/src/php-src/Zend/zend_inheritance.c

Source
/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright © Zend Technologies Ltd., a subsidiary company of          |
   |     Perforce Software, Inc., and Contributors.                       |
   +----------------------------------------------------------------------+
   | This source file is subject to the Modified BSD License that is      |
   | bundled with this package in the file LICENSE, and is available      |
   | through the World Wide Web at <https://www.php.net/license/>.        |
   |                                                                      |
   | SPDX-License-Identifier: BSD-3-Clause                                |
   +----------------------------------------------------------------------+
   | Authors: Andi Gutmans <andi@php.net>                                 |
   |          Zeev Suraski <zeev@php.net>                                 |
   +----------------------------------------------------------------------+
*/

#include "zend.h"
#include "zend_API.h"
#include "zend_compile.h"
#include "zend_execute.h"
#include "zend_inheritance.h"
#include "zend_interfaces.h"
#include "zend_closures.h"
#include "zend_smart_str.h"
#include "zend_operators.h"
#include "zend_exceptions.h"
#include "zend_enum.h"
#include "zend_attributes.h"
#include "zend_constants.h"
#include "zend_observer.h"

ZEND_API zend_class_entry* (*zend_inheritance_cache_get)(zend_class_entry *ce, zend_class_entry *parent, zend_class_entry **traits_and_interfaces) = NULL;
ZEND_API zend_class_entry* (*zend_inheritance_cache_add)(zend_class_entry *ce, zend_class_entry *proto, zend_class_entry *parent, zend_class_entry **traits_and_interfaces, HashTable *dependencies) = NULL;

/* Unresolved means that class declarations that are currently not available are needed to
 * determine whether the inheritance is valid or not. At runtime UNRESOLVED should be treated
 * as an ERROR. */
typedef zend_inheritance_status inheritance_status;

typedef enum {
  PROP_INVARIANT,
  PROP_COVARIANT,
  PROP_CONTRAVARIANT,
} prop_variance;

static void add_dependency_obligation(zend_class_entry *ce, zend_class_entry *dependency_ce);
static void add_compatibility_obligation(
    zend_class_entry *ce, const zend_function *child_fn, zend_class_entry *child_scope,
    const zend_function *parent_fn, zend_class_entry *parent_scope);
static void add_property_compatibility_obligation(
    zend_class_entry *ce, const zend_property_info *child_prop,
    const zend_property_info *parent_prop, prop_variance variance);
static void add_class_constant_compatibility_obligation(
    zend_class_entry *ce, const zend_class_constant *child_const,
    const zend_class_constant *parent_const, const zend_string *const_name);
static void add_property_hook_obligation(
    zend_class_entry *ce, const zend_property_info *hooked_prop, const zend_function *hook_func);

static void ZEND_COLD emit_incompatible_method_error(
    const zend_function *child, const zend_class_entry *child_scope,
    const zend_function *parent, const zend_class_entry *parent_scope,
    inheritance_status status);

static void zend_type_copy_ctor(zend_type *const type, bool use_arena, bool persistent);

static void zend_type_list_copy_ctor(
  zend_type *const parent_type,
  bool use_arena,
  bool persistent
) {
  const zend_type_list *const old_list = ZEND_TYPE_LIST(*parent_type);
  size_t size = ZEND_TYPE_LIST_SIZE(old_list->num_types);
  zend_type_list *new_list = use_arena
    ? zend_arena_alloc(&CG(arena), size) : pemalloc(size, persistent);

  memcpy(new_list, old_list, size);
  ZEND_TYPE_SET_LIST(*parent_type, new_list);
  if (use_arena) {
    ZEND_TYPE_FULL_MASK(*parent_type) |= _ZEND_TYPE_ARENA_BIT;
  }

  zend_type *list_type;
  ZEND_TYPE_LIST_FOREACH_MUTABLE(new_list, list_type) {
    zend_type_copy_ctor(list_type, use_arena, persistent);
  } ZEND_TYPE_LIST_FOREACH_END();
}

static void zend_type_copy_ctor(zend_type *const type, bool use_arena, bool persistent) {
  if (ZEND_TYPE_HAS_LIST(*type)) {
    zend_type_list_copy_ctor(type, use_arena, persistent);
  } else if (ZEND_TYPE_HAS_NAME(*type)) {
    zend_string_addref(ZEND_TYPE_NAME(*type));
  }
}

static zend_function *zend_duplicate_internal_function(const zend_function *func, const zend_class_entry *ce) /* {{{ */
{
  zend_function *new_function;

  if (UNEXPECTED(ce->type == ZEND_INTERNAL_CLASS)) {
    new_function = (zend_function *)pemalloc(sizeof(zend_internal_function), 1);
    memcpy(new_function, func, sizeof(zend_internal_function));
  } else {
    new_function = zend_arena_alloc(&CG(arena), sizeof(zend_internal_function));
    memcpy(new_function, func, sizeof(zend_internal_function));
    new_function->common.fn_flags |= ZEND_ACC_ARENA_ALLOCATED;
  }
  if (EXPECTED(new_function->common.function_name)) {
    zend_string_addref(new_function->common.function_name);
  }
  return new_function;
}
/* }}} */

static zend_always_inline zend_function *zend_duplicate_function(zend_function *func, const zend_class_entry *ce) /* {{{ */
{
  if (UNEXPECTED(func->type == ZEND_INTERNAL_FUNCTION)) {
    return zend_duplicate_internal_function(func, ce);
  } else {
    if (func->op_array.refcount) {
      (*func->op_array.refcount)++;
    }
    if (EXPECTED(func->op_array.function_name)) {
      zend_string_addref(func->op_array.function_name);
    }
    return func;
  }
}
/* }}} */

static void do_inherit_parent_constructor(zend_class_entry *ce) /* {{{ */
{
  zend_class_entry *parent = ce->parent;

  ZEND_ASSERT(parent != NULL);

  /* You cannot change create_object */
  ce->create_object = parent->create_object;

  /* Inherit special functions if needed */
  if (EXPECTED(!ce->get_iterator)) {
    ce->get_iterator = parent->get_iterator;
  }
  if (EXPECTED(!ce->__get)) {
    ce->__get = parent->__get;
  }
  if (EXPECTED(!ce->__set)) {
    ce->__set = parent->__set;
  }
  if (EXPECTED(!ce->__unset)) {
    ce->__unset = parent->__unset;
  }
  if (EXPECTED(!ce->__isset)) {
    ce->__isset = parent->__isset;
  }
  if (EXPECTED(!ce->__call)) {
    ce->__call = parent->__call;
  }
  if (EXPECTED(!ce->__callstatic)) {
    ce->__callstatic = parent->__callstatic;
  }
  if (EXPECTED(!ce->__tostring)) {
    ce->__tostring = parent->__tostring;
  }
  if (EXPECTED(!ce->clone)) {
    ce->clone = parent->clone;
  }
  if (EXPECTED(!ce->__serialize)) {
    ce->__serialize = parent->__serialize;
  }
  if (EXPECTED(!ce->__unserialize)) {
    ce->__unserialize = parent->__unserialize;
  }
  if (EXPECTED(!ce->serialize)) {
    ce->serialize = parent->serialize;
  }
  if (EXPECTED(!ce->unserialize)) {
    ce->unserialize = parent->unserialize;
  }
  if (!ce->destructor) {
    ce->destructor = parent->destructor;
  }
  if (EXPECTED(!ce->__debugInfo)) {
    ce->__debugInfo = parent->__debugInfo;
  }

  if (ce->constructor) {
    if (parent->constructor && UNEXPECTED(parent->constructor->common.fn_flags & ZEND_ACC_FINAL)) {
      zend_error_noreturn(E_ERROR, "Cannot override final %s::__construct() with %s::__construct()",
        ZSTR_VAL(parent->name),
        ZSTR_VAL(ce->name));
    }
    return;
  }

  ce->constructor = parent->constructor;
}
/* }}} */

const char *zend_visibility_string(uint32_t fn_flags) /* {{{ */
{
  if (fn_flags & ZEND_ACC_PUBLIC) {
    return "public";
  } else if (fn_flags & ZEND_ACC_PRIVATE) {
    return "private";
  } else {
    ZEND_ASSERT(fn_flags & ZEND_ACC_PROTECTED);
    return "protected";
  }
}
/* }}} */

static const char *zend_asymmetric_visibility_string(uint32_t fn_flags) /* {{{ */
{
  if (fn_flags & ZEND_ACC_PRIVATE_SET) {
    return "private(set)";
  } else if (fn_flags & ZEND_ACC_PROTECTED_SET) {
    return "protected(set)";
  } else {
    ZEND_ASSERT(!(fn_flags & ZEND_ACC_PUBLIC_SET));
    return "omitted";
  }
}

static zend_string *resolve_class_name(const zend_class_entry *scope, zend_string *name) {
  ZEND_ASSERT(scope);
  if (zend_string_equals_ci(name, ZSTR_KNOWN(ZEND_STR_PARENT)) && scope->parent) {
    if (scope->ce_flags & ZEND_ACC_RESOLVED_PARENT) {
      return scope->parent->name;
    } else {
      return scope->parent_name;
    }
  } else if (zend_string_equals_ci(name, ZSTR_KNOWN(ZEND_STR_SELF))) {
    return scope->name;
  } else {
    return name;
  }
}

static bool class_visible(const zend_class_entry *ce) {
  if (ce->type == ZEND_INTERNAL_CLASS) {
    return !(CG(compiler_options) & ZEND_COMPILE_IGNORE_INTERNAL_CLASSES);
  } else {
    ZEND_ASSERT(ce->type == ZEND_USER_CLASS);
    return !(CG(compiler_options) & ZEND_COMPILE_IGNORE_OTHER_FILES)
      || ce->info.user.filename == CG(compiled_filename);
  }
}

static zend_always_inline void register_unresolved_class(zend_string *name) {
  /* We'll autoload this class and process delayed variance obligations later. */
  if (!CG(delayed_autoloads)) {
    ALLOC_HASHTABLE(CG(delayed_autoloads));
    zend_hash_init(CG(delayed_autoloads), 0, NULL, NULL, 0);
  }
  zend_hash_add_empty_element(CG(delayed_autoloads), name);
}

static zend_class_entry *lookup_class_ex(
    zend_class_entry *scope, zend_string *name, bool register_unresolved) {
  zend_class_entry *ce;
  bool in_preload = CG(compiler_options) & ZEND_COMPILE_PRELOAD;

  if (UNEXPECTED(!EG(active) && !in_preload)) {
    ce = zend_hash_find_ptr_lc(CG(class_table), name);

    if (register_unresolved && !ce) {
      zend_error_noreturn(
        E_COMPILE_ERROR, "%s must be registered before %s",
        ZSTR_VAL(name), ZSTR_VAL(scope->name));
      }

    return ce;
  }

  ce = zend_lookup_class_ex(
      name, NULL, ZEND_FETCH_CLASS_ALLOW_UNLINKED | ZEND_FETCH_CLASS_NO_AUTOLOAD);

  if (!CG(in_compilation) || in_preload) {
    if (ce) {
      return ce;
    }

    if (register_unresolved) {
      register_unresolved_class(name);
    }
  } else {
    if (ce && class_visible(ce)) {
      return ce;
    }

    /* The current class may not be registered yet, so check for it explicitly. */
    if (zend_string_equals_ci(scope->name, name)) {
      return scope;
    }
  }

  return NULL;
}

static zend_class_entry *lookup_class(zend_class_entry *scope, zend_string *name) {
  return lookup_class_ex(scope, name, /* register_unresolved */ false);
}

/* Instanceof that's safe to use on unlinked classes. */
static bool unlinked_instanceof(const zend_class_entry *ce1, const zend_class_entry *ce2) {
  if (ce1 == ce2) {
    return true;
  }

  if (ce1->ce_flags & ZEND_ACC_LINKED) {
    return instanceof_function(ce1, ce2);
  }

  if (ce1->parent) {
    const zend_class_entry *parent_ce;
    if (ce1->ce_flags & ZEND_ACC_RESOLVED_PARENT) {
      parent_ce = ce1->parent;
    } else {
      parent_ce = zend_lookup_class_ex(ce1->parent_name, NULL,
        ZEND_FETCH_CLASS_ALLOW_UNLINKED | ZEND_FETCH_CLASS_NO_AUTOLOAD);
    }

    /* It's not sufficient to only check the parent chain itself, as need to do a full
     * recursive instanceof in case the parent interfaces haven't been copied yet. */
    if (parent_ce && unlinked_instanceof(parent_ce, ce2)) {
      return true;
    }
  }

  if (ce1->num_interfaces) {
    uint32_t i;
    if (ce1->ce_flags & ZEND_ACC_RESOLVED_INTERFACES) {
      /* Unlike the normal instanceof_function(), we have to perform a recursive
       * check here, as the parent interfaces might not have been fully copied yet. */
      for (i = 0; i < ce1->num_interfaces; i++) {
        if (unlinked_instanceof(ce1->interfaces[i], ce2)) {
          return true;
        }
      }
    } else {
      for (i = 0; i < ce1->num_interfaces; i++) {
        const zend_class_entry *ce = zend_lookup_class_ex(
          ce1->interface_names[i].name, ce1->interface_names[i].lc_name,
          ZEND_FETCH_CLASS_ALLOW_UNLINKED | ZEND_FETCH_CLASS_NO_AUTOLOAD);
        /* Avoid recursing if class implements itself. */
        if (ce && ce != ce1 && unlinked_instanceof(ce, ce2)) {
          return true;
        }
      }
    }
  }

  return false;
}

static bool zend_type_permits_self(
    const zend_type type, const zend_class_entry *scope, zend_class_entry *self) {
  if (ZEND_TYPE_FULL_MASK(type) & MAY_BE_OBJECT) {
    return true;
  }

  /* Any types that may satisfy self must have already been loaded at this point
   * (as a parent or interface), so we never need to register delayed variance obligations
   * for this case. */
  const zend_type *single_type;
  ZEND_TYPE_FOREACH(type, single_type) {
    if (ZEND_TYPE_HAS_NAME(*single_type)) {
      zend_string *name = resolve_class_name(scope, ZEND_TYPE_NAME(*single_type));
      const zend_class_entry *ce = lookup_class(self, name);
      if (ce && unlinked_instanceof(self, ce)) {
        return true;
      }
    }
  } ZEND_TYPE_FOREACH_END();
  return false;
}

static void track_class_dependency(zend_class_entry *ce, zend_string *class_name)
{
  HashTable *ht;

  ZEND_ASSERT(class_name);
  if (!CG(current_linking_class) || ce == CG(current_linking_class)) {
    return;
  } else if (zend_string_equals_ci(class_name, ZSTR_KNOWN(ZEND_STR_SELF))
          || zend_string_equals_ci(class_name, ZSTR_KNOWN(ZEND_STR_PARENT))) {
    return;
  }

#ifndef ZEND_WIN32
  /* On non-Windows systems, internal classes are always the same,
   * so there is no need to explicitly track them. */
  if (ce->type == ZEND_INTERNAL_CLASS) {
    return;
  }
#endif

  ht = (HashTable*)CG(current_linking_class)->inheritance_cache;

  if (!(ce->ce_flags & ZEND_ACC_IMMUTABLE)) {
    // TODO: dependency on not-immutable class ???
    if (ht) {
      zend_hash_destroy(ht);
      FREE_HASHTABLE(ht);
      CG(current_linking_class)->inheritance_cache = NULL;
    }
    CG(current_linking_class)->ce_flags &= ~ZEND_ACC_CACHEABLE;
    CG(current_linking_class) = NULL;
    return;
  }

  /* Record dependency */
  if (!ht) {
    ALLOC_HASHTABLE(ht);
    zend_hash_init(ht, 0, NULL, NULL, 0);
    CG(current_linking_class)->inheritance_cache = (zend_inheritance_cache_entry*)ht;
  }
  zend_hash_add_ptr(ht, class_name, ce);
}

/* Check whether any type in the fe_type intersection type is a subtype of the proto class. */
static inheritance_status zend_is_intersection_subtype_of_class(
    zend_class_entry *fe_scope, const zend_type fe_type,
    zend_class_entry *proto_scope, zend_string *proto_class_name, zend_class_entry *proto_ce)
{
  ZEND_ASSERT(ZEND_TYPE_IS_INTERSECTION(fe_type));
  bool have_unresolved = false;
  const zend_type *single_type;

  /* Traverse the list of child types and check that at least one is
   * a subtype of the parent type being checked */
  ZEND_TYPE_FOREACH(fe_type, single_type) {
    zend_class_entry *fe_ce;
    zend_string *fe_class_name = NULL;
    if (ZEND_TYPE_HAS_NAME(*single_type)) {
      fe_class_name =
        resolve_class_name(fe_scope, ZEND_TYPE_NAME(*single_type));
      if (zend_string_equals_ci(fe_class_name, proto_class_name)) {
        return INHERITANCE_SUCCESS;
      }

      if (!proto_ce) proto_ce = lookup_class(proto_scope, proto_class_name);
      fe_ce = lookup_class(fe_scope, fe_class_name);
    } else {
      /* standard type in an intersection type is impossible,
       * because it would be a fatal compile error */
      ZEND_UNREACHABLE();
      continue;
    }

    if (!fe_ce || !proto_ce) {
      have_unresolved = true;
      continue;
    }
    if (unlinked_instanceof(fe_ce, proto_ce)) {
      track_class_dependency(fe_ce, fe_class_name);
      track_class_dependency(proto_ce, proto_class_name);
      return INHERITANCE_SUCCESS;
    }
  } ZEND_TYPE_FOREACH_END();

  return have_unresolved ? INHERITANCE_UNRESOLVED : INHERITANCE_ERROR;
}

/* Check whether a single class proto type is a subtype of a potentially complex fe_type. */
static inheritance_status zend_is_class_subtype_of_type(
    zend_class_entry *fe_scope, zend_string *fe_class_name,
    zend_class_entry *proto_scope, const zend_type proto_type) {
  zend_class_entry *fe_ce = NULL;
  bool have_unresolved = false;

  /* If the parent has 'object' as a return type, any class satisfies the co-variant check */
  if (ZEND_TYPE_FULL_MASK(proto_type) & MAY_BE_OBJECT) {
    /* Currently, any class name would be allowed here. We still perform a class lookup
     * for forward-compatibility reasons, as we may have named types in the future that
     * are not classes (such as typedefs). */
    if (!fe_ce) fe_ce = lookup_class(fe_scope, fe_class_name);
    if (!fe_ce) {
      have_unresolved = true;
    } else {
      track_class_dependency(fe_ce, fe_class_name);
      return INHERITANCE_SUCCESS;
    }
  }

  /* If the parent has 'callable' as a return type, then Closure satisfies the co-variant check */
  if (ZEND_TYPE_FULL_MASK(proto_type) & MAY_BE_CALLABLE) {
    if (!fe_ce) fe_ce = lookup_class(fe_scope, fe_class_name);
    if (!fe_ce) {
      have_unresolved = true;
    } else if (fe_ce == zend_ce_closure) {
      track_class_dependency(fe_ce, fe_class_name);
      return INHERITANCE_SUCCESS;
    }
  }

  /* If the parent has 'static' as a return type, then final classes could replace it with self */
  if ((ZEND_TYPE_FULL_MASK(proto_type) & MAY_BE_STATIC) && (fe_scope->ce_flags & ZEND_ACC_FINAL)) {
    if (!fe_ce) fe_ce = lookup_class(fe_scope, fe_class_name);
    if (!fe_ce) {
      have_unresolved = true;
    } else if (fe_ce == fe_scope) {
      track_class_dependency(fe_ce, fe_class_name);
      return INHERITANCE_SUCCESS;
    }
  }

  const zend_type *single_type;

  /* Traverse the list of parent types and check if the current child (FE)
   * class is the subtype of at least one of them (union) or all of them (intersection). */
  bool is_intersection = ZEND_TYPE_IS_INTERSECTION(proto_type);
  ZEND_TYPE_FOREACH(proto_type, single_type) {
    if (ZEND_TYPE_IS_INTERSECTION(*single_type)) {
      inheritance_status subtype_status = zend_is_class_subtype_of_type(
        fe_scope, fe_class_name, proto_scope, *single_type);

      switch (subtype_status) {
        case INHERITANCE_ERROR:
          if (is_intersection) {
            return INHERITANCE_ERROR;
          }
          continue;
        case INHERITANCE_UNRESOLVED:
          have_unresolved = true;
          continue;
        case INHERITANCE_SUCCESS:
          if (!is_intersection) {
            return INHERITANCE_SUCCESS;
          }
          continue;
        default: ZEND_UNREACHABLE();
      }
    }

    zend_class_entry *proto_ce;
    zend_string *proto_class_name = NULL;
    if (ZEND_TYPE_HAS_NAME(*single_type)) {
      proto_class_name =
        resolve_class_name(proto_scope, ZEND_TYPE_NAME(*single_type));
      if (zend_string_equals_ci(fe_class_name, proto_class_name)) {
        if (!is_intersection) {
          return INHERITANCE_SUCCESS;
        }
        continue;
      }

      if (!fe_ce) fe_ce = lookup_class(fe_scope, fe_class_name);
      proto_ce = lookup_class(proto_scope, proto_class_name);
    } else {
      /* standard type */
      ZEND_ASSERT(!is_intersection);
      continue;
    }

    if (!fe_ce || !proto_ce) {
      have_unresolved = true;
      continue;
    }
    if (unlinked_instanceof(fe_ce, proto_ce)) {
      track_class_dependency(fe_ce, fe_class_name);
      track_class_dependency(proto_ce, proto_class_name);
      if (!is_intersection) {
        return INHERITANCE_SUCCESS;
      }
    } else {
      if (is_intersection) {
        return INHERITANCE_ERROR;
      }
    }
  } ZEND_TYPE_FOREACH_END();

  if (have_unresolved) {
    return INHERITANCE_UNRESOLVED;
  }
  return is_intersection ? INHERITANCE_SUCCESS : INHERITANCE_ERROR;
}

static zend_string *get_class_from_type(const zend_class_entry *scope, const zend_type single_type) {
  if (ZEND_TYPE_HAS_NAME(single_type)) {
    return resolve_class_name(scope, ZEND_TYPE_NAME(single_type));
  }
  return NULL;
}

static void register_unresolved_classes(zend_class_entry *scope, const zend_type type) {
  const zend_type *single_type;
  ZEND_TYPE_FOREACH(type, single_type) {
    if (ZEND_TYPE_HAS_LIST(*single_type)) {
      register_unresolved_classes(scope, *single_type);
      continue;
    }
    if (ZEND_TYPE_HAS_NAME(*single_type)) {
      zend_string *class_name = resolve_class_name(scope, ZEND_TYPE_NAME(*single_type));
      lookup_class_ex(scope, class_name, /* register_unresolved */ true);
    }
  } ZEND_TYPE_FOREACH_END();
}

static inheritance_status zend_is_intersection_subtype_of_type(
  zend_class_entry *fe_scope, const zend_type fe_type,
  zend_class_entry *proto_scope, const zend_type proto_type)
{
  bool have_unresolved = false;
  const zend_type *single_type;
  uint32_t proto_type_mask = ZEND_TYPE_PURE_MASK(proto_type);

