RegexArrayShapeMatcher: Fix non-emptiness of leading optional groups

Author: staabm

src/Type/Php/RegexArrayShapeMatcher.php

@@ -286,12 +286,13 @@ private function buildArrayType(
 		$countGroups = count($captureGroups);
 		$i = 0;
 		foreach ($captureGroups as $captureGroup) {
+			$isTrailingOptional = $i >= $countGroups - $trailingOptionals;
 			$groupValueType = $this->getValueType($captureGroup->getType(), $flags);
 
 			if (!$wasMatched->yes()) {
 				$optional = true;
 			} else {
-				if ($i < $countGroups - $trailingOptionals) {
+				if (!$isTrailingOptional) {
 					$optional = false;
 					if ($this->containsUnmatchedAsNull($flags) && !$captureGroup->isOptional()) {
 						$groupValueType = TypeCombinator::removeNull($groupValueType);
@@ -303,7 +304,7 @@ private function buildArrayType(
 				}
 			}
 
-			if (!$optional && $captureGroup->isOptional() && !$this->containsUnmatchedAsNull($flags)) {
+			if (!$isTrailingOptional && $captureGroup->isOptional() && !$this->containsUnmatchedAsNull($flags)) {
 				$groupValueType = TypeCombinator::union($groupValueType, new ConstantStringType(''));
 			}
 

tests/PHPStan/Analyser/nsrt/preg_match_shapes.php

@@ -525,3 +525,18 @@ function (string $s): void {
 	assertType("array{0?: string, 1?: ''|numeric-string}", $matches);
 };
 
+class Bug11376
+{
+	public function test(string $str): void
+	{
+		preg_match('~^(?:(\w+)::)?(\w+)$~', $str, $matches);
+		assertType('array{0?: string, 1?: string, 2?: non-empty-string}', $matches);
+	}
+
+	public function test2(string $str): void
+	{
+		if (preg_match('~^(?:(\w+)::)?(\w+)$~', $str, $matches) === 1) {
+			assertType('array{string, string, non-empty-string}', $matches);
+		}
+	}
+}