Description:
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As reported in #67576 , the doc says "The maximum number of captured substrings is 65535. ". However, the test script failed. It raised a warning: 
> Warning: preg_match(): Compilation failed: regular expression is too large at offset 21000

and followed by the instructions in #67576 , if I edit 7000 to 6552, everything works. So is it a documentation problem or I misunderstand something?

Test script:
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<?php
ini_set("pcre.backtrack_limit", -1);
ini_set("pcre.recursion_limit", -1);
$test2 = str_repeat('a',10000);
//7000 is much smaller than 65535
if (preg_match('/'.str_repeat('(a)',7000).'/', $test2, $regs2)) {
    var_dump($regs2);
} else {
    echo 'Not find';
}

Expected result:
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output the results of preg_match

Actual result:
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Warning: preg_match(): Compilation failed: regular expression is too large at offset 21000