RegexArrayShapeMatcher - trailling groups are not optional when PREG_UNMATCHED_AS_NULL

Author: staabm

src/Php/PhpVersion.php

@@ -309,6 +309,13 @@ public function supportsNeverReturnTypeInArrowFunction(): bool
 		return $this->versionId >= 80200;
 	}
 
+	public function supportsPregUnmatchedAsNull(): bool
+	{
+		// while PREG_UNMATCHED_AS_NULL is defined in php-src since 7.2.x it starts working like described in the report with 7.4.x
+		// https://3v4l.org/v3HE4
+		return $this->versionId >= 70400;
+	}
+
 	public function hasDateTimeExceptions(): bool
 	{
 		return $this->versionId >= 80300;

src/Type/Php/RegexArrayShapeMatcher.php

@@ -7,6 +7,7 @@
 use Hoa\Compiler\Llk\TreeNode;
 use Hoa\Exception\Exception;
 use Hoa\File\Read;
+use PHPStan\Php\PhpVersion;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
@@ -33,6 +34,12 @@ final class RegexArrayShapeMatcher
 
 	private static ?Parser $parser = null;
 
+	public function __construct(
+		private PhpVersion $phpVersion,
+	)
+	{
+	}
+
 	public function matchType(Type $patternType, ?Type $flagsType, TrinaryLogic $wasMatched): ?Type
 	{
 		if ($wasMatched->no()) {
@@ -111,6 +118,7 @@ private function matchRegex(string $regex, ?int $flags, TrinaryLogic $wasMatched
 				$valueType,
 				$wasMatched,
 				$trailingOptionals,
+				$flags ?? 0,
 			);
 
 			return TypeCombinator::union(
@@ -145,6 +153,7 @@ private function matchRegex(string $regex, ?int $flags, TrinaryLogic $wasMatched
 					$valueType,
 					$wasMatched,
 					$trailingOptionals,
+					$flags ?? 0,
 				);
 
 				$combiTypes[] = $combiType;
@@ -167,6 +176,7 @@ private function matchRegex(string $regex, ?int $flags, TrinaryLogic $wasMatched
 			$valueType,
 			$wasMatched,
 			$trailingOptionals,
+			$flags ?? 0,
 		);
 	}
 
@@ -228,6 +238,7 @@ private function buildArrayType(
 		Type $valueType,
 		TrinaryLogic $wasMatched,
 		int $trailingOptionals,
+		int $flags,
 	): Type
 	{
 		$builder = ConstantArrayTypeBuilder::createEmpty();
@@ -247,6 +258,8 @@ private function buildArrayType(
 			} else {
 				if ($i < $countGroups - $trailingOptionals) {
 					$optional = false;
+				} elseif (($flags & PREG_UNMATCHED_AS_NULL) !== 0 && $this->phpVersion->supportsPregUnmatchedAsNull()) {
+					$optional = false;
 				} else {
 					$optional = $captureGroup->isOptional();
 				}
@@ -285,7 +298,7 @@ private function getValueType(int $flags): Type
 	{
 		$valueType = new StringType();
 		$offsetType = IntegerRangeType::fromInterval(0, null);
-		if (($flags & PREG_UNMATCHED_AS_NULL) !== 0) {
+		if (($flags & PREG_UNMATCHED_AS_NULL) !== 0 && $this->phpVersion->supportsPregUnmatchedAsNull()) {
 			$valueType = TypeCombinator::addNull($valueType);
 			// unmatched groups return -1 as offset
 			$offsetType = IntegerRangeType::fromInterval(-1, null);

tests/PHPStan/Analyser/nsrt/bug-11311-php72.php

@@ -0,0 +1,12 @@
+<?php // lint < 7.4
+
+namespace Bug11311;
+
+use function PHPStan\Testing\assertType;
+
+function doFoo() {
+	if (1 === preg_match('/(?<major>\d+)\.(?<minor>\d+)(?:\.(?<patch>\d+))?/', '12.5', $matches, PREG_UNMATCHED_AS_NULL)) {
+        // on PHP < 7.4, unmatched-as-null does not return null values; see https://3v4l.org/v3HE4
+		assertType('array{0: string, major: string, 1: string, minor: string, 2: string, patch?: string, 3?: string}', $matches);
+	}
+}

tests/PHPStan/Analyser/nsrt/bug-11311.php

@@ -0,0 +1,12 @@
+<?php // lint >= 7.4
+
+namespace Bug11311;
+
+use function PHPStan\Testing\assertType;
+
+function doFoo() {
+	if (1 === preg_match('/(?<major>\d+)\.(?<minor>\d+)(?:\.(?<patch>\d+))?/', '12.5', $matches, PREG_UNMATCHED_AS_NULL)) {
+
+		assertType('array{0: string, major: string|null, 1: string|null, minor: string|null, 2: string|null, patch: string|null, 3: string|null}', $matches);
+	}
+}