Refactor: Add BleedingEdgeToggle::withBleedingEdge() and use it instead of manual set/restore in tests

[phpstan-bot]

Summary

Several tests manually back up the global bleeding-edge toggle with BleedingEdgeToggle::isBleedingEdge(), call setBleedingEdge(), and restore the previous value afterwards — sometimes via ad-hoc try/finally blocks, sometimes by restoring at the end of a data provider that yields while the toggle is held. This is repetitive and, in data providers, fragile: holding the toggle across a yield can leak it into unrelated tests.

This PR introduces a single helper, BleedingEdgeToggle::withBleedingEdge(), that encapsulates the set/restore handling, and rewrites every manual set/restore site to use it.

Changes

• src/DependencyInjection/BleedingEdgeToggle.php: add withBleedingEdge(bool $bleedingEdge, callable $callback). It backs up the current value, sets the toggle, runs the callback, and restores the previous value in a finally. It throws ShouldNotHappenException if the callback returns a Generator, because that would mean the toggle is held across yield.
• tests/PHPStan/Type/TypeCombinatorTest.php: replace the four identical backup/setBleedingEdge(true)/restore blocks in testUnion, testUnionInversed, testIntersect, testIntersectInversed with a withBleedingEdge(true, ...) call that resolves the type strings inside the callback.
• tests/PHPStan/Type/Constant/ConstantArrayTypeTest.php:
  • testIsSuperTypeOf, testEqualsTreatsLegacyNullAndSealedMarkerAsEqual, testSealedness: replace try/finally set/restore with withBleedingEdge(), returning the constructed types from the callback and asserting on them afterwards.
  • dataAccepts, dataGetArraySize: build the data sets inside withBleedingEdge() callbacks and yield from the returned arrays, instead of holding the toggle across yield.
• tests/PHPStan/Type/Constant/ConstantArrayTypeBuilderTest.php: testGetArraySealedEmptyStaysConstantArrayType now constructs its array via withBleedingEdge(true, ...).
• tests/PHPStan/DependencyInjection/BleedingEdgeToggleTest.php (new): unit tests for the helper.
• src/DependencyInjection/ContainerFactory.php is intentionally left untouched: it performs a one-way set when building the container, not a set/restore, so it is not a candidate for withBleedingEdge().

Root cause

This is a refactor, not a bug fix. The repeated isBleedingEdge() backup + setBleedingEdge() restore pattern was scattered across tests. The data-provider variants additionally restored the toggle only when the generator was fully consumed, so the toggle stayed mutated while PHPUnit held the generator open between yields. withBleedingEdge() centralizes the set/restore in a finally and forbids returning a Generator, forcing data providers to construct their objects while the toggle is set and return them, eliminating the leak.

Test

• New BleedingEdgeToggleTest verifies: the toggle is set during the callback and restored afterwards (both when previously disabled and enabled), the callback's return value is propagated, the previous value is restored even when the callback throws, returning a Generator throws ShouldNotHappenException while still restoring the toggle, and data sets are produced while the toggle is set.
• All refactored call sites (TypeCombinatorTest, ConstantArrayTypeTest, ConstantArrayTypeBuilderTest) continue to pass, confirming behavior is preserved.

Fixes phpstan/phpstan#14859