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Fix phpstan/phpstan#14270: Regression: regex matches after checking non-empty array #5209

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Merged
ondrejmirtes merged 5 commits into from
Mar 12, 2026
Merged

Fix phpstan/phpstan#14270: Regression: regex matches after checking non-empty array #5209

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a39c294
Fix regression in offset access check on non-empty narrowed arrays
phpstan-bot Mar 12, 2026
90d004a
Revert incorrect flattenTypes() fix for bug-14270
phpstan-bot Mar 12, 2026
9d5dba4
Fix preg_match type inference: return union of empty and matched types
phpstan-bot Mar 12, 2026
4c08be2
Remove outdated 'could be' comments from preg_match test
phpstan-bot Mar 12, 2026
3dda0a3
added regression test
staabm Mar 12, 2026
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13 changes: 12 additions & 1 deletion src/Type/Php/PregMatchParameterOutTypeExtension.php
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Expand Up @@ -8,8 +8,10 @@
use PHPStan\Reflection\FunctionReflection;
use PHPStan\Reflection\ParameterReflection;
use PHPStan\TrinaryLogic;
use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
use PHPStan\Type\FunctionParameterOutTypeExtension;
use PHPStan\Type\Type;
use PHPStan\Type\TypeCombinator;
use function in_array;
use function strtolower;

Expand Down Expand Up @@ -49,8 +51,17 @@ public function getParameterOutTypeFromFunctionCall(FunctionReflection $function
}

if ($functionReflection->getName() === 'preg_match') {
return $this->regexShapeMatcher->matchExpr($patternArg->value, $flagsType, TrinaryLogic::createMaybe(), $scope);
$matchedType = $this->regexShapeMatcher->matchExpr($patternArg->value, $flagsType, TrinaryLogic::createYes(), $scope);
if ($matchedType === null) {
return null;
}

return TypeCombinator::union(
ConstantArrayTypeBuilder::createEmpty()->getArray(),
$matchedType,
);
}

return $this->regexShapeMatcher->matchAllExpr($patternArg->value, $flagsType, TrinaryLogic::createMaybe(), $scope);
}

Expand Down
4 changes: 2 additions & 2 deletions tests/PHPStan/Analyser/data/param-out.php
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Expand Up @@ -494,10 +494,10 @@ function fooMatch(string $input): void {
assertType('list<array{string}>', $matches);

preg_match('/@[a-z\d](?:[a-z\d]|-(?=[a-z\d])){0,38}(?!\w)/', $input, $matches, PREG_UNMATCHED_AS_NULL);
assertType("array{0?: string}", $matches);
assertType("array{}|array{non-falsy-string}", $matches);
}

function testMatch() {
preg_match('#.*#', 'foo', $matches);
assertType('array{0?: string}', $matches);
assertType('array{}|array{string}', $matches);
}
6 changes: 3 additions & 3 deletions tests/PHPStan/Analyser/nsrt/bug-11293.php
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Expand Up @@ -30,7 +30,7 @@ public function sayHello3(string $s): void
public function sayHello4(string $s): void
{
if (preg_match('/data-(\d{6})\.json$/', $s, $matches) <= 0) {
assertType('list{0?: string, 1?: non-falsy-string&numeric-string}', $matches);
assertType('array{}|array{non-falsy-string, non-falsy-string&numeric-string}', $matches);

return;
}
Expand All @@ -41,7 +41,7 @@ public function sayHello4(string $s): void
public function sayHello5(string $s): void
{
if (preg_match('/data-(\d{6})\.json$/', $s, $matches) < 1) {
assertType('list{0?: string, 1?: non-falsy-string&numeric-string}', $matches);
assertType('array{}|array{non-falsy-string, non-falsy-string&numeric-string}', $matches);

