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Fix phpstan/phpstan#13981: Assignment inside match statement no longer recognized #5120

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Merged
VincentLanglet merged 3 commits into from
Mar 5, 2026
+91 −3
Merged

Fix phpstan/phpstan#13981: Assignment inside match statement no longer recognized #5120

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418ecc5
Fix assignment inside match arm condition not recognized
staabm Mar 2, 2026
a9fb98b
Rework
VincentLanglet Mar 3, 2026
d24d99c
Fix
VincentLanglet Mar 3, 2026
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13 changes: 10 additions & 3 deletions src/Analyser/NodeScopeResolver.php
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Original file line number Diff line number Diff line change
Expand Up @@ -4386,6 +4386,8 @@ function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $context, $sto
$filteringExprs = [];
$armCondScope = $matchScope;
$condNodes = [];
$armCondResultScope = $matchScope;
$bodyScope = null;
foreach ($arm->conds as $j => $armCond) {
if (isset($armCondsToSkip[$i][$j])) {
continue;
Expand All @@ -4401,12 +4403,17 @@ function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $context, $sto
if ($armCondType->isTrue()->yes()) {
$hasAlwaysTrueCond = true;
}
$armCondScope = $armCondResult->getScope()->filterByFalseyValue($armCondExpr);
$armCondScope = $armCondResultScope->filterByFalseyValue($armCondExpr);
if ($bodyScope === null) {
$bodyScope = $armCondResultScope->filterByTruthyValue($armCondExpr);
} else {
$bodyScope = $bodyScope->mergeWith($armCondResultScope->filterByTruthyValue($armCondExpr));
}
Comment on lines +4406 to +4411
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@staabm staabm Mar 5, 2026 •
edited
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seeing this I feared this would slow down match/match-arm analysis.

running vendor/bin/phpunit tests/PHPStan/Analyser/AnalyserIntegrationTest.php in contrast reveals though, that it now runs in 20-21 seconds while it took 21-22 seconds before -> so we actually got a bit faster :)

$filteringExprs[] = $armCond;
}

$filteringExpr = $this->getFilteringExprForMatchArm($expr, $filteringExprs);
$bodyScope = $matchScope->filterByTruthyValue($filteringExpr);
$bodyScope ??= $matchScope->filterByTruthyValue($filteringExpr);
$matchArmBody = new MatchExpressionArmBody($bodyScope, $arm->body);
$armNodes[$i] = new MatchExpressionArm($matchArmBody, $condNodes, $arm->getStartLine());

Expand All @@ -4423,7 +4430,7 @@ function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $context, $sto
$hasYield = $hasYield || $armResult->hasYield();
$throwPoints = array_merge($throwPoints, $armResult->getThrowPoints());
$impurePoints = array_merge($impurePoints, $armResult->getImpurePoints());
$matchScope = $matchScope->filterByFalseyValue($filteringExpr);
$matchScope = $armCondScope->filterByFalseyValue($filteringExpr);
}

if (!$hasDefaultCond && !$hasAlwaysTrueCond && $condType->isBoolean()->yes() && $condType->isConstantScalarValue()->yes()) {
Expand Down
20 changes: 20 additions & 0 deletions tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php
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Expand Up @@ -1235,6 +1235,26 @@ public function testBug10909(): void
$this->analyse([__DIR__ . '/data/bug-10909.php'], []);
}

#[RequiresPhp('>= 8.0')]
public function testBug13981(): void
{
$this->cliArgumentsVariablesRegistered = true;
$this->polluteScopeWithLoopInitialAssignments = true;
$this->checkMaybeUndefinedVariables = true;
$this->polluteScopeWithAlwaysIterableForeach = true;

$this->analyse([__DIR__ . '/data/bug-13981.php'], [
[
'Undefined variable: $baseDir',
34,
],
[
'Variable $baseDir might not be defined.',
46,
],
]);
}

#[RequiresPhp('>= 8.0')]
public function testBug7705(): void
{
Expand Down
61 changes: 61 additions & 0 deletions tests/PHPStan/Rules/Variables/data/bug-13981.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,61 @@
<?php // lint >= 8.0

declare(strict_types = 1);

namespace Bug13981;

function foo(): string
{
$path = match (true) {
is_dir($baseDir = dirname(__DIR__).'/lang') => $baseDir,
default => '/translations',
};

return $path;
}

function foo2(): string
{
if (rand(0, 1)) {
$baseDir = '';
}

$path = match (true) {
is_dir($baseDir = dirname(__DIR__).'/lang') => $baseDir,
default => '/translations',
};

return $path;
}

function foo3(): string
{
$path = match (true) {
is_dir(dirname(__DIR__).'/lang2') => $baseDir,
is_dir($baseDir = dirname(__DIR__).'/lang') => $baseDir,
default => '/translations',
};

return $path;
}

function foo4(): string
{
$path = match (true) {
is_dir(dirname(__DIR__).'/lang2'),
is_dir($baseDir = dirname(__DIR__).'/lang') => $baseDir,
default => '/translations',
};

return $path;
}

function foo5(): string
{
$path = match (true) {
is_dir($baseDir = dirname(__DIR__).'/lang') => '$baseDir',
default => $baseDir,
};

return $path;
}
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