Fix TypeVar resolution order in union type aliases

[Adist319]

Summary

Union type aliases like Result = Ok[_T] | Error[_TE] were collecting type parameters in the wrong order because union members get sorted alphabetically during simplification. This caused Result[T, TE] to incorrectly match T to _TE instead of _T.

The fix sorts collected type parameters by their source location after traversal, restoring the user's intended order.

Fixes #1759.

Test Plan

• Added test_union_type_alias_typevar_order - original issue reproduction
• Added test_union_type_alias_typevar_order_multiple - 3 TypeVars with reversed alphabetical order
• Added test_union_type_alias_duplicate_typevar - same TypeVar appearing multiple times

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

Expression (https://github.com/cognitedata/Expression)
+  WARN expression/core/fn.py:39:27-50: Redundant cast: `TailCall[_P]` is the same type as `TailCall[_P]` [redundant-cast]
- ERROR expression/core/fn.py:29:30-58: Expected a valid ParamSpec expression, got `_TResult` [invalid-param-spec]
- ERROR expression/core/fn.py:29:30-58: `ParamSpec` cannot be used for type parameter [invalid-param-spec]
- ERROR expression/core/fn.py:37:29-57: Expected a valid ParamSpec expression, got `_TResult` [invalid-param-spec]
- ERROR expression/core/fn.py:37:29-57: `ParamSpec` cannot be used for type parameter [invalid-param-spec]
+  WARN expression/core/fn.py:58:27-50: Redundant cast: `TailCall[_P]` is the same type as `TailCall[_P]` [redundant-cast]
- ERROR expression/core/fn.py:53:46-74: Expected a valid ParamSpec expression, got `_TResult` [invalid-param-spec]
- ERROR expression/core/fn.py:53:46-74: `ParamSpec` cannot be used for type parameter [invalid-param-spec]
- ERROR expression/core/fn.py:56:35-63: Expected a valid ParamSpec expression, got `_TResult` [invalid-param-spec]
- ERROR expression/core/fn.py:56:35-63: `ParamSpec` cannot be used for type parameter [invalid-param-spec]
+ ::warning file=expression/core/fn.py,line=39,col=27,endLine=39,endColumn=50,title=Pyrefly redundant-cast::Redundant cast: `TailCall[_P]` is the same type as `TailCall[_P]`
- ::error file=expression/core/fn.py,line=29,col=30,endLine=29,endColumn=58,title=Pyrefly invalid-param-spec::Expected a valid ParamSpec expression, got `_TResult`
- ::error file=expression/core/fn.py,line=29,col=30,endLine=29,endColumn=58,title=Pyrefly invalid-param-spec::`ParamSpec` cannot be used for type parameter
- ::error file=expression/core/fn.py,line=37,col=29,endLine=37,endColumn=57,title=Pyrefly invalid-param-spec::Expected a valid ParamSpec expression, got `_TResult`
- ::error file=expression/core/fn.py,line=37,col=29,endLine=37,endColumn=57,title=Pyrefly invalid-param-spec::`ParamSpec` cannot be used for type parameter
+ ::warning file=expression/core/fn.py,line=58,col=27,endLine=58,endColumn=50,title=Pyrefly redundant-cast::Redundant cast: `TailCall[_P]` is the same type as `TailCall[_P]`
- ::error file=expression/core/fn.py,line=53,col=46,endLine=53,endColumn=74,title=Pyrefly invalid-param-spec::Expected a valid ParamSpec expression, got `_TResult`
- ::error file=expression/core/fn.py,line=53,col=46,endLine=53,endColumn=74,title=Pyrefly invalid-param-spec::`ParamSpec` cannot be used for type parameter
- ::error file=expression/core/fn.py,line=56,col=35,endLine=56,endColumn=63,title=Pyrefly invalid-param-spec::Expected a valid ParamSpec expression, got `_TResult`
- ::error file=expression/core/fn.py,line=56,col=35,endLine=56,endColumn=63,title=Pyrefly invalid-param-spec::`ParamSpec` cannot be used for type parameter

