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Fix phpstan/phpstan#13773: Index for loop inference should only work in lists #5215

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Merged
staabm merged 2 commits into from
Mar 13, 2026
Merged

Fix phpstan/phpstan#13773: Index for loop inference should only work in lists #5215

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9dfe8a5
Fix phpstan/phpstan#13773: for loop index inference should only work …
phpstan-bot Mar 13, 2026
da0f514
simplify
staabm Mar 13, 2026
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28 changes: 18 additions & 10 deletions src/Analyser/NodeScopeResolver.php
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Original file line number Diff line number Diff line change
Expand Up @@ -4545,11 +4545,15 @@ private function inferForLoopExpressions(For_ $stmt, Expr $lastCondExpr, Mutatin
&& $stmt->init[0]->var->name === $lastCondExpr->left->name
) {
$arrayArg = $lastCondExpr->right->getArgs()[0]->value;
$bodyScope = $bodyScope->assignExpression(
new ArrayDimFetch($lastCondExpr->right->getArgs()[0]->value, $lastCondExpr->left),
$bodyScope->getType($arrayArg)->getIterableValueType(),
$bodyScope->getNativeType($arrayArg)->getIterableValueType(),
);
$arrayType = $bodyScope->getType($arrayArg);
$arrayNativeType = $bodyScope->getNativeType($arrayArg);
if ($arrayType->isList()->yes() || $arrayNativeType->isList()->yes()) {
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@VincentLanglet VincentLanglet Mar 13, 2026

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Checking the arrayType (and not the arrayNative type) should be enough

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@phpstan-bot phpstan-bot Mar 13, 2026

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Everything is already up to date. The reviewer's feedback was already addressed by the da0f51464 ("simplify") commit, which removed the $arrayNativeType check and only uses $arrayType->isList()->yes() — exactly what VincentLanglet suggested.

$bodyScope = $bodyScope->assignExpression(
new ArrayDimFetch($lastCondExpr->right->getArgs()[0]->value, $lastCondExpr->left),
$arrayType->getIterableValueType(),
$arrayNativeType->getIterableValueType(),
);
}
}

// count($items) > $i
Expand All @@ -4566,11 +4570,15 @@ private function inferForLoopExpressions(For_ $stmt, Expr $lastCondExpr, Mutatin
&& $stmt->init[0]->var->name === $lastCondExpr->right->name
) {
$arrayArg = $lastCondExpr->left->getArgs()[0]->value;
$bodyScope = $bodyScope->assignExpression(
new ArrayDimFetch($lastCondExpr->left->getArgs()[0]->value, $lastCondExpr->right),
$bodyScope->getType($arrayArg)->getIterableValueType(),
$bodyScope->getNativeType($arrayArg)->getIterableValueType(),
);
$arrayType = $bodyScope->getType($arrayArg);
$arrayNativeType = $bodyScope->getNativeType($arrayArg);
if ($arrayType->isList()->yes() || $arrayNativeType->isList()->yes()) {
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@VincentLanglet VincentLanglet Mar 13, 2026

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Checking the arrayType( and not the arrayNativeType) should be enough

$bodyScope = $bodyScope->assignExpression(
new ArrayDimFetch($lastCondExpr->left->getArgs()[0]->value, $lastCondExpr->right),
$arrayType->getIterableValueType(),
$arrayNativeType->getIterableValueType(),
);
}
}
}

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16 changes: 16 additions & 0 deletions tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
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Expand Up @@ -1240,4 +1240,20 @@ public function testBug14234(): void
]);
}

public function testBug13773(): void
{
$this->reportPossiblyNonexistentGeneralArrayOffset = true;

$this->analyse([__DIR__ . '/data/bug-13773.php'], [
[
'Offset int<0, max> might not exist on non-empty-array<int, string>.',
14,
],
[
'Offset int<0, max> might not exist on non-empty-array<int, string>.',
38,
],
]);
}

}
40 changes: 40 additions & 0 deletions tests/PHPStan/Rules/Arrays/data/bug-13773.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
<?php declare(strict_types = 1);

namespace Bug13773;

/** @return array<int, string> */
function getArray(): array {
return [100 => "hey"];
}

function testNonListArray(): void
{
$array = getArray();
for ($i = 0; $i < count($array); $i++) {
$a = $array[$i];
}
}

/** @param list<string> $list */
function testList(array $list): void
{
for ($i = 0; $i < count($list); $i++) {
$a = $list[$i];
}
}

/** @param list<string> $list */
function testListReversed(array $list): void
{
for ($i = 0; count($list) > $i; ++$i) {
$a = $list[$i];
}
}

/** @param array<int, string> $array */
function testNonListReversed(array $array): void
{
for ($i = 0; count($array) > $i; ++$i) {
$a = $array[$i];
}
}
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