  /* Currently, for object type any class name would be allowed here.
   * We still perform a class lookup for forward-compatibility reasons,
   * as we may have named types in the future that are not classes
   * (such as typedefs). */
  if (proto_type_mask & MAY_BE_OBJECT) {
    ZEND_TYPE_FOREACH(fe_type, single_type) {
      zend_string *fe_class_name = get_class_from_type(fe_scope, *single_type);
      if (!fe_class_name) {
        continue;
      }
      zend_class_entry *fe_ce = lookup_class(fe_scope, fe_class_name);
      if (fe_ce) {
        track_class_dependency(fe_ce, fe_class_name);
        return INHERITANCE_SUCCESS;
      } else {
        have_unresolved = true;
      }
    } ZEND_TYPE_FOREACH_END();
  }

  /* U_1&...&U_n < V_1&...&V_m if forall V_j. exists U_i. U_i < V_j.
   * U_1&...&U_n < V_1|...|V_m if exists V_j. exists U_i. U_i < V_j.
   * As such, we need to iterate over proto_type (V_j) first and use a different
   * quantifier depending on whether fe_type is a union or an intersection. */
  inheritance_status early_exit_status =
    ZEND_TYPE_IS_INTERSECTION(proto_type) ? INHERITANCE_ERROR : INHERITANCE_SUCCESS;
  ZEND_TYPE_FOREACH(proto_type, single_type) {
    inheritance_status status;

    if (ZEND_TYPE_IS_INTERSECTION(*single_type)) {
      status = zend_is_intersection_subtype_of_type(
        fe_scope, fe_type, proto_scope, *single_type);
    } else {
      zend_string *proto_class_name = get_class_from_type(proto_scope, *single_type);
      if (!proto_class_name) {
        continue;
      }

      zend_class_entry *proto_ce = NULL;
      status = zend_is_intersection_subtype_of_class(
        fe_scope, fe_type, proto_scope, proto_class_name, proto_ce);
    }

    if (status == early_exit_status) {
      return status;
    }
    if (status == INHERITANCE_UNRESOLVED) {
      have_unresolved = true;
    }
  } ZEND_TYPE_FOREACH_END();

  if (have_unresolved) {
    return INHERITANCE_UNRESOLVED;
  }

  return early_exit_status == INHERITANCE_ERROR ? INHERITANCE_SUCCESS : INHERITANCE_ERROR;
}

static inheritance_status zend_perform_covariant_type_check(
    zend_class_entry *fe_scope, const zend_type fe_type,
    zend_class_entry *proto_scope, const zend_type proto_type)
{
  ZEND_ASSERT(ZEND_TYPE_IS_SET(fe_type) && ZEND_TYPE_IS_SET(proto_type));

  /* Apart from void, everything is trivially covariant to the mixed type.
   * Handle this case separately to ensure it never requires class loading. */
  if (ZEND_TYPE_PURE_MASK(proto_type) == MAY_BE_ANY &&
      !ZEND_TYPE_CONTAINS_CODE(fe_type, IS_VOID)) {
    return INHERITANCE_SUCCESS;
  }

  /* Builtin types may be removed, but not added */
  uint32_t fe_type_mask = ZEND_TYPE_PURE_MASK(fe_type);
  uint32_t proto_type_mask = ZEND_TYPE_PURE_MASK(proto_type);
  uint32_t added_types = fe_type_mask & ~proto_type_mask;
  if (added_types) {
    if ((added_types & MAY_BE_STATIC)
        && zend_type_permits_self(proto_type, proto_scope, fe_scope)) {
      /* Replacing type that accepts self with static is okay */
      added_types &= ~MAY_BE_STATIC;
    }

    if (added_types == MAY_BE_NEVER) {
      /* never is the bottom type */
      return INHERITANCE_SUCCESS;
    }

    if (added_types) {
      /* Otherwise adding new types is illegal */
      return INHERITANCE_ERROR;
    }
  }

  inheritance_status early_exit_status;
  bool have_unresolved = false;

  if (ZEND_TYPE_IS_INTERSECTION(fe_type)) {
    early_exit_status =
      ZEND_TYPE_IS_INTERSECTION(proto_type) ? INHERITANCE_ERROR : INHERITANCE_SUCCESS;
    inheritance_status status = zend_is_intersection_subtype_of_type(
      fe_scope, fe_type, proto_scope, proto_type);

    if (status == early_exit_status) {
      return status;
    }
    if (status == INHERITANCE_UNRESOLVED) {
      have_unresolved = true;
    }
  } else {
    /* U_1|...|U_n < V_1|...|V_m if forall U_i. exists V_j. U_i < V_j.
     * U_1|...|U_n < V_1&...&V_m if forall U_i. forall V_j. U_i < V_j.
     * We need to iterate over fe_type (U_i) first and the logic is independent of
     * whether proto_type is a union or intersection (only the inner check differs). */
    early_exit_status = INHERITANCE_ERROR;
    const zend_type *single_type;
    ZEND_TYPE_FOREACH(fe_type, single_type) {
      inheritance_status status;
      /* Union has an intersection type as it's member */
      if (ZEND_TYPE_IS_INTERSECTION(*single_type)) {
        status = zend_is_intersection_subtype_of_type(
          fe_scope, *single_type, proto_scope, proto_type);
      } else {
        zend_string *fe_class_name = get_class_from_type(fe_scope, *single_type);
        if (!fe_class_name) {
          continue;
        }

        status = zend_is_class_subtype_of_type(
          fe_scope, fe_class_name, proto_scope, proto_type);
      }

      if (status == early_exit_status) {
        return status;
      }
      if (status == INHERITANCE_UNRESOLVED) {
        have_unresolved = true;
      }
    } ZEND_TYPE_FOREACH_END();
  }

  if (!have_unresolved) {
    return early_exit_status == INHERITANCE_ERROR ? INHERITANCE_SUCCESS : INHERITANCE_ERROR;
  }

  register_unresolved_classes(fe_scope, fe_type);
  register_unresolved_classes(proto_scope, proto_type);
  return INHERITANCE_UNRESOLVED;
}

static inheritance_status zend_do_perform_arg_type_hint_check(
    zend_class_entry *fe_scope, const zend_arg_info *fe_arg_info,
    zend_class_entry *proto_scope, const zend_arg_info *proto_arg_info) /* {{{ */
{
  if (!ZEND_TYPE_IS_SET(fe_arg_info->type) || ZEND_TYPE_PURE_MASK(fe_arg_info->type) == MAY_BE_ANY) {
    /* Child with no type or mixed type is always compatible */
    return INHERITANCE_SUCCESS;
  }

  if (!ZEND_TYPE_IS_SET(proto_arg_info->type)) {
    /* Child defines a type, but parent doesn't, violates LSP */
    return INHERITANCE_ERROR;
  }

  /* Contravariant type check is performed as a covariant type check with swapped
   * argument order. */
  return zend_perform_covariant_type_check(
    proto_scope, proto_arg_info->type, fe_scope, fe_arg_info->type);
}
/* }}} */

/* For trait methods, fe_scope/proto_scope may differ from fe/proto->common.scope,
 * as self will refer to the self of the class the trait is used in, not the trait
 * the method was declared in. */
static inheritance_status zend_do_perform_implementation_check(
    const zend_function *fe, zend_class_entry *fe_scope,
    const zend_function *proto, zend_class_entry *proto_scope) /* {{{ */
{
  uint32_t num_args, proto_num_args, fe_num_args;
  inheritance_status status, local_status;
  bool proto_is_variadic, fe_is_variadic;

  /* Checks for constructors only if they are declared in an interface,
   * or explicitly marked as abstract
   */
  ZEND_ASSERT(!((fe->common.fn_flags & ZEND_ACC_CTOR)
    && ((proto->common.scope->ce_flags & ZEND_ACC_INTERFACE) == 0
      && (proto->common.fn_flags & ZEND_ACC_ABSTRACT) == 0)));

  /* If the prototype method is private and not abstract, we do not enforce a signature.
   * private abstract methods can only occur in traits. */
  ZEND_ASSERT(!(proto->common.fn_flags & ZEND_ACC_PRIVATE)
      || (proto->common.fn_flags & ZEND_ACC_ABSTRACT));

  /* The number of required arguments cannot increase. */
  if (proto->common.required_num_args < fe->common.required_num_args) {
    return INHERITANCE_ERROR;
  }

  /* by-ref constraints on return values are covariant */
  if ((proto->common.fn_flags & ZEND_ACC_RETURN_REFERENCE)
    && !(fe->common.fn_flags & ZEND_ACC_RETURN_REFERENCE)) {
    return INHERITANCE_ERROR;
  }

  proto_is_variadic = (proto->common.fn_flags & ZEND_ACC_VARIADIC) != 0;
  fe_is_variadic = (fe->common.fn_flags & ZEND_ACC_VARIADIC) != 0;

  /* A variadic function cannot become non-variadic */
  if (proto_is_variadic && !fe_is_variadic) {
    return INHERITANCE_ERROR;
  }

  /* The variadic argument is not included in the stored argument count. */
  proto_num_args = proto->common.num_args + proto_is_variadic;
  fe_num_args = fe->common.num_args + fe_is_variadic;
  num_args = MAX(proto_num_args, fe_num_args);

  status = INHERITANCE_SUCCESS;
  for (uint32_t i = 0; i < num_args; i++) {
    zend_arg_info *proto_arg_info =
      i < proto_num_args ? &proto->common.arg_info[i] :
      proto_is_variadic ? &proto->common.arg_info[proto_num_args - 1] : NULL;
    zend_arg_info *fe_arg_info =
      i < fe_num_args ? &fe->common.arg_info[i] :
      fe_is_variadic ? &fe->common.arg_info[fe_num_args - 1] : NULL;
    if (!proto_arg_info) {
      /* A new (optional) argument has been added, which is fine. */
      continue;
    }
    if (!fe_arg_info) {
      /* An argument has been removed. This is considered illegal, because arity checks
       * work based on a model where passing more than the declared number of parameters
       * to a function is an error. */
      return INHERITANCE_ERROR;
    }

    local_status = zend_do_perform_arg_type_hint_check(
      fe_scope, fe_arg_info, proto_scope, proto_arg_info);

    if (UNEXPECTED(local_status != INHERITANCE_SUCCESS)) {
      if (UNEXPECTED(local_status == INHERITANCE_ERROR)) {
        return INHERITANCE_ERROR;
      }
      ZEND_ASSERT(local_status == INHERITANCE_UNRESOLVED);
      status = INHERITANCE_UNRESOLVED;
    }

    /* by-ref constraints on arguments are invariant */
    if (ZEND_ARG_SEND_MODE(fe_arg_info) != ZEND_ARG_SEND_MODE(proto_arg_info)) {
      return INHERITANCE_ERROR;
    }
  }

  /* Check return type compatibility, but only if the prototype already specifies
   * a return type. Adding a new return type is always valid. */
  if (proto->common.fn_flags & ZEND_ACC_HAS_RETURN_TYPE) {
    /* Removing a return type is not valid, unless the parent return type is tentative. */
    if (!(fe->common.fn_flags & ZEND_ACC_HAS_RETURN_TYPE)) {
      if (!ZEND_ARG_TYPE_IS_TENTATIVE(&proto->common.arg_info[-1])) {
        return INHERITANCE_ERROR;
      }
      if (status == INHERITANCE_SUCCESS) {
        return INHERITANCE_WARNING;
      }
      return status;
    }

    local_status = zend_perform_covariant_type_check(
      fe_scope, fe->common.arg_info[-1].type, proto_scope, proto->common.arg_info[-1].type);

    if (UNEXPECTED(local_status != INHERITANCE_SUCCESS)) {
      if (local_status == INHERITANCE_ERROR
          && ZEND_ARG_TYPE_IS_TENTATIVE(&proto->common.arg_info[-1])) {
        local_status = INHERITANCE_WARNING;
      }
      return local_status;
    }
  }

  return status;
}
/* }}} */

static ZEND_COLD void zend_append_type_hint(
    smart_str *str, const zend_class_entry *scope, const zend_arg_info *arg_info, bool return_hint) /* {{{ */
{
  if (ZEND_TYPE_IS_SET(arg_info->type)) {
    zend_string *type_str = zend_type_to_string_resolved(arg_info->type, scope);
    smart_str_append(str, type_str);
    zend_string_release(type_str);
    if (!return_hint) {
      smart_str_appendc(str, ' ');
    }
  }
}
/* }}} */

static ZEND_COLD zend_string *zend_get_function_declaration(
    const zend_function *fptr, const zend_class_entry *scope) /* {{{ */
{
  smart_str str = {0};

  if (fptr->op_array.fn_flags & ZEND_ACC_RETURN_REFERENCE) {
    smart_str_appendc(&str, '&');
  }

  if (fptr->common.scope) {
    if (fptr->common.scope->ce_flags & ZEND_ACC_ANON_CLASS) {
      /* cut off on NULL byte ... class@anonymous */
      smart_str_appends(&str, ZSTR_VAL(fptr->common.scope->name));
    } else {
      smart_str_append(&str, fptr->common.scope->name);
    }
    smart_str_appends(&str, "::");
  }

  smart_str_append(&str, fptr->common.function_name);
  smart_str_appendc(&str, '(');

  if (fptr->common.arg_info) {
    uint32_t num_args, required;
    zend_arg_info *arg_info = fptr->common.arg_info;

    required = fptr->common.required_num_args;
    num_args = fptr->common.num_args;
    if (fptr->common.fn_flags & ZEND_ACC_VARIADIC) {
      num_args++;
    }
    for (uint32_t i = 0; i < num_args;) {
      zend_append_type_hint(&str, scope, arg_info, false);

      if (ZEND_ARG_SEND_MODE(arg_info)) {
        smart_str_appendc(&str, '&');
      }

      if (ZEND_ARG_IS_VARIADIC(arg_info)) {
        smart_str_appends(&str, "...");
      }

      smart_str_appendc(&str, '$');
      smart_str_append(&str, arg_info->name);

      if (i >= required && !ZEND_ARG_IS_VARIADIC(arg_info)) {
        smart_str_appends(&str, " = ");

        if (fptr->type == ZEND_INTERNAL_FUNCTION) {
          if (arg_info->default_value) {
            smart_str_append(&str, arg_info->default_value);
          } else {
            smart_str_appends(&str, "<default>");
          }
        } else {
          zend_op *precv = NULL;
          {
            uint32_t idx  = i;
            zend_op *op = fptr->op_array.opcodes;
            const zend_op *end = op + fptr->op_array.last;

            ++idx;
            while (op < end) {
              if ((op->opcode == ZEND_RECV || op->opcode == ZEND_RECV_INIT)
                  && op->op1.num == (zend_ulong)idx)
              {
                precv = op;
              }
              ++op;
            }
          }
          if (precv && precv->opcode == ZEND_RECV_INIT && precv->op2_type != IS_UNUSED) {
            zval *zv = RT_CONSTANT(precv, precv->op2);

            if (Z_TYPE_P(zv) == IS_FALSE) {
              smart_str_appends(&str, "false");
            } else if (Z_TYPE_P(zv) == IS_TRUE) {
              smart_str_appends(&str, "true");
            } else if (Z_TYPE_P(zv) == IS_NULL) {
              smart_str_appends(&str, "null");
            } else if (Z_TYPE_P(zv) == IS_STRING) {
              smart_str_appendc(&str, '\'');
              smart_str_appendl(&str, Z_STRVAL_P(zv), MIN(Z_STRLEN_P(zv), 10));
              if (Z_STRLEN_P(zv) > 10) {
                smart_str_appends(&str, "...");
              }
              smart_str_appendc(&str, '\'');
            } else if (Z_TYPE_P(zv) == IS_ARRAY) {
              if (zend_hash_num_elements(Z_ARRVAL_P(zv)) == 0) {
                smart_str_appends(&str, "[]");
              } else {
                smart_str_appends(&str, "[...]");
              }
            } else if (Z_TYPE_P(zv) == IS_CONSTANT_AST) {
              zend_ast *ast = Z_ASTVAL_P(zv);
              if (ast->kind == ZEND_AST_CONSTANT) {
                smart_str_append(&str, zend_ast_get_constant_name(ast));
              } else if (ast->kind == ZEND_AST_CLASS_CONST
               && ast->child[1]->kind == ZEND_AST_ZVAL
               && Z_TYPE_P(zend_ast_get_zval(ast->child[1])) == IS_STRING) {
                smart_str_append(&str, zend_ast_get_str(ast->child[0]));
                smart_str_appends(&str, "::");
                smart_str_append(&str, zend_ast_get_str(ast->child[1]));
              } else {
                smart_str_appends(&str, "<expression>");
              }
            } else {
              zend_string *tmp_zv_str;
              zend_string *zv_str = zval_get_tmp_string(zv, &tmp_zv_str);
              smart_str_append(&str, zv_str);
              zend_tmp_string_release(tmp_zv_str);
            }
          }
        }
      }

      if (++i < num_args) {
        smart_str_appends(&str, ", ");
      }
      arg_info++;
    }
  }

  smart_str_appendc(&str, ')');

  if (fptr->common.fn_flags & ZEND_ACC_HAS_RETURN_TYPE) {
    smart_str_appends(&str, ": ");
    zend_append_type_hint(&str, scope, fptr->common.arg_info - 1, true);
  }
  smart_str_0(&str);

  return str.s;
}
/* }}} */

static zend_always_inline zend_string *func_filename(const zend_function *fn) {
  return fn->common.type == ZEND_USER_FUNCTION ? fn->op_array.filename : NULL;
}

static zend_always_inline uint32_t func_lineno(const zend_function *fn) {
  return fn->common.type == ZEND_USER_FUNCTION ? fn->op_array.line_start : 0;
}

static void ZEND_COLD emit_incompatible_method_error(
    const zend_function *child, const zend_class_entry *child_scope,
    const zend_function *parent, const zend_class_entry *parent_scope,
    inheritance_status status) {
  zend_string *parent_prototype = zend_get_function_declaration(parent, parent_scope);
  zend_string *child_prototype = zend_get_function_declaration(child, child_scope);
  if (status == INHERITANCE_UNRESOLVED) {
    // TODO Improve error message if first unresolved class is present in child and parent?
    /* Fetch the first unresolved class from registered autoloads */
    const zend_string *unresolved_class = NULL;
    ZEND_HASH_MAP_FOREACH_STR_KEY(CG(delayed_autoloads), unresolved_class) {
      break;
    } ZEND_HASH_FOREACH_END();
    ZEND_ASSERT(unresolved_class);

    zend_error_at(E_COMPILE_ERROR, func_filename(child), func_lineno(child),
      "Could not check compatibility between %s and %s, because class %s is not available",
      ZSTR_VAL(child_prototype), ZSTR_VAL(parent_prototype), ZSTR_VAL(unresolved_class));
  } else if (status == INHERITANCE_WARNING) {
    const zend_attribute *return_type_will_change_attribute = zend_get_attribute_str(
      child->common.attributes,
      "returntypewillchange",
      sizeof("returntypewillchange")-1
    );

    if (!return_type_will_change_attribute) {
      zend_error_at(E_DEPRECATED, func_filename(child), func_lineno(child),
        "Return type of %s should either be compatible with %s, "
        "or the #[\\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice",
        ZSTR_VAL(child_prototype), ZSTR_VAL(parent_prototype));
      ZEND_ASSERT(!EG(exception));
    }
  } else {
    zend_error_at(E_COMPILE_ERROR, func_filename(child), func_lineno(child),
      "Declaration of %s must be compatible with %s",
      ZSTR_VAL(child_prototype), ZSTR_VAL(parent_prototype));
  }
  zend_string_efree(child_prototype);
  zend_string_efree(parent_prototype);
}

static void perform_delayable_implementation_check(
    zend_class_entry *ce,
    const zend_function *fe, zend_class_entry *fe_scope,
    const zend_function *proto, zend_class_entry *proto_scope)
{
  inheritance_status status =
    zend_do_perform_implementation_check(fe, fe_scope, proto, proto_scope);
  if (UNEXPECTED(status != INHERITANCE_SUCCESS)) {
    if (EXPECTED(status == INHERITANCE_UNRESOLVED)) {
      add_compatibility_obligation(ce, fe, fe_scope, proto, proto_scope);
    } else {
      ZEND_ASSERT(status == INHERITANCE_ERROR || status == INHERITANCE_WARNING);
      emit_incompatible_method_error(fe, fe_scope, proto, proto_scope, status);
    }
  }
}

#define ZEND_INHERITANCE_LAZY_CHILD_CLONE     (1<<0)
#define ZEND_INHERITANCE_CHECK_SILENT         (1<<1) /* don't throw errors */
#define ZEND_INHERITANCE_CHECK_PROTO          (1<<2) /* check method prototype (it might be already checked before) */
#define ZEND_INHERITANCE_CHECK_VISIBILITY     (1<<3)
#define ZEND_INHERITANCE_SET_CHILD_CHANGED    (1<<4)
#define ZEND_INHERITANCE_SET_CHILD_PROTO      (1<<5)
#define ZEND_INHERITANCE_RESET_CHILD_OVERRIDE (1<<6)

static inheritance_status do_inheritance_check_on_method(
    zend_function *child, zend_class_entry *child_scope,
    zend_function *parent, zend_class_entry *parent_scope,
    zend_class_entry *ce, zval *child_zv, uint32_t flags) /* {{{ */
{
  uint32_t child_flags;
  uint32_t parent_flags = parent->common.fn_flags;
  zend_function *proto;