schemathesis (https://github.com/schemathesis/schemathesis)
- ERROR src/schemathesis/cli/commands/run/handlers/output.py:992:34-48: Object of class `Exception` has no attribute `probes` [missing-attribute]
- ERROR src/schemathesis/engine/events.py:77:14-45: `ProbePayload` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/engine/events.py:81:66-97: `ProbePayload` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/engine/phases/probes.py:41:14-45: `ProbePayload` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/engine/phases/probes.py:54:22-49: Argument `ProbePayload` is not assignable to parameter `value` with type `Exception` in function `schemathesis.core.result.Ok.__init__` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:52:22-57: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:71:30-41: Argument `InvalidSchema` is not assignable to parameter `object` with type `APIOperation[Unknown, Unknown, Unknown]` in function `list.append` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:73:27-39: Argument `APIOperation[Unknown, Unknown, Unknown]` is not assignable to parameter `object` with type `InvalidSchema` in function `list.append` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:228:62-71: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.phases_for` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:236:77-86: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `get_strategy_kwargs` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:237:69-84: Object of class `InvalidSchema` has no attribute `label` [missing-attribute]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:241:39-48: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.generation.hypothesis.builder.create_test` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:245:87-96: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.get_hypothesis_settings` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:259:35-44: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.engine.phases.unit._executor.run_test` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/__init__.py:269:30-35: Argument `APIOperation[Unknown, Unknown, Unknown]` is not assignable to parameter `error` with type `Exception` in function `on_error` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/_layered_scheduler.py:50:33-68: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/engine/phases/unit/_layered_scheduler.py:65:31-64: Argument `APIOperation[Unknown, Unknown, Unknown]` is not assignable to parameter `value` with type `InvalidSchema` in function `schemathesis.core.result.Ok.__init__` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/_layered_scheduler.py:83:32-57: Argument `InvalidSchema` is not assignable to parameter `error` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.core.result.Err.__init__` [bad-argument-type]
- ERROR src/schemathesis/engine/phases/unit/_pool.py:24:41-76: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/engine/phases/unit/_pool.py:28:33-68: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/pytest/lazy.py:48:16-68: `tuple[APIOperation[Unknown, Unknown, Unknown], (...) -> Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/pytest/lazy.py:54:58-67: Argument `InvalidSchema` is not assignable to parameter with type `APIOperation[Unknown, Unknown, Unknown]` [bad-argument-type]
- ERROR src/schemathesis/pytest/lazy.py:60:57-66: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.phases_for` [bad-argument-type]
- ERROR src/schemathesis/pytest/lazy.py:71:27-36: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.generation.hypothesis.builder.create_test` [bad-argument-type]
- ERROR src/schemathesis/pytest/lazy.py:74:90-99: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.get_hypothesis_settings` [bad-argument-type]
- ERROR src/schemathesis/pytest/lazy.py:82:22-39: Argument `tuple[InvalidSchema, (...) -> Unknown]` is not assignable to parameter `value` with type `InvalidSchema` in function `schemathesis.core.result.Ok.__init__` [bad-argument-type]
- ERROR src/schemathesis/pytest/lazy.py:84:19-25: Type of yielded value `Err[APIOperation[Unknown, Unknown, Unknown]]` is not assignable to declared return type `Err[tuple[APIOperation[Unknown, Unknown, Unknown], (...) -> Unknown]] | Ok[InvalidSchema]` [invalid-yield]
- ERROR src/schemathesis/pytest/lazy.py:265:25-44: Type `InvalidSchema` is not iterable [not-iterable]
- ERROR src/schemathesis/pytest/lazy.py:269:49-61: Argument `tuple[APIOperation[Unknown, Unknown, Unknown], (...) -> Unknown]` is not assignable to parameter `error` with type `InvalidSchema` in function `_schema_error` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:109:34-69: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/pytest/plugin.py:141:62-71: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.auth_for` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:146:68-77: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.headers_for` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:150:62-71: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.generation.overrides.for_operation` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:156:66-75: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.phases_for` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:167:31-40: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.generation.hypothesis.builder.create_test` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:171:87-96: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.get_hypothesis_settings` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:184:40-49: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `SchemathesisCase._get_test_name` [bad-argument-type]
- ERROR src/schemathesis/pytest/plugin.py:187:23-53: Object of class `APIOperation` has no attribute `as_failing_test_function` [missing-attribute]
- ERROR src/schemathesis/schemas.py:311:47-82: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/schemas.py:486:13-39: Object of class `InvalidSchema` has no attribute `as_strategy` [missing-attribute]
