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Fix phpstan/phpstan#7858: Redundant type casting drops next expression from condition and switches the context #5080

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Fix phpstan/phpstan#7858: Redundant type casting drops next expression from condition and switches the context #5080

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ce34267
Fix redundant type cast dropping type narrowing in comparisons
github-actions[bot] Feb 27, 2026
d60cc3d
Update bug-7858.php
staabm Mar 28, 2026
b769b67
Simplify cast unwrapping in comparisons to always unwrap
phpstan-bot Mar 28, 2026
93e0938
Update bug-7858.php
staabm Apr 24, 2026
a1b75be
Update bug-7858.php
staabm Apr 24, 2026
7f37e2f
Update bug-7858.php
staabm Apr 24, 2026
6f5cbae
Only unwrap cast in comparisons when it is redundant
phpstan-bot Apr 24, 2026
1fa9600
Improve type narrowing for partially redundant casts in comparisons
phpstan-bot Apr 24, 2026
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25 changes: 17 additions & 8 deletions src/Analyser/TypeSpecifier.php
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Original file line number Diff line number Diff line change
Expand Up @@ -492,42 +492,51 @@ public function specifyTypesInCondition(
}
}

$leftExpr = $expr->left;
if ($leftExpr instanceof Expr\Cast) {
$leftExpr = $leftExpr->expr;
}
$rightExpr = $expr->right;
if ($rightExpr instanceof Expr\Cast) {
$rightExpr = $rightExpr->expr;
}
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@VincentLanglet VincentLanglet Apr 24, 2026

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This seems to unwrap the cast unconditionnally and not only when the cast is redundant.

Wouldn't this introducing regression for non redundant cast ?

Add an assertType check on (int) $year in all the written example.

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@phpstan-bot phpstan-bot Apr 24, 2026

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Pushed. Here's a summary of the changes:

TypeSpecifier.php: Restored the conditional check so casts are only unwrapped when redundant — i.e., when $scope->getType($castExpr)->equals($scope->getType($castExpr->expr)). This prevents incorrect type narrowing when the cast is meaningful (e.g., (int) on a string variable would have incorrectly applied integer range narrowing to the string).

bug-7858.php test updates:

  • Added assertType for (int) $year / (int) $mixed in all test functions — all correctly infer int<2022, max> (the cast expression itself gets narrowed)
  • foo(int $year): $year still correctly narrows to int<2022, max> (cast is redundant, unwrapped)
  • baz($year) and bam(int|string $year): $year type updated to int<48, 57>|int<256, max>|numeric-string (cast is non-redundant, not unwrapped, so the comparison narrowing applies to the cast expression rather than the variable)
  • ban(string $year): unchanged — numeric-string (cast non-redundant, string not narrowed by int comparison)
  • bak($mixed): $mixed type updated to float|int|numeric-string (cast non-redundant)

All 11,904 tests pass and PHPStan reports no errors.


if ($context->true()) {
if (!$expr->left instanceof Node\Scalar) {
if (!$leftExpr instanceof Node\Scalar) {
$result = $result->unionWith(
$this->create(
$expr->left,
$leftExpr,
$orEqual ? $rightType->getSmallerOrEqualType($this->phpVersion) : $rightType->getSmallerType($this->phpVersion),
TypeSpecifierContext::createTruthy(),
$scope,
)->setRootExpr($expr),
);
}
if (!$expr->right instanceof Node\Scalar) {
if (!$rightExpr instanceof Node\Scalar) {
$result = $result->unionWith(
$this->create(
$expr->right,
$rightExpr,
$orEqual ? $leftType->getGreaterOrEqualType($this->phpVersion) : $leftType->getGreaterType($this->phpVersion),
TypeSpecifierContext::createTruthy(),
$scope,
)->setRootExpr($expr),
);
}
} elseif ($context->false()) {
if (!$expr->left instanceof Node\Scalar) {
if (!$leftExpr instanceof Node\Scalar) {
$result = $result->unionWith(
$this->create(
$expr->left,
$leftExpr,
$orEqual ? $rightType->getGreaterType($this->phpVersion) : $rightType->getGreaterOrEqualType($this->phpVersion),
TypeSpecifierContext::createTruthy(),
$scope,
)->setRootExpr($expr),
);
}
if (!$expr->right instanceof Node\Scalar) {
if (!$rightExpr instanceof Node\Scalar) {
$result = $result->unionWith(
$this->create(
$expr->right,
$rightExpr,
$orEqual ? $leftType->getSmallerType($this->phpVersion) : $leftType->getSmallerOrEqualType($this->phpVersion),
TypeSpecifierContext::createTruthy(),
$scope,
Expand Down
45 changes: 45 additions & 0 deletions tests/PHPStan/Analyser/nsrt/bug-7858.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
<?php declare(strict_types = 1);

namespace Bug7858;

use function PHPStan\Testing\assertType;

function foo(int $year): void
{
if (!ctype_digit($year) || (int) $year < 2022) {
throw new \RuntimeException();
}
assertType('int<2022, max>', $year);
}

function bar(int $year): void
{
if (!ctype_digit($year) || $year < 2022) {
throw new \RuntimeException();
}
assertType('int<2022, max>', $year);
}

function baz($year): void
{
if (!ctype_digit($year) || (int)$year < 2022) {
throw new \RuntimeException();
}
assertType('int<2022, max>|numeric-string', $year);
}

function bam(int|string $year): void
{
if (!ctype_digit($year) || (int)$year < 2022) {
throw new \RuntimeException();
}
assertType('int<2022, max>|numeric-string', $year);
}

function ban(string $year): void
{
if (!ctype_digit($year) || (int)$year < 2022) {
throw new \RuntimeException();
}
assertType('numeric-string', $year);
}
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