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False Positive on Match Arm Comparison with Incremented Bounded Integer #5003

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Merged
VincentLanglet merged 4 commits into from
Feb 21, 2026
Merged

False Positive on Match Arm Comparison with Incremented Bounded Integer #5003

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1df597b
Fix match expression with post/pre-increment condition using wrong type
phpstan-bot Feb 17, 2026
9ca2718
Fix CI failures [claude-ci-fix]
phpstan-bot Feb 17, 2026
535cebc
Rework
VincentLanglet Feb 19, 2026
ea28257
Add tests
VincentLanglet Feb 21, 2026
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6 changes: 3 additions & 3 deletions src/Analyser/MutatingScope.php
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Original file line number Diff line number Diff line change
Expand Up @@ -2987,7 +2987,7 @@ private static function intersectButNotNever(Type $nativeType, Type $inferredTyp
return $result;
}

public function enterMatch(Expr\Match_ $expr): self
public function enterMatch(Expr\Match_ $expr, Type $condType, Type $condNativeType): self
{
if ($expr->cond instanceof Variable) {
return $this;
Expand All @@ -3001,8 +3001,8 @@ public function enterMatch(Expr\Match_ $expr): self
return $this;
}

$type = $this->getType($cond);
$nativeType = $this->getNativeType($cond);
$type = $condType;
$nativeType = $condNativeType;
$condExpr = new AlwaysRememberedExpr($cond, $type, $nativeType);
$expr->cond = $condExpr;

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3 changes: 2 additions & 1 deletion src/Analyser/NodeScopeResolver.php
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Expand Up @@ -4179,13 +4179,14 @@ function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $context, $sto
} elseif ($expr instanceof Expr\Match_) {
$deepContext = $context->enterDeep();
$condType = $scope->getType($expr->cond);
$condNativeType = $scope->getNativeType($expr->cond);
$condResult = $this->processExprNode($stmt, $expr->cond, $scope, $storage, $nodeCallback, $deepContext);
$scope = $condResult->getScope();
$hasYield = $condResult->hasYield();
$throwPoints = $condResult->getThrowPoints();
$impurePoints = $condResult->getImpurePoints();
$isAlwaysTerminating = $condResult->isAlwaysTerminating();
$matchScope = $scope->enterMatch($expr);
$matchScope = $scope->enterMatch($expr, $condType, $condNativeType);
$armNodes = [];
$hasDefaultCond = false;
$hasAlwaysTrueCond = false;
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11 changes: 11 additions & 0 deletions tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -446,4 +446,15 @@ public function testBug9534(): void
]);
}

#[RequiresPhp('>= 8.0')]
public function testBug11310(): void
{
$this->analyse([__DIR__ . '/data/bug-11310.php'], [
[
'Match arm comparison between int<1, max> and 0 is always false.',
24,
],
]);
}

}
28 changes: 28 additions & 0 deletions tests/PHPStan/Rules/Comparison/data/bug-11310.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,28 @@
<?php // lint >= 8.0

namespace Bug11310;

/** @param int<0, max> $i */
function foo(int $i): void {
echo match ($i++) {
0 => 'zero',
default => 'default',
};
}

/** @param int<0, max> $i */
function bar(int $i): void {
echo match ($i--) {
0 => 'zero',
default => 'default',
};
}

/** @param int<0, max> $i */
function baz(int $i): void {
echo match (++$i) {
0 => 'zero',
1 => 'one',
default => 'default',
};
}
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