#define SEPARATE_METHOD() do { \
      if ((flags & ZEND_INHERITANCE_LAZY_CHILD_CLONE) \
       && child_scope != ce \
       /* Trait methods have already been separated at this point. However, their */ \
       /* scope isn't fixed until after inheritance checks to preserve the scope */ \
       /* in error messages. Skip them here explicitly. */ \
       && !(child_scope->ce_flags & ZEND_ACC_TRAIT) \
       && child->type == ZEND_USER_FUNCTION) { \
        /* op_array wasn't duplicated yet */ \
        zend_function *new_function = zend_arena_alloc(&CG(arena), sizeof(zend_op_array)); \
        memcpy(new_function, child, sizeof(zend_op_array)); \
        Z_PTR_P(child_zv) = child = new_function; \
        flags &= ~ZEND_INHERITANCE_LAZY_CHILD_CLONE; \
      } \
    } while(0)

  if (UNEXPECTED((parent_flags & (ZEND_ACC_PRIVATE|ZEND_ACC_ABSTRACT|ZEND_ACC_CTOR)) == ZEND_ACC_PRIVATE)) {
    if (flags & ZEND_INHERITANCE_SET_CHILD_CHANGED) {
      SEPARATE_METHOD();
      child->common.fn_flags |= ZEND_ACC_CHANGED;
    }
    /* The parent method is private and not an abstract so we don't need to check any inheritance rules */
    return INHERITANCE_SUCCESS;
  }

  if ((flags & ZEND_INHERITANCE_CHECK_PROTO) && UNEXPECTED(parent_flags & ZEND_ACC_FINAL)) {
    if (flags & ZEND_INHERITANCE_CHECK_SILENT) {
      return INHERITANCE_ERROR;
    }
    zend_error_at_noreturn(E_COMPILE_ERROR, func_filename(child), func_lineno(child),
      "Cannot override final method %s::%s()",
      ZEND_FN_SCOPE_NAME(parent), ZSTR_VAL(child->common.function_name));
  }

  child_flags = child->common.fn_flags;
  /* You cannot change from static to non static and vice versa.
   */
  if ((flags & ZEND_INHERITANCE_CHECK_PROTO)
   && UNEXPECTED((child_flags & ZEND_ACC_STATIC) != (parent_flags & ZEND_ACC_STATIC))) {
    if (flags & ZEND_INHERITANCE_CHECK_SILENT) {
      return INHERITANCE_ERROR;
    }
    if (child_flags & ZEND_ACC_STATIC) {
      zend_error_at_noreturn(E_COMPILE_ERROR, func_filename(child), func_lineno(child),
        "Cannot make non static method %s::%s() static in class %s",
        ZEND_FN_SCOPE_NAME(parent), ZSTR_VAL(child->common.function_name), ZEND_FN_SCOPE_NAME(child));
    } else {
      zend_error_at_noreturn(E_COMPILE_ERROR, func_filename(child), func_lineno(child),
        "Cannot make static method %s::%s() non static in class %s",
        ZEND_FN_SCOPE_NAME(parent), ZSTR_VAL(child->common.function_name), ZEND_FN_SCOPE_NAME(child));
    }
  }

  /* Disallow making an inherited method abstract. */
  if ((flags & ZEND_INHERITANCE_CHECK_PROTO)
   && UNEXPECTED((child_flags & ZEND_ACC_ABSTRACT) > (parent_flags & ZEND_ACC_ABSTRACT))) {
    if (flags & ZEND_INHERITANCE_CHECK_SILENT) {
      return INHERITANCE_ERROR;
    }
    zend_error_at_noreturn(E_COMPILE_ERROR, func_filename(child), func_lineno(child),
      "Cannot make non abstract method %s::%s() abstract in class %s",
      ZEND_FN_SCOPE_NAME(parent), ZSTR_VAL(child->common.function_name), ZEND_FN_SCOPE_NAME(child));
  }

  if ((flags & ZEND_INHERITANCE_SET_CHILD_CHANGED)
   && (parent_flags & (ZEND_ACC_PRIVATE|ZEND_ACC_CHANGED))) {
    SEPARATE_METHOD();
    child->common.fn_flags |= ZEND_ACC_CHANGED;
  }

  proto = parent->common.prototype ?
    parent->common.prototype : parent;

  if (parent_flags & ZEND_ACC_CTOR) {
    /* ctors only have a prototype if is abstract (or comes from an interface) */
    /* and if that is the case, we want to check inheritance against it */
    if (!(proto->common.fn_flags & ZEND_ACC_ABSTRACT)) {
      return INHERITANCE_SUCCESS;
    }
    parent = proto;
  }

  if ((flags & ZEND_INHERITANCE_SET_CHILD_PROTO)
   && child->common.prototype != proto) {
    SEPARATE_METHOD();
    child->common.prototype = proto;
  }

  /* Prevent derived classes from restricting access that was available in parent classes (except deriving from non-abstract ctors) */
  if ((flags & ZEND_INHERITANCE_CHECK_VISIBILITY)
      && (child_flags & ZEND_ACC_PPP_MASK) > (parent_flags & ZEND_ACC_PPP_MASK)) {
    if (flags & ZEND_INHERITANCE_CHECK_SILENT) {
      return INHERITANCE_ERROR;
    }
    zend_error_at_noreturn(E_COMPILE_ERROR, func_filename(child), func_lineno(child),
      "Access level to %s::%s() must be %s (as in class %s)%s",
      ZEND_FN_SCOPE_NAME(child), ZSTR_VAL(child->common.function_name), zend_visibility_string(parent_flags), ZEND_FN_SCOPE_NAME(parent), (parent_flags&ZEND_ACC_PUBLIC) ? "" : " or weaker");
  }

  if (flags & ZEND_INHERITANCE_CHECK_PROTO) {
    if (flags & ZEND_INHERITANCE_CHECK_SILENT) {
      return zend_do_perform_implementation_check(child, child_scope, parent, parent_scope);
    }
    perform_delayable_implementation_check(ce, child, child_scope, parent, parent_scope);
  }

  if ((flags & ZEND_INHERITANCE_RESET_CHILD_OVERRIDE)
   && (child->common.fn_flags & ZEND_ACC_OVERRIDE)) {
    SEPARATE_METHOD();
    child->common.fn_flags &= ~ZEND_ACC_OVERRIDE;
  }

#undef SEPARATE_METHOD

  return INHERITANCE_SUCCESS;
}
/* }}} */

static void do_inherit_method(zend_string *key, zend_function *parent, zend_class_entry *ce, bool is_interface, uint32_t flags) /* {{{ */
{
  zval *child = zend_hash_find_known_hash(&ce->function_table, key);

  if (child) {
    zend_function *func = (zend_function*)Z_PTR_P(child);

    if (is_interface && UNEXPECTED(func == parent)) {
      /* The same method in interface may be inherited few times */
      return;
    }

    do_inheritance_check_on_method(
      func, func->common.scope, parent, parent->common.scope, ce, child, flags);
  } else {

    if (is_interface || (parent->common.fn_flags & (ZEND_ACC_ABSTRACT))) {
      ce->ce_flags |= ZEND_ACC_IMPLICIT_ABSTRACT_CLASS;
    }

    parent = zend_duplicate_function(parent, ce);

    if (!is_interface) {
      _zend_hash_append_ptr(&ce->function_table, key, parent);
    } else {
      zend_hash_add_new_ptr(&ce->function_table, key, parent);
    }
  }
}
/* }}} */

static inheritance_status full_property_types_compatible(
    const zend_property_info *parent_info, const zend_property_info *child_info,
    prop_variance variance) {
  if (ZEND_TYPE_PURE_MASK(parent_info->type) == ZEND_TYPE_PURE_MASK(child_info->type)
      && ZEND_TYPE_NAME(parent_info->type) == ZEND_TYPE_NAME(child_info->type)) {
    return INHERITANCE_SUCCESS;
  }

  if (ZEND_TYPE_IS_SET(parent_info->type) != ZEND_TYPE_IS_SET(child_info->type)) {
    return INHERITANCE_ERROR;
  }

  /* Perform a covariant type check in both directions to determined invariance. */
  inheritance_status status1 = variance == PROP_CONTRAVARIANT ? INHERITANCE_SUCCESS :
    zend_perform_covariant_type_check(
      child_info->ce, child_info->type, parent_info->ce, parent_info->type);
  inheritance_status status2 = variance == PROP_COVARIANT ? INHERITANCE_SUCCESS :
    zend_perform_covariant_type_check(
      parent_info->ce, parent_info->type, child_info->ce, child_info->type);
  if (status1 == INHERITANCE_SUCCESS && status2 == INHERITANCE_SUCCESS) {
    return INHERITANCE_SUCCESS;
  }
  if (status1 == INHERITANCE_ERROR || status2 == INHERITANCE_ERROR) {
    return INHERITANCE_ERROR;
  }
  ZEND_ASSERT(status1 == INHERITANCE_UNRESOLVED || status2 == INHERITANCE_UNRESOLVED);
  return INHERITANCE_UNRESOLVED;
}

static ZEND_COLD void emit_incompatible_property_error(
    const zend_property_info *child, const zend_property_info *parent, prop_variance variance) {
  zend_string *type_str = zend_type_to_string_resolved(parent->type, parent->ce);
  zend_error_noreturn(E_COMPILE_ERROR,
    "Type of %s::$%s must be %s%s (as in class %s)",
    ZSTR_VAL(child->ce->name),
    zend_get_unmangled_property_name(child->name),
    variance == PROP_INVARIANT ? "" :
    variance == PROP_COVARIANT ? "subtype of " : "supertype of ",
    ZSTR_VAL(type_str),
    ZSTR_VAL(parent->ce->name));
}

static ZEND_COLD void emit_set_hook_type_error(const zend_property_info *child, const zend_property_info *parent)
{
  zend_type set_type = parent->hooks[ZEND_PROPERTY_HOOK_SET]->common.arg_info[0].type;
  zend_string *type_str = zend_type_to_string_resolved(set_type, parent->ce);
  zend_error_noreturn(E_COMPILE_ERROR,
    "Set type of %s::$%s must be supertype of %s (as in %s %s)",
    ZSTR_VAL(child->ce->name),
    zend_get_unmangled_property_name(child->name),
    ZSTR_VAL(type_str),
    zend_get_object_type_case(parent->ce, false),
    ZSTR_VAL(parent->ce->name));
}

static inheritance_status verify_property_type_compatibility(
  const zend_property_info *parent_info,
  const zend_property_info *child_info,
  prop_variance variance,
  bool throw_on_error,
  bool throw_on_unresolved
) {
  inheritance_status result = full_property_types_compatible(parent_info, child_info, variance);
  if ((result == INHERITANCE_ERROR && throw_on_error) || (result == INHERITANCE_UNRESOLVED && throw_on_unresolved)) {
    emit_incompatible_property_error(child_info, parent_info, variance);
  }
  if (result != INHERITANCE_SUCCESS) {
    return result;
  }
  if (parent_info->flags & ZEND_ACC_ABSTRACT) {
    ZEND_ASSERT(parent_info->hooks);
    if (parent_info->hooks[ZEND_PROPERTY_HOOK_SET]
     && (!child_info->hooks || !child_info->hooks[ZEND_PROPERTY_HOOK_SET])) {
      zend_type set_type = parent_info->hooks[ZEND_PROPERTY_HOOK_SET]->common.arg_info[0].type;
      inheritance_status result = zend_perform_covariant_type_check(
        parent_info->ce, set_type, child_info->ce, child_info->type);
      if ((result == INHERITANCE_ERROR && throw_on_error) || (result == INHERITANCE_UNRESOLVED && throw_on_unresolved)) {
        emit_set_hook_type_error(child_info, parent_info);
      }
    }
  }
  return INHERITANCE_SUCCESS;
}

static bool property_has_operation(const zend_property_info *prop_info, zend_property_hook_kind kind)
{
  return (!(prop_info->flags & ZEND_ACC_VIRTUAL)
      && (kind == ZEND_PROPERTY_HOOK_GET || !(prop_info->flags & ZEND_ACC_READONLY)))
    || (prop_info->hooks && prop_info->hooks[kind]);
}

static void inherit_property_hook(
  zend_class_entry *ce,
  zend_property_info *parent_info,
  zend_property_info *child_info,
  zend_property_hook_kind kind
) {
  zend_function *parent = parent_info->hooks ? parent_info->hooks[kind] : NULL;
  zend_function *child = child_info->hooks ? child_info->hooks[kind] : NULL;

  if (child
   && (child->common.fn_flags & ZEND_ACC_OVERRIDE)
   && property_has_operation(parent_info, kind)) {
    child->common.fn_flags &= ~ZEND_ACC_OVERRIDE;
  }

  if (!parent) {
    return;
  }

  if (!child) {
    if (parent->common.fn_flags & ZEND_ACC_ABSTRACT) {
      /* Backed properties are considered to always implement get, and set when they are not readonly. */
      if (property_has_operation(child_info, kind)) {
        return;
      }
      ce->ce_flags |= ZEND_ACC_IMPLICIT_ABSTRACT_CLASS;
    }
    if (!child_info->hooks) {
      ce->num_hooked_props++;
      child_info->hooks = zend_arena_alloc(&CG(arena), ZEND_PROPERTY_HOOK_STRUCT_SIZE);
      memset(child_info->hooks, 0, ZEND_PROPERTY_HOOK_STRUCT_SIZE);
    }
    child_info->hooks[kind] = zend_duplicate_function(parent, ce);
    return;
  }

  child->common.prototype = parent->common.prototype ? parent->common.prototype : parent;

  uint32_t parent_flags = parent->common.fn_flags;
  if (parent_flags & ZEND_ACC_PRIVATE) {
    child->common.fn_flags |= ZEND_ACC_CHANGED;
    return;
  }

  if (parent_flags & ZEND_ACC_FINAL) {
    zend_error_noreturn(E_COMPILE_ERROR,
      "Cannot override final property hook %s::%s()",
      ZSTR_VAL(parent->common.scope->name),
      ZSTR_VAL(parent->common.function_name));
  }

  do_inheritance_check_on_method(
    child, child->common.scope, parent, parent->common.scope, ce, /* child */ NULL,
    ZEND_INHERITANCE_CHECK_PROTO | ZEND_INHERITANCE_CHECK_VISIBILITY
      | ZEND_INHERITANCE_SET_CHILD_CHANGED | ZEND_INHERITANCE_SET_CHILD_PROTO
      | ZEND_INHERITANCE_RESET_CHILD_OVERRIDE);

  /* Other signature compatibility issues should already be covered either by the
   * properties being compatible (types), or certain signatures being forbidden by the
   * compiler (variadic and by-ref args, etc). */
}

static prop_variance prop_get_variance(const zend_property_info *prop_info) {
  bool unbacked = prop_info->flags & ZEND_ACC_VIRTUAL;
  if (unbacked && prop_info->hooks) {
    if (!prop_info->hooks[ZEND_PROPERTY_HOOK_SET]) {
      return PROP_COVARIANT;
    }
    if (!prop_info->hooks[ZEND_PROPERTY_HOOK_GET]) {
      return PROP_CONTRAVARIANT;
    }
  }
  return PROP_INVARIANT;
}

static void do_inherit_property(zend_property_info *parent_info, zend_string *key, zend_class_entry *ce) /* {{{ */
{
  zval *child = zend_hash_find_known_hash(&ce->properties_info, key);

  if (UNEXPECTED(child)) {
    zend_property_info *child_info = Z_PTR_P(child);
    if (parent_info->flags & (ZEND_ACC_PRIVATE|ZEND_ACC_CHANGED)) {
      child_info->flags |= ZEND_ACC_CHANGED;
    }
    if (parent_info->flags & ZEND_ACC_FINAL) {
      zend_error_noreturn(E_COMPILE_ERROR, "Cannot override final property %s::$%s",
        ZSTR_VAL(parent_info->ce->name), ZSTR_VAL(key));
    }
    if (!(parent_info->flags & ZEND_ACC_PRIVATE)) {
      if (!(parent_info->ce->ce_flags & ZEND_ACC_INTERFACE)) {
        child_info->prototype = parent_info->prototype;
      }

      if (UNEXPECTED((parent_info->flags & ZEND_ACC_STATIC) != (child_info->flags & ZEND_ACC_STATIC))) {
        zend_error_noreturn(E_COMPILE_ERROR, "Cannot redeclare %s%s::$%s as %s%s::$%s",
          (parent_info->flags & ZEND_ACC_STATIC) ? "static " : "non static ", ZSTR_VAL(parent_info->ce->name), ZSTR_VAL(key),
          (child_info->flags & ZEND_ACC_STATIC) ? "static " : "non static ", ZSTR_VAL(ce->name), ZSTR_VAL(key));
      }
      if (UNEXPECTED((child_info->flags & ZEND_ACC_READONLY) != (parent_info->flags & ZEND_ACC_READONLY))) {
        if (!(parent_info->flags & ZEND_ACC_ABSTRACT)) {
          zend_error_noreturn(E_COMPILE_ERROR,
            "Cannot redeclare %s property %s::$%s as %s %s::$%s",
            parent_info->flags & ZEND_ACC_READONLY ? "readonly" : "non-readonly",
            ZSTR_VAL(parent_info->ce->name), ZSTR_VAL(key),
            child_info->flags & ZEND_ACC_READONLY ? "readonly" : "non-readonly",
            ZSTR_VAL(ce->name), ZSTR_VAL(key));
        }
      }
      if (UNEXPECTED((child_info->flags & ZEND_ACC_PPP_SET_MASK))
       /* Get-only virtual properties have no set visibility, so any child visibility is fine. */
       && !(parent_info->hooks && (parent_info->flags & ZEND_ACC_VIRTUAL) && !parent_info->hooks[ZEND_PROPERTY_HOOK_SET])) {
        uint32_t parent_set_visibility = parent_info->flags & ZEND_ACC_PPP_SET_MASK;
        /* Adding set protection is fine if it's the same or weaker than
         * the parents full property visibility. */
        if (!parent_set_visibility) {
          parent_set_visibility = zend_visibility_to_set_visibility(parent_info->flags & ZEND_ACC_PPP_MASK);
        }
        uint32_t child_set_visibility = child_info->flags & ZEND_ACC_PPP_SET_MASK;
        if (child_set_visibility > parent_set_visibility) {
          zend_error_noreturn(
            E_COMPILE_ERROR,
            "Set access level of %s::$%s must be %s (as in class %s)%s",
            ZSTR_VAL(ce->name), ZSTR_VAL(key),
            zend_asymmetric_visibility_string(parent_info->flags), ZSTR_VAL(parent_info->ce->name),
            !(parent_info->flags & ZEND_ACC_PPP_SET_MASK) ? "" : " or weaker");
        }
      }

      if (UNEXPECTED((child_info->flags & ZEND_ACC_PPP_MASK) > (parent_info->flags & ZEND_ACC_PPP_MASK))) {
        zend_error_noreturn(E_COMPILE_ERROR, "Access level to %s::$%s must be %s (as in class %s)%s", ZSTR_VAL(ce->name), ZSTR_VAL(key), zend_visibility_string(parent_info->flags), ZSTR_VAL(parent_info->ce->name), (parent_info->flags&ZEND_ACC_PUBLIC) ? "" : " or weaker");
      }
      if (!(child_info->flags & ZEND_ACC_STATIC) && !(parent_info->flags & ZEND_ACC_VIRTUAL)) {
        /* If we added hooks to the child property, we use the child's slot for
         * storage to keep the parent slot set to IS_UNDEF. This automatically
         * picks the slow path in the JIT. */
        bool use_child_prop = !parent_info->hooks && child_info->hooks;

        if (use_child_prop && child_info->offset == ZEND_VIRTUAL_PROPERTY_OFFSET) {
          child_info->offset = OBJ_PROP_TO_OFFSET(ce->default_properties_count);
          ce->default_properties_count++;
          ce->default_properties_table = perealloc(ce->default_properties_table, sizeof(zval) * ce->default_properties_count, ce->type == ZEND_INTERNAL_CLASS);
          zval *property_default_ptr = &ce->default_properties_table[OBJ_PROP_TO_NUM(child_info->offset)];
          ZVAL_UNDEF(property_default_ptr);
          Z_PROP_FLAG_P(property_default_ptr) = IS_PROP_UNINIT;
        }

        int parent_num = OBJ_PROP_TO_NUM(parent_info->offset);
        /* Don't keep default properties in GC (they may be freed by opcache) */
        zval_ptr_dtor_nogc(&(ce->default_properties_table[parent_num]));
        if (child_info->offset != ZEND_VIRTUAL_PROPERTY_OFFSET) {
          if (use_child_prop) {
            ZVAL_UNDEF(&ce->default_properties_table[parent_num]);
          } else {
            int child_num = OBJ_PROP_TO_NUM(child_info->offset);
            ce->default_properties_table[parent_num] = ce->default_properties_table[child_num];
            ZVAL_UNDEF(&ce->default_properties_table[child_num]);
          }
        } else {
          /* Default value was removed in child, remove it from parent too. */
          if (ZEND_TYPE_IS_SET(child_info->type)) {
            ZVAL_UNDEF(&ce->default_properties_table[parent_num]);
          } else {
            ZVAL_NULL(&ce->default_properties_table[parent_num]);
          }
        }

        if (!use_child_prop) {
          child_info->offset = parent_info->offset;
        }
        child_info->flags &= ~ZEND_ACC_VIRTUAL;
      }

      if (parent_info->hooks || child_info->hooks) {
        for (uint32_t i = 0; i < ZEND_PROPERTY_HOOK_COUNT; i++) {
          inherit_property_hook(ce, parent_info, child_info, i);
        }
      }

      prop_variance variance = prop_get_variance(parent_info);
      if (ZEND_TYPE_IS_SET(parent_info->type)) {
        inheritance_status status = verify_property_type_compatibility(
          parent_info, child_info, variance, true, false);
        if (status == INHERITANCE_UNRESOLVED) {
          add_property_compatibility_obligation(ce, child_info, parent_info, variance);
        }
      } else if (UNEXPECTED(ZEND_TYPE_IS_SET(child_info->type) && !ZEND_TYPE_IS_SET(parent_info->type))) {
        zend_error_noreturn(E_COMPILE_ERROR,
            "Type of %s::$%s must be omitted to match the parent definition in class %s",
            ZSTR_VAL(ce->name),
            ZSTR_VAL(key),
            ZSTR_VAL(parent_info->ce->name));
      }

      if (child_info->ce == ce) {
        child_info->flags &= ~ZEND_ACC_OVERRIDE;
      }
    }
  } else {
    zend_function **hooks = parent_info->hooks;
    if (hooks) {
      ce->num_hooked_props++;
      if (parent_info->flags & ZEND_ACC_ABSTRACT) {
        ce->ce_flags |= ZEND_ACC_IMPLICIT_ABSTRACT_CLASS;
      }
    }

