Fixed bug #79022 (class_exists returns True for classes that are not ready to be used)

Author: laruence

NEWS

@@ -4,6 +4,8 @@ PHP                                                                        NEWS
 ?? ??? ????, PHP 7.4.2
 
 - Core:
+  . Fixed bug #79022 (class_exists returns True for classes that are not ready
+    to be used). (Laruence)
   . Fixed bug #78929 (plus signs in cookie values are converted to spaces).
     (Alexey Kachalin)
   . Fixed bug #78973 (Destructor during CV freeing causes segfault if opline

Zend/tests/bug79022.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Bug #79022 (class_exists returns True for classes that are not ready to be used)
+--FILE--
+<?php
+function my_autoloader($class) {
+    if (class_exists('Foo', 0)) {
+		new Foo();
+    }
+	if ($class == 'Foo') {
+		eval("class Foo extends Bar{}");
+	}
+
+	if ($class == 'Bar') {
+		eval("class Bar {}");
+    }
+}
+spl_autoload_register('my_autoloader');
+new Foo();
+echo "okey";
+?>
+--EXPECT--
+okey

Zend/zend_builtin_functions.c

@@ -1487,7 +1487,7 @@ static inline void class_exists_impl(INTERNAL_FUNCTION_PARAMETERS, int flags, in
    Checks if the class exists */
 ZEND_FUNCTION(class_exists)
 {
-	class_exists_impl(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0, ZEND_ACC_INTERFACE | ZEND_ACC_TRAIT);
+	class_exists_impl(INTERNAL_FUNCTION_PARAM_PASSTHRU, ZEND_ACC_LINKED, ZEND_ACC_INTERFACE | ZEND_ACC_TRAIT);
 }
 /* }}} */