Run loop convergence at all nesting depths in NodeScopeResolver

[phpstan-bot]

Summary

When array-modifying functions like array_pop() or array_shift() were used inside a nested loop, PHPStan incorrectly narrowed the array type to array{} because the inner loop didn't converge during the outer loop's convergence analysis. This caused false positives like "Variable $text in empty() always exists and is always falsy."

The fix removes the if ($context->isTopLevel()) guard from loop convergence blocks so that nested loops always converge, while preserving $context->enterDeep() in the convergence body to suppress other top-level behaviors.

Changes

• src/Analyser/NodeScopeResolver.php: Removed if ($context->isTopLevel()) guard from convergence blocks in all four loop types:
  • Foreach (was line 1453)
  • While (was line 1676)
  • Do-while (was line 1767)
  • For (was line 1885)
• $context->enterDeep() is preserved unchanged in convergence body processing — this suppresses top-level-only behaviors like alwaysIterates/neverIterates detection and always-false-condition early exit for nested loops
• Updated two existing test expectations that reflected the old less-precise analysis:
  • tests/PHPStan/Analyser/nsrt/generalize-scope-recursive.php: array{}|array{foo?: array} → array{}|array{foo: array<array>} (more precise recursive type)
  • tests/PHPStan/Analyser/nsrt/bug-10438.php: array<string, array{}|array{string}|string> → array<string, list<string>|string> (correctly generalizes to list)

Root cause

The convergence loop (do-while that iterates up to LOOP_SCOPE_ITERATIONS times to find stable types) was guarded by if ($context->isTopLevel()). The convergence body was processed with $context->enterDeep(), which set isTopLevel() to false. This caused nested loops to skip convergence entirely, getting only a single pass through their body.

For the reported bug: the outer while loop's convergence processed its body (containing the inner while loop) with enterDeep(). The inner while loop skipped convergence and executed only once, adding just 1 element to the array. Then array_pop() removed it, producing array{}. This incorrect type propagated to the outer loop's condition scope.

The fix decouples "run convergence" from "is top-level" by removing the guard. Convergence now runs at all depths, each bounded by LOOP_SCOPE_ITERATIONS (3). The enterDeep() in the body still suppresses other top-level behaviors, preventing regressions from nested loops getting full top-level treatment.

Test

• Added tests/PHPStan/Rules/Variables/data/bug-10666.php with four variants covering all combinations: while+array_pop, while+array_shift, do-while+array_pop, for+array_pop — all inside an outer while loop with empty() check
• Added tests/PHPStan/Rules/Variables/EmptyRuleTest::testBug10666() expecting no errors (false positive fix)
• Added tests/PHPStan/Analyser/nsrt/bug-10666.php with assertType checks verifying correct list types after pop/shift in nested loops

Fixes phpstan/phpstan#10666