    _zend_hash_append_ptr(&ce->properties_info, key, parent_info);
  }
}
/* }}} */

static inline void do_implement_interface(zend_class_entry *ce, zend_class_entry *iface) /* {{{ */
{
  if (!(ce->ce_flags & ZEND_ACC_INTERFACE) && iface->interface_gets_implemented && iface->interface_gets_implemented(iface, ce) == FAILURE) {
    zend_error_noreturn(E_CORE_ERROR, "%s %s could not implement interface %s", zend_get_object_type_uc(ce), ZSTR_VAL(ce->name), ZSTR_VAL(iface->name));
  }
  /* This should be prevented by the class lookup logic. */
  ZEND_ASSERT(ce != iface);
}
/* }}} */

static void zend_do_inherit_interfaces(zend_class_entry *ce, const zend_class_entry *iface) /* {{{ */
{
  /* expects interface to be contained in ce's interface list already */
  uint32_t i, ce_num, if_num = iface->num_interfaces;

  ce_num = ce->num_interfaces;

  ce->interfaces = (zend_class_entry **) perealloc(ce->interfaces, sizeof(zend_class_entry *) * (ce_num + if_num), ce->type == ZEND_INTERNAL_CLASS);

  /* Inherit the interfaces, only if they're not already inherited by the class */
  while (if_num--) {
    zend_class_entry *entry = iface->interfaces[if_num];
    for (i = 0; i < ce_num; i++) {
      if (ce->interfaces[i] == entry) {
        break;
      }
    }
    if (i == ce_num) {
      ce->interfaces[ce->num_interfaces++] = entry;
    }
  }
  ce->ce_flags |= ZEND_ACC_RESOLVED_INTERFACES;

  /* and now call the implementing handlers */
  while (ce_num < ce->num_interfaces) {
    do_implement_interface(ce, ce->interfaces[ce_num++]);
  }
}
/* }}} */

static void emit_incompatible_class_constant_error(
    const zend_class_constant *child, const zend_class_constant *parent, const zend_string *const_name) {
  zend_string *type_str = zend_type_to_string_resolved(parent->type, parent->ce);
  zend_error_noreturn(E_COMPILE_ERROR,
    "Type of %s::%s must be compatible with %s::%s of type %s",
    ZSTR_VAL(child->ce->name),
    ZSTR_VAL(const_name),
    ZSTR_VAL(parent->ce->name),
    ZSTR_VAL(const_name),
    ZSTR_VAL(type_str));
}

static inheritance_status class_constant_types_compatible(const zend_class_constant *parent, const zend_class_constant *child)
{
  ZEND_ASSERT(ZEND_TYPE_IS_SET(parent->type));

  if (!ZEND_TYPE_IS_SET(child->type)) {
    return INHERITANCE_ERROR;
  }

  return zend_perform_covariant_type_check(child->ce, child->type, parent->ce, parent->type);
}

static bool do_inherit_constant_check(
  zend_class_entry *ce, const zend_class_constant *parent_constant, zend_string *name);

static void do_inherit_class_constant(zend_string *name, zend_class_constant *parent_const, zend_class_entry *ce) /* {{{ */
{
  zval *zv = zend_hash_find_known_hash(&ce->constants_table, name);
  zend_class_constant *c;

  if (zv != NULL) {
    c = (zend_class_constant*)Z_PTR_P(zv);
    bool inherit = do_inherit_constant_check(ce, parent_const, name);
    ZEND_ASSERT(!inherit);
  } else if (!(ZEND_CLASS_CONST_FLAGS(parent_const) & ZEND_ACC_PRIVATE)) {
    if (Z_TYPE(parent_const->value) == IS_CONSTANT_AST) {
      ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
      ce->ce_flags |= ZEND_ACC_HAS_AST_CONSTANTS;
      if (ce->parent->ce_flags & ZEND_ACC_IMMUTABLE) {
        c = zend_arena_alloc(&CG(arena), sizeof(zend_class_constant));
        memcpy(c, parent_const, sizeof(zend_class_constant));
        parent_const = c;
        Z_CONSTANT_FLAGS(c->value) |= CONST_OWNED;
      }
    }
    if (ce->type == ZEND_INTERNAL_CLASS) {
      c = pemalloc(sizeof(zend_class_constant), 1);
      memcpy(c, parent_const, sizeof(zend_class_constant));
      parent_const = c;
    }
    _zend_hash_append_ptr(&ce->constants_table, name, parent_const);
  }
}
/* }}} */

void zend_build_properties_info_table(zend_class_entry *ce)
{
  zend_property_info **table, *prop;
  size_t size;
  if (ce->default_properties_count == 0) {
    return;
  }

  ZEND_ASSERT(ce->properties_info_table == NULL);
  size = sizeof(zend_property_info *) * ce->default_properties_count;
  if (ce->type == ZEND_USER_CLASS) {
    ce->properties_info_table = table = zend_arena_alloc(&CG(arena), size);
  } else {
    ce->properties_info_table = table = pemalloc(size, 1);
  }

  /* Dead slots may be left behind during inheritance. Make sure these are NULLed out. */
  memset(table, 0, size);

  if (ce->parent && ce->parent->default_properties_count != 0) {
    zend_property_info **parent_table = ce->parent->properties_info_table;
    memcpy(
      table, parent_table,
      sizeof(zend_property_info *) * ce->parent->default_properties_count
    );

    /* Child did not add any new properties, we are done */
    if (ce->default_properties_count == ce->parent->default_properties_count) {
      return;
    }
  }

  ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&ce->properties_info, zend_string *key, prop) {
    if (prop->ce == ce && (prop->flags & ZEND_ACC_STATIC) == 0
     && !(prop->flags & ZEND_ACC_VIRTUAL)) {
      const zend_property_info *root_prop = prop->prototype;
      if (UNEXPECTED(root_prop->flags & ZEND_ACC_VIRTUAL)) {
        /* Prototype is virtual, we need to manually hunt down the first backed property. */
        root_prop = prop;
        zend_class_entry *parent_ce;
        while ((parent_ce = root_prop->ce->parent)) {
          zend_property_info *parent_prop = zend_hash_find_ptr(&parent_ce->properties_info, key);
          if (!parent_prop
           || parent_prop->prototype != prop->prototype
           || (parent_prop->flags & ZEND_ACC_VIRTUAL)) {
            break;
          }
          root_prop = parent_prop;
        }
      }
      uint32_t prop_table_offset = OBJ_PROP_TO_NUM(root_prop->offset);
      table[prop_table_offset] = prop;
    }
  } ZEND_HASH_FOREACH_END();
}

ZEND_API void zend_verify_hooked_property(const zend_class_entry *ce, zend_property_info *prop_info, zend_string *prop_name)
{
  if (!prop_info->hooks) {
    return;
  }
  bool abstract_error = prop_info->flags & ZEND_ACC_ABSTRACT;
  /* We specified a default value (otherwise offset would be -1), but the virtual flag wasn't
   * removed during inheritance. */
  if ((prop_info->flags & ZEND_ACC_VIRTUAL) && prop_info->offset != ZEND_VIRTUAL_PROPERTY_OFFSET) {
    if (Z_TYPE(ce->default_properties_table[OBJ_PROP_TO_NUM(prop_info->offset)]) == IS_UNDEF) {
      prop_info->offset = ZEND_VIRTUAL_PROPERTY_OFFSET;
    } else {
      zend_error_noreturn(E_COMPILE_ERROR,
        "Cannot specify default value for virtual hooked property %s::$%s", ZSTR_VAL(ce->name), ZSTR_VAL(prop_name));
    }
  }
  /* If the property turns backed during inheritance and no type and default value are set, we want
   * the default value to be null. */
  if (!(prop_info->flags & ZEND_ACC_VIRTUAL)
   && !ZEND_TYPE_IS_SET(prop_info->type)
   && Z_TYPE(ce->default_properties_table[OBJ_PROP_TO_NUM(prop_info->offset)]) == IS_UNDEF) {
    ZVAL_NULL(&ce->default_properties_table[OBJ_PROP_TO_NUM(prop_info->offset)]);
  }
  for (uint32_t i = 0; i < ZEND_PROPERTY_HOOK_COUNT; i++) {
    const zend_function *func = prop_info->hooks[i];
    if (func) {
      if ((zend_property_hook_kind)i == ZEND_PROPERTY_HOOK_GET
       && (func->op_array.fn_flags & ZEND_ACC_RETURN_REFERENCE)
       && !(prop_info->flags & ZEND_ACC_VIRTUAL)
       && prop_info->hooks[ZEND_PROPERTY_HOOK_SET]) {
        zend_error_noreturn(E_COMPILE_ERROR, "Get hook of backed property %s::%s with set hook may not return by reference",
          ZSTR_VAL(ce->name), ZSTR_VAL(prop_name));
      }
      if (func->common.fn_flags & ZEND_ACC_ABSTRACT) {
        abstract_error = false;
      }
    }
  }
  if (abstract_error) {
    zend_error_noreturn(E_COMPILE_ERROR,
      "Abstract property %s::$%s must specify at least one abstract hook", ZSTR_VAL(ce->name), ZSTR_VAL(prop_name));
  }
  if ((prop_info->flags & ZEND_ACC_VIRTUAL)
   && (prop_info->flags & ZEND_ACC_PPP_SET_MASK)
   && (!prop_info->hooks[ZEND_PROPERTY_HOOK_GET] || !prop_info->hooks[ZEND_PROPERTY_HOOK_SET])) {
    const char *prefix = !prop_info->hooks[ZEND_PROPERTY_HOOK_GET]
      ? "set-only" : "get-only";
    zend_error_noreturn(E_COMPILE_ERROR,
      "%s virtual property %s::$%s must not specify asymmetric visibility",
      prefix, ZSTR_VAL(ce->name), ZSTR_VAL(prop_name));
  }
}

ZEND_API ZEND_COLD ZEND_NORETURN void zend_hooked_property_variance_error_ex(zend_string *value_param_name, zend_string *class_name, zend_string *prop_name)
{
  zend_error_noreturn(E_COMPILE_ERROR, "Type of parameter $%s of hook %s::$%s::set must be compatible with property type",
    ZSTR_VAL(value_param_name), ZSTR_VAL(class_name), zend_get_unmangled_property_name(prop_name));
}

ZEND_API ZEND_COLD ZEND_NORETURN void zend_hooked_property_variance_error(const zend_property_info *prop_info)
{
  zend_string *value_param_name = prop_info->hooks[ZEND_PROPERTY_HOOK_SET]->op_array.arg_info[0].name;
  zend_hooked_property_variance_error_ex(value_param_name, prop_info->ce->name, prop_info->name);
}

ZEND_API inheritance_status zend_verify_property_hook_variance(const zend_property_info *prop_info, const zend_function *func)
{
  ZEND_ASSERT(prop_info->hooks && prop_info->hooks[ZEND_PROPERTY_HOOK_SET] == func);

  zend_arg_info *value_arg_info = &func->op_array.arg_info[0];
  if (!ZEND_TYPE_IS_SET(value_arg_info->type)) {
    return INHERITANCE_SUCCESS;
  }

  if (!ZEND_TYPE_IS_SET(prop_info->type)) {
    return INHERITANCE_ERROR;
  }

  zend_class_entry *ce = prop_info->ce;
  return zend_perform_covariant_type_check(ce, prop_info->type, ce, value_arg_info->type);
}

#ifdef ZEND_OPCACHE_SHM_REATTACHMENT
/* Hooked properties set get_iterator, which causes issues on for shm
 * reattachment. Avoid early-binding on Windows and set get_iterator during
 * inheritance. The linked class may not use inheritance cache. */
static void zend_link_hooked_object_iter(zend_class_entry *ce) {
  if (!ce->get_iterator && ce->num_hooked_props) {
    ce->get_iterator = zend_hooked_object_get_iterator;
    ce->ce_flags &= ~ZEND_ACC_CACHEABLE;
    if (CG(current_linking_class) == ce) {
# if ZEND_DEBUG
      /* This check is executed before inheriting any elements that can
       * track dependencies. */
      HashTable *ht = (HashTable*)ce->inheritance_cache;
      ZEND_ASSERT(!ht);
# endif
      CG(current_linking_class) = NULL;
    }
  }
}
#endif

ZEND_API void zend_do_inheritance_ex(zend_class_entry *ce, zend_class_entry *parent_ce, bool checked) /* {{{ */
{
  zend_property_info *property_info;
  zend_string *key;

  if (UNEXPECTED(ce->ce_flags & ZEND_ACC_INTERFACE)) {
    /* Interface can only inherit other interfaces */
    if (UNEXPECTED(!(parent_ce->ce_flags & ZEND_ACC_INTERFACE))) {
      zend_error_noreturn(E_COMPILE_ERROR, "Interface %s cannot extend class %s", ZSTR_VAL(ce->name), ZSTR_VAL(parent_ce->name));
    }
  } else if (UNEXPECTED(parent_ce->ce_flags & (ZEND_ACC_INTERFACE|ZEND_ACC_TRAIT|ZEND_ACC_FINAL|ZEND_ACC_ENUM))) {
    /* Class must not extend an enum (GH-16315); check enums first since
     * enums are implemented as final classes */
    if (parent_ce->ce_flags & ZEND_ACC_ENUM) {
      zend_error_noreturn(E_COMPILE_ERROR, "Class %s cannot extend enum %s", ZSTR_VAL(ce->name), ZSTR_VAL(parent_ce->name));
    }
    /* Class must not extend a final class */
    if (parent_ce->ce_flags & ZEND_ACC_FINAL) {
      zend_error_noreturn(E_COMPILE_ERROR, "Class %s cannot extend final class %s", ZSTR_VAL(ce->name), ZSTR_VAL(parent_ce->name));
    }

    /* Class declaration must not extend traits or interfaces */
    if ((parent_ce->ce_flags & ZEND_ACC_INTERFACE) || (parent_ce->ce_flags & ZEND_ACC_TRAIT)) {
      zend_error_noreturn(E_COMPILE_ERROR, "Class %s cannot extend %s %s",
        ZSTR_VAL(ce->name), parent_ce->ce_flags & ZEND_ACC_INTERFACE ? "interface" : "trait", ZSTR_VAL(parent_ce->name)
      );
    }
  }

  if (UNEXPECTED((ce->ce_flags & ZEND_ACC_READONLY_CLASS) != (parent_ce->ce_flags & ZEND_ACC_READONLY_CLASS))) {
    zend_error_noreturn(E_COMPILE_ERROR, "%s class %s cannot extend %s class %s",
      ce->ce_flags & ZEND_ACC_READONLY_CLASS ? "Readonly" : "Non-readonly", ZSTR_VAL(ce->name),
      parent_ce->ce_flags & ZEND_ACC_READONLY_CLASS ? "readonly" : "non-readonly", ZSTR_VAL(parent_ce->name)
    );
  }

  if (ce->parent_name) {
    zend_string_release_ex(ce->parent_name, 0);
  }
  ce->parent = parent_ce;
  ce->default_object_handlers = parent_ce->default_object_handlers;
  ce->ce_flags |= ZEND_ACC_RESOLVED_PARENT;

  /* Inherit properties */
  if (parent_ce->default_properties_count) {
    zval *src, *dst, *end;

    if (ce->default_properties_count) {
      zval *table = pemalloc(sizeof(zval) * (ce->default_properties_count + parent_ce->default_properties_count), ce->type == ZEND_INTERNAL_CLASS);
      src = ce->default_properties_table + ce->default_properties_count;
      end = table + parent_ce->default_properties_count;
      dst = end + ce->default_properties_count;
      ce->default_properties_table = table;
      do {
        dst--;
        src--;
        ZVAL_COPY_VALUE_PROP(dst, src);
      } while (dst != end);
      pefree(src, ce->type == ZEND_INTERNAL_CLASS);
      end = ce->default_properties_table;
    } else {
      end = pemalloc(sizeof(zval) * parent_ce->default_properties_count, ce->type == ZEND_INTERNAL_CLASS);
      dst = end + parent_ce->default_properties_count;
      ce->default_properties_table = end;
    }
    src = parent_ce->default_properties_table + parent_ce->default_properties_count;
    if (UNEXPECTED(parent_ce->type != ce->type)) {
      /* User class extends internal */
      do {
        dst--;
        src--;
        /* We don't have to account for refcounting because
         * zend_declare_typed_property() disallows refcounted defaults for internal classes. */
        ZEND_ASSERT(!Z_REFCOUNTED_P(src));
        ZVAL_COPY_VALUE_PROP(dst, src);
        if (Z_OPT_TYPE_P(dst) == IS_CONSTANT_AST) {
          ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
          ce->ce_flags |= ZEND_ACC_HAS_AST_PROPERTIES;
        }
        continue;
      } while (dst != end);
    } else {
      do {
        dst--;
        src--;
        ZVAL_COPY_PROP(dst, src);
        if (Z_OPT_TYPE_P(dst) == IS_CONSTANT_AST) {
          ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
          ce->ce_flags |= ZEND_ACC_HAS_AST_PROPERTIES;
        }
        continue;
      } while (dst != end);
    }
    ce->default_properties_count += parent_ce->default_properties_count;
  }

  if (parent_ce->default_static_members_count) {
    zval *src, *dst, *end;

    if (ce->default_static_members_count) {
      zval *table = pemalloc(sizeof(zval) * (ce->default_static_members_count + parent_ce->default_static_members_count), ce->type == ZEND_INTERNAL_CLASS);
      src = ce->default_static_members_table + ce->default_static_members_count;
      end = table + parent_ce->default_static_members_count;
      dst = end + ce->default_static_members_count;
      ce->default_static_members_table = table;
      do {
        dst--;
        src--;
        ZVAL_COPY_VALUE(dst, src);
      } while (dst != end);
      pefree(src, ce->type == ZEND_INTERNAL_CLASS);
      end = ce->default_static_members_table;
    } else {
      end = pemalloc(sizeof(zval) * parent_ce->default_static_members_count, ce->type == ZEND_INTERNAL_CLASS);
      dst = end + parent_ce->default_static_members_count;
      ce->default_static_members_table = end;
    }
    src = parent_ce->default_static_members_table + parent_ce->default_static_members_count;
    do {
      dst--;
      src--;
      if (Z_TYPE_P(src) == IS_INDIRECT) {
        ZVAL_INDIRECT(dst, Z_INDIRECT_P(src));
      } else {
        ZVAL_INDIRECT(dst, src);
      }
      if (Z_TYPE_P(Z_INDIRECT_P(dst)) == IS_CONSTANT_AST) {
        ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
        ce->ce_flags |= ZEND_ACC_HAS_AST_STATICS;
      }
    } while (dst != end);
    ce->default_static_members_count += parent_ce->default_static_members_count;
    if (!ZEND_MAP_PTR(ce->static_members_table)) {
      if (ce->type == ZEND_INTERNAL_CLASS &&
          ce->info.internal.module->type == MODULE_PERSISTENT) {
        ZEND_MAP_PTR_NEW(ce->static_members_table);
      }
    }
  }

  ZEND_HASH_MAP_FOREACH_PTR(&ce->properties_info, property_info) {
    if (property_info->ce == ce) {
      if (property_info->flags & ZEND_ACC_STATIC) {
        property_info->offset += parent_ce->default_static_members_count;
      } else if (property_info->offset != ZEND_VIRTUAL_PROPERTY_OFFSET) {
        property_info->offset += parent_ce->default_properties_count * sizeof(zval);
      }
    }
  } ZEND_HASH_FOREACH_END();

  if (zend_hash_num_elements(&parent_ce->properties_info)) {
    zend_hash_extend(&ce->properties_info,
      zend_hash_num_elements(&ce->properties_info) +
      zend_hash_num_elements(&parent_ce->properties_info), 0);

    ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&parent_ce->properties_info, key, property_info) {
      do_inherit_property(property_info, key, ce);
    } ZEND_HASH_FOREACH_END();
  }

  if (ce->num_hooked_props) {
    ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&ce->properties_info, key, property_info) {
      if (property_info->ce == ce && property_info->hooks) {
        zend_verify_hooked_property(ce, property_info, key);
      }
    } ZEND_HASH_FOREACH_END();
  }

  if (zend_hash_num_elements(&parent_ce->constants_table)) {
    zend_class_constant *c;

    zend_hash_extend(&ce->constants_table,
      zend_hash_num_elements(&ce->constants_table) +
      zend_hash_num_elements(&parent_ce->constants_table), 0);

    ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&parent_ce->constants_table, key, c) {
      do_inherit_class_constant(key, c, ce);
    } ZEND_HASH_FOREACH_END();
  }

  if (zend_hash_num_elements(&parent_ce->function_table)) {
    zend_hash_extend(&ce->function_table,
      zend_hash_num_elements(&ce->function_table) +
      zend_hash_num_elements(&parent_ce->function_table), 0);
    uint32_t flags =
      ZEND_INHERITANCE_LAZY_CHILD_CLONE |
      ZEND_INHERITANCE_SET_CHILD_CHANGED |
      ZEND_INHERITANCE_SET_CHILD_PROTO |
      ZEND_INHERITANCE_RESET_CHILD_OVERRIDE;

    if (!checked) {
      flags |= ZEND_INHERITANCE_CHECK_PROTO | ZEND_INHERITANCE_CHECK_VISIBILITY;
    }
    zend_function *func;
    ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&parent_ce->function_table, key, func) {
      do_inherit_method(key, func, ce, false, flags);
    } ZEND_HASH_FOREACH_END();
  }

  do_inherit_parent_constructor(ce);

  if (ce->type == ZEND_INTERNAL_CLASS) {
    if (parent_ce->num_interfaces) {
      zend_do_inherit_interfaces(ce, parent_ce);
    }

    if (ce->ce_flags & ZEND_ACC_IMPLICIT_ABSTRACT_CLASS) {
      ce->ce_flags |= ZEND_ACC_EXPLICIT_ABSTRACT_CLASS;
    }
  }
  ce->ce_flags |= parent_ce->ce_flags & (ZEND_HAS_STATIC_IN_METHODS | ZEND_ACC_HAS_TYPE_HINTS | ZEND_ACC_HAS_READONLY_PROPS | ZEND_ACC_USE_GUARDS | ZEND_ACC_NOT_SERIALIZABLE | ZEND_ACC_ALLOW_DYNAMIC_PROPERTIES);
}
/* }}} */

static zend_always_inline bool check_trait_property_or_constant_value_compatibility(zend_class_entry *ce, zval *op1, zval *op2) /* {{{ */
{
  bool is_compatible;
  zval op1_tmp, op2_tmp;

