Two-stage collapse for oversized constant arrays#5555
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ondrejmirtes merged 2 commits into2.1.xfrom Apr 27, 2026
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Backport of `TypeCombinator` changes from two `unsealed`-branch commits, plus their test updates: - `optimizeConstantArrays` now runs a stage 1 same-key-set collapse before falling back to the lossy generalization. Variants sharing a key signature `mergeWith` losslessly into a single shape; the per-position record structure survives, only the values widen. - `reduceArrays` final pass collapses the loop-accumulator triangular variant pattern (conditional `$xs[] = …` push sites leaving behind list variants of progressively longer length) into a single `non-empty-list<unionValueType>` when their cumulative `countConstantArrayValueTypes` exceeds the limit. Skips when every list variant shares one key signature — those are stage 1's job (per-position precision instead of a flat fold), and on 2.1.x without the unsealed-branch's `getUnsealedTypes()` pre-pass the flat fold would otherwise pre-empt stage 1 and regress bug-7963's 144-record literal. Knock-on effects: - bug-10717: language-code lookup now produces the precise union of every code instead of `bool|literal-string`. - bug-13509: alert variants land on the precise union of seven record shapes instead of the previous `&oversized-array` decomposition. - New nsrt `oversized-array-stages.php` exercises both phases: Phase 1 (small literal preserved as-is) and Phase 2 (eight conditional pushes with same-shape records — the triangular union of list variants pushes the count past the limit, list-collapse folds them into a `non-empty-list` whose value type preserves the per-record `(kind, value, opts)` correlation as a tagged union of the eight original record shapes). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Closes phpstan/phpstan#8636 Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
optimizeConstantArraysruns a stage 1 same-key-set collapse before its lossy generalization fallback. Variants sharing a key signaturemergeWithlosslessly into a single shape; per-position record structure survives, only the values widen to a union.reduceArraysfinal pass collapses the loop-accumulator triangular variant pattern (conditional$xs[] = …push sites leaving behind list variants of progressively longer length) into a singlenon-empty-list<unionValueType>when their cumulativecountConstantArrayValueTypesexceeds the limit. Skips when every list variant shares one key signature — those are stage 1's job.Knock-on effects
bool|literal-string.&oversized-arraydecomposition.oversized-array-stages.phpexercises both phases — Phase 1 (small literal preserved as-is) and Phase 2 (eight conditional pushes whose triangular union triggers list-collapse, preserving the per-record(kind, value, opts)correlation as a tagged union of the eight original record shapes).bug-8636(rule test onReturnTypeRule): the playground sample from issue #8636 — a 30-entry HUGE_CONST whose[$c]['p7']lookup previously inferred toarray<int, string>|string— now analyses clean.Closes phpstan/phpstan#8636
Test plan
vendor/bin/phpunit tests/PHPStan/Analyser/NodeScopeResolverTest.php— 1547 / 1547 pass.vendor/bin/phpunit tests/PHPStan/Analyser/AnalyserIntegrationTest.php— 175 / 175 pass (testBug7963 stays green).vendor/bin/phpunit tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php --filter testBug8636— passes; TDD-validated to fail whenTypeCombinator.phpis restored to pre-fix state.🤖 Generated with Claude Code