuple[int, str]): pass
[builtins fixtures/tuple.pyi]

-- Synthetic types crashes
-- -----------------------

Expand Down
6 changes: 3 additions & 3 deletions test-data/unit/check-generics.test
Original file line number Diff line number Diff line change
Expand Up @@ -654,14 +654,14 @@ reveal_type(f3()) # E: Revealed type is 'Union[builtins.int, __main__.Node[built
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
IntNode = Node[int, S] # This is on purpose, to test basic forward references to aliases
AnyNode = Node[S, T]

class Node(Generic[T, S]):
def __init__(self, x: T, y: S) -> None:
self.x = x
self.y = y

IntNode = Node[int, S]
AnyNode = Node[S, T]

def output() -> IntNode[str]:
return Node(1, 'x')
x = output() # type: IntNode # This is OK (implicit Any)
Expand Down
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