Keep unions of general array types separate#5506
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ondrejmirtes wants to merge 2 commits into2.1.xfrom
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Previously `TypeCombinator::processArrayTypes` collapsed multiple general array members into a single `ArrayType` with unioned keys and values, so `array<int>|array<string>` was indistinguishable from `array<int|string>` (phpstan/phpstan#8963). Under `BleedingEdgeToggle::isBleedingEdge()` the members are now kept as distinct union branches; the outer `union()` loop handles subsumption via `compareTypesInUnion`. The `array{} | non-empty- array<X>` -> `array<X>` simplification is preserved by falling back to the old collapse path whenever an empty constant array is present.
Drops the BleedingEdgeToggle gate so CI exercises the new path on all configs. Revert before merging.
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Summary
TypeCombinator::processArrayTypesno longer collapses multiple general array members into a singleArrayTypewith unioned keys and values, soarray<int>|array<string>stays distinct fromarray<int|string>(fixes Union of arrays is not array of unions phpstan#8963). Subsumption (array<int>|array<int|string>→array<int|string>) is handled by the existing outerunion()loop viacompareTypesInUnion.array{} | non-empty-array<X>→array<X>simplification is preserved by falling back to the old collapse path whenever an empty constant array is present — that merge is lossless and not expressible as a keep-separate result.is_string($list[0])onlist<int>|list<string>narrows tolist<string>(withhasOffsetValue(0, string)).array<mixed~'foo'>|non-empty-array<mixed>where the old collapse was lossless; those need a follow-up heuristic before removing the WIP gate.TMP WIP commit (
8c3554c54c) runs the new path for everyone, not just bleeding edge, so CI exercises it. Revert before merge.Test plan
tests/PHPStan/Analyser/nsrt/array-union-keep-separate.phpadded — covers the issue repro, subsumption cases, narrowing via offset access, constant + general mixing, iterationNodeScopeResolverTestgreen except 10 known Bucket B filesLegacyNodeScopeResolverTest, coreTypeunit tests greenTypeCombinatorTesthas 18 describe-output failures under the WIP (no bleedingEdge); expected, to be re-baselinedarray<X>|non-empty-array<Y>) before removing WIP gate🤖 Generated with Claude Code