non-negative-int evaluated to int

Bug report

To reproduce the unexpected behavior, I made a simplified snippet that contains essentially a method that iterates over two indices in a single for loop. Originally it comes from a piece of code dealing with 2D arrays (a matrix/linear algebra library). This snippet triggers Parameter #1 of method expects int<0, max>, int given, although I added a set of checks to make sure that both indices are non-negative during the iteration.

Interestingly, the error disappeared if:
either we replace $columnIndex = 0; with e.g. $columnIndex = 1; (a value that is > 0) on Line 20 before the loop
or we replace $columnIndex = 0; with e.g. $columnIndex = 1; (a value that is > 0) on Line 27 inside the loop

Code snippet that reproduces the problem

https://phpstan.org/r/3471ec19-7077-4e36-a3d4-27d2dc643fa8

Expected output

It is expected that the parameter/variable remains non-negative-int.

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Excellent tools for checking/dealing with non-empty-list and non-negative-int in my linear algebra objects :)

@ondrejmirtes

I feel like it's an easy fix I could try ; any idea where I should look in the code @ondrejmirtes ?

There's a loop involved. That always changes my "simple" to "could be impossible" 😁
Having said that, I would step-debug through the loop analysis to figure out more.

Yeah, the logic is wrong probably somewhere here: https://github.com/phpstan/phpstan-src/blob/b225f74805542bddc5249156d84143c0eddbc51e/src/Analyser/MutatingScope.php#L5130-L5440

This code (called from https://github.com/phpstan/phpstan-src/blob/b225f74805542bddc5249156d84143c0eddbc51e/src/Analyser/NodeScopeResolver.php#L1432-L1438 in case of for loops) deals with differentiating whether a loop does $i++ (an ever-changing value which has to be generalized), or $i = 3 (stable value that can be kept as 3).

After some tries, it seems that MutatingScope::generalizeType has the following behavior:

generalizeType(0, 0|1) => int<0, max>
generalizeType(1, 0|1) => int<min, 1>
generalizeType(1, 1|2) => int<min, 1>
generalizeType(1, 0|1|2) => int<min, max>
generalizeType(0, int<0, 1>) => int<0, 1>
generalizeType(1, int<0, 1>) => int<0, 1>
generalizeType(1, int<1, 2>) => int<1, 2>
generalizeType(1, int<0, 2>) => int<0, 2>

So a union of integers and an integerRange does not give the same results.

I'm unsure if TypeCombinator::union should always transform union of scalar into integerRange like

        $constantIntegerTypes = $scalarTypes[ConstantIntegerType::class] ?? [];
		$count = count($constantIntegerTypes);
		if ($count > 1) {
			$constantIntegerValues = array_map(
				static fn (ConstantIntegerType $type): int => $type->getValue(),
				$constantIntegerTypes,
			);
			sort($constantIntegerValues);
			if ($constantIntegerValues[$count - 1] - $constantIntegerValues[0] === $count - 1) {
				$integerRangeTypes[] = IntegerRangeType::fromInterval($constantIntegerValues[0], $constantIntegerValues[$count - 1]);
				unset($scalarTypes[ConstantIntegerType::class]);
			}
		}

or if this logic should be only done inside MutatingScope::generalizeType or if it's the wrong direction...

My gut feeling is that

generalizeType(1, 0|1|2) => int<min, max>

Should lead to int<0, 2> instead. Whether this fixes the problem is another question :-)

My gut feeling is that

generalizeType(1, 0|1|2) => int<min, max>

Should lead to int<0, 2> instead. Whether this fixes the problem is another question :-)

I now understand why it's that simplified.
phpstan/phpstan-src@b225f74/src/Analyser/NodeScopeResolver.php#L1432-L1438 calls generalizeType only a limiting time. And if we don't generalize generalizeType(1, 0|1|2) we end up with 100 failures because lot of int<0, max> integers are now considered 0|1|2|3|4|5|6 or similar unions.

There's a loop involved. That always changes my "simple" to "could be impossible"

I now understand ^^'

Fix non-negative-int generalized to int in for loop

Fix phpstan/phpstan#12163: non-negative-int evaluated to int (#5176)

Closed via merging phpstan/phpstan-src#5176

Updated PHPStan to commit 9d660fbb57ec8219679d156c9588aadfb85ae015

Updated PHPStan to commit e8d1deeeeca6a97bd5c9b857118decbb26546922

Fix phpstan/phpstan#12163: non-negative-int evaluated to int (phpstan…

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non-negative-int evaluated to int #12163

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non-negative-int evaluated to int #12163

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VincentLanglet commented on Mar 30, 2025

herndlm commented on Mar 30, 2025

ondrejmirtes commented on Mar 30, 2025

VincentLanglet commented on Mar 30, 2025

staabm commented on Mar 30, 2025

VincentLanglet commented on Mar 30, 2025

phpstan-bot commented on Mar 12, 2026

github-actions commented on Apr 13, 2026

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