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c0768dfd96
## Summary
We currently infer a `@Todo` type whenever we access an attribute on an
intersection type with negative components. This can happen very
naturally. Consequently, this `@Todo` type is rather pervasive and hides
a lot of true positives that ty could otherwise detect:
```py
class Foo:
attr: int = 1
def _(f: Foo | None):
if f:
reveal_type(f) # Foo & ~AlwaysFalsy
reveal_type(f.attr) # now: int, previously: @Todo
```
The changeset here proposes to handle member access on these
intersection types by simply ignoring all negative contributions. This
is not always ideal: a negative contribution like `~<Protocol with
members 'attr'>` could be a hint that `.attr` should not be accessible
on the full intersection type. The behavior can certainly be improved in
the future, but this seems like a reasonable initial step to get rid of
this unnecessary `@Todo` type.
## Ecosystem analysis
There are quite a few changes here. I spot-checked them and found one
bug where attribute access on pure negation types (`~P == object & ~P`)
would not allow attributes on `object` to be accessed. After that was
fixed, I only see true positives and known problems. The fact that a lot
of `unused-ignore-comment` diagnostics go away are also evidence for the
fact that this touches a sensitive area, where static analysis clashes
with dynamically adding attributes to objects:
```py
… # type: ignore # Runtime attribute access
```
## Test Plan
Updated tests.
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|---|---|---|
| .. | ||
| annotations | ||
| assignment | ||
| binary | ||
| boolean | ||
| boundness_declaredness | ||
| call | ||
| class | ||
| comparison | ||
| comprehensions | ||
| conditional | ||
| dataclasses | ||
| declaration | ||
| diagnostics | ||
| directives | ||
| doc | ||
| exception | ||
| expression | ||
| function | ||
| generics | ||
| ide_support | ||
| import | ||
| literal | ||
| loops | ||
| narrow | ||
| regression | ||
| scopes | ||
| shadowing | ||
| snapshots | ||
| stubs | ||
| subscript | ||
| suppressions | ||
| type_compendium | ||
| type_of | ||
| type_properties | ||
| type_qualifiers | ||
| unary | ||
| with | ||
| .mdformat.toml | ||
| attributes.md | ||
| cycle.md | ||
| decorators.md | ||
| del.md | ||
| deprecated.md | ||
| descriptor_protocol.md | ||
| enums.md | ||
| exhaustiveness_checking.md | ||
| final.md | ||
| instance_layout_conflict.md | ||
| intersection_types.md | ||
| invalid_syntax.md | ||
| known_constants.md | ||
| mdtest_config.md | ||
| mdtest_custom_typeshed.md | ||
| metaclass.md | ||
| mro.md | ||
| named_tuple.md | ||
| overloads.md | ||
| pep695_type_aliases.md | ||
| properties.md | ||
| protocols.md | ||
| public_types.md | ||
| statically_known_branches.md | ||
| sys_platform.md | ||
| sys_version_info.md | ||
| terminal_statements.md | ||
| ty_extensions.md | ||
| typed_dict.md | ||
| union_types.md | ||
| unpacking.md | ||
| unreachable.md | ||