  /* if any of the values is a constant, we try to resolve it */
  if (UNEXPECTED(Z_TYPE_P(op1) == IS_CONSTANT_AST)) {
    ZVAL_COPY_OR_DUP(&op1_tmp, op1);
    if (UNEXPECTED(zval_update_constant_ex(&op1_tmp, ce) != SUCCESS)) {
      zval_ptr_dtor(&op1_tmp);
      return false;
    }
    op1 = &op1_tmp;
  }
  if (UNEXPECTED(Z_TYPE_P(op2) == IS_CONSTANT_AST)) {
    ZVAL_COPY_OR_DUP(&op2_tmp, op2);
    if (UNEXPECTED(zval_update_constant_ex(&op2_tmp, ce) != SUCCESS)) {
      zval_ptr_dtor(&op2_tmp);
      return false;
    }
    op2 = &op2_tmp;
  }

  is_compatible = fast_is_identical_function(op1, op2);

  if (op1 == &op1_tmp) {
    zval_ptr_dtor_nogc(&op1_tmp);
  }
  if (op2 == &op2_tmp) {
    zval_ptr_dtor_nogc(&op2_tmp);
  }

  return is_compatible;
}
/* }}} */

/** @return bool Returns true if the class constant should be inherited, i.e. whether it doesn't already exist. */
static bool do_inherit_constant_check(
  zend_class_entry *ce, const zend_class_constant *parent_constant, zend_string *name
) {
  zval *zv = zend_hash_find_known_hash(&ce->constants_table, name);
  if (zv == NULL) {
    return true;
  }

  zend_class_constant *child_constant = Z_PTR_P(zv);
  if (parent_constant->ce != child_constant->ce && (ZEND_CLASS_CONST_FLAGS(parent_constant) & ZEND_ACC_FINAL)) {
    zend_error_noreturn(E_COMPILE_ERROR, "%s::%s cannot override final constant %s::%s",
      ZSTR_VAL(child_constant->ce->name), ZSTR_VAL(name),
      ZSTR_VAL(parent_constant->ce->name), ZSTR_VAL(name)
    );
  }

  if (child_constant->ce != parent_constant->ce && child_constant->ce != ce) {
    zend_error_noreturn(E_COMPILE_ERROR,
      "%s %s inherits both %s::%s and %s::%s, which is ambiguous",
      zend_get_object_type_uc(ce),
      ZSTR_VAL(ce->name),
      ZSTR_VAL(child_constant->ce->name), ZSTR_VAL(name),
      ZSTR_VAL(parent_constant->ce->name), ZSTR_VAL(name));
  }

  if (UNEXPECTED((ZEND_CLASS_CONST_FLAGS(child_constant) & ZEND_ACC_PPP_MASK) > (ZEND_CLASS_CONST_FLAGS(parent_constant) & ZEND_ACC_PPP_MASK))) {
    zend_error_noreturn(E_COMPILE_ERROR, "Access level to %s::%s must be %s (as in %s %s)%s",
      ZSTR_VAL(ce->name), ZSTR_VAL(name),
      zend_visibility_string(ZEND_CLASS_CONST_FLAGS(parent_constant)),
      zend_get_object_type(parent_constant->ce),
      ZSTR_VAL(parent_constant->ce->name),
      (ZEND_CLASS_CONST_FLAGS(parent_constant) & ZEND_ACC_PUBLIC) ? "" : " or weaker"
    );
  }

  if (!(ZEND_CLASS_CONST_FLAGS(parent_constant) & ZEND_ACC_PRIVATE)) {
    if (child_constant->ce == ce) {
      ZEND_CLASS_CONST_FLAGS(child_constant) &= ~ZEND_ACC_OVERRIDE;
    }
  }

  if (!(ZEND_CLASS_CONST_FLAGS(parent_constant) & ZEND_ACC_PRIVATE) && ZEND_TYPE_IS_SET(parent_constant->type)) {
    inheritance_status status = class_constant_types_compatible(parent_constant, child_constant);
    if (status == INHERITANCE_ERROR) {
      emit_incompatible_class_constant_error(child_constant, parent_constant, name);
    } else if (status == INHERITANCE_UNRESOLVED) {
      add_class_constant_compatibility_obligation(ce, child_constant, parent_constant, name);
    }
  }

  return false;
}
/* }}} */

static void do_inherit_iface_constant(zend_string *name, zend_class_constant *c, zend_class_entry *ce, const zend_class_entry *iface) /* {{{ */
{
  if (do_inherit_constant_check(ce, c, name)) {
    zend_class_constant *ct;
    if (Z_TYPE(c->value) == IS_CONSTANT_AST) {
      ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
      ce->ce_flags |= ZEND_ACC_HAS_AST_CONSTANTS;
      if (iface->ce_flags & ZEND_ACC_IMMUTABLE) {
        ct = zend_arena_alloc(&CG(arena), sizeof(zend_class_constant));
        memcpy(ct, c, sizeof(zend_class_constant));
        c = ct;
        Z_CONSTANT_FLAGS(c->value) |= CONST_OWNED;
      }
    }
    if (ce->type == ZEND_INTERNAL_CLASS) {
      ct = pemalloc(sizeof(zend_class_constant), 1);
      memcpy(ct, c, sizeof(zend_class_constant));
      c = ct;
    }
    zend_hash_update_ptr(&ce->constants_table, name, c);
  }
}
/* }}} */

static void do_interface_implementation(zend_class_entry *ce, zend_class_entry *iface) /* {{{ */
{
  zend_function *func;
  zend_string *key;
  zend_class_constant *c;
  uint32_t flags = ZEND_INHERITANCE_CHECK_PROTO | ZEND_INHERITANCE_CHECK_VISIBILITY;

  if (iface->num_interfaces) {
    zend_do_inherit_interfaces(ce, iface);
  }

  if (!(ce->ce_flags & ZEND_ACC_INTERFACE)) {
    /* We are not setting the prototype of overridden interface methods because of abstract
     * constructors. See Zend/tests/interface_constructor_prototype_001.phpt. */
    flags |=
      ZEND_INHERITANCE_LAZY_CHILD_CLONE |
      ZEND_INHERITANCE_SET_CHILD_PROTO |
      ZEND_INHERITANCE_RESET_CHILD_OVERRIDE;
  } else {
    flags |=
      ZEND_INHERITANCE_LAZY_CHILD_CLONE |
      ZEND_INHERITANCE_RESET_CHILD_OVERRIDE;
  }

  ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&iface->constants_table, key, c) {
    do_inherit_iface_constant(key, c, ce, iface);
  } ZEND_HASH_FOREACH_END();

  ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&iface->function_table, key, func) {
    do_inherit_method(key, func, ce, true, flags);
  } ZEND_HASH_FOREACH_END();

  zend_hash_extend(&ce->properties_info,
    zend_hash_num_elements(&ce->properties_info) +
    zend_hash_num_elements(&iface->properties_info), 0);

  zend_property_info *prop;
  ZEND_HASH_FOREACH_STR_KEY_PTR(&iface->properties_info, key, prop) {
    do_inherit_property(prop, key, ce);
  } ZEND_HASH_FOREACH_END();

  do_implement_interface(ce, iface);
}
/* }}} */

ZEND_API void zend_do_implement_interface(zend_class_entry *ce, zend_class_entry *iface) /* {{{ */
{
  bool ignore = false;
  uint32_t current_iface_num = ce->num_interfaces;
  uint32_t parent_iface_num  = ce->parent ? ce->parent->num_interfaces : 0;

  ZEND_ASSERT(ce->ce_flags & ZEND_ACC_LINKED);

  for (uint32_t i = 0; i < ce->num_interfaces; i++) {
    if (ce->interfaces[i] == NULL) {
      memmove(ce->interfaces + i, ce->interfaces + i + 1, sizeof(zend_class_entry*) * (--ce->num_interfaces - i));
      i--;
    } else if (ce->interfaces[i] == iface) {
      if (EXPECTED(i < parent_iface_num)) {
        ignore = true;
      } else {
        zend_error_noreturn(E_COMPILE_ERROR, "Class %s cannot implement previously implemented interface %s", ZSTR_VAL(ce->name), ZSTR_VAL(iface->name));
      }
    }
  }
  if (ignore) {
    zend_string *key;
    zend_class_constant *c;
    /* Check for attempt to redeclare interface constants */
    ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&iface->constants_table, key, c) {
      do_inherit_constant_check(ce, c, key);
    } ZEND_HASH_FOREACH_END();
  } else {
    if (ce->num_interfaces >= current_iface_num) {
      ce->interfaces = (zend_class_entry **) perealloc(ce->interfaces, sizeof(zend_class_entry *) * (++current_iface_num), ce->type == ZEND_INTERNAL_CLASS);
    }
    ce->interfaces[ce->num_interfaces++] = iface;

    do_interface_implementation(ce, iface);
  }
}
/* }}} */

static void zend_do_implement_interfaces(zend_class_entry *ce, zend_class_entry **interfaces) /* {{{ */
{
  uint32_t num_parent_interfaces = ce->parent ? ce->parent->num_interfaces : 0;
  uint32_t num_interfaces = num_parent_interfaces;
  zend_string *key;
  zend_class_constant *c;
  uint32_t i;

  for (i = 0; i < ce->num_interfaces; i++) {
    zend_class_entry *iface = interfaces[num_parent_interfaces + i];
    if (!(iface->ce_flags & ZEND_ACC_LINKED)) {
      add_dependency_obligation(ce, iface);
    }
    if (UNEXPECTED(!(iface->ce_flags & ZEND_ACC_INTERFACE))) {
      efree(interfaces);
      zend_error_noreturn(E_ERROR, "%s cannot implement %s - it is not an interface", ZSTR_VAL(ce->name), ZSTR_VAL(iface->name));
    }
    for (uint32_t j = 0; j < num_interfaces; j++) {
      if (interfaces[j] == iface) {
        if (j >= num_parent_interfaces) {
          efree(interfaces);
          zend_error_noreturn(E_COMPILE_ERROR, "%s %s cannot implement previously implemented interface %s",
            zend_get_object_type_uc(ce),
            ZSTR_VAL(ce->name),
            ZSTR_VAL(iface->name));
        }
        /* skip duplications */
        ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&iface->constants_table, key, c) {
          do_inherit_constant_check(ce, c, key);
        } ZEND_HASH_FOREACH_END();

        iface = NULL;
        break;
      }
    }
    if (iface) {
      interfaces[num_interfaces] = iface;
      num_interfaces++;
    }
  }

  if (!(ce->ce_flags & ZEND_ACC_CACHED)) {
    for (i = 0; i < ce->num_interfaces; i++) {
      zend_string_release_ex(ce->interface_names[i].name, 0);
      zend_string_release_ex(ce->interface_names[i].lc_name, 0);
    }
    efree(ce->interface_names);
  }

  ce->num_interfaces = num_interfaces;
  ce->interfaces = interfaces;
  ce->ce_flags |= ZEND_ACC_RESOLVED_INTERFACES;

  for (i = 0; i < num_parent_interfaces; i++) {
    do_implement_interface(ce, ce->interfaces[i]);
  }
  /* Note that new interfaces can be added during this loop due to interface inheritance.
   * Use num_interfaces rather than ce->num_interfaces to not re-process the new ones. */
  for (; i < num_interfaces; i++) {
    do_interface_implementation(ce, ce->interfaces[i]);
  }
}
/* }}} */


void zend_inheritance_check_override(const zend_class_entry *ce)
{
  if (ce->ce_flags & ZEND_ACC_TRAIT) {
    return;
  }

  ZEND_HASH_MAP_FOREACH_PTR(&ce->function_table, zend_function *f) {
    if (f->common.fn_flags & ZEND_ACC_OVERRIDE) {
      ZEND_ASSERT(f->type != ZEND_INTERNAL_FUNCTION);

      zend_error_at_noreturn(
        E_COMPILE_ERROR, f->op_array.filename, f->op_array.line_start,
        "%s::%s() has #[\\Override] attribute, but no matching parent method exists",
        ZEND_FN_SCOPE_NAME(f), ZSTR_VAL(f->common.function_name));
    }
  } ZEND_HASH_FOREACH_END();

  ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&ce->constants_table, zend_string *name, zend_class_constant *c) {
    if (ZEND_CLASS_CONST_FLAGS(c) & ZEND_ACC_OVERRIDE) {
      zend_error_noreturn(
        E_COMPILE_ERROR,
        "%s::%s has #[\\Override] attribute, but no matching parent constant exists",
        ZSTR_VAL(ce->name), ZSTR_VAL(name));
    }
  } ZEND_HASH_FOREACH_END();

  ZEND_HASH_MAP_FOREACH_PTR(&ce->properties_info, zend_property_info *prop) {
    if (prop->flags & ZEND_ACC_OVERRIDE) {
      zend_error_noreturn(
        E_COMPILE_ERROR,
        "%s::$%s has #[\\Override] attribute, but no matching parent property exists",
        ZSTR_VAL(ce->name), zend_get_unmangled_property_name(prop->name));
    }

    if (prop->hooks) {
      for (uint32_t i = 0; i < ZEND_PROPERTY_HOOK_COUNT; i++) {
        zend_function *f = prop->hooks[i];
        if (f && f->common.fn_flags & ZEND_ACC_OVERRIDE) {
          ZEND_ASSERT(f->type != ZEND_INTERNAL_FUNCTION);

          zend_error_at_noreturn(
            E_COMPILE_ERROR, f->op_array.filename, f->op_array.line_start,
            "%s::%s() has #[\\Override] attribute, but no matching parent method exists",
            ZEND_FN_SCOPE_NAME(f), ZSTR_VAL(f->common.function_name));
        }
      }
    }
  } ZEND_HASH_FOREACH_END();
}


static zend_class_entry *fixup_trait_scope(const zend_function *fn, zend_class_entry *ce)
{
  /* self in trait methods should be resolved to the using class, not the trait. */
  return fn->common.scope->ce_flags & ZEND_ACC_TRAIT ? ce : fn->common.scope;
}

static void zend_add_trait_method(zend_class_entry *ce, zend_string *name, zend_string *key, zend_function *fn) /* {{{ */
{
  zend_function *existing_fn = NULL;
  zend_function *new_fn;

  if ((existing_fn = zend_hash_find_ptr(&ce->function_table, key)) != NULL) {
    /* if it is the same function with the same visibility and has not been assigned a class scope yet, regardless
     * of where it is coming from there is no conflict and we do not need to add it again */
    if (existing_fn->op_array.opcodes == fn->op_array.opcodes &&
      (existing_fn->common.fn_flags & ZEND_ACC_PPP_MASK) == (fn->common.fn_flags & ZEND_ACC_PPP_MASK) &&
      (existing_fn->common.scope->ce_flags & ZEND_ACC_TRAIT)) {
      return;
    }

    /* Abstract method signatures from the trait must be satisfied. */
    if (fn->common.fn_flags & ZEND_ACC_ABSTRACT) {
      /* "abstract private" methods in traits were not available prior to PHP 8.
       * As such, "abstract protected" was sometimes used to indicate trait requirements,
       * even though the "implementing" method was private. Do not check visibility
       * requirements to maintain backwards-compatibility with such usage.
       */
      do_inheritance_check_on_method(
        existing_fn, fixup_trait_scope(existing_fn, ce), fn, fixup_trait_scope(fn, ce),
        ce, NULL, ZEND_INHERITANCE_CHECK_PROTO | ZEND_INHERITANCE_RESET_CHILD_OVERRIDE);
      return;
    }

    if (existing_fn->common.scope == ce) {
      /* members from the current class override trait methods */
      return;
    } else if (UNEXPECTED((existing_fn->common.scope->ce_flags & ZEND_ACC_TRAIT)
        && !(existing_fn->common.fn_flags & ZEND_ACC_ABSTRACT))) {
      /* two traits can't define the same non-abstract method */
      zend_error_noreturn(E_COMPILE_ERROR, "Trait method %s::%s has not been applied as %s::%s, because of collision with %s::%s",
        ZSTR_VAL(fn->common.scope->name), ZSTR_VAL(fn->common.function_name),
        ZSTR_VAL(ce->name), ZSTR_VAL(name),
        ZSTR_VAL(existing_fn->common.scope->name), ZSTR_VAL(existing_fn->common.function_name));
    }
  }

  if (ce->type == ZEND_INTERNAL_CLASS) {
    ZEND_ASSERT(fn->type == ZEND_INTERNAL_FUNCTION);
    new_fn = (zend_function*)(uintptr_t)malloc(sizeof(zend_internal_function));
    memcpy(new_fn, fn, sizeof(zend_internal_function));
  } else if (UNEXPECTED(fn->type == ZEND_INTERNAL_FUNCTION)) {
    new_fn = zend_arena_alloc(&CG(arena), sizeof(zend_internal_function));
    memcpy(new_fn, fn, sizeof(zend_internal_function));
    new_fn->common.fn_flags |= ZEND_ACC_ARENA_ALLOCATED;
  } else {
    new_fn = zend_arena_alloc(&CG(arena), sizeof(zend_op_array));
    memcpy(new_fn, fn, sizeof(zend_op_array));
    new_fn->op_array.fn_flags &= ~ZEND_ACC_IMMUTABLE;
  }
  new_fn->common.fn_flags |= ZEND_ACC_TRAIT_CLONE;

  /* Reassign method name, in case it is an alias. */
  new_fn->common.function_name = name;
  function_add_ref(new_fn);
  fn = zend_hash_update_ptr(&ce->function_table, key, new_fn);
  zend_add_magic_method(ce, fn, key);
}
/* }}} */

static void zend_fixup_trait_method(zend_function *fn, zend_class_entry *ce) /* {{{ */
{
  if (fn->common.scope->ce_flags & ZEND_ACC_TRAIT) {

    fn->common.scope = ce;

    if (fn->common.fn_flags & ZEND_ACC_ABSTRACT) {
      ce->ce_flags |= ZEND_ACC_IMPLICIT_ABSTRACT_CLASS;
    }
    if (fn->type == ZEND_USER_FUNCTION && fn->op_array.static_variables) {
      ce->ce_flags |= ZEND_HAS_STATIC_IN_METHODS;
    }
  }
}
/* }}} */

static void zend_traits_check_private_final_inheritance(uint32_t original_fn_flags, const zend_function *fn_copy, const zend_string *name)
{
  /* If the function was originally already private+final, then it will have
   * already been warned about. Only emit this error when the used trait method
   * explicitly became final, avoiding errors for `as private` where it was
   * already final. */
  if (!(original_fn_flags & ZEND_ACC_FINAL)
    && (fn_copy->common.fn_flags & (ZEND_ACC_PRIVATE | ZEND_ACC_FINAL)) == (ZEND_ACC_PRIVATE | ZEND_ACC_FINAL)
    && !zend_string_equals_literal_ci(name, ZEND_CONSTRUCTOR_FUNC_NAME)) {
    zend_error(E_COMPILE_WARNING, "Private methods cannot be final as they are never overridden by other classes");
  }
}

static void zend_traits_copy_functions(zend_string *fnname, zend_function *fn, zend_class_entry *ce, HashTable *exclude_table, zend_class_entry **aliases) /* {{{ */
{
  zend_trait_alias  *alias, **alias_ptr;
  zend_function      fn_copy;
  int                i;

  /* apply aliases which are qualified with a class name, there should not be any ambiguity */
  if (ce->trait_aliases) {
    alias_ptr = ce->trait_aliases;
    alias = *alias_ptr;
    i = 0;
    while (alias) {
      /* Scope unset or equal to the function we compare to, and the alias applies to fn */
      if (alias->alias != NULL
        && fn->common.scope == aliases[i]
        && zend_string_equals_ci(alias->trait_method.method_name, fnname)
      ) {
        fn_copy = *fn;
        if (alias->modifiers & ZEND_ACC_PPP_MASK) {
          fn_copy.common.fn_flags = alias->modifiers | (fn->common.fn_flags & ~ZEND_ACC_PPP_MASK);
        } else {
          fn_copy.common.fn_flags = alias->modifiers | fn->common.fn_flags;
        }

        zend_traits_check_private_final_inheritance(fn->common.fn_flags, &fn_copy, alias->alias);

        zend_string *lcname = zend_string_tolower(alias->alias);
        zend_add_trait_method(ce, alias->alias, lcname, &fn_copy);
        zend_string_release_ex(lcname, 0);
      }
      alias_ptr++;
      alias = *alias_ptr;
      i++;
    }
  }

  if (exclude_table == NULL || zend_hash_find(exclude_table, fnname) == NULL) {
    /* is not in hashtable, thus, function is not to be excluded */
    memcpy(&fn_copy, fn, fn->type == ZEND_USER_FUNCTION ? sizeof(zend_op_array) : sizeof(zend_internal_function));

    /* apply aliases which have not alias name, just setting visibility */
    if (ce->trait_aliases) {
      alias_ptr = ce->trait_aliases;
      alias = *alias_ptr;
      i = 0;
      while (alias) {
        /* Scope unset or equal to the function we compare to, and the alias applies to fn */
        if (alias->alias == NULL && alias->modifiers != 0
          && fn->common.scope == aliases[i]
          && zend_string_equals_ci(alias->trait_method.method_name, fnname)
        ) {
          if (alias->modifiers & ZEND_ACC_PPP_MASK) {
            fn_copy.common.fn_flags = alias->modifiers | (fn->common.fn_flags & ~ZEND_ACC_PPP_MASK);
          } else {
            fn_copy.common.fn_flags = alias->modifiers | fn->common.fn_flags;
          }
        }
        alias_ptr++;
        alias = *alias_ptr;
        i++;
      }
    }

    zend_traits_check_private_final_inheritance(fn->common.fn_flags, &fn_copy, fnname);

    zend_add_trait_method(ce, fn->common.function_name, fnname, &fn_copy);
  }
}
/* }}} */

static uint32_t zend_check_trait_usage(const zend_class_entry *ce, const zend_class_entry *trait, zend_class_entry **traits) /* {{{ */
{
  if (UNEXPECTED((trait->ce_flags & ZEND_ACC_TRAIT) != ZEND_ACC_TRAIT)) {
    zend_error_noreturn(E_COMPILE_ERROR, "Class %s is not a trait, Only traits may be used in 'as' and 'insteadof' statements", ZSTR_VAL(trait->name));
  }

  for (uint32_t i = 0; i < ce->num_traits; i++) {
    if (traits[i] == trait) {
      return i;
    }
  }
  zend_error_noreturn(E_COMPILE_ERROR, "Required Trait %s wasn't added to %s", ZSTR_VAL(trait->name), ZSTR_VAL(ce->name));
}
/* }}} */

static void zend_traits_init_trait_structures(zend_class_entry *ce, zend_class_entry **traits, HashTable ***exclude_tables_ptr, zend_class_entry ***aliases_ptr) /* {{{ */
{
  size_t i, j = 0;
  zend_trait_precedence *cur_precedence;
  zend_trait_method_reference *cur_method_ref;
  zend_string *lcname;
  HashTable **exclude_tables = NULL;
  zend_class_entry **aliases = NULL;
  zend_class_entry *trait;

