Douglas Creager 416e956fe0 [ty] Infer better specializations of unions with None (etc) (#20749) ... This PR adds a specialization inference special case that lets us handle the following examples better: ```py def f[T](t: T | None) -> T: ... def g[T](t: T | int | None) -> T | int: ... def _(x: str | None): reveal_type(f(x)) # revealed: str (previously str | None) def _(y: str | int | None): reveal_type(g(x)) # revealed: str | int (previously str | int | None) ``` We already have a special case for when the formal is a union where one element is a typevar, but it maps the entire actual type to the typevar (as you can see in the "previously" results above). The new special case kicks in when the actual is also a union. Now, we filter out any actual union elements that are already subtypes of the formal, and only bind whatever types remain to the typevar. (The `| None` pattern appears quite often in the ecosystem results, but it's more general and works with any number of non-typevar union elements.) The new constraint solver should handle this case as well, but it's worth adding this heuristic now with the old solver because it eliminates some false positives from the ecosystem report, and makes the ecosystem report less noisy on the other constraint solver PRs.		2025-10-07 13:33:42 -04:00
..
annotations	[ty] Use typing.Self for the first parameter of instance methods (#20517)	2025-09-29 21:08:08 +02:00
assignment	[ty] More precise type inference for dictionary literals (#20523)	2025-09-24 18:12:00 -04:00
binary	Update default and latest Python versions for 3.14 (#20725)	2025-10-07 12:23:11 -04:00
boolean	Revert "[ty] Better control flow for boolean expressions that are inside if (#18010)" (#18150)	2025-05-17 08:27:32 -04:00
boundness_declaredness	[ty] Reformulation of public symbol inference test suite (#20667)	2025-10-01 14:26:17 +02:00
call	Update default and latest Python versions for 3.14 (#20725)	2025-10-07 12:23:11 -04:00
class	[ty] Rename "possibly unbound" diagnostics to "possibly missing" (#20492)	2025-09-23 14:26:55 +00:00
comparison	[ty] detect cycles in binary comparison inference (#20446)	2025-09-17 09:45:25 +02:00
comprehensions	[ty] Async for loops and async iterables (#19634)	2025-07-30 17:40:24 +02:00
conditional	[ty] Support as-patterns in reachability analysis (#19728)	2025-08-04 20:13:50 +02:00
dataclasses	[ty] initial support for slots=True in dataclasses (#20278)	2025-09-07 18:25:35 +01:00
declaration	[ty] Format conflicting types as an enumeration (#18956)	2025-06-26 14:29:33 +02:00
diagnostics	[ty] Use fully qualified names to distinguish ambiguous protocols in diagnostics (#20627)	2025-09-29 12:02:07 +00:00
directives	[ty] Use annotated parameters as type context (#20635)	2025-10-03 17:14:51 -04:00
doc
exception	[ty] Use separate Rust types for bound and unbound type variables (#19796)	2025-08-11 15:29:58 -04:00
expression	[ty] Rename "possibly unbound" diagnostics to "possibly missing" (#20492)	2025-09-23 14:26:55 +00:00
function	[ty] Improve disambiguation of types via fully qualified names (#20141)	2025-08-29 08:44:18 +00:00
generics	[ty] Infer better specializations of unions with None (etc) (#20749)	2025-10-07 13:33:42 -04:00
ide_support	[ty] Include NamedTupleFallback members in NamedTuple instance completions (#20356)	2025-09-15 11:00:03 +02:00
import	[ty] No union with Unknown for module-global symbols (#20664)	2025-10-01 16:40:30 +02:00
literal	[ty] More precise type inference for dictionary literals (#20523)	2025-09-24 18:12:00 -04:00
loops	[ty] Add more tests for subtyping/assignability between two protocol types (#20573)	2025-09-26 12:07:57 +01:00
narrow	[ty] No union with Unknown for module-global symbols (#20664)	2025-10-01 16:40:30 +02:00
regression
scopes	Update default and latest Python versions for 3.14 (#20725)	2025-10-07 12:23:11 -04:00
shadowing
snapshots	Update default and latest Python versions for 3.14 (#20725)	2025-10-07 12:23:11 -04:00
