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Use of result of impure function in max(...) prevents type narrowing #12731

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claudepache opened this issue Mar 12, 2025 · 2 comments · May be fixed by phpstan/phpstan-src#3928
Open

Use of result of impure function in max(...) prevents type narrowing #12731

claudepache opened this issue Mar 12, 2025 · 2 comments · May be fixed by phpstan/phpstan-src#3928

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@claudepache
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claudepache commented Mar 12, 2025 •
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Bug report

Given an impure function f() returning an int, PHPStan fails to narrow the type of max(4, f()) to int<4, max> (it considers it as int).

Code snippet that reproduces the problem

https://phpstan.org/r/bace30de-7627-425a-9098-9ea3b9b6cf5b

Expected output

Lline 19: Dumped type: int<4, max>

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@claudepache claudepache changed the title Use of result of impure function in max(...) prevents type narrowing> Use of result of impure function in max(...) prevents type narrowing Mar 12, 2025
@staabm
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staabm commented Mar 12, 2025

Likly needs a fix in https://github.com/phpstan/phpstan-src/blob/2.1.x/src/Type/Php/MinMaxFunctionReturnTypeExtension.php or in logic triggered from it

@claudepache
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Likly needs a fix in https://github.com/phpstan/phpstan-src/blob/2.1.x/src/Type/Php/MinMaxFunctionReturnTypeExtension.php or in logic triggered from it

Indeed, on line 54:

// rewrite min($x, $y) as $x < $y ? $x : $y

is incorrect if $y is not constant.

@cs278 cs278 linked a pull request Apr 9, 2025 that will close this issue
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Remember value of arguments passed to {min,max}() cs278/phpstan-src
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@staabm @claudepache