Fix phpstan/phpstan#9349: Throw point are not properly recognized

[phpstan-bot]

Summary

When a try block contains a method with @throws RuntimeException followed by other method calls (like $pdo->query()), and the catch block catches PDOException (which extends RuntimeException), PHPStan incorrectly reported $sql as "Undefined variable" instead of "Variable $sql might not be defined". This was because implicit throw points from other method calls were excluded from the catch scope.

Changes

• Modified the implicit throw point matching logic in src/Analyser/NodeScopeResolver.php (Phase 3 of try-catch processing)
• Added a $hasDirectExplicitNonThrowMatch flag that tracks whether any explicit @throws annotation has a definitive (yes) type match with the catch type
• Phase 3 (implicit throw points) now runs unless there is a definitive explicit match, rather than being skipped whenever any explicit non-throw-expression match exists
• Added regression test tests/PHPStan/Rules/Variables/data/bug-9349.php and corresponding test method in DefinedVariableRuleTest

Root cause

The try-catch throw point matching has three phases: (1) Throwable catches all, (2) explicit @throws matching, (3) implicit throw point matching. Phase 3 was guarded by a condition that skipped it when explicit non-throw-expression matches existed (!$onlyExplicitIsThrow). The problem was that @throws RuntimeException on maybeThrows() "maybe" matched PDOException (since PDOException extends RuntimeException), causing Phase 3 to be skipped entirely. This excluded the implicit throw point from $pdo->query() (which executes after $sql is assigned) from the catch scope.

The fix adds tracking of whether the explicit match is definitive (the throw type IS a subtype of the catch type, i.e. isSuperTypeOf returns yes) vs merely possible (maybe). Phase 3 is only skipped when there's a definitive explicit match, ensuring implicit throw points are included when the explicit @throws type only partially overlaps with the catch type.

Test

Added tests/PHPStan/Rules/Variables/data/bug-9349.php that reproduces the original issue: a try block with $this->maybeThrows() (annotated @throws RuntimeException), then $sql assignment, then $pdo->query($sql), caught by PDOException. The test verifies PHPStan reports "Variable $sql might not be defined" instead of "Undefined variable: $sql".

Fixes phpstan/phpstan#9349

[phpstan-bot]

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