The **const** modifier needs to be added to read-only parameters of all ZendAPI and PHPAPI functions

Description

Many functions in the php source code receive the zval parameter. The value of the parameter is not modified in the function implementation. These parameters are read-only, but the const modifier is not added.

As a result, C/C++underlying developers do not know whether the function is a read-only operation or a write operation, and will pollute all downstream functions. If these PHPAPI or ZEND_API functions are used in a C++function, even if the function is designed to be read-only, the const modifier cannot be used, or only unsafe const_cast can be used to cast.

An example:

class Variant {
  protected:
    zval val;
    void destroy() {
        zval_ptr_dtor(&val);
    }

  public:
    Variant(const zval *v) noexcept {
        ZVAL_COPY_VALUE(&val, v);
    }
    const zval *const_ptr() const {
        return &val;
    }
    // fast_equal_check_function should be `fast_equal_check_function(const zval *op1, const zval *op2)`
     bool equals(const Variant &v) const {
        return fast_equal_check_function(const_ptr(), v.const_ptr());         
    }
}

Problem function:

• fast_equal_check_function
• php_debug_zval_dump
• php_var_dump
• php_var_unserialize
• concat_function
• add_function
• is_equal_function
• zval_get_string
• zval_get_double // version 8.1

... a lot more functions

まず、fast_equal_check_function、php_debug_zval_dump、php_var_dump、php_var_unserialize、concat_function、add_function、is_equal_function、zval_get_string、zval_get_double の PHPAPI および ZEND_API の宣言と実装を探します。変更されていない zval パラメーターを特定し、該当するシグネチャを影響を受けるすべての関数で一貫して更新してから、PHP のソースが引き続きビルドできることを確認します。