RequiredPhpVersionVisitor: report native union types as requiring PHP 8.0

[phpstan-bot]

Summary

RequiredPhpVersionVisitor detects the minimum PHP version a test fixture needs to parse, so CI can skip fixtures on older PHP versions instead of hitting hard parse errors. It already reported intersection types (PHP 8.1), DNF types (8.2) and the standalone true type (8.2), but it did not report native union types (A|B), which are a parse error on PHP 7.4 and lower. This change makes the visitor report a PHP 8.0 requirement for native union types.

Changes

• build/PHPStan/Build/RequiredPhpVersionVisitor.php: when visiting a Node\UnionType, call require(self::PHP_8_0, 'union types', $node). The pre-existing per-inner-type checks (intersection inside a union -> DNF -> 8.2, standalone true -> 8.2) still win because require() keeps the highest version.
• tests/PHPStan/Build/RequiredPhpVersionCommentTest.php: add union type, union return type and nullable union type (A|null) cases asserting 80000.
• Added // lint >= 8.0 comments to the 26 fixtures that newly trip the detector because they use native union types in signatures without advertising a minimum PHP version (under tests/PHPStan/Analyser/data, tests/PHPStan/Analyser/nsrt, and several tests/PHPStan/Rules/*/data directories).
  • For data fixtures the comment is appended to line 1 (the established pattern).
  • For nsrt fixtures the comment must immediately follow <?php (enforced by TypeInferenceTestCase). For the ones that had declare(strict_types = 1) on line 1, declare was moved onto the formerly-blank line 2 so no line-sensitive assertType() assertions shift.
• Intersection types were already handled (Node\IntersectionType -> 8.1), so the second half of the issue needed no code change. The visitor's other type-syntax families (standalone null/false/true, mixed) were probed and are already correct.

Root cause

The visitor enumerated several type-declaration syntactic features but omitted the most basic PHP 8.0 type-declaration feature: native union types. A Node\UnionType node corresponds to syntax (A|B) that does not exist before PHP 8.0, so any fixture using it must be skipped on older PHP. Because the visitor never emitted a requirement for the union node itself (only for special inner types), fixtures relying solely on plain union types could slip through without a // lint >= 8.0 guard and would have parse-errored on PHP 7.4 in CI.

Test

• RequiredPhpVersionCommentTest::testDetectedVersion gains three cases proving a native union type — in a parameter, in a return type, and the nullable A|null form — is detected as requiring PHP 8.0. These fail without the visitor change.
• RequiredPhpVersionCommentTest::testFixtureHasRequiredLintComment now passes for the whole fixture corpus after the 26 fixtures gained their // lint >= 8.0 comment; it would fail (26 fixtures) without those comments, proving the detector now catches the previously-missed syntax.
• NodeScopeResolverTest and the affected rule tests still pass, confirming the relocated declare / appended comments did not shift any line-sensitive assertions.

Fixes phpstan/phpstan#14824

[staabm]

We need another PR for intersection types on 8.1

[VincentLanglet]

We need another PR for intersection types on 8.1

It was already supported I think, cf

if ($node instanceof Node\IntersectionType) {
			$this->require(self::PHP_8_1, 'pure intersection types', $node);
		}