Introduce CombinationsHelper

src/Internal/CombinationsHelper.php

@@ -0,0 +1,35 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Internal;
+
+use function array_shift;
+
+final class CombinationsHelper
+{
+
+	/**
+	 * @param array<mixed> $arrays
+	 * @return iterable<mixed>
+	 */
+	public static function combinations(array $arrays): iterable
+	{
+		// from https://stackoverflow.com/a/70800936/565782 by Arnaud Le Blanc
+		if ($arrays === []) {
+			yield [];
+			return;
+		}
+
+		$head = array_shift($arrays);
+
+		foreach ($head as $elem) {
+			foreach (self::combinations($arrays) as $combination) {
+				$comb = [$elem];
+				foreach ($combination as $c) {
+					$comb[] = $c;
+				}
+				yield $comb;
+			}
+		}
+	}
+
+}

src/Type/Php/SprintfFunctionDynamicReturnTypeExtension.php

@@ -4,6 +4,7 @@
 
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
+use PHPStan\Internal\CombinationsHelper;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Reflection\InitializerExprTypeResolver;
 use PHPStan\Reflection\ParametersAcceptorSelector;
@@ -94,7 +95,7 @@ public function getTypeFromFunctionCall(
 			$values[] = $argType->getConstantScalarValues();
 		}
 
-		$combinations = $this->combinations($values);
+		$combinations = CombinationsHelper::combinations($values);
 		$returnTypes = [];
 		foreach ($combinations as $combination) {
 			$format = array_shift($combination);
@@ -120,29 +121,4 @@ public function getTypeFromFunctionCall(
 		return TypeCombinator::union(...$returnTypes);
 	}
 
-	/**
-	 * @param array<mixed> $arrays
-	 * @return iterable<mixed>
-	 */
-	private function combinations(array $arrays): iterable
-	{
-		// from https://stackoverflow.com/a/70800936/565782 by Arnaud Le Blanc
-		if ($arrays === []) {
-			yield [];
-			return;
-		}
-
-		$head = array_shift($arrays);
-
-		foreach ($head as $elem) {
-			foreach ($this->combinations($arrays) as $combination) {
-				$comb = [$elem];
-				foreach ($combination as $c) {
-					$comb[] = $c;
-				}
-				yield $comb;
-			}
-		}
-	}
-
 }