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merged 1 commit into from
Nov 7, 2025
Merged

Understand always-overwritten arrays in foreach #4534

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15 changes: 13 additions & 2 deletions src/Analyser/MutatingScope.php
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@
use PHPStan\Node\Expr\GetIterableValueTypeExpr;
use PHPStan\Node\Expr\GetOffsetValueTypeExpr;
use PHPStan\Node\Expr\NativeTypeExpr;
use PHPStan\Node\Expr\OriginalForeachKeyExpr;
use PHPStan\Node\Expr\OriginalPropertyTypeExpr;
use PHPStan\Node\Expr\ParameterVariableOriginalValueExpr;
use PHPStan\Node\Expr\PropertyInitializationExpr;
Expand Down Expand Up @@ -3949,13 +3950,19 @@ public function enterForeachKey(self $originalScope, Expr $iteratee, string $key
{
$iterateeType = $originalScope->getType($iteratee);
$nativeIterateeType = $originalScope->getNativeType($iteratee);

$keyType = $originalScope->getIterableKeyType($iterateeType);
$nativeKeyType = $originalScope->getIterableKeyType($nativeIterateeType);

$scope = $this->assignVariable(
$keyName,
$originalScope->getIterableKeyType($iterateeType),
$originalScope->getIterableKeyType($nativeIterateeType),
$keyType,
$nativeKeyType,
TrinaryLogic::createYes(),
);

$originalForeachKeyExpr = new OriginalForeachKeyExpr($keyName);
$scope = $scope->assignExpression($originalForeachKeyExpr, $keyType, $nativeKeyType);
if ($iterateeType->isArray()->yes()) {
$scope = $scope->assignExpression(
new Expr\ArrayDimFetch($iteratee, new Variable($keyName)),
Expand Down Expand Up @@ -4139,6 +4146,10 @@ public function assignVariable(string $variableName, Type $type, Type $nativeTyp
unset($scope->expressionTypes[$parameterOriginalValueExprString]);
unset($scope->nativeExpressionTypes[$parameterOriginalValueExprString]);

$originalForeachKeyExpr = $this->getNodeKey(new OriginalForeachKeyExpr($variableName));
unset($scope->expressionTypes[$originalForeachKeyExpr]);
unset($scope->nativeExpressionTypes[$originalForeachKeyExpr]);

return $scope;
}

Expand Down
85 changes: 83 additions & 2 deletions src/Analyser/NodeScopeResolver.php
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Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,7 @@
use PHPStan\Node\Expr\GetIterableValueTypeExpr;
use PHPStan\Node\Expr\GetOffsetValueTypeExpr;
use PHPStan\Node\Expr\NativeTypeExpr;
use PHPStan\Node\Expr\OriginalForeachKeyExpr;
use PHPStan\Node\Expr\OriginalPropertyTypeExpr;
use PHPStan\Node\Expr\PropertyInitializationExpr;
use PHPStan\Node\Expr\SetExistingOffsetValueTypeExpr;
Expand Down Expand Up @@ -1247,14 +1248,94 @@ private function processStmtNode(
$bodyScope = $this->enterForeach($bodyScope, $originalScope, $stmt, $nodeCallback);
$finalScopeResult = $this->processStmtNodes($stmt, $stmt->stmts, $bodyScope, $nodeCallback, $context)->filterOutLoopExitPoints();
$finalScope = $finalScopeResult->getScope();
$scopesWithIterableValueType = [];

$originalKeyVarExpr = null;
$continueExitPointHasUnoriginalKeyType = false;
if ($stmt->keyVar instanceof Variable && is_string($stmt->keyVar->name)) {
$originalKeyVarExpr = new OriginalForeachKeyExpr($stmt->keyVar->name);
if ($finalScope->hasExpressionType($originalKeyVarExpr)->yes()) {
$scopesWithIterableValueType[] = $finalScope;
} else {
$continueExitPointHasUnoriginalKeyType = true;
}
}

foreach ($finalScopeResult->getExitPointsByType(Continue_::class) as $continueExitPoint) {
$finalScope = $continueExitPoint->getScope()->mergeWith($finalScope);
$continueScope = $continueExitPoint->getScope();
$finalScope = $continueScope->mergeWith($finalScope);
if ($originalKeyVarExpr === null || !$continueScope->hasExpressionType($originalKeyVarExpr)->yes()) {
$continueExitPointHasUnoriginalKeyType = true;
continue;
}
$scopesWithIterableValueType[] = $continueScope;
}
foreach ($finalScopeResult->getExitPointsByType(Break_::class) as $breakExitPoint) {
$breakExitPoints = $finalScopeResult->getExitPointsByType(Break_::class);
foreach ($breakExitPoints as $breakExitPoint) {
$finalScope = $breakExitPoint->getScope()->mergeWith($finalScope);
}