return;
}
Expand All @@ -52,7 +52,7 @@ public function sayHello5(string $s): void
public function sayHello6(string $s): void
{
if (1 > preg_match('/data-(\d{6})\.json$/', $s, $matches)) {
assertType('list{0?: string, 1?: non-falsy-string&numeric-string}', $matches);
assertType('array{}|array{non-falsy-string, non-falsy-string&numeric-string}', $matches);

return;
}
Expand Down
6 changes: 3 additions & 3 deletions tests/PHPStan/Analyser/nsrt/bug-11311.php
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Expand Up @@ -191,12 +191,12 @@ function (string $s): void {

function (string $s): void {
preg_match('/%a(\d*)/', $s, $matches, PREG_UNMATCHED_AS_NULL);
assertType("list{0?: string, 1?: ''|numeric-string|null}", $matches); // could be array{0?: string, 1?: ''|numeric-string}
assertType("array{}|array{non-falsy-string, ''|numeric-string}", $matches); // could be array{0?: string, 1?: ''|numeric-string}
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@staabm staabm Mar 12, 2026

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we should drop the "could be" comments now

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@phpstan-bot phpstan-bot Mar 12, 2026

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Done. I removed the two outdated "could be" comments from tests/PHPStan/Analyser/nsrt/bug-11311.php (lines 194 and 199) that were no longer applicable now that preg_match returns a proper union type. The commit has been pushed.

  • make phpstan passes with no errors
  • The one test failure in RawErrorFormatterTest is pre-existing and unrelated to this change

};

function (string $s): void {
preg_match('/%a(\d*)?/', $s, $matches, PREG_UNMATCHED_AS_NULL);
assertType("list{0?: string, 1?: ''|numeric-string|null}", $matches); // could be array{0?: string, 1?: ''|numeric-string}
assertType("array{}|array{non-falsy-string, ''|numeric-string|null}", $matches); // could be array{0?: string, 1?: ''|numeric-string}
};

function (string $s): void {
Expand All @@ -222,5 +222,5 @@ function (string $s): void {

function (string $s): void {
preg_match('~a|(\d)|(\s)~', $s, $matches, PREG_UNMATCHED_AS_NULL);
assertType("list{0?: string, 1?: numeric-string|null, 2?: non-empty-string|null}", $matches);
assertType("array{}|array{non-empty-string, numeric-string|null, non-empty-string|null}", $matches);
};
2 changes: 1 addition & 1 deletion tests/PHPStan/Analyser/nsrt/bug-11580.php
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Expand Up @@ -26,7 +26,7 @@ public function bad2(string $in): void
public function bad3(string $in): void
{
$result = preg_match('~^/xxx/([\w\-]+)/?([\w\-]+)?/?$~', $in, $matches);
assertType('list{0?: string, 1?: non-empty-string, 2?: non-empty-string}', $matches);
assertType('array{}|array{0: non-falsy-string, 1: non-empty-string, 2?: non-empty-string}', $matches);
if ($result) {
assertType('array{0: non-falsy-string, 1: non-empty-string, 2?: non-empty-string}', $matches);
}
Expand Down
2 changes: 1 addition & 1 deletion tests/PHPStan/Analyser/nsrt/count-type.php
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Expand Up @@ -94,7 +94,7 @@ public function constantArrayWhichCanBecomeList(string $h): void
return;
}

assertType('array{string, non-empty-string}', $matches);
assertType('array{non-falsy-string, non-empty-string}', $matches);
}

