mb_str_pad is an impure function #4849
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ondrejmirtes
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Feb 2, 2026
| 'mb_scrub' => ['hasSideEffects' => false], | ||
| 'mb_split' => ['hasSideEffects' => false], | ||
| 'mb_str_pad' => ['hasSideEffects' => false], | ||
| 'mb_str_pad' => ['hasSideEffects' => true], |
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What side effect does this function have?
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mb_str_pad(
string $string,
int $length,
string $pad_string = " ",
int $pad_type = STR_PAD_RIGHT,
?string $encoding = null
): string
If $encoding is null then the internal encoding is used, which can be changed by mb_internal_encoding(). This is not a side effect but means it's not entirely a pure function?
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Alright, good enough :) Thank you.
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Reasoning for this change is in JetBrains/phpstorm-stubs#1793 - I think this is the correct change to make on the PHPStan side.
Helps #4845 and in turn phpstan/phpstan#14041