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Fix non-existent offset when guarding #4539

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Fix non-existent offset when guarding #4539

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b73b7a3
Fix non-existent offset when guarding
SplotyCode Nov 8, 2025
679d274
Dont set root expression
SplotyCode Nov 8, 2025
fa337a9
add more test cases
SplotyCode Nov 11, 2025
2c7e290
Fix test because of more explicit type
SplotyCode Nov 11, 2025
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23 changes: 22 additions & 1 deletion src/Analyser/TypeSpecifier.php
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Original file line number Diff line number Diff line change
Expand Up @@ -273,7 +273,8 @@ public function specifyTypesInCondition(
&& in_array(strtolower((string) $expr->right->name), ['count', 'sizeof'], true)
&& $leftType->isInteger()->yes()
) {
$argType = $scope->getType($expr->right->getArgs()[0]->value);
$argExpr = $expr->right->getArgs()[0]->value;
$argType = $scope->getType($argExpr);

if ($leftType instanceof ConstantIntegerType) {
if ($orEqual) {
Expand All @@ -291,6 +292,26 @@ public function specifyTypesInCondition(
if ($specifiedTypes !== null) {
$result = $result->unionWith($specifiedTypes);
}
if (
$context->true()
&& $expr instanceof Node\Expr\BinaryOp\Smaller
&& $argType->isList()->yes()
&& $argExpr instanceof Expr\Variable
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@staabm staabm Nov 11, 2025 •
edited
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instanceof Expr\Variable is usually a bug as most logic works for other expressions (e.g. a pure function call can also be remembered).

most of the time this works just by dropping this line

&& IntegerRangeType::fromInterval(0, null)->isSuperTypeOf($leftType)->yes()
) {
$dimFetch = new ArrayDimFetch(
$argExpr,
$expr->left,
);
$result = $result->unionWith(
$this->create(
$dimFetch,
$argType->getIterableValueType(),
TypeSpecifierContext::createTrue(),
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@staabm staabm Nov 11, 2025

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usually we pass thru the $context, instead of creating a new one.

$scope,
)
);
}

if (
$context->true() && (IntegerRangeType::createAllGreaterThanOrEqualTo(1 - $offset)->isSuperTypeOf($leftType)->yes())
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2 changes: 1 addition & 1 deletion tests/PHPStan/Analyser/nsrt/bug-10264.php
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Expand Up @@ -33,7 +33,7 @@ public function sayHello(array $c): void
assertType('list<int>', $c);
if (count($c) > 0) {
$c = array_map(fn() => new stdClass(), $c);
assertType('non-empty-list<stdClass>', $c);
assertType('non-empty-list<stdClass>&hasOffsetValue(0, stdClass)', $c);
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@staabm staabm Nov 11, 2025

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this type does not make sense, because non-empty-list<stdClass> already implies that the list has a offset 0 with value stdClass

} else {
assertType('array{}', $c);
}
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32 changes: 32 additions & 0 deletions tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -700,6 +700,22 @@ public static function dataReportPossiblyNonexistentArrayOffset(): iterable
"Offset 'foo' might not exist on array.",
9,
],
[
'Offset int might not exist on list<int>.',
77
],
[
'Offset int<0, max> might not exist on list<int>.',
88
],
[
'Offset int<0, max> might not exist on array<int, int>.',
100
],
[
'Offset int<0, max> might not exist on array<int<min, 4>|int<6, max>, int>.',
112
],
]];
yield [true, true, [
[
Expand All @@ -710,6 +726,22 @@ public static function dataReportPossiblyNonexistentArrayOffset(): iterable
'Offset string might not exist on array{foo: 1}.',
20,
],
[
'Offset int might not exist on list<int>.',
77
],
[
'Offset int<0, max> might not exist on list<int>.',
88
],
[
'Offset int<0, max> might not exist on array<int, int>.',
100
],
[
'Offset int<0, max> might not exist on array<int<min, 4>|int<6, max>, int>.',
112
],
]];
}

Expand Down
56 changes: 56 additions & 0 deletions tests/PHPStan/Rules/Arrays/data/report-possibly-nonexistent-array-offset.php
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Expand Up @@ -57,4 +57,60 @@ public function nonEmpty(array $a): void
echo $a[0];
}

/**
* @param list<int> $array
* @param non-negative-int $index
*/
public function guard(array $array, int $index) {
if ($index < count($array)) {
return $array[$index];
}
return null;
}


/**
* @param list<int> $array
*/
public function guardNotSafeLowerBound(array $array, int $index) {
if ($index < count($array)) {
return $array[$index];
}
return null;
}

/**
* @param list<int> $array
* @param non-negative-int $index
*/
public function guardNotSafeUpperBound(array $array, int $index) {
if ($index <= count($array)) {
return $array[$index];
}
return null;
}


/**
* @param array<int, int> $array
* @param non-negative-int $index
*/
public function guardNotSafeArray(array $array, int $index) {
if ($index <= count($array)) {
return $array[$index];
}
return null;
}

/**
* @param array<int, int> $array
* @param non-negative-int $index
*/
public function guardNotSafeBecauseRewrite(array $array, int $index) {
if ($index <= count($array)) {
unset($array[5]);
return $array[$index];
}
return null;
}
}
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