}
Expand Down
4 changes: 2 additions & 2 deletions tests/PHPStan/Analyser/nsrt/if.php
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Expand Up @@ -392,7 +392,7 @@ function () {
assertVariableCertainty(TrinaryLogic::createYes(), $anotherF);
assertType('int<1, max>', $anotherF);
assertVariableCertainty(TrinaryLogic::createYes(), $matches);
assertType('array{0?: string}', $matches);
assertType('array{}|array{string}', $matches);
assertVariableCertainty(TrinaryLogic::createYes(), $anotherArray);
assertType('array{test: array{\'another\'}}', $anotherArray);
assertVariableCertainty(TrinaryLogic::createYes(), $ifVar);
Expand All @@ -405,7 +405,7 @@ function () {
assertType('1|2|3', $ifNotNestedVar);
assertVariableCertainty(TrinaryLogic::createNo(), $variableOnlyInEarlyTerminatingElse);
assertVariableCertainty(TrinaryLogic::createMaybe(), $matches2);
assertType('array{0?: string}', $matches2);
assertType('array{}|array{string}', $matches2);
assertVariableCertainty(TrinaryLogic::createYes(), $inTry);
assertType('1', $inTry);
assertVariableCertainty(TrinaryLogic::createYes(), $matches3);
Expand Down
10 changes: 5 additions & 5 deletions tests/PHPStan/Analyser/nsrt/preg_match_shapes.php
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Expand Up @@ -525,15 +525,15 @@ function bug11323(string $s): void {

function (string $s): void {
preg_match('/%a(\d*)/', $s, $matches);
assertType("list{0?: string, 1?: ''|numeric-string}", $matches);
assertType("array{}|array{non-falsy-string, ''|numeric-string}", $matches);
};

class Bug11376
{
public function test(string $str): void
{
preg_match('~^(?:(\w+)::)?(\w+)$~', $str, $matches);
assertType('list{0?: string, 1?: string, 2?: non-empty-string}', $matches);
assertType("array{}|array{non-empty-string, string, non-empty-string}", $matches);
}

public function test2(string $str): void
Expand Down Expand Up @@ -706,7 +706,7 @@ static public function sayHello(string $source): void
// 2 => '1',
//)

assertType("array{0?: string, dateFrom?: ''|numeric-string, 1?: ''|numeric-string, dateTo?: numeric-string, 2?: numeric-string}", $matches);
assertType("array{}|array{0: string, dateFrom?: ''|numeric-string, 1?: ''|numeric-string, dateTo?: numeric-string, 2?: numeric-string}", $matches);
}
}

Expand All @@ -730,7 +730,7 @@ function (string $s): void {

function (string $s): void {
preg_match('~a|(\d)|(\s)~', $s, $matches);
assertType("list{0?: string, 1?: '', 2?: non-empty-string}|list{0?: string, 1?: numeric-string}", $matches);
assertType("array{}|array{0: non-empty-string, 1?: numeric-string}|array{non-empty-string, '', non-empty-string}", $matches);
};

function bug11490 (string $expression): void {
Expand Down Expand Up @@ -1013,7 +1013,7 @@ function bug12749f(string $str): void

function bug12397(string $string): void {
$m = preg_match('#\b([A-Z]{2,})-(\d+)#', $string, $match);
assertType('list{0?: string, 1?: non-falsy-string, 2?: numeric-string}', $match);
assertType("array{}|array{non-falsy-string, non-falsy-string, numeric-string}", $match);
}

function bug12792(string $string): void {
Expand Down
5 changes: 5 additions & 0 deletions tests/PHPStan/Rules/Arrays/ArrayDestructuringRuleTest.php
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Expand Up @@ -49,6 +49,11 @@ public function testRule(): void
]);
}

public function testBug14270(): void
{
$this->analyse([__DIR__ . '/data/bug-14270.php'], []);
}

#[RequiresPhp('>= 8.0')]
public function testRuleWithNullsafeVariant(): void
{
Expand Down
14 changes: 14 additions & 0 deletions tests/PHPStan/Rules/Arrays/data/bug-14270.php
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@@ -0,0 +1,14 @@
<?php declare(strict_types = 1);

namespace Bug14270;

class Foo
{
public function getDuration(string $path): void {
preg_match('~^([a-z]+)\:\/\/(.+)~', $path, $matches);
$scheme = null;
if ($matches !== []) {
[, $scheme, $path] = $matches;
}
}
}
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