- ERROR src/schemathesis/specs/graphql/schemas.py:191:47-82: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/specs/graphql/schemas.py:203:26-35: Argument `APIOperation[Unknown, Unknown, Unknown]` is not assignable to parameter `value` with type `InvalidSchema` in function `schemathesis.core.result.Ok.__init__` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/analysis.py:114:57-72: Object of class `InvalidSchema` has no attribute `label` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/analysis.py:116:29-48: Object of class `InvalidSchema` has no attribute `responses` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/analysis.py:123:35-50: Argument `object` is not assignable to parameter `operation` with type `str` in function `schemathesis.resources.repository.ResourceRepository.record_response` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/analysis.py:192:61-70: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.specs.openapi.warnings.detect_missing_deserializers` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/analysis.py:193:34-49: Object of class `InvalidSchema` has no attribute `label` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/analysis.py:194:63-72: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.specs.openapi.warnings.detect_unsupported_regex` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/analysis.py:195:34-49: Object of class `InvalidSchema` has no attribute `label` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/schemas.py:291:47-82: `APIOperation[Unknown, Unknown, Unknown]` is not assignable to upper bound `Exception` of type variable `E` [bad-specialization]
- ERROR src/schemathesis/specs/openapi/schemas.py:342:38-47: Argument `APIOperation[Unknown, Unknown, Unknown]` is not assignable to parameter `value` with type `InvalidSchema` in function `schemathesis.core.result.Ok.__init__` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/schemas.py:344:35-68: Type of yielded value `Err[InvalidSchema]` is not assignable to declared return type `Err[APIOperation[Unknown, Unknown, Unknown]] | Ok[InvalidSchema]` [invalid-yield]
- ERROR src/schemathesis/specs/openapi/schemas.py:346:23-56: Type of yielded value `Err[InvalidSchema]` is not assignable to declared return type `Err[APIOperation[Unknown, Unknown, Unknown]] | Ok[InvalidSchema]` [invalid-yield]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:120:39-49: Argument `list[InvalidSchema]` is not assignable to parameter `operations` with type `list[APIOperation[Unknown, Unknown, Unknown]]` in function `collect_transitions` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:127:28-47: Object of class `InvalidSchema` has no attribute `responses` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:130:12-27: Object of class `InvalidSchema` has no attribute `label` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:132:48-63: Cannot index into `dict[str, OperationTransitions]` [bad-index]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:138:32-47: Cannot set item in `dict[str, (StepOutput) -> str | None]` [unsupported-operation]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:162:39-49: Argument `list[InvalidSchema]` is not assignable to parameter `operations` with type `list[APIOperation[Unknown, Unknown, Unknown]]` in function `classify_root_transitions` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:165:12-24: Object of class `InvalidSchema` has no attribute `label` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:166:47-59: Cannot index into `dict[str, OperationTransitions]` [bad-index]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:167:61-67: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown] | None` in function `schemathesis.config._projects.ProjectConfig.generation_for` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:173:102-114: Argument `object` is not assignable to parameter `target` with type `str` in function `is_transition_allowed` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:178:56-62: Argument `InvalidSchema` is not assignable to parameter `target` with type `APIOperation[Unknown, Unknown, Unknown]` in function `into_step_input` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:185:37-55: Object of class `InvalidSchema` has no attribute `as_strategy` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:188:33-51: Object of class `InvalidSchema` has no attribute `as_strategy` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:202:60-72: Argument `object` is not assignable to parameter `label` with type `str` in function `is_root_allowed` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/__init__.py:338:33-45: `Exception | NotSet` is not assignable to attribute `body` with type `NotSet | bool | bytes | dict[str, Any] | float | int | list[Unknown] | str` [bad-assignment]
- ERROR src/schemathesis/specs/openapi/stateful/dependencies/__init__.py:67:31-40: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.specs.openapi.stateful.dependencies.inputs.extract_inputs` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/dependencies/__init__.py:74:31-40: Argument `InvalidSchema` is not assignable to parameter `operation` with type `APIOperation[Unknown, Unknown, Unknown]` in function `schemathesis.specs.openapi.stateful.dependencies.outputs.extract_outputs` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/dependencies/__init__.py:80:28-43: Object of class `InvalidSchema` has no attribute `label` [missing-attribute]
- ERROR src/schemathesis/specs/openapi/stateful/dependencies/__init__.py:81:28-44: Argument `str | None` is not assignable to parameter `method` with type `str` in function `schemathesis.specs.openapi.stateful.dependencies.models.OperationNode.__init__` [bad-argument-type]
- ERROR src/schemathesis/specs/openapi/stateful/dependencies/__init__.py:82:26-40: Argument `str | None` is not assignable to parameter `path` with type `str` in function `schemathesis.specs.openapi.stateful.dependencies.models.OperationNode.__init__` [bad-argument-type]
- ::error file=src/schemathesis/cli/commands/run/handlers/output.py,line=992,col=34,endLine=992,endColumn=48,title=Pyrefly missing-attribute::Object of class `Exception` has no attribute `probes`
- ::error file=src/schemathesis/engine/events.py,line=77,col=14,endLine=77,endColumn=45,title=Pyrefly bad-specialization::`ProbePayload` is not assignable to upper bound `Exception` of type variable `E`
- ::error file=src/schemathesis/engine/events.py,line=81,col=66,endLine=81,endColumn=97,title=Pyrefly bad-specialization::`ProbePayload` is not assignable to upper bound `Exception` of type variable `E`
- ::error file=src/schemathesis/engine/phases/probes.py,line=41,col=14,endLine=41,endColumn=45,title=Pyrefly bad-specialization::`ProbePayload` is not assignable to upper bound `Exception` of type variable `E`

... (truncated 69 lines) ...

[meta-codesync]

@stroxler has imported this pull request. If you are a Meta employee, you can view this in D90423141.

[stroxler]

Thanks for the PR! It looks reasonable to me, I'll aim to get a second review and see if I can get it merged

[grievejia]

Review automatically exported from Phabricator review in Meta.

[meta-codesync]

@stroxler merged this pull request in 6bef521.

[yangdanny97]

wow, nice work @Adist319!