Skip to content

Infer non-empty-array after array_key_first/last() #4536

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
staabm merged 8 commits into from
Feb 10, 2026
+110 −0
Merged

Infer non-empty-array after array_key_first/last() #4536

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
0ea52a0
Infer non-empty-array after array_key_first/last()
staabm Nov 8, 2025
d1aece6
Update bug-13546.php
staabm Nov 8, 2025
37ea055
add test
staabm Nov 8, 2025
2505ba4
test maybe null
staabm Nov 8, 2025
1427f89
fix php 7.4 compat
staabm Nov 8, 2025
7d4c4dc
Update bug-13546.php
staabm Nov 8, 2025
c8f2b3b
add test
staabm Feb 10, 2026
3532071
Update TypeSpecifier.php
staabm Feb 10, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 16 additions & 0 deletions src/Analyser/TypeSpecifier.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2383,6 +2383,22 @@ private function resolveNormalizedIdentical(Expr\BinaryOