Retain class_exists expression types in closure

src/Analyser/MutatingScope.php

@@ -2157,7 +2157,17 @@ private function expressionTypeIsUnchangeable(ExpressionTypeHolder $typeHolder):
 		return $expr instanceof FuncCall
 			&& !$expr->isFirstClassCallable()
 			&& $expr->name instanceof FullyQualified
-			&& $expr->name->toLowerString() === 'function_exists'
+			&& in_array(
+				$expr->name->toLowerString(),
+				[
+					'class_exists',
+					'interface_exists',
+					'trait_exists',
+					'enum_exists',
+					'function_exists',
+				],
+				true,
+			)
 			&& isset($expr->getArgs()[0])
 			&& count($this->getType($expr->getArgs()[0]->value)->getConstantStrings()) === 1
 			&& $type->isTrue()->yes();

src/Type/Php/ClassExistsFunctionTypeSpecifyingExtension.php

@@ -45,11 +45,11 @@
 	}
 
 	public function specifyTypes(FunctionReflection $functionReflection, FuncCall $node, Scope $scope, TypeSpecifierContext $context): SpecifiedTypes
 	{
 		$args = $node->getArgs();
 		$argType = $scope->getType($args[0]->value);
 		if ($argType instanceof ConstantStringType) {
-			$funcCall = new FuncCall(new FullyQualified('class_exists'), [
+			$funcCall = new FuncCall(new FullyQualified($functionReflection->getName()), [
 				new Arg(new String_(ltrim($argType->getValue(), '\\'))),
 			]);
 			return $this->typeSpecifier->create(

tests/PHPStan/Analyser/nsrt/closure-retain-expression-types.php

@@ -3,7 +3,9 @@
 namespace ClosureRetainExpressionTypes;
 
 use function class_exists;
-use function defined;
+use function interface_exists;
+use function enum_exists;
+use function trait_exists;
 use function function_exists;
 use function PHPStan\Testing\assertType;
 
@@ -21,3 +23,63 @@ function () {
 		};
 	}
 };
+
+function () {
+	assertType('bool', class_exists('foo345'));
+	if (class_exists('foo345')) {
+		assertType('true', class_exists('foo345'));
+		function () {
+			assertType('true', class_exists('foo345'));
+		};
+	} else {
+		assertType('false', class_exists('foo345'));
+		function () {
+			assertType('bool', class_exists('foo345'));
+		};
+	}
+};
+
+function () {
+	assertType('bool', enum_exists('foo567'));
+	if (enum_exists('foo567')) {
+		assertType('true', enum_exists('foo567'));
+		function () {
+			assertType('true', enum_exists('foo567'));
+		};
+	} else {
+		assertType('false', enum_exists('foo567'));
+		function () {
+			assertType('bool', enum_exists('foo567'));
+		};
+	}
+};
+
+function () {
+	assertType('bool', interface_exists('foo890'));
+	if (interface_exists('foo890')) {
+		assertType('true', interface_exists('foo890'));
+		function () {
+			assertType('true', interface_exists('foo890'));
+		};
+	} else {
+		assertType('false', interface_exists('foo890'));
+		function () {
+			assertType('bool', interface_exists('foo890'));
+		};
+	}
+};
+
+function () {
+	assertType('bool', trait_exists('fooabc'));
+	if (trait_exists('fooabc')) {
+		assertType('true', trait_exists('fooabc'));
+		function () {
+			assertType('true', trait_exists('fooabc'));
+		};
+	} else {
+		assertType('false', trait_exists('fooabc'));
+		function () {
+			assertType('bool', trait_exists('fooabc'));
+		};
+	}
+};