$exprType = $scope->getType($stmt->expr);
$hasExpr = $scope->hasExpressionType($stmt->expr);
if (
count($breakExitPoints) === 0
&& count($scopesWithIterableValueType) > 0
&& !$continueExitPointHasUnoriginalKeyType
&& $stmt->keyVar !== null
&& $exprType->isArray()->yes()
&& $exprType->isConstantArray()->no()
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@staabm staabm Nov 8, 2025

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tbh I did not yet understand why this PR works, but I wonder whether we could use the same logic to also infer a better result when the iteratee is a known constant array?

like in

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@ondrejmirtes ondrejmirtes Nov 8, 2025

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Why this works - I look at $a[$k] type at the end of the loop and at each continue point and if some other conditions are true (like there are zero break points), I rewrite the whole array value type with the $a[$k] type unioned from all the points I looked at.

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@ondrejmirtes ondrejmirtes Nov 8, 2025

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When $foreach->expr is a constant array I feel like we need a different approach, possibly analysing the foreach separately for each item (but run $nodeCallback for the rules still only once).

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@ondrejmirtes ondrejmirtes Nov 8, 2025

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Also I want to look at foreach ($a as &$v) to understand it better that also needs a different approach.

&& !$hasExpr->no()
) {
$arrayExprDimFetch = new ArrayDimFetch($stmt->expr, $stmt->keyVar);
$arrayDimFetchLoopTypes = [];
foreach ($scopesWithIterableValueType as $scopeWithIterableValueType) {
$arrayDimFetchLoopTypes[] = $scopeWithIterableValueType->getType($arrayExprDimFetch);
}

$arrayDimFetchLoopType = TypeCombinator::union(...$arrayDimFetchLoopTypes);

$arrayDimFetchLoopNativeTypes = [];
foreach ($scopesWithIterableValueType as $scopeWithIterableValueType) {
$arrayDimFetchLoopNativeTypes[] = $scopeWithIterableValueType->getNativeType($arrayExprDimFetch);
}

$arrayDimFetchLoopNativeType = TypeCombinator::union(...$arrayDimFetchLoopNativeTypes);

if (!$arrayDimFetchLoopType->equals($exprType->getIterableValueType())) {
$newExprType = TypeTraverser::map($exprType, static function (Type $type, callable $traverse) use ($arrayDimFetchLoopType): Type {
if ($type instanceof UnionType || $type instanceof IntersectionType) {
return $traverse($type);
}

if (!$type instanceof ArrayType) {
return $type;
}

return new ArrayType($type->getKeyType(), $arrayDimFetchLoopType);
});
$newExprNativeType = TypeTraverser::map($scope->getNativeType($stmt->expr), static function (Type $type, callable $traverse) use ($arrayDimFetchLoopNativeType): Type {
if ($type instanceof UnionType || $type instanceof IntersectionType) {
return $traverse($type);
}

if (!$type instanceof ArrayType) {
return $type;
}

return new ArrayType($type->getKeyType(), $arrayDimFetchLoopNativeType);
});

if ($stmt->expr instanceof Variable && is_string($stmt->expr->name)) {
$finalScope = $finalScope->assignVariable(
$stmt->expr->name,
$newExprType,
$newExprNativeType,
$hasExpr,
);
}
}
}

$isIterableAtLeastOnce = $exprType->isIterableAtLeastOnce();
if ($exprType->isIterable()->no() || $isIterableAtLeastOnce->maybe()) {
$finalScope = $finalScope->mergeWith($scope->filterByTruthyValue(new BooleanOr(
Expand Down
37 changes: 37 additions & 0 deletions src/Node/Expr/OriginalForeachKeyExpr.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,37 @@
<?php declare(strict_types = 1);

namespace PHPStan\Node\Expr;

use Override;
use PhpParser\Node\Expr;
use PHPStan\Node\VirtualNode;

final class OriginalForeachKeyExpr extends Expr implements VirtualNode
{

public function __construct(private string $variableName)
{
parent::__construct([]);
}

public function getVariableName(): string
{
return $this->variableName;
}

#[Override]
public function getType(): string
{
return 'PHPStan_Node_OriginalForeachKeyExpr';
}

/**
* @return string[]
*/
#[Override]
public function getSubNodeNames(): array
{
return [];
}

