Description:
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When mbstring.func_overload=0, mb_substr returns "" when you call it with an out of bounds range. This is consistent with the documentation. However, when mbstring.func_overload=7, mb_substr returns boolean false. This is inconsistent with the documentation. I expect the behavior to be consistent regardless of the value of mbstring.func_overload.

This is different from Bug #55241.

Test script:
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<?php
$result = mb_substr('abc', 5, 2);
var_dump($result);


Expected result:
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When mbstring.func_overload=0:

string(0) ""

When mbstring.func_overload=7:

string(0) ""

Actual result:
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When mbstring.func_overload=0:

string(0) ""

When mbstring.func_overload=7:

bool(false)