  /* resolve class references */
  if (ce->trait_precedences) {
    exclude_tables = ecalloc(ce->num_traits, sizeof(HashTable*));
    i = 0;
    zend_trait_precedence **precedences = ce->trait_precedences;
    ce->trait_precedences = NULL;
    while ((cur_precedence = precedences[i])) {
      /** Resolve classes for all precedence operations. */
      cur_method_ref = &cur_precedence->trait_method;
      trait = zend_hash_find_ptr_lc(EG(class_table), cur_method_ref->class_name);
      if (!trait || !(trait->ce_flags & ZEND_ACC_LINKED)) {
        zend_error_noreturn(E_COMPILE_ERROR, "Could not find trait %s", ZSTR_VAL(cur_method_ref->class_name));
      }
      zend_check_trait_usage(ce, trait, traits);

      /** Ensure that the preferred method is actually available. */
      lcname = zend_string_tolower(cur_method_ref->method_name);
      if (!zend_hash_exists(&trait->function_table, lcname)) {
        zend_error_noreturn(E_COMPILE_ERROR,
               "A precedence rule was defined for %s::%s but this method does not exist",
               ZSTR_VAL(trait->name),
               ZSTR_VAL(cur_method_ref->method_name));
      }

      /** With the other traits, we are more permissive.
        We do not give errors for those. This allows to be more
        defensive in such definitions.
        However, we want to make sure that the insteadof declaration
        is consistent in itself.
       */

      for (j = 0; j < cur_precedence->num_excludes; j++) {
        zend_string* class_name = cur_precedence->exclude_class_names[j];
        zend_class_entry *exclude_ce;
        uint32_t trait_num;

        exclude_ce = zend_hash_find_ptr_lc(EG(class_table), class_name);
        if (!exclude_ce || !(exclude_ce->ce_flags & ZEND_ACC_LINKED)) {
          zend_error_noreturn(E_COMPILE_ERROR, "Could not find trait %s", ZSTR_VAL(class_name));
        }
        trait_num = zend_check_trait_usage(ce, exclude_ce, traits);
        if (!exclude_tables[trait_num]) {
          ALLOC_HASHTABLE(exclude_tables[trait_num]);
          zend_hash_init(exclude_tables[trait_num], 0, NULL, NULL, 0);
        }
        if (zend_hash_add_empty_element(exclude_tables[trait_num], lcname) == NULL) {
          zend_error_noreturn(E_COMPILE_ERROR, "Failed to evaluate a trait precedence (%s). Method of trait %s was defined to be excluded multiple times", ZSTR_VAL(precedences[i]->trait_method.method_name), ZSTR_VAL(exclude_ce->name));
        }

        /* make sure that the trait method is not from a class mentioned in
         exclude_from_classes, for consistency */
        if (trait == exclude_ce) {
          zend_error_noreturn(E_COMPILE_ERROR,
                 "Inconsistent insteadof definition. "
                 "The method %s is to be used from %s, but %s is also on the exclude list",
                 ZSTR_VAL(cur_method_ref->method_name),
                 ZSTR_VAL(trait->name),
                 ZSTR_VAL(trait->name));
        }
      }
      zend_string_release_ex(lcname, 0);
      i++;
    }
    ce->trait_precedences = precedences;
  }

  if (ce->trait_aliases) {
    i = 0;
    while (ce->trait_aliases[i]) {
      i++;
    }
    aliases = ecalloc(i, sizeof(zend_class_entry*));
    i = 0;
    while (ce->trait_aliases[i]) {
      const zend_trait_alias *cur_alias = ce->trait_aliases[i];
      cur_method_ref = &ce->trait_aliases[i]->trait_method;
      lcname = zend_string_tolower(cur_method_ref->method_name);
      if (cur_method_ref->class_name) {
        /* For all aliases with an explicit class name, resolve the class now. */
        trait = zend_hash_find_ptr_lc(EG(class_table), cur_method_ref->class_name);
        if (!trait || !(trait->ce_flags & ZEND_ACC_LINKED)) {
          zend_error_noreturn(E_COMPILE_ERROR, "Could not find trait %s", ZSTR_VAL(cur_method_ref->class_name));
        }
        zend_check_trait_usage(ce, trait, traits);
        aliases[i] = trait;

        /* And, ensure that the referenced method is resolvable, too. */
        if (!zend_hash_exists(&trait->function_table, lcname)) {
          zend_error_noreturn(E_COMPILE_ERROR, "An alias was defined for %s::%s but this method does not exist", ZSTR_VAL(trait->name), ZSTR_VAL(cur_method_ref->method_name));
        }
      } else {
        /* Find out which trait this method refers to. */
        trait = NULL;
        for (j = 0; j < ce->num_traits; j++) {
          if (traits[j]) {
            if (zend_hash_exists(&traits[j]->function_table, lcname)) {
              if (!trait) {
                trait = traits[j];
                continue;
              }

              zend_error_noreturn(E_COMPILE_ERROR,
                "An alias was defined for method %s(), which exists in both %s and %s. Use %s::%s or %s::%s to resolve the ambiguity",
                ZSTR_VAL(cur_method_ref->method_name),
                ZSTR_VAL(trait->name), ZSTR_VAL(traits[j]->name),
                ZSTR_VAL(trait->name), ZSTR_VAL(cur_method_ref->method_name),
                ZSTR_VAL(traits[j]->name), ZSTR_VAL(cur_method_ref->method_name));
            }
          }
        }

        /* Non-absolute method reference refers to method that does not exist. */
        if (!trait) {
          if (cur_alias->alias) {
            zend_error_noreturn(E_COMPILE_ERROR,
              "An alias (%s) was defined for method %s(), but this method does not exist",
              ZSTR_VAL(cur_alias->alias),
              ZSTR_VAL(cur_alias->trait_method.method_name));
          } else {
            zend_error_noreturn(E_COMPILE_ERROR,
              "The modifiers of the trait method %s() are changed, but this method does not exist. Error",
              ZSTR_VAL(cur_alias->trait_method.method_name));
          }
        }

        aliases[i] = trait;
      }
      zend_string_release_ex(lcname, 0);
      i++;
    }
  }

  *exclude_tables_ptr = exclude_tables;
  *aliases_ptr = aliases;
}
/* }}} */

static void zend_do_traits_method_binding(zend_class_entry *ce, zend_class_entry **traits, HashTable **exclude_tables, zend_class_entry **aliases, bool verify_abstract, bool *contains_abstract_methods) /* {{{ */
{
  uint32_t i;
  zend_string *key;
  zend_function *fn;

  if (exclude_tables) {
    for (i = 0; i < ce->num_traits; i++) {
      if (traits[i]) {
        /* copies functions, applies defined aliasing, and excludes unused trait methods */
        ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&traits[i]->function_table, key, fn) {
          bool is_abstract = (bool) (fn->common.fn_flags & ZEND_ACC_ABSTRACT);
          *contains_abstract_methods |= is_abstract;
          if (verify_abstract != is_abstract) {
            continue;
          }
          zend_traits_copy_functions(key, fn, ce, exclude_tables[i], aliases);
        } ZEND_HASH_FOREACH_END();

        if (exclude_tables[i]) {
          zend_hash_destroy(exclude_tables[i]);
          FREE_HASHTABLE(exclude_tables[i]);
          exclude_tables[i] = NULL;
        }
      }
    }
  } else {
    for (i = 0; i < ce->num_traits; i++) {
      if (traits[i]) {
        ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&traits[i]->function_table, key, fn) {
          bool is_abstract = (bool) (fn->common.fn_flags & ZEND_ACC_ABSTRACT);
          *contains_abstract_methods |= is_abstract;
          if (verify_abstract != is_abstract) {
            continue;
          }
          zend_traits_copy_functions(key, fn, ce, NULL, aliases);
        } ZEND_HASH_FOREACH_END();
      }
    }
  }
}
/* }}} */

static const zend_class_entry* find_first_constant_definition(const zend_class_entry *ce, zend_class_entry **traits, size_t current_trait, zend_string *constant_name, const zend_class_entry *colliding_ce) /* {{{ */
{
  /* This function is used to show the place of the existing conflicting
   * definition in error messages when conflicts occur. Since trait constants
   * are flattened into the constants table of the composing class, and thus
   * we lose information about which constant was defined in which trait, a
   * process like this is needed to find the location of the first definition
   * of the constant from traits.
   */
  if (colliding_ce == ce) {
    for (size_t i = 0; i < current_trait; i++) {
      if (traits[i]
        && zend_hash_exists(&traits[i]->constants_table, constant_name)) {
        return traits[i];
      }
    }
  }
  /* Traits don't have it, then the composing class (or trait) itself has it. */
  return colliding_ce;
}
/* }}} */

static void emit_incompatible_trait_constant_error(
  const zend_class_entry *ce, const zend_class_constant *existing_constant, const zend_class_constant *trait_constant, zend_string *name,
  zend_class_entry **traits, size_t current_trait
) {
  zend_error_noreturn(E_COMPILE_ERROR,
    "%s and %s define the same constant (%s) in the composition of %s. However, the definition differs and is considered incompatible. Class was composed",
    ZSTR_VAL(find_first_constant_definition(ce, traits, current_trait, name, existing_constant->ce)->name),
    ZSTR_VAL(trait_constant->ce->name),
    ZSTR_VAL(name),
    ZSTR_VAL(ce->name)
  );
}

static void emit_trait_constant_enum_case_conflict_error(
  const zend_class_entry *ce, const zend_class_constant *trait_constant, zend_string *name
) {
  zend_error_noreturn(E_COMPILE_ERROR,
    "Cannot use trait %s, because %s::%s conflicts with enum case %s::%s",
    ZSTR_VAL(trait_constant->ce->name),
    ZSTR_VAL(trait_constant->ce->name),
    ZSTR_VAL(name),
    ZSTR_VAL(ce->name),
    ZSTR_VAL(name)
  );
}

static bool do_trait_constant_check(
  zend_class_entry *ce, zend_class_constant *trait_constant, zend_string *name, zend_class_entry **traits, size_t current_trait
) {
  uint32_t flags_mask = ZEND_ACC_PPP_MASK | ZEND_ACC_FINAL;

  zval *zv = zend_hash_find_known_hash(&ce->constants_table, name);
  if (zv == NULL) {
    /* No existing constant of the same name, so this one can be added */
    return true;
  }

  zend_class_constant *existing_constant = Z_PTR_P(zv);

  if (UNEXPECTED(ZEND_CLASS_CONST_FLAGS(existing_constant) & ZEND_CLASS_CONST_IS_CASE)) {
    emit_trait_constant_enum_case_conflict_error(ce, trait_constant, name);
    return false;
  }

  if ((ZEND_CLASS_CONST_FLAGS(trait_constant) & flags_mask) != (ZEND_CLASS_CONST_FLAGS(existing_constant) & flags_mask)) {
    emit_incompatible_trait_constant_error(ce, existing_constant, trait_constant, name, traits, current_trait);
    return false;
  }

  if (ZEND_TYPE_IS_SET(trait_constant->type) != ZEND_TYPE_IS_SET(existing_constant->type)) {
    emit_incompatible_trait_constant_error(ce, existing_constant, trait_constant, name, traits, current_trait);
    return false;
  } else if (ZEND_TYPE_IS_SET(trait_constant->type)) {
    inheritance_status status1 = zend_perform_covariant_type_check(ce, existing_constant->type, traits[current_trait], trait_constant->type);
    inheritance_status status2 = zend_perform_covariant_type_check(traits[current_trait], trait_constant->type, ce, existing_constant->type);
    if (status1 == INHERITANCE_ERROR || status2 == INHERITANCE_ERROR) {
      emit_incompatible_trait_constant_error(ce, existing_constant, trait_constant, name, traits, current_trait);
      return false;
    }
  }

  if (!check_trait_property_or_constant_value_compatibility(ce, &trait_constant->value, &existing_constant->value)) {
    /* There is an existing constant of the same name, and it conflicts with the new one, so let's throw a fatal error */
    emit_incompatible_trait_constant_error(ce, existing_constant, trait_constant, name, traits, current_trait);
    return false;
  }

  /* There is an existing constant which is compatible with the new one, so no need to add it */
  return false;
}

static void zend_do_traits_constant_binding(zend_class_entry *ce, zend_class_entry **traits) /* {{{ */
{
  for (uint32_t i = 0; i < ce->num_traits; i++) {
    zend_string *constant_name;
    zend_class_constant *constant;

    if (!traits[i]) {
      continue;
    }

    ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&traits[i]->constants_table, constant_name, constant) {
      if (do_trait_constant_check(ce, constant, constant_name, traits, i)) {
        zend_class_constant *ct = NULL;

        if (ce->type == ZEND_INTERNAL_CLASS) {
          ct = malloc(sizeof(zend_class_constant));
        } else {
          ct = zend_arena_alloc(&CG(arena),sizeof(zend_class_constant));
        }
        memcpy(ct, constant, sizeof(zend_class_constant));
        constant = ct;

        if (Z_TYPE(constant->value) == IS_CONSTANT_AST) {
          ce->ce_flags &= ~ZEND_ACC_CONSTANTS_UPDATED;
          ce->ce_flags |= ZEND_ACC_HAS_AST_CONSTANTS;
        }

        /* Unlike interface implementations and class inheritances,
         * access control of the trait constants is done by the scope
         * of the composing class. So let's replace the ce here.
         */
        constant->ce = ce;

        Z_TRY_ADDREF(constant->value);
        constant->doc_comment = constant->doc_comment ? zend_string_copy(constant->doc_comment) : NULL;
        if (constant->attributes && (!(GC_FLAGS(constant->attributes) & IS_ARRAY_IMMUTABLE))) {
          GC_ADDREF(constant->attributes);
        }

        zend_hash_update_ptr(&ce->constants_table, constant_name, constant);
      }
    } ZEND_HASH_FOREACH_END();
  }
}
/* }}} */

static const zend_class_entry* find_first_property_definition(const zend_class_entry *ce, zend_class_entry **traits, size_t current_trait, zend_string *prop_name, const zend_class_entry *colliding_ce) /* {{{ */
{
  if (colliding_ce == ce) {
    for (size_t i = 0; i < current_trait; i++) {
      if (traits[i]
       && zend_hash_exists(&traits[i]->properties_info, prop_name)) {
        return traits[i];
      }
    }
  }

  return colliding_ce;
}
/* }}} */

static void zend_do_traits_property_binding(zend_class_entry *ce, zend_class_entry **traits) /* {{{ */
{
  zend_property_info *property_info;
  const zend_property_info *colliding_prop;
  zend_string* prop_name;
  zval* prop_value;

  /* In the following steps the properties are inserted into the property table
   * for that, a very strict approach is applied:
   * - check for compatibility, if not compatible with any property in class -> fatal
   * - if compatible, then strict notice
   */
  for (uint32_t i = 0; i < ce->num_traits; i++) {
    if (!traits[i]) {
      continue;
    }
    ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&traits[i]->properties_info, prop_name, property_info) {
      uint32_t flags = property_info->flags;

      /* next: check for conflicts with current class */
      if ((colliding_prop = zend_hash_find_ptr(&ce->properties_info, prop_name)) != NULL) {
        if ((colliding_prop->flags & ZEND_ACC_PRIVATE) && colliding_prop->ce != ce) {
          zend_hash_del(&ce->properties_info, prop_name);
          flags |= ZEND_ACC_CHANGED;
        } else {
          bool is_compatible = false;
          uint32_t flags_mask = ZEND_ACC_PPP_MASK | ZEND_ACC_STATIC | ZEND_ACC_READONLY;

          if (colliding_prop->hooks || property_info->hooks) {
            zend_error_noreturn(E_COMPILE_ERROR,
              "%s and %s define the same hooked property ($%s) in the composition of %s. Conflict resolution between hooked properties is currently not supported. Class was composed",
              ZSTR_VAL(find_first_property_definition(ce, traits, i, prop_name, colliding_prop->ce)->name),
              ZSTR_VAL(property_info->ce->name),
              ZSTR_VAL(prop_name),
              ZSTR_VAL(ce->name));
          }

          if ((colliding_prop->flags & flags_mask) == (flags & flags_mask) &&
            verify_property_type_compatibility(property_info, colliding_prop, PROP_INVARIANT, false, false) == INHERITANCE_SUCCESS
          ) {
            /* the flags are identical, thus, the properties may be compatible */
            zval *op1, *op2;

            if (flags & ZEND_ACC_STATIC) {
              op1 = &ce->default_static_members_table[colliding_prop->offset];
              op2 = &traits[i]->default_static_members_table[property_info->offset];
              ZVAL_DEINDIRECT(op1);
              ZVAL_DEINDIRECT(op2);
            } else {
              op1 = &ce->default_properties_table[OBJ_PROP_TO_NUM(colliding_prop->offset)];
              op2 = &traits[i]->default_properties_table[OBJ_PROP_TO_NUM(property_info->offset)];
            }
            is_compatible = check_trait_property_or_constant_value_compatibility(ce, op1, op2);
          }

          if (!is_compatible) {
            zend_error_noreturn(E_COMPILE_ERROR,
                "%s and %s define the same property ($%s) in the composition of %s. However, the definition differs and is considered incompatible. Class was composed",
                ZSTR_VAL(find_first_property_definition(ce, traits, i, prop_name, colliding_prop->ce)->name),
                ZSTR_VAL(property_info->ce->name),
                ZSTR_VAL(prop_name),
                ZSTR_VAL(ce->name));
          }
          continue;
        }
      }

      if ((ce->ce_flags & ZEND_ACC_READONLY_CLASS) && !(property_info->flags & ZEND_ACC_READONLY)) {
        zend_error_noreturn(E_COMPILE_ERROR,
          "Readonly class %s cannot use trait with a non-readonly property %s::$%s",
          ZSTR_VAL(ce->name),
          ZSTR_VAL(property_info->ce->name),
          ZSTR_VAL(prop_name)
        );
      }

      /* property not found, so lets add it */
      zval tmp_prop_value;
      if (!(flags & ZEND_ACC_VIRTUAL)) {
        if (flags & ZEND_ACC_STATIC) {
          prop_value = &traits[i]->default_static_members_table[property_info->offset];
          ZEND_ASSERT(Z_TYPE_P(prop_value) != IS_INDIRECT);
        } else {
          prop_value = &traits[i]->default_properties_table[OBJ_PROP_TO_NUM(property_info->offset)];
        }
        Z_TRY_ADDREF_P(prop_value);
      } else {
        prop_value = &tmp_prop_value;
        ZVAL_UNDEF(&tmp_prop_value);
      }

      zend_string *doc_comment = property_info->doc_comment ? zend_string_copy(property_info->doc_comment) : NULL;

      zend_type type = property_info->type;
      /* Assumption: only userland classes can use traits, as such the type must be arena allocated */
      zend_type_copy_ctor(&type, /* use arena */ true, /* persistent */ false);
      zend_property_info *new_prop = zend_declare_typed_property(ce, prop_name, prop_value, flags, doc_comment, type);

      if (property_info->attributes) {
        new_prop->attributes = property_info->attributes;

        if (!(GC_FLAGS(new_prop->attributes) & IS_ARRAY_IMMUTABLE)) {
          GC_ADDREF(new_prop->attributes);
        }
      }
      if (property_info->hooks) {
        zend_function **hooks = new_prop->hooks =
          zend_arena_alloc(&CG(arena), ZEND_PROPERTY_HOOK_STRUCT_SIZE);
        memcpy(hooks, property_info->hooks, ZEND_PROPERTY_HOOK_STRUCT_SIZE);
        for (uint32_t j = 0; j < ZEND_PROPERTY_HOOK_COUNT; j++) {
          if (hooks[j]) {
            zend_function *old_fn = hooks[j];

            /* Hooks are not yet supported for internal properties. */
            ZEND_ASSERT(ZEND_USER_CODE(old_fn->type));

            /* Copy the function, because we need to adjust the scope. */
            zend_function *new_fn = zend_arena_alloc(&CG(arena), sizeof(zend_op_array));
            memcpy(new_fn, old_fn, sizeof(zend_op_array));
            new_fn->op_array.fn_flags &= ~ZEND_ACC_IMMUTABLE;
            new_fn->common.fn_flags |= ZEND_ACC_TRAIT_CLONE;
            new_fn->common.prop_info = new_prop;
            function_add_ref(new_fn);

            zend_fixup_trait_method(new_fn, ce);

            hooks[j] = new_fn;
          }
        }
        ce->num_hooked_props++;
      }
    } ZEND_HASH_FOREACH_END();
  }
}
/* }}} */

ZEND_API void zend_class_use_internal_traits(zend_class_entry *class_entry, int num_traits, ...)
{
  ZEND_ASSERT(class_entry->ce_flags & ZEND_ACC_LINKED);
  ZEND_ASSERT(num_traits >= 0);

  if (UNEXPECTED(num_traits == 0)) {
    return;
  }

  zend_class_entry **traits = safe_pemalloc(num_traits, sizeof(zend_class_entry *), 0, /* persistent */ true);
  class_entry->trait_names = safe_pemalloc(num_traits, sizeof(zend_class_name), 0, /* persistent */ true);
  class_entry->num_traits = num_traits;

  va_list trait_list;
  va_start(trait_list, num_traits);
  for (int i = 0; i < num_traits; i++) {
    zend_class_entry *trait_entry = va_arg(trait_list, zend_class_entry *);
    class_entry->trait_names[i].name = zend_string_copy(trait_entry->name);
    class_entry->trait_names[i].lc_name = zend_string_tolower_ex(zend_string_copy(trait_entry->name), /* persistent */ true);

    if (UNEXPECTED(!(trait_entry->ce_flags & ZEND_ACC_TRAIT))) {
      free(traits);
      zend_error_noreturn(E_COMPILE_ERROR, "Class %s cannot use %s - it is not a trait",
        ZSTR_VAL(class_entry->name), ZSTR_VAL(trait_entry->name));
    }
    traits[i] = trait_entry;
  }
  va_end(trait_list);

  bool contains_abstract_methods = false;
  zend_do_traits_method_binding(class_entry, traits, NULL, NULL, false, &contains_abstract_methods);
  zend_do_traits_constant_binding(class_entry, traits);
  zend_do_traits_property_binding(class_entry, traits);