}
6 changes: 6 additions & 0 deletions src/Node/Printer/Printer.php
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Expand Up @@ -11,6 +11,7 @@
use PHPStan\Node\Expr\GetIterableValueTypeExpr;
use PHPStan\Node\Expr\GetOffsetValueTypeExpr;
use PHPStan\Node\Expr\NativeTypeExpr;
use PHPStan\Node\Expr\OriginalForeachKeyExpr;
use PHPStan\Node\Expr\OriginalPropertyTypeExpr;
use PHPStan\Node\Expr\ParameterVariableOriginalValueExpr;
use PHPStan\Node\Expr\PropertyInitializationExpr;
Expand Down Expand Up @@ -99,6 +100,11 @@ protected function pPHPStan_Node_ParameterVariableOriginalValueExpr(ParameterVar
return sprintf('__phpstanParameterVariableOriginalValue(%s)', $expr->getVariableName());
}

protected function pPHPStan_Node_OriginalForeachKeyExpr(OriginalForeachKeyExpr $expr): string // phpcs:ignore
{
return sprintf('__phpstanOriginalForeachKey(%s)', $expr->getVariableName());
}

protected function pPHPStan_Node_IssetExpr(IssetExpr $expr): string // phpcs:ignore
{
return sprintf('__phpstanIssetExpr(%s)', $this->p($expr->getExpr()));
Expand Down
2 changes: 1 addition & 1 deletion tests/PHPStan/Analyser/nsrt/bug-12274.php
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Expand Up @@ -15,7 +15,7 @@ function getItems(array $items): array
$items[$index] = 1;
}

assertType('non-empty-list<int>', $items);
assertType('non-empty-list<1>', $items);
return $items;
}

Expand Down
24 changes: 24 additions & 0 deletions tests/PHPStan/Analyser/nsrt/bug-13730.php
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@@ -0,0 +1,24 @@
<?php declare(strict_types = 1);

namespace Bug13730;

use function PHPStan\dumpType;
use function PHPStan\Testing\assertType;

class HelloWorld
{
/**
* @param array<string|null> $arr
* @return array<string>
*/
public function sayHello(array $arr): array
{
foreach($arr as $k => $v) {
$arr[$k] = $v ?? '';
}

assertType('array<string>', $arr);

return $arr;
}
}
22 changes: 22 additions & 0 deletions tests/PHPStan/Analyser/nsrt/bug-2273.php
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@@ -0,0 +1,22 @@
<?php

namespace Bug2273;

use function PHPStan\Testing\assertType;

class Foo {
/**
* @param string[] $x
*/
public function doFoo(array $x): void
{
foreach ($x as $k => $v) {
$x[$k] = \realpath($v);
if ($x[$k] === false) {
throw new \Exception();
}
}

assertType('array<non-empty-string>', $x);
}
}
131 changes: 131 additions & 0 deletions tests/PHPStan/Analyser/nsrt/overwritten-arrays.php
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@@ -0,0 +1,131 @@
<?php

namespace OverwrittenArrays;

use function PHPStan\Testing\assertType;
use function rad2deg;

class Foo
{

/**
* @param array<int, string> $a
*/
public function doFoo(array $a): void
{
foreach ($a as $k => $v) {
$a[$k] = 1;
}

assertType('array<int, 1>', $a);
}

/**
* @param array<int, string> $a
*/
public function doFoo2(array $a): void
{
foreach ($a as $k => $v) {
if (rand(0, 1)) {
$a[$k] = 2;
continue;
}
$a[$k] = 1;
}

assertType('array<int, 1|2>', $a);
}

/**
* @param array<int, string> $a
*/
public function doFoo3(array $a): void
{
foreach ($a as $k => $v) {
if (rand(0, 1)) {
break;
}
if (rand(0, 1)) {
$a[$k] = 2;
continue;
}
$a[$k] = 1;
}

assertType('array<int, 1|2|string>', $a);
}

/**
* @param array<int, string> $a
*/
public function doFoo4(array $a): void
{
foreach ($a as $k => $v) {
$k++;
$a[$k] = 1;
}

assertType('array<int, 1|string>', $a);
}

/**
* @param array<int, string> $a
*/
public function doFoo5(array $a): void
{
foreach ($a as $k => $v) {
if (rand(0, 1)) {
$k++;
$a[$k] = 2;
continue;
}
$a[$k] = 1;
}

assertType('array<int, 1|2|string>', $a);
}

/**
* @param array<int, string> $a
*/
public function doFoo6(array $a): void
{
foreach ($a as $k => $v) {
if (rand(0, 1)) {
$a[$k] = 2;
continue;
}
$k++;
$a[$k] = 1;
}

assertType('array<int, 1|2|string>', $a);
}

/**
* @param array<int, string> $a
*/
public function doFoo7(array $a): void
{
foreach ($a as &$v) {
$v = 1;
}

assertType('array<int, 1>', $a);
}

/**
* @param array<int, string> $a
*/
public function doFoo8(array $a): void
{
foreach ($a as &$v) {
if (rand(0, 1)) {
$v = 1;
}
}

assertType('array<int, 1|string>', $a);
}

}
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