Fix #1482: method_exists() with string

src/Type/Php/MethodExistsTypeSpecifyingExtension.php

@@ -13,7 +13,9 @@
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\FunctionTypeSpecifyingExtension;
 use PHPStan\Type\IntersectionType;
+use PHPStan\Type\ObjectType;
 use PHPStan\Type\ObjectWithoutClassType;
+use PHPStan\Type\StringType;
 
 class MethodExistsTypeSpecifyingExtension implements FunctionTypeSpecifyingExtension, TypeSpecifierAwareExtension
 {
@@ -44,6 +46,13 @@ public function specifyTypes(
 TypeSpecifierContext $context
 ): SpecifiedTypes
 {
+$objectType = $scope->getType($node->args[0]->value);
+if (!$objectType instanceof ObjectType) {
+if ((new StringType())->isSuperTypeOf($objectType)->yes()) {
+return new SpecifiedTypes([], []);
+}
+}
+
 $methodNameType = $scope->getType($node->args[1]->value);
 if (!$methodNameType instanceof ConstantStringType) {
 return new SpecifiedTypes([], []);

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -137,10 +137,6 @@ public function testImpossibleCheckTypeFunctionCall(): void
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'testWithStringFirst…\' will always evaluate to true.',
 585,
 ],
-[
-'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'undefinedMethod\' will always evaluate to false.',
-588,
-],
 [
 'Call to function method_exists() with \'UndefinedClass\' and string will always evaluate to false.',
 594,
@@ -151,43 +147,43 @@ public function testImpossibleCheckTypeFunctionCall(): void
 ],
 [
 'Call to function method_exists() with CheckTypeFunctionCall\MethodExists and \'testWithNewObjectIn…\' will always evaluate to true.',
-606,
+609,
 ],
 [
 'Call to function method_exists() with $this(CheckTypeFunctionCall\MethodExistsWithTrait) and \'method\' will always evaluate to true.',
-621,
+624,
 ],
 [
 'Call to function method_exists() with $this(CheckTypeFunctionCall\MethodExistsWithTrait) and \'someAnother\' will always evaluate to true.',
-624,
+627,
 ],
 [
 'Call to function method_exists() with $this(CheckTypeFunctionCall\MethodExistsWithTrait) and \'unknown\' will always evaluate to false.',
-627,
+630,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'method\' will always evaluate to true.',
-630,
+633,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'someAnother\' will always evaluate to true.',
-633,
+636,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'unknown\' will always evaluate to false.',
-636,
+639,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'method\' will always evaluate to true.',
-639,
+642,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'someAnother\' will always evaluate to true.',
-642,
+645,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'unknown\' will always evaluate to false.',
-645,
+648,
 ],
 ]
 );
@@ -259,10 +255,6 @@ public function testImpossibleCheckTypeFunctionCallWithoutAlwaysTrue(): void
 'Call to function is_callable() with mixed will always evaluate to false.',
 571,
 ],
-[
-'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'undefinedMethod\' will always evaluate to false.',
-588,
-],
 [
 'Call to function method_exists() with \'UndefinedClass\' and string will always evaluate to false.',
 594,
@@ -273,15 +265,15 @@ public function testImpossibleCheckTypeFunctionCallWithoutAlwaysTrue(): void
 ],
 [
 'Call to function method_exists() with $this(CheckTypeFunctionCall\MethodExistsWithTrait) and \'unknown\' will always evaluate to false.',
-627,
+630,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'unknown\' will always evaluate to false.',
-636,
+639,
 ],
 [
 'Call to function method_exists() with \'CheckTypeFunctionCa…\' and \'unknown\' will always evaluate to false.',
-645,
+648,
 ],
 ]
 );

tests/PHPStan/Rules/Comparison/data/check-type-function-call.php

@@ -596,6 +596,9 @@ public function testWithStringFirstArgument(): void
 
 if (method_exists('UndefinedClass', 'test')) {
 }
+
+if (method_exists($string, 'test')) {
+}
 }
 
 public function testWithNewObjectInFirstArgument(): void