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Fix phpstan/phpstan#14369: Null coalescing assignment operator combined with throwing #5297

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Merged
VincentLanglet merged 3 commits into from
Mar 25, 2026
Merged

Fix phpstan/phpstan#14369: Null coalescing assignment operator combined with throwing #5297

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1eb6eb9
Fix phpstan/phpstan#14369: Null coalescing assignment with throw not …
phpstan-bot Mar 25, 2026
9d63db2
Handle always-null LHS and always-terminating LHS in null coalescing …
phpstan-bot Mar 25, 2026
6435689
Add test for maybe-null case in null coalescing assignment
phpstan-bot Mar 25, 2026
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3 changes: 2 additions & 1 deletion src/Analyser/ExprHandler/AssignOpHandler.php
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Original file line number Diff line number Diff line change
Expand Up @@ -66,10 +66,11 @@ static function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $contex
$exprResult = $nodeScopeResolver->processExprNode($stmt, $expr->expr, $scope, $storage, $nodeCallback, $context->enterDeep());
if ($expr instanceof Expr\AssignOp\Coalesce) {
$nodeScopeResolver->storeBeforeScope($storage, $expr, $originalScope);
$isAlwaysTerminating = $exprResult->isAlwaysTerminating() && $originalScope->getType($expr->var)->isNull()->yes();
return new ExpressionResult(
$exprResult->getScope()->mergeWith($originalScope),
$exprResult->hasYield(),
$exprResult->isAlwaysTerminating(),
$isAlwaysTerminating,
$exprResult->getThrowPoints(),
$exprResult->getImpurePoints(),
);
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35 changes: 35 additions & 0 deletions tests/PHPStan/Analyser/nsrt/bug-14369.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
<?php // lint >= 8.0

declare(strict_types = 1);

namespace Bug14369;

use Exception;
use function PHPStan\Testing\assertType;

function test(string|null $test): void
{
$test ??= throw new Exception();

assertType('string', $test);
}

function testMaybeNull(): void
{
if (rand(0, 1)) {
$test = null;
} else {
$test = 'hello';
}
$test ??= throw new Exception();

assertType("'hello'", $test);
}

function testAlwaysNull(): void
{
$test = null;
$test ??= throw new Exception();
Comment on lines +31 to +32
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@staabm staabm Mar 25, 2026

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I would add another test in which $test is maybe null

like

if (rand(0,1)) {
  $test = null;
} else {
  $test = 'hallo';
}

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@VincentLanglet VincentLanglet Mar 25, 2026 •
edited
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That's already the original issue with $test being ?string (line 12)

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@phpstan-bot phpstan-bot Mar 25, 2026

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The working tree is clean and all the reviewer feedback has already been addressed in previous commits:

  1. VincentLanglet's latest comment is just noting that the ?string case is already covered at line 12 — no action needed.
  2. staabm's request for a "maybe null" test was already addressed in commit 6435689ae.
  3. Both reviewers have approved the PR.

There are no outstanding changes to make. The branch is already up to date with the remote.

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@phpstan-bot phpstan-bot Mar 25, 2026

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This task already completed too — all 11658 tests passed. The commit addressing staabm's review feedback has already been pushed. Everything is done.


assertType('*NEVER*', $test);
}
15 changes: 15 additions & 0 deletions tests/PHPStan/Rules/DeadCode/UnreachableStatementRuleTest.php
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Expand Up @@ -397,4 +397,19 @@ public function testBug14328(): void
]);
}

public function testBug14369(): void
{
$this->treatPhpDocTypesAsCertain = true;
$this->analyse([__DIR__ . '/data/bug-14369.php'], [
[
'Unreachable statement - code above always terminates.',
33,
],
[
'Unreachable statement - code above always terminates.',
40,
],
]);
}

}
47 changes: 47 additions & 0 deletions tests/PHPStan/Rules/DeadCode/data/bug-14369.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
<?php // lint >= 8.0

declare(strict_types = 1);

namespace Bug14369DeadCode;

use Exception;

function test(string|null $test): void
{
$test ??= throw new Exception();

echo $test;
}

function testMaybeNull(): void
{
if (rand(0, 1)) {
$test = null;
} else {
$test = 'hello';
}
$test ??= throw new Exception();

echo $test;
}

function testAlwaysNull(): void
{
$test = null;
$test ??= throw new Exception();

echo $test;
}

function testAlwaysTerminatingLhs(): void
{
alwaysThrows()->prop ??= throw new Exception();

echo 'unreachable';
}

/** @return never */
function alwaysThrows(): never
{
throw new Exception();
}
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