Report function calls with an argument count no variant accepts

When no variant of a function accepts the number of arguments, the variants are combined into one whose parameters missing from some variant are optional. mt_rand() and rand() have the variants () and ($min, $max), so mt_rand(1) was accepted although it throws ArgumentCountError. Such a count is now checked against the variant closest to it. The functionMap was wrong for a few functions with such gaps: levenshtein() accepts each cost separately since PHP 8.0, and the $flags and $all parameters of uopz_add_function() and uopz_del_function() are optional. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Dhb4ssXuKVWcVBcNFpsdn7
ondrejmirtes · Sep 22, 2026 · Sep 22, 2026 · Sep 22, 2026 · Sep 22, 2026 · Sep 22, 2026
commit 03a2a3ad12c5ccd58714d26d37f513008d81e6c0
diff --git a/resources/functionMap.php b/resources/functionMap.php
@@ -11186,15 +11186,15 @@
 'unregister_tick_function' => ['void', 'function_name'=>'callable'],
 'unserialize' => ['mixed', 'variable_representation'=>'string', 'allowed_classes='=>'array{allowed_classes?:string[]|bool}'],
 'untaint' => ['bool', '&rw_string'=>'string', '&...rw_strings='=>'string'],
-'uopz_add_function' => ['bool', 'class'=>'string', 'function'=>'string', 'handler'=>'Closure', '$flags'=>'int', '$all'=>'bool'],
-'uopz_add_function\'1' => ['bool', 'function'=>'string', 'handler'=>'Closure', '$flags'=>'int'],
+'uopz_add_function' => ['bool', 'class'=>'string', 'function'=>'string', 'handler'=>'Closure', 'flags='=>'int', 'all='=>'bool'],
+'uopz_add_function\'1' => ['bool', 'function'=>'string', 'handler'=>'Closure', 'flags='=>'int'],
 'uopz_allow_exit' => ['void', 'allow'=>'bool'],
 'uopz_backup' => ['void', 'class'=>'string', 'function'=>'string'],
 'uopz_backup\'1' => ['void', 'function'=>'string'],
 'uopz_compose' => ['void', 'name'=>'string', 'classes'=>'array', 'methods='=>'array', 'properties='=>'array', 'flags='=>'int'],
 'uopz_copy' => ['Closure', 'class'=>'string', 'function'=>'string'],
 'uopz_copy\'1' => ['Closure', 'function'=>'string'],
-'uopz_del_function' => ['bool', 'class'=>'string', 'function'=>'string', '$all'=>'bool'],
+'uopz_del_function' => ['bool', 'class'=>'string', 'function'=>'string', 'all='=>'bool'],
 'uopz_del_function\'1' => ['bool', 'function'=>'string'],
 'uopz_delete' => ['void', 'class'=>'string', 'function'=>'string'],
 'uopz_delete\'1' => ['void', 'function'=>'string'],

