Php/docs/migration71.other-changes

其它改动

无效字符串计算的通知和警告

New E_WARNING and E_NOTICE errors have been introduced when invalid strings are coerced using operators expecting numbers (+ - * / ** % << >> | & ^) or their assignment equivalents. An E_NOTICE is emitted when the string begins with a numeric value but contains trailing non-numeric characters, and an E_WARNING is emitted when the string does not contain a numeric value.

<?php'1b' + 'something';

以上例程会输出：

Notice: A non well formed numeric value encountered in %s on line %d
Warning: A non-numeric value encountered in %s on line %d

八进制转义序列溢出时发出警告

Previously, 3-octet octal string escape sequences would overflow silently. Now, they will still overflow, but E_WARNING will be emitted.

<?phpvar_dump("\500");

以上例程会输出：

Warning: Octal escape sequence overflow \500 is greater than \377 in %s on line %d
string(1) "@"

`$this` 不一致的修正

Whilst $this is considered a special variable in PHP, it lacked proper checks to ensure it wasn't used as a variable name or reassigned. This has now been rectified to ensure that $this cannot be a user-defined variable, reassigned to a different value, or be globalised.

无需散列即可生成 Session ID

Session ID 将不再在生成时进行哈希。这一变化，会导致以下四个 ini 设置不再使用：

session.entropy_file
session.entropy_length
session.hash_function
session.hash_bits_per_character

并增加以下两个 ini 设置：

session.sid_length - 定义会话 ID 的长度（为了向后兼容，默认为 32 个字符）
session.sid_bits_per_character - 定义了每个字符的存储位数（即增加了会话 ID 中可使用的字符范围），为了向后兼容，默认为 4

INI 文件处理的变化

precision: If the value is set to -1, then the dtoa mode 0 is used. The default value is still 14.
serialize_precision: If the value is set to -1, then the dtoa mode 0 is used. The value -1 is now used by default.
gd.jpeg_ignore_warning: The default of this php.ini setting has been changed to 1, so by default libjpeg warnings are ignored.
opcache.enable_cli: The default of this php.ini setting has been changed to 1 (enabled) in PHP 7.1.2, and back to 0 (disabled) in PHP 7.1.7.

Session ID generation with a CSPRNG only

Session IDs will now only be generated with a CSPRNG.

More informative TypeError messages when `null` is allowed

TypeError exceptions for arg_info type checks will now provide more informative error messages. If the parameter type or return type accepts null (by either having a default value of null or being a nullable type), then the error message will now mention this with a message of "must be ... or null" or "must ... or be null."