stubs	Update default and latest Python versions for 3.14 (#20725)	2025-10-07 12:23:11 -04:00
subscript	[ty] Rename "possibly unbound" diagnostics to "possibly missing" (#20492)	2025-09-23 14:26:55 +00:00
suppressions	[ty] Consistent use of American english (in rules) (#19488)	2025-07-22 16:10:38 +02:00
type_compendium	[ty] Infer more precise types for collection literals (#20360)	2025-09-17 18:51:50 -04:00
type_of	[ty] Improve the Display for generic type[] types (#19667)	2025-07-31 19:45:01 +01:00
type_properties	[ty] Introduce TypeRelation::Redundancy (#20602)	2025-10-03 18:35:30 +01:00
type_qualifiers	[ty] Allow annotation expressions to be ast::Attribute nodes (#20413)	2025-09-15 12:06:48 +01:00
unary
with	[ty] Use typing.Self for the first parameter of instance methods (#20517)	2025-09-29 21:08:08 +02:00
.mdformat.toml
async.md	[ty] Support async/await, async with and yield from (#19595)	2025-07-30 11:51:21 +02:00
attributes.md	Update default and latest Python versions for 3.14 (#20725)	2025-10-07 12:23:11 -04:00
classes.md	[ty] don't assume that deferred type inference means deferred name resolution (#20160)	2025-08-29 16:19:45 -07:00
cycle.md
decorators.md
del.md	[ty] No union with Unknown for module-global symbols (#20664)	2025-10-01 16:40:30 +02:00
deprecated.md	[ty] Consistent use of American english (in rules) (#19488)	2025-07-22 16:10:38 +02:00
descriptor_protocol.md	[ty] Use typing.Self for the first parameter of instance methods (#20517)	2025-09-29 21:08:08 +02:00
enums.md	[ty] Enums: allow multiple aliases to point to the same member (#20669)	2025-10-01 15:51:53 +02:00
exhaustiveness_checking.md	[ty] Fix subtyping for dynamic specializations (#20592)	2025-09-26 15:05:03 +02:00
final.md
implicit_type_aliases.md	[ty] no more diverging query cycles in type expressions (#20359)	2025-09-16 16:44:11 -07:00
instance_layout_conflict.md	[ty] initial support for slots=True in dataclasses (#20278)	2025-09-07 18:25:35 +01:00
intersection_types.md	[ty] Expansion of enums into unions of literals (#19382)	2025-07-21 19:37:55 +02:00
invalid_syntax.md
known_constants.md
mdtest_config.md
mdtest_custom_typeshed.md	[ty] Remove Type::Tuple (#19669)	2025-08-11 22:03:32 +01:00
metaclass.md
mro.md	[ty] Treat Hashable, and similar protocols, equivalently to object for subtyping/assignability (#20284)	2025-09-10 11:38:58 +01:00
named_tuple.md	[ty] Use typing.Self for the first parameter of instance methods (#20517)	2025-09-29 21:08:08 +02:00
overloads.md	[ty] Use C[T] instead of C[Unknown] for the upper bound of Self (#20479)	2025-09-23 14:02:25 +02:00
pep695_type_aliases.md	[ty] Use typing.Self for the first parameter of instance methods (#20517)	2025-09-29 21:08:08 +02:00
properties.md	[ty] "foo".startswith is not an instance of types.MethodWrapperType (#20317)	2025-09-10 11:14:26 +00:00
protocols.md	[ty] Fix tiny mistake in protocol tests (#20743)	2025-10-07 11:58:35 +00:00
public_types.md	[ty] No union with Unknown for module-global symbols (#20664)	2025-10-01 16:40:30 +02:00
statically_known_branches.md	[ty] Rename "possibly unbound" diagnostics to "possibly missing" (#20492)	2025-09-23 14:26:55 +00:00
sys_platform.md
sys_version_info.md
t_strings.md	[ty] Add support for PEP 750 t-strings (#20085)	2025-08-25 18:49:49 +00:00
terminal_statements.md	[ty] improve lazy scope place lookup (#19321)	2025-07-25 07:11:11 +00:00
ty_extensions.md	[ty] Fix CallableTypeOf[…] for classmethods (#20345)	2025-09-11 10:14:38 +02:00
typed_dict.md	[ty] Use annotated parameters as type context (#20635)	2025-10-03 17:14:51 -04:00
union_types.md	[ty] Introduce TypeRelation::Redundancy (#20602)	2025-10-03 18:35:30 +01:00
unpacking.md	[ty] Infer more precise types for collection literals (#20360)	2025-09-17 18:51:50 -04:00
unreachable.md	[ty] Rename "possibly unbound" diagnostics to "possibly missing" (#20492)	2025-09-23 14:26:55 +00:00