  ZEND_HASH_MAP_FOREACH_PTR(&class_entry->function_table, zend_function *fn) {
    zend_fixup_trait_method(fn, class_entry);
  } ZEND_HASH_FOREACH_END();

  free(traits);

  /* TODO: Verify abstract trait method implementation requirements are enforced. */
}

#define MAX_ABSTRACT_INFO_CNT 3
#define MAX_ABSTRACT_INFO_FMT "%s%s%s%s"
#define DISPLAY_ABSTRACT_FN(idx) \
  ai.afn[idx] ? ZEND_FN_SCOPE_NAME(ai.afn[idx]) : "", \
  ai.afn[idx] ? "::" : "", \
  ai.afn[idx] ? ZSTR_VAL(ai.afn[idx]->common.function_name) : "", \
  ai.afn[idx] && ai.afn[idx + 1] ? ", " : (ai.afn[idx] && ai.cnt > MAX_ABSTRACT_INFO_CNT ? ", ..." : "")

typedef struct _zend_abstract_info {
  const zend_function *afn[MAX_ABSTRACT_INFO_CNT + 1];
  int cnt;
} zend_abstract_info;

static void zend_verify_abstract_class_function(const zend_function *fn, zend_abstract_info *ai) /* {{{ */
{
  if (ai->cnt < MAX_ABSTRACT_INFO_CNT) {
    ai->afn[ai->cnt] = fn;
  }
  ai->cnt++;
}
/* }}} */

void zend_verify_abstract_class(zend_class_entry *ce) /* {{{ */
{
  const zend_function *func;
  zend_abstract_info ai;
  bool is_explicit_abstract = (ce->ce_flags & ZEND_ACC_EXPLICIT_ABSTRACT_CLASS) != 0;
  bool can_be_abstract = (ce->ce_flags & (ZEND_ACC_ENUM|ZEND_ACC_ANON_CLASS)) == 0;
  memset(&ai, 0, sizeof(ai));

  ZEND_HASH_MAP_FOREACH_PTR(&ce->function_table, func) {
    if (func->common.fn_flags & ZEND_ACC_ABSTRACT) {
      /* If the class is explicitly abstract, we only check private abstract methods,
       * because only they must be declared in the same class. */
      if (!is_explicit_abstract || (func->common.fn_flags & ZEND_ACC_PRIVATE)) {
        zend_verify_abstract_class_function(func, &ai);
      }
    }
  } ZEND_HASH_FOREACH_END();

  if (!is_explicit_abstract) {
    const zend_property_info *prop_info;
    ZEND_HASH_FOREACH_PTR(&ce->properties_info, prop_info) {
      if (prop_info->hooks) {
        for (uint32_t i = 0; i < ZEND_PROPERTY_HOOK_COUNT; i++) {
          const zend_function *fn = prop_info->hooks[i];
          if (fn && (fn->common.fn_flags & ZEND_ACC_ABSTRACT)) {
            zend_verify_abstract_class_function(fn, &ai);
          }
        }
      }
    } ZEND_HASH_FOREACH_END();
  }

  if (ai.cnt) {
    if (!is_explicit_abstract && can_be_abstract) {
      zend_error_noreturn(E_ERROR,
        "%s %s contains %d abstract method%s and must therefore be declared abstract or implement the remaining method%s (" MAX_ABSTRACT_INFO_FMT MAX_ABSTRACT_INFO_FMT MAX_ABSTRACT_INFO_FMT ")",
        zend_get_object_type_uc(ce),
        ZSTR_VAL(ce->name), ai.cnt,
        ai.cnt > 1 ? "s" : "",
        ai.cnt > 1 ? "s" : "",
        DISPLAY_ABSTRACT_FN(0),
        DISPLAY_ABSTRACT_FN(1),
        DISPLAY_ABSTRACT_FN(2)
      );
    } else {
      zend_error_noreturn(E_ERROR,
        "%s %s must implement %d abstract method%s (" MAX_ABSTRACT_INFO_FMT MAX_ABSTRACT_INFO_FMT MAX_ABSTRACT_INFO_FMT ")",
        zend_get_object_type_uc(ce),
        ZSTR_VAL(ce->name), ai.cnt,
        ai.cnt > 1 ? "s" : "",
        DISPLAY_ABSTRACT_FN(0),
        DISPLAY_ABSTRACT_FN(1),
        DISPLAY_ABSTRACT_FN(2)
      );
    }
  } else {
    /* now everything should be fine and an added ZEND_ACC_IMPLICIT_ABSTRACT_CLASS should be removed */
    ce->ce_flags &= ~ZEND_ACC_IMPLICIT_ABSTRACT_CLASS;
  }
}
/* }}} */

typedef struct {
  enum {
    OBLIGATION_DEPENDENCY,
    OBLIGATION_COMPATIBILITY,
    OBLIGATION_PROPERTY_COMPATIBILITY,
    OBLIGATION_CLASS_CONSTANT_COMPATIBILITY,
    OBLIGATION_PROPERTY_HOOK,
  } type;
  union {
    zend_class_entry *dependency_ce;
    struct {
      /* Traits may use temporary on-stack functions during inheritance checks,
       * so use copies of functions here as well. */
      zend_function parent_fn;
      zend_function child_fn;
      zend_class_entry *child_scope;
      zend_class_entry *parent_scope;
    };
    struct {
      const zend_property_info *parent_prop;
      const zend_property_info *child_prop;
      prop_variance variance;
    };
    struct {
      const zend_string *const_name;
      const zend_class_constant *parent_const;
      const zend_class_constant *child_const;
    };
    struct {
      const zend_property_info *hooked_prop;
      const zend_function *hook_func;
    };
  };
} variance_obligation;

static void variance_obligation_dtor(zval *zv) {
  efree(Z_PTR_P(zv));
}

static void variance_obligation_ht_dtor(zval *zv) {
  zend_hash_destroy(Z_PTR_P(zv));
  FREE_HASHTABLE(Z_PTR_P(zv));
}

static HashTable *get_or_init_obligations_for_class(zend_class_entry *ce) {
  HashTable *ht;
  zend_ulong key;
  if (!CG(delayed_variance_obligations)) {
    ALLOC_HASHTABLE(CG(delayed_variance_obligations));
    zend_hash_init(CG(delayed_variance_obligations), 0, NULL, variance_obligation_ht_dtor, 0);
  }

  key = (zend_ulong) (uintptr_t) ce;
  ht = zend_hash_index_find_ptr(CG(delayed_variance_obligations), key);
  if (ht) {
    return ht;
  }

  ALLOC_HASHTABLE(ht);
  zend_hash_init(ht, 0, NULL, variance_obligation_dtor, 0);
  zend_hash_index_add_new_ptr(CG(delayed_variance_obligations), key, ht);
  ce->ce_flags |= ZEND_ACC_UNRESOLVED_VARIANCE;
  return ht;
}

static void add_dependency_obligation(zend_class_entry *ce, zend_class_entry *dependency_ce) {
  HashTable *obligations = get_or_init_obligations_for_class(ce);
  variance_obligation *obligation = emalloc(sizeof(variance_obligation));
  obligation->type = OBLIGATION_DEPENDENCY;
  obligation->dependency_ce = dependency_ce;
  zend_hash_next_index_insert_ptr(obligations, obligation);
}

static void add_compatibility_obligation(
    zend_class_entry *ce,
    const zend_function *child_fn, zend_class_entry *child_scope,
    const zend_function *parent_fn, zend_class_entry *parent_scope) {
  HashTable *obligations = get_or_init_obligations_for_class(ce);
  variance_obligation *obligation = emalloc(sizeof(variance_obligation));
  obligation->type = OBLIGATION_COMPATIBILITY;
  /* Copy functions, because they may be stack-allocated in the case of traits. */
  if (child_fn->common.type == ZEND_INTERNAL_FUNCTION) {
    memcpy(&obligation->child_fn, child_fn, sizeof(zend_internal_function));
  } else {
    memcpy(&obligation->child_fn, child_fn, sizeof(zend_op_array));
  }
  if (parent_fn->common.type == ZEND_INTERNAL_FUNCTION) {
    memcpy(&obligation->parent_fn, parent_fn, sizeof(zend_internal_function));
  } else {
    memcpy(&obligation->parent_fn, parent_fn, sizeof(zend_op_array));
  }
  obligation->child_scope = child_scope;
  obligation->parent_scope = parent_scope;
  zend_hash_next_index_insert_ptr(obligations, obligation);
}

static void add_property_compatibility_obligation(
    zend_class_entry *ce, const zend_property_info *child_prop,
    const zend_property_info *parent_prop, prop_variance variance) {
  HashTable *obligations = get_or_init_obligations_for_class(ce);
  variance_obligation *obligation = emalloc(sizeof(variance_obligation));
  obligation->type = OBLIGATION_PROPERTY_COMPATIBILITY;
  obligation->child_prop = child_prop;
  obligation->parent_prop = parent_prop;
  obligation->variance = variance;
  zend_hash_next_index_insert_ptr(obligations, obligation);
}

static void add_class_constant_compatibility_obligation(
    zend_class_entry *ce, const zend_class_constant *child_const,
    const zend_class_constant *parent_const, const zend_string *const_name) {
  HashTable *obligations = get_or_init_obligations_for_class(ce);
  variance_obligation *obligation = emalloc(sizeof(variance_obligation));
  obligation->type = OBLIGATION_CLASS_CONSTANT_COMPATIBILITY;
  obligation->const_name = const_name;
  obligation->child_const = child_const;
  obligation->parent_const = parent_const;
  zend_hash_next_index_insert_ptr(obligations, obligation);
}

static void add_property_hook_obligation(
    zend_class_entry *ce, const zend_property_info *hooked_prop, const zend_function *hook_func) {
  HashTable *obligations = get_or_init_obligations_for_class(ce);
  variance_obligation *obligation = emalloc(sizeof(variance_obligation));
  obligation->type = OBLIGATION_PROPERTY_HOOK;
  obligation->hooked_prop = hooked_prop;
  obligation->hook_func = hook_func;
  zend_hash_next_index_insert_ptr(obligations, obligation);
}

static void resolve_delayed_variance_obligations(zend_class_entry *ce);

static void check_variance_obligation(const variance_obligation *obligation) {
  if (obligation->type == OBLIGATION_DEPENDENCY) {
    zend_class_entry *dependency_ce = obligation->dependency_ce;
    if (dependency_ce->ce_flags & ZEND_ACC_UNRESOLVED_VARIANCE) {
      zend_class_entry *orig_linking_class = CG(current_linking_class);

      CG(current_linking_class) =
        (dependency_ce->ce_flags & ZEND_ACC_CACHEABLE) ? dependency_ce : NULL;
      resolve_delayed_variance_obligations(dependency_ce);
      CG(current_linking_class) = orig_linking_class;
    }
  } else if (obligation->type == OBLIGATION_COMPATIBILITY) {
    inheritance_status status = zend_do_perform_implementation_check(
      &obligation->child_fn, obligation->child_scope,
      &obligation->parent_fn, obligation->parent_scope);
    if (UNEXPECTED(status != INHERITANCE_SUCCESS)) {
      emit_incompatible_method_error(
        &obligation->child_fn, obligation->child_scope,
        &obligation->parent_fn, obligation->parent_scope, status);
    }
    /* Either the compatibility check was successful or only threw a warning. */
  } else if (obligation->type == OBLIGATION_PROPERTY_COMPATIBILITY) {
    verify_property_type_compatibility(obligation->parent_prop, obligation->child_prop, obligation->variance, true, true);
  } else if (obligation->type == OBLIGATION_CLASS_CONSTANT_COMPATIBILITY) {
    inheritance_status status =
    class_constant_types_compatible(obligation->parent_const, obligation->child_const);
    if (status != INHERITANCE_SUCCESS) {
      emit_incompatible_class_constant_error(obligation->child_const, obligation->parent_const, obligation->const_name);
    }
  } else if (obligation->type == OBLIGATION_PROPERTY_HOOK) {
    inheritance_status status = zend_verify_property_hook_variance(obligation->hooked_prop, obligation->hook_func);
    if (status != INHERITANCE_SUCCESS) {
      zend_hooked_property_variance_error(obligation->hooked_prop);
    }
  } else {
    ZEND_UNREACHABLE();
  }
}

static void load_delayed_classes(const zend_class_entry *ce) {
  HashTable *delayed_autoloads = CG(delayed_autoloads);
  if (!delayed_autoloads) {
    return;
  }

  /* Autoloading can trigger linking of another class, which may register new delayed autoloads.
   * For that reason, this code uses a loop that pops and loads the first element of the HT. If
   * this triggers linking, then the remaining classes may get loaded when linking the newly
   * loaded class. This is important, as otherwise necessary dependencies may not be available
   * if the new class is lower in the hierarchy than the current one. */
  HashPosition pos = 0;
  zend_string *name;
  zend_ulong idx;
  while (zend_hash_get_current_key_ex(delayed_autoloads, &name, &idx, &pos)
      != HASH_KEY_NON_EXISTENT) {
    zend_string_addref(name);
    zend_hash_del(delayed_autoloads, name);
    zend_lookup_class(name);
    zend_string_release(name);
    if (EG(exception)) {
      zend_exception_uncaught_error(
        "During inheritance of %s, while autoloading %s",
        ZSTR_VAL(ce->name), ZSTR_VAL(name));
    }
  }
}

static void resolve_delayed_variance_obligations(zend_class_entry *ce) {
  HashTable *all_obligations = CG(delayed_variance_obligations);
  zend_ulong num_key = (zend_ulong) (uintptr_t) ce;

  ZEND_ASSERT(all_obligations != NULL);
  const HashTable *obligations = zend_hash_index_find_ptr(all_obligations, num_key);
  ZEND_ASSERT(obligations != NULL);

  variance_obligation *obligation;
  ZEND_HASH_FOREACH_PTR(obligations, obligation) {
    check_variance_obligation(obligation);
  } ZEND_HASH_FOREACH_END();

  zend_inheritance_check_override(ce);

  ce->ce_flags &= ~ZEND_ACC_UNRESOLVED_VARIANCE;
  ce->ce_flags |= ZEND_ACC_LINKED;
  zend_hash_index_del(all_obligations, num_key);
}

static void check_unrecoverable_load_failure(const zend_class_entry *ce) {
  /* If this class has been used while unlinked through a variance obligation, it is not legal
   * to remove the class from the class table and throw an exception, because there is already
   * a dependence on the inheritance hierarchy of this specific class. Instead we fall back to
   * a fatal error, as would happen if we did not allow exceptions in the first place. */
  if (CG(unlinked_uses)
      && zend_hash_index_del(CG(unlinked_uses), (zend_ulong)(uintptr_t)ce) == SUCCESS) {
    zend_exception_uncaught_error(
      "During inheritance of %s with variance dependencies", ZSTR_VAL(ce->name));
  }
}

#define zend_update_inherited_handler(handler) do { \
    if (ce->handler == (zend_function*)op_array) { \
      ce->handler = (zend_function*)new_op_array; \
    } \
  } while (0)

static zend_op_array *zend_lazy_method_load(
    const zend_op_array *op_array, zend_class_entry *ce, const zend_class_entry *pce) {
  ZEND_ASSERT(op_array->type == ZEND_USER_FUNCTION);
  ZEND_ASSERT(op_array->scope == pce);
  ZEND_ASSERT(op_array->prototype == NULL);
  zend_op_array *new_op_array = zend_arena_alloc(&CG(arena), sizeof(zend_op_array));
  memcpy(new_op_array, op_array, sizeof(zend_op_array));
  new_op_array->fn_flags &= ~ZEND_ACC_IMMUTABLE;
  new_op_array->scope = ce;
  ZEND_MAP_PTR_INIT(new_op_array->run_time_cache, NULL);
  ZEND_MAP_PTR_INIT(new_op_array->static_variables_ptr, NULL);

  return new_op_array;
}

static zend_class_entry *zend_lazy_class_load(const zend_class_entry *pce)
{
  zend_class_entry *ce = zend_arena_alloc(&CG(arena), sizeof(zend_class_entry));

  memcpy(ce, pce, sizeof(zend_class_entry));
  ce->ce_flags &= ~ZEND_ACC_IMMUTABLE;
  ce->refcount = 1;
  ce->inheritance_cache = NULL;
  if (CG(compiler_options) & ZEND_COMPILE_PRELOAD) {
    ZEND_MAP_PTR_NEW(ce->mutable_data);
  } else {
    ZEND_MAP_PTR_INIT(ce->mutable_data, NULL);
  }

  /* properties */
  if (ce->default_properties_table) {
    zval *dst = emalloc(sizeof(zval) * ce->default_properties_count);
    zval *src = ce->default_properties_table;
    const zval *end = src + ce->default_properties_count;

    ce->default_properties_table = dst;
    for (; src != end; src++, dst++) {
      ZVAL_COPY_VALUE_PROP(dst, src);
    }
  }

  /* methods */
  ce->function_table.pDestructor = ZEND_FUNCTION_DTOR;
  if (!(HT_FLAGS(&ce->function_table) & HASH_FLAG_UNINITIALIZED)) {
    Bucket *p = emalloc(HT_SIZE(&ce->function_table));
    memcpy(p, HT_GET_DATA_ADDR(&ce->function_table), HT_USED_SIZE(&ce->function_table));
    HT_SET_DATA_ADDR(&ce->function_table, p);
    p = ce->function_table.arData;
    const Bucket *end = p + ce->function_table.nNumUsed;
    for (; p != end; p++) {
      zend_op_array *op_array = Z_PTR(p->val);
      zend_op_array *new_op_array = Z_PTR(p->val) = zend_lazy_method_load(op_array, ce, pce);

      zend_update_inherited_handler(constructor);
      zend_update_inherited_handler(destructor);
      zend_update_inherited_handler(clone);
      zend_update_inherited_handler(__get);
      zend_update_inherited_handler(__set);
      zend_update_inherited_handler(__call);
      zend_update_inherited_handler(__isset);
      zend_update_inherited_handler(__unset);
      zend_update_inherited_handler(__tostring);
      zend_update_inherited_handler(__callstatic);
      zend_update_inherited_handler(__debugInfo);
      zend_update_inherited_handler(__serialize);
      zend_update_inherited_handler(__unserialize);
    }
  }

  /* static members */
  if (ce->default_static_members_table) {
    zval *dst = emalloc(sizeof(zval) * ce->default_static_members_count);
    zval *src = ce->default_static_members_table;
    const zval *end = src + ce->default_static_members_count;

    ce->default_static_members_table = dst;
    for (; src != end; src++, dst++) {
      ZVAL_COPY_VALUE(dst, src);
    }
  }
  ZEND_MAP_PTR_INIT(ce->static_members_table, NULL);

  /* properties_info */
  if (!(HT_FLAGS(&ce->properties_info) & HASH_FLAG_UNINITIALIZED)) {
    Bucket *p = emalloc(HT_SIZE(&ce->properties_info));
    memcpy(p, HT_GET_DATA_ADDR(&ce->properties_info), HT_USED_SIZE(&ce->properties_info));
    HT_SET_DATA_ADDR(&ce->properties_info, p);
    p = ce->properties_info.arData;
    const Bucket *end = p + ce->properties_info.nNumUsed;
    for (; p != end; p++) {
      zend_property_info *new_prop_info;

      const zend_property_info *prop_info = Z_PTR(p->val);
      ZEND_ASSERT(prop_info->ce == pce);
      ZEND_ASSERT(prop_info->prototype == prop_info);
      new_prop_info= zend_arena_alloc(&CG(arena), sizeof(zend_property_info));
      Z_PTR(p->val) = new_prop_info;
      memcpy(new_prop_info, prop_info, sizeof(zend_property_info));
      new_prop_info->ce = ce;
      new_prop_info->prototype = new_prop_info;
      /* Deep copy the type information */
      zend_type_copy_ctor(&new_prop_info->type, /* use_arena */ true, /* persistent */ false);
      if (new_prop_info->hooks) {
        new_prop_info->hooks = zend_arena_alloc(&CG(arena), ZEND_PROPERTY_HOOK_STRUCT_SIZE);
        memcpy(new_prop_info->hooks, prop_info->hooks, ZEND_PROPERTY_HOOK_STRUCT_SIZE);
        for (uint32_t i = 0; i < ZEND_PROPERTY_HOOK_COUNT; i++) {
          if (new_prop_info->hooks[i]) {
            zend_op_array *hook = zend_lazy_method_load((zend_op_array *) new_prop_info->hooks[i], ce, pce);
            ZEND_ASSERT(hook->prop_info == prop_info);
            hook->prop_info = new_prop_info;
            new_prop_info->ce = ce;
            new_prop_info->hooks[i] = (zend_function *) hook;
          }
        }
      }
    }
  }

  /* constants table */
  if (!(HT_FLAGS(&ce->constants_table) & HASH_FLAG_UNINITIALIZED)) {
    Bucket *p = emalloc(HT_SIZE(&ce->constants_table));
    memcpy(p, HT_GET_DATA_ADDR(&ce->constants_table), HT_USED_SIZE(&ce->constants_table));
    HT_SET_DATA_ADDR(&ce->constants_table, p);
    p = ce->constants_table.arData;
    const Bucket *end = p + ce->constants_table.nNumUsed;
    for (; p != end; p++) {
      zend_class_constant *new_c;

      const zend_class_constant *c = Z_PTR(p->val);
      ZEND_ASSERT(c->ce == pce);
      new_c = zend_arena_alloc(&CG(arena), sizeof(zend_class_constant));
      Z_PTR(p->val) = new_c;
      memcpy(new_c, c, sizeof(zend_class_constant));
      new_c->ce = ce;
    }
  }

  return ce;
}

#ifndef ZEND_OPCACHE_SHM_REATTACHMENT
# define UPDATE_IS_CACHEABLE(ce) do { \
      if ((ce)->type == ZEND_USER_CLASS) { \
        is_cacheable &= (ce)->ce_flags; \
      } \
    } while (0)
#else
// TODO: ASLR may cause different addresses in different workers ???
# define UPDATE_IS_CACHEABLE(ce) do { \
      is_cacheable &= (ce)->ce_flags; \
    } while (0)
#endif