diff --git a/resources/functionMap_php80delta.php b/resources/functionMap_php80delta.php
@@ -85,6 +85,7 @@
 		'getenv' => ['string|false', 'varname'=>'string', 'local_only='=>'bool'],
 		'getenv\'1' => ['array<string, string>', 'varname='=>'null', 'local_only='=>'bool'],
 		'ldap_set_rebind_proc' => ['bool', 'ldap'=>'resource', 'callback'=>'?callable'],
+		'levenshtein' => ['int', 'string1'=>'string', 'string2'=>'string', 'insertion_cost='=>'int', 'replacement_cost='=>'int', 'deletion_cost='=>'int'],
 		'mb_decode_numericentity' => ['string|false', 'string'=>'string', 'convmap'=>'array', 'encoding='=>'string'],
 		'mb_detect_order' => ['bool', 'encoding_list'=>'non-empty-list<non-falsy-string>|non-falsy-string'],
 		'mb_detect_order\'1' => ['list<non-falsy-string>', 'encoding_list='=>'null'],
@@ -245,6 +246,8 @@
 		'ldap_control_paged_result_response' => ['bool', 'link_identifier'=>'resource', 'result_identifier'=>'resource', '&w_cookie='=>'string', '&w_estimated='=>'int'],
 		'ldap_set_rebind_proc' => ['bool', 'link_identifier'=>'resource', 'callback'=>'callable'],
 		'ldap_sort' => ['bool', 'link_identifier'=>'resource', 'result_identifier'=>'resource', 'sortfilter'=>'string'],
+		'levenshtein' => ['int', 'str1'=>'string', 'str2'=>'string'],
+		'levenshtein\'1' => ['int', 'str1'=>'string', 'str2'=>'string', 'cost_ins'=>'int', 'cost_rep'=>'int', 'cost_del'=>'int'],
 		'mb_decode_numericentity' => ['string|false', 'string'=>'string', 'convmap'=>'array', 'encoding='=>'string', 'is_hex='=>'bool'],
 		'mb_strlen' => ['0|positive-int', 'str'=>'string', 'encoding='=>'string'],
 		'mktime' => ['int|false', 'hour='=>'int', 'minute='=>'int', 'second='=>'int', 'month='=>'int', 'day='=>'int', 'year='=>'int'],

diff --git a/src/Rules/Functions/CallToFunctionParametersRule.php b/src/Rules/Functions/CallToFunctionParametersRule.php
@@ -9,10 +9,12 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\RegisteredRule;
 use PHPStan\Internal\SprintfHelper;
+use PHPStan\Reflection\ParametersAcceptor;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\Rules\FunctionCallParametersCheck;
 use PHPStan\Rules\Rule;
+use function count;
 
 /**
  * @implements Rule<Node\Expr\FuncCall>
@@ -43,13 +45,15 @@ public function processNode(Node $node, Scope&NodeCallbackInvoker&CollectedDataE
 		$function = $this->reflectionProvider->getFunction($node->name, $scope);
 		$functionName = SprintfHelper::escapeFormatString($function->getName());
 
+		$parametersAcceptor = ParametersAcceptorSelector::selectFromArgs(
+			$scope,
+			$node->getArgs(),
+			$function->getVariants(),
+			$function->getNamedArgumentsVariants(),
+		);
+
 		return $this->check->check(
-			ParametersAcceptorSelector::selectFromArgs(
-				$scope,
-				$node->getArgs(),
-				$function->getVariants(),
-				$function->getNamedArgumentsVariants(),
-			),
+			self::getVariantForArgumentsCount($node->getArgs(), $function->getVariants(), $parametersAcceptor) ?? $parametersAcceptor,
 			$scope,
 			$function->isBuiltin(),
 			$node,
@@ -77,4 +81,75 @@ public function processNode(Node $node, Scope&NodeCallbackInvoker&CollectedDataE
 		);
 	}
 
+	/**
+	 * When no variant accepts the number of arguments, they are combined into
+	 * one whose parameters missing from some variant are optional, so mt_rand()
+	 * with the variants () and ($min, $max) would accept a single argument.
+	 * Such a count is checked against the variant closest to it instead.
+	 *
+	 * @param Node\Arg[] $args
+	 * @param list<ParametersAcceptor> $variants
+	 */
+	private static function getVariantForArgumentsCount(array $args, array $variants, ParametersAcceptor $selectedParametersAcceptor): ?ParametersAcceptor
+	{
+		if (count($variants) < 2) {
+			return null;
+		}
+
+		foreach ($args as $arg) {
+			if ($arg->unpack || $arg->name !== null) {
+				return null;
+			}
+		}
+
+		$argsCount = count($args);
+		if (!self::acceptsArgumentsCount($selectedParametersAcceptor, $argsCount)) {
+			return null;
+		}
+
+		$closestVariant = null;
+		$closestDistance = null;
+		foreach ($variants as $variant) {
+			if (self::acceptsArgumentsCount($variant, $argsCount)) {
+				return null;
+			}
+
+			[$minCount, $maxCount] = self::getArgumentsCountRange($variant);
+			$isInsufficient = $argsCount < $minCount;
+			$distance = $isInsufficient ? $minCount - $argsCount : $argsCount - (int) $maxCount;
+			if ($closestDistance !== null && ($distance > $closestDistance || ($distance === $closestDistance && !$isInsufficient))) {
+				continue;
+			}
+
+			$closestVariant = $variant;
+			$closestDistance = $distance;
+		}
+
+		return $closestVariant;
+	}
+
+	private static function acceptsArgumentsCount(ParametersAcceptor $parametersAcceptor, int $argsCount): bool
+	{
+		[$minCount, $maxCount] = self::getArgumentsCountRange($parametersAcceptor);
+
+		return $argsCount >= $minCount && ($maxCount === null || $argsCount <= $maxCount);
+	}
+
+	/**
+	 * @return array{int, int|null}
+	 */
+	private static function getArgumentsCountRange(ParametersAcceptor $parametersAcceptor): array
+	{
+		$minCount = 0;
+		foreach ($parametersAcceptor->getParameters() as $parameter) {
+			if ($parameter->isOptional()) {
+				continue;
+			}
+
+			$minCount++;
+		}
+
+		return [$minCount, $parametersAcceptor->isVariadic() ? null : count($parametersAcceptor->getParameters())];
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
@@ -3123,4 +3123,32 @@ public function testBug11041(): void
 		$this->analyse([__DIR__ . '/data/bug-11041.php'], []);
 	}
 
+	public function testArgumentsCountAcceptedByNoVariant(): void
+	{
+		$this->analyse([__DIR__ . '/data/arguments-count-accepted-by-no-variant.php'], [
+			[
+				'Function mt_rand invoked with 1 parameter, 2 required.',
+				12,
+			],
+			[
+				'Function rand invoked with 1 parameter, 2 required.',
+				15,
+			],
+			[
+				'Function mt_rand invoked with 3 parameters, 0-2 required.',
+				16,
+			],
+			[
+				'Function stream_context_set_option invoked with 3 parameters, 4 required.',
+				20,
+			],
+		]);
+	}
+
+	#[RequiresPhp('>= 8.0.0')]
+	public function testLevenshteinArgumentsCount(): void
+	{
+		$this->analyse([__DIR__ . '/data/levenshtein-arguments-count.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/data/arguments-count-accepted-by-no-variant.php b/tests/PHPStan/Rules/Functions/data/arguments-count-accepted-by-no-variant.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace ArgumentsCountAcceptedByNoVariant;
+
+/**
+ * @param resource $context
+ */
+function doFoo($context): void
+{
+	$a = mt_rand();
+	$a = mt_rand(1, 2);
+	$a = mt_rand(1);
+	$a = rand();
+	$a = rand(1, 2);
+	$a = rand(1);
+	$a = mt_rand(1, 2, 3);
+
+	stream_context_set_option($context, 'http', 'method', 'POST');
+	stream_context_set_option($context, ['http' => ['method' => 'POST']]);
+	stream_context_set_option($context, 'http', 'method');
+
+	$cb = static fn ($a, $b): int => $a <=> $b;
+	$b = array_intersect_uassoc([1], [1], $cb);
+	$b = array_intersect_uassoc([1], [1], [1], $cb);
+	$b = array_intersect_ukey([1], [1], [1], $cb);
+
+	$handler = static function (): void {
+	};
+	uopz_add_function('Foo', 'bar', $handler, 1);
+	uopz_add_function('bar', $handler);
+	uopz_del_function('Foo', 'bar');
+}
diff --git a/tests/PHPStan/Rules/Functions/data/levenshtein-arguments-count.php b/tests/PHPStan/Rules/Functions/data/levenshtein-arguments-count.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace LevenshteinArgumentsCount;
+
+function doFoo(string $a, string $b): void
+{
+	$c = levenshtein($a, $b);
+	$c = levenshtein($a, $b, 1);
+	$c = levenshtein($a, $b, 1, 2);
+	$c = levenshtein($a, $b, 1, 2, 3);
+}