ZEND_API zend_class_entry *zend_do_link_class(zend_class_entry *ce, zend_string *lc_parent_name, const zend_string *key) /* {{{ */
{
  /* Load parent/interface dependencies first, so we can still gracefully abort linking
   * with an exception and remove the class from the class table. This is only possible
   * if no variance obligations on the current class have been added during autoloading. */
  zend_class_entry *parent = NULL;
  zend_class_entry **traits_and_interfaces = NULL;
  zend_class_entry *proto = NULL;
  zend_class_entry *orig_linking_class;
  uint32_t is_cacheable = ce->ce_flags & ZEND_ACC_IMMUTABLE;
  uint32_t i, j;
  zval *zv;
  ALLOCA_FLAG(use_heap)

  SET_ALLOCA_FLAG(use_heap);
  ZEND_ASSERT(!(ce->ce_flags & ZEND_ACC_LINKED));

  if (ce->parent_name) {
    parent = zend_fetch_class_by_name(
      ce->parent_name, lc_parent_name,
      ZEND_FETCH_CLASS_ALLOW_NEARLY_LINKED | ZEND_FETCH_CLASS_EXCEPTION);
    if (!parent) {
      check_unrecoverable_load_failure(ce);
      return NULL;
    }
    UPDATE_IS_CACHEABLE(parent);
  }

  if (ce->num_traits || ce->num_interfaces) {
    traits_and_interfaces = do_alloca(sizeof(zend_class_entry*) * (ce->num_traits + ce->num_interfaces), use_heap);

    for (i = 0; i < ce->num_traits; i++) {
      zend_class_entry *trait = zend_fetch_class_by_name(ce->trait_names[i].name,
        ce->trait_names[i].lc_name, ZEND_FETCH_CLASS_TRAIT | ZEND_FETCH_CLASS_EXCEPTION);
      if (UNEXPECTED(trait == NULL)) {
        free_alloca(traits_and_interfaces, use_heap);
        return NULL;
      }
      if (UNEXPECTED(!(trait->ce_flags & ZEND_ACC_TRAIT))) {
        zend_throw_error(NULL, "%s cannot use %s - it is not a trait", ZSTR_VAL(ce->name), ZSTR_VAL(trait->name));
        free_alloca(traits_and_interfaces, use_heap);
        return NULL;
      }
      if (UNEXPECTED(trait->ce_flags & ZEND_ACC_DEPRECATED)) {
        zend_use_of_deprecated_trait(trait, ce->name);
        if (UNEXPECTED(EG(exception))) {
          free_alloca(traits_and_interfaces, use_heap);
          return NULL;
        }
      }
      for (j = 0; j < i; j++) {
        if (traits_and_interfaces[j] == trait) {
          /* skip duplications */
          trait = NULL;
          break;
        }
      }
      traits_and_interfaces[i] = trait;
      if (trait) {
        UPDATE_IS_CACHEABLE(trait);
      }
    }
  }

  if (ce->num_interfaces) {
    for (i = 0; i < ce->num_interfaces; i++) {
      zend_class_entry *iface = zend_fetch_class_by_name(
        ce->interface_names[i].name, ce->interface_names[i].lc_name,
        ZEND_FETCH_CLASS_INTERFACE |
        ZEND_FETCH_CLASS_ALLOW_NEARLY_LINKED | ZEND_FETCH_CLASS_EXCEPTION);
      if (!iface) {
        check_unrecoverable_load_failure(ce);
        free_alloca(traits_and_interfaces, use_heap);
        return NULL;
      }
      traits_and_interfaces[ce->num_traits + i] = iface;
      if (iface) {
        UPDATE_IS_CACHEABLE(iface);
      }
    }
  }

#ifndef ZEND_WIN32
  if (ce->ce_flags & ZEND_ACC_ENUM) {
    /* We will add internal methods. */
    is_cacheable = false;
  }
#endif

  if (ce->ce_flags & ZEND_ACC_IMMUTABLE && is_cacheable) {
    if (zend_inheritance_cache_get && zend_inheritance_cache_add) {
      zend_class_entry *ret = zend_inheritance_cache_get(ce, parent, traits_and_interfaces);
      if (ret) {
        if (traits_and_interfaces) {
          free_alloca(traits_and_interfaces, use_heap);
        }
        zv = zend_hash_find_known_hash(CG(class_table), key);
        Z_CE_P(zv) = ret;
        return ret;
      }
    } else {
      is_cacheable = 0;
    }
    proto = ce;
  }

  /* Delay and record warnings (such as deprecations) thrown during
   * inheritance, so they will be recorded in the inheritance cache.
   * Warnings must be delayed in all cases so that we get a consistent
   * behavior regardless of cacheability. */
  bool orig_record_errors = EG(record_errors);
  if (!orig_record_errors) {
    zend_begin_record_errors();
  }

  zend_try {
    if (ce->ce_flags & ZEND_ACC_IMMUTABLE) {
      /* Lazy class loading */
      ce = zend_lazy_class_load(ce);
      zv = zend_hash_find_known_hash(CG(class_table), key);
      Z_CE_P(zv) = ce;
    } else if (ce->ce_flags & ZEND_ACC_FILE_CACHED) {
      /* Lazy class loading */
      ce = zend_lazy_class_load(ce);
      ce->ce_flags &= ~ZEND_ACC_FILE_CACHED;
      zv = zend_hash_find_known_hash(CG(class_table), key);
      Z_CE_P(zv) = ce;
    }

    if (CG(unlinked_uses)) {
      zend_hash_index_del(CG(unlinked_uses), (zend_ulong)(uintptr_t) ce);
    }

    orig_linking_class = CG(current_linking_class);
    CG(current_linking_class) = is_cacheable ? ce : NULL;

    if (ce->ce_flags & ZEND_ACC_ENUM) {
      /* Only register builtin enum methods during inheritance to avoid persisting them in
       * opcache. */
      zend_enum_register_funcs(ce);
    }

#ifdef ZEND_OPCACHE_SHM_REATTACHMENT
    zend_link_hooked_object_iter(ce);
#endif

    HashTable **trait_exclude_tables;
    zend_class_entry **trait_aliases;
    bool trait_contains_abstract_methods = false;
    if (ce->num_traits) {
      zend_traits_init_trait_structures(ce, traits_and_interfaces, &trait_exclude_tables, &trait_aliases);
      zend_do_traits_method_binding(ce, traits_and_interfaces, trait_exclude_tables, trait_aliases, false, &trait_contains_abstract_methods);
      zend_do_traits_constant_binding(ce, traits_and_interfaces);
      zend_do_traits_property_binding(ce, traits_and_interfaces);

      zend_function *fn;
      ZEND_HASH_MAP_FOREACH_PTR(&ce->function_table, fn) {
        zend_fixup_trait_method(fn, ce);
      } ZEND_HASH_FOREACH_END();
    }
    if (parent) {
      if (!(parent->ce_flags & ZEND_ACC_LINKED)) {
        add_dependency_obligation(ce, parent);
      }
      zend_do_inheritance(ce, parent);
    }
    if (ce->num_traits) {
      if (trait_contains_abstract_methods) {
        zend_do_traits_method_binding(ce, traits_and_interfaces, trait_exclude_tables, trait_aliases, true, &trait_contains_abstract_methods);

        /* New abstract methods may have been added, make sure to add
         * ZEND_ACC_IMPLICIT_ABSTRACT_CLASS to ce. */
        zend_function *fn;
        ZEND_HASH_MAP_FOREACH_PTR(&ce->function_table, fn) {
          zend_fixup_trait_method(fn, ce);
        } ZEND_HASH_FOREACH_END();
      }

      if (trait_exclude_tables) {
        for (i = 0; i < ce->num_traits; i++) {
          if (traits_and_interfaces[i]) {
            if (trait_exclude_tables[i]) {
              zend_hash_destroy(trait_exclude_tables[i]);
              FREE_HASHTABLE(trait_exclude_tables[i]);
            }
          }
        }
        efree(trait_exclude_tables);
      }
      if (trait_aliases) {
        efree(trait_aliases);
      }
    }
    if (ce->num_interfaces) {
      /* Also copy the parent interfaces here, so we don't need to reallocate later. */
      uint32_t num_parent_interfaces = parent ? parent->num_interfaces : 0;
      zend_class_entry **interfaces = emalloc(
          sizeof(zend_class_entry *) * (ce->num_interfaces + num_parent_interfaces));

      if (num_parent_interfaces) {
        memcpy(interfaces, parent->interfaces,
             sizeof(zend_class_entry *) * num_parent_interfaces);
      }
      memcpy(interfaces + num_parent_interfaces, traits_and_interfaces + ce->num_traits,
           sizeof(zend_class_entry *) * ce->num_interfaces);

      zend_do_implement_interfaces(ce, interfaces);
    } else if (parent && parent->num_interfaces) {
      zend_do_inherit_interfaces(ce, parent);
    }
    if (!(ce->ce_flags & (ZEND_ACC_INTERFACE|ZEND_ACC_TRAIT))
      && (ce->ce_flags & (ZEND_ACC_IMPLICIT_ABSTRACT_CLASS|ZEND_ACC_EXPLICIT_ABSTRACT_CLASS))
        ) {
      zend_verify_abstract_class(ce);
    }
    if (ce->ce_flags & ZEND_ACC_ENUM) {
      zend_verify_enum(ce);
    }
    if (ce->num_hooked_prop_variance_checks) {
      const zend_property_info *prop_info;
      ZEND_HASH_MAP_FOREACH_PTR(&ce->properties_info, prop_info) {
        if (prop_info->ce == ce && prop_info->hooks && prop_info->hooks[ZEND_PROPERTY_HOOK_SET]) {
          switch (zend_verify_property_hook_variance(prop_info, prop_info->hooks[ZEND_PROPERTY_HOOK_SET])) {
            case INHERITANCE_SUCCESS:
              break;
            case INHERITANCE_ERROR:
              zend_hooked_property_variance_error(prop_info);
              break;
            case INHERITANCE_UNRESOLVED:
              add_property_hook_obligation(ce, prop_info, prop_info->hooks[ZEND_PROPERTY_HOOK_SET]);
              break;
            case INHERITANCE_WARNING:
              ZEND_UNREACHABLE();
          }
        }
      } ZEND_HASH_FOREACH_END();
    }

    /* Normally Stringable is added during compilation. However, if it is imported from a trait,
     * we need to explicitly add the interface here. */
    if (ce->__tostring && !(ce->ce_flags & ZEND_ACC_TRAIT)
      && !zend_class_implements_interface(ce, zend_ce_stringable)) {
      ZEND_ASSERT(ce->__tostring->common.fn_flags & ZEND_ACC_TRAIT_CLONE);
      ce->ce_flags |= ZEND_ACC_RESOLVED_INTERFACES;
      ce->num_interfaces++;
      ce->interfaces = perealloc(ce->interfaces,
                     sizeof(zend_class_entry *) * ce->num_interfaces, ce->type == ZEND_INTERNAL_CLASS);
      ce->interfaces[ce->num_interfaces - 1] = zend_ce_stringable;
      do_interface_implementation(ce, zend_ce_stringable);
    }

    zend_build_properties_info_table(ce);
  } zend_catch {
    /* Do not leak recorded errors to the next linked class. */
    if (!orig_record_errors) {
      EG(record_errors) = false;
      zend_free_recorded_errors();
    }
    zend_bailout();
  } zend_end_try();

  EG(record_errors) = orig_record_errors;

  if (!(ce->ce_flags & ZEND_ACC_UNRESOLVED_VARIANCE)) {
    zend_inheritance_check_override(ce);
    ce->ce_flags |= ZEND_ACC_LINKED;
  } else {
    ce->ce_flags |= ZEND_ACC_NEARLY_LINKED;
    if (CG(current_linking_class)) {
      ce->ce_flags |= ZEND_ACC_CACHEABLE;
    }
    load_delayed_classes(ce);
    if (ce->ce_flags & ZEND_ACC_UNRESOLVED_VARIANCE) {
      resolve_delayed_variance_obligations(ce);
    }
    /* Delayed variance resolution can re-enter linking before the full
     * hierarchy is linked. See ext/opcache/tests/gh20469*.phpt. */
    if (CG(unlinked_uses) && zend_hash_index_exists(CG(unlinked_uses), (zend_long)(uintptr_t) ce)) {
      ce->ce_flags &= ~ZEND_ACC_CACHEABLE;
    }
    if (ce->ce_flags & ZEND_ACC_CACHEABLE) {
      ce->ce_flags &= ~ZEND_ACC_CACHEABLE;
    } else {
      CG(current_linking_class) = NULL;
    }
  }

  bool was_cacheable = is_cacheable;
  if (!CG(current_linking_class)) {
    is_cacheable = 0;
  }
  CG(current_linking_class) = orig_linking_class;

  if (is_cacheable) {
    HashTable *ht = (HashTable*)ce->inheritance_cache;
    zend_class_entry *new_ce;

    ce->inheritance_cache = NULL;
    new_ce = zend_inheritance_cache_add(ce, proto, parent, traits_and_interfaces, ht);
    if (new_ce) {
      zv = zend_hash_find_known_hash(CG(class_table), key);
      ce = new_ce;
      Z_CE_P(zv) = ce;
    }
    if (ht) {
      zend_hash_destroy(ht);
      FREE_HASHTABLE(ht);
    }
  } else if (was_cacheable && ce->inheritance_cache) {
    /* Cacheability can be disabled after dependency tracking prepared
     * an inheritance-cache dependency table. Discard it here. */
    HashTable *ht = (HashTable*)ce->inheritance_cache;
    ce->inheritance_cache = NULL;
    zend_hash_destroy(ht);
    FREE_HASHTABLE(ht);
  }

  if (!orig_record_errors) {
    zend_emit_recorded_errors();
    zend_free_recorded_errors();
  }
  if (traits_and_interfaces) {
    free_alloca(traits_and_interfaces, use_heap);
  }

  if (ZSTR_HAS_CE_CACHE(ce->name)) {
    ZSTR_SET_CE_CACHE(ce->name, ce);
  }

  return ce;
}
/* }}} */

/* Check whether early binding is prevented due to unresolved types in inheritance checks. */
static inheritance_status zend_can_early_bind(zend_class_entry *ce, const zend_class_entry *parent_ce) /* {{{ */
{
  zend_string *key;
  zend_function *parent_func;
  const zend_property_info *parent_info;
  const zend_class_constant *parent_const;
  inheritance_status overall_status = INHERITANCE_SUCCESS;

  ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&parent_ce->function_table, key, parent_func) {
    zval *zv = zend_hash_find_known_hash(&ce->function_table, key);
    if (zv) {
      zend_function *child_func = Z_FUNC_P(zv);
      inheritance_status status =
        do_inheritance_check_on_method(
          child_func, child_func->common.scope,
          parent_func, parent_func->common.scope,
          ce, NULL,
          ZEND_INHERITANCE_CHECK_SILENT | ZEND_INHERITANCE_CHECK_PROTO | ZEND_INHERITANCE_CHECK_VISIBILITY);
      if (UNEXPECTED(status == INHERITANCE_WARNING)) {
        overall_status = INHERITANCE_WARNING;
      } else if (UNEXPECTED(status != INHERITANCE_SUCCESS)) {
        return status;
      }
    }
  } ZEND_HASH_FOREACH_END();

  ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&parent_ce->properties_info, key, parent_info) {
    const zval *zv;
    if ((parent_info->flags & ZEND_ACC_PRIVATE) || !ZEND_TYPE_IS_SET(parent_info->type)) {
      continue;
    }

    zv = zend_hash_find_known_hash(&ce->properties_info, key);
    if (zv) {
      const zend_property_info *child_info = Z_PTR_P(zv);
      if (ZEND_TYPE_IS_SET(child_info->type)) {
        inheritance_status status = verify_property_type_compatibility(parent_info, child_info, prop_get_variance(parent_info), false, false);
        if (UNEXPECTED(status != INHERITANCE_SUCCESS)) {
          return status;
        }
      }
    }
  } ZEND_HASH_FOREACH_END();

  ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&parent_ce->constants_table, key, parent_const) {
    const zval *zv;
    if ((ZEND_CLASS_CONST_FLAGS(parent_const) & ZEND_ACC_PRIVATE) || !ZEND_TYPE_IS_SET(parent_const->type)) {
      continue;
    }

    zv = zend_hash_find_known_hash(&ce->constants_table, key);
    if (zv) {
      const zend_class_constant *child_const = Z_PTR_P(zv);
      if (ZEND_TYPE_IS_SET(child_const->type)) {
        inheritance_status status = class_constant_types_compatible(parent_const, child_const);
        ZEND_ASSERT(status != INHERITANCE_WARNING);
        if (UNEXPECTED(status != INHERITANCE_SUCCESS)) {
          return status;
        }
      }
    }
  } ZEND_HASH_FOREACH_END();

  return overall_status;
}
/* }}} */

static zend_always_inline bool register_early_bound_ce(zval *delayed_early_binding, zend_string *lcname, zend_class_entry *ce) {
  if (delayed_early_binding) {
    if (EXPECTED(!(ce->ce_flags & ZEND_ACC_PRELOADED))) {
      if (zend_hash_set_bucket_key(EG(class_table), (Bucket *)delayed_early_binding, lcname) != NULL) {
        Z_CE_P(delayed_early_binding) = ce;
        return true;
      }
    } else {
      /* If preloading is used, don't replace the existing bucket, add a new one. */
      if (zend_hash_add_ptr(EG(class_table), lcname, ce) != NULL) {
        return true;
      }
    }
    zend_class_entry *old_ce = zend_hash_find_ptr(EG(class_table), lcname);
    ZEND_ASSERT(old_ce);
    zend_class_redeclaration_error(E_COMPILE_ERROR, old_ce);
    return false;
  }
  if (zend_hash_add_ptr(CG(class_table), lcname, ce) != NULL) {
    return true;
  }
  return false;
}

ZEND_API zend_class_entry *zend_try_early_bind(zend_class_entry *ce, zend_class_entry *parent_ce, zend_string *lcname, zval *delayed_early_binding) /* {{{ */
{
  inheritance_status status;
  zend_class_entry *proto = NULL;
  zend_class_entry *orig_linking_class;

  if (ce->ce_flags & ZEND_ACC_LINKED) {
    ZEND_ASSERT(ce->parent == NULL);
    if (UNEXPECTED(!register_early_bound_ce(delayed_early_binding, lcname, ce))) {
      return NULL;
    }
    zend_observer_class_linked_notify(ce, lcname);
    return ce;
  }

  uint32_t is_cacheable = ce->ce_flags & ZEND_ACC_IMMUTABLE;
  UPDATE_IS_CACHEABLE(parent_ce);
  if (is_cacheable) {
    if (zend_inheritance_cache_get && zend_inheritance_cache_add) {
      zend_class_entry *ret = zend_inheritance_cache_get(ce, parent_ce, NULL);
      if (ret) {
        if (UNEXPECTED(!register_early_bound_ce(delayed_early_binding, lcname, ret))) {
          return NULL;
        }
        zend_observer_class_linked_notify(ret, lcname);
        return ret;
      }
    } else {
      is_cacheable = 0;
    }
    proto = ce;
  }

  orig_linking_class = CG(current_linking_class);
  CG(current_linking_class) = NULL;
  status = zend_can_early_bind(ce, parent_ce);
  CG(current_linking_class) = orig_linking_class;
  if (EXPECTED(status != INHERITANCE_UNRESOLVED)) {
    if (ce->ce_flags & ZEND_ACC_IMMUTABLE) {
      /* Lazy class loading */
      ce = zend_lazy_class_load(ce);
    } else if (ce->ce_flags & ZEND_ACC_FILE_CACHED) {
      /* Lazy class loading */
      ce = zend_lazy_class_load(ce);
      ce->ce_flags &= ~ZEND_ACC_FILE_CACHED;
    }

    if (UNEXPECTED(!register_early_bound_ce(delayed_early_binding, lcname, ce))) {
      return NULL;
    }

    orig_linking_class = CG(current_linking_class);
    CG(current_linking_class) = is_cacheable ? ce : NULL;

    bool orig_record_errors = EG(record_errors);

    zend_try{
      CG(zend_lineno) = ce->info.user.line_start;

      if (!orig_record_errors) {
        zend_begin_record_errors();
      }

#ifdef ZEND_OPCACHE_SHM_REATTACHMENT
      zend_link_hooked_object_iter(ce);
#endif

      zend_do_inheritance_ex(ce, parent_ce, status == INHERITANCE_SUCCESS);
      if (parent_ce && parent_ce->num_interfaces) {
        zend_do_inherit_interfaces(ce, parent_ce);
      }
      zend_build_properties_info_table(ce);
      if ((ce->ce_flags & (ZEND_ACC_IMPLICIT_ABSTRACT_CLASS|ZEND_ACC_INTERFACE|ZEND_ACC_TRAIT|ZEND_ACC_EXPLICIT_ABSTRACT_CLASS)) == ZEND_ACC_IMPLICIT_ABSTRACT_CLASS) {
        zend_verify_abstract_class(ce);
      }
      zend_inheritance_check_override(ce);
      ZEND_ASSERT(!(ce->ce_flags & ZEND_ACC_UNRESOLVED_VARIANCE));
      ce->ce_flags |= ZEND_ACC_LINKED;

      CG(current_linking_class) = orig_linking_class;
    } zend_catch {
      if (!orig_record_errors) {
        EG(record_errors) = false;
        zend_free_recorded_errors();
      }
      zend_bailout();
    } zend_end_try();

    if (is_cacheable) {
      HashTable *ht = (HashTable*)ce->inheritance_cache;
      zend_class_entry *new_ce;

      ce->inheritance_cache = NULL;
      new_ce = zend_inheritance_cache_add(ce, proto, parent_ce, NULL, ht);
      if (new_ce) {
        zval *zv = zend_hash_find_known_hash(CG(class_table), lcname);
        ce = new_ce;
        Z_CE_P(zv) = ce;
      }
      if (ht) {
        zend_hash_destroy(ht);
        FREE_HASHTABLE(ht);
      }
    }

    if (!orig_record_errors) {
      zend_emit_recorded_errors();
      zend_free_recorded_errors();
    }

    if (ZSTR_HAS_CE_CACHE(ce->name)) {
      ZSTR_SET_CE_CACHE(ce->name, ce);
    }
    zend_observer_class_linked_notify(ce, lcname);

    return ce;
  }
  return NULL;
}
/* }}} */

Coverage Report

Created: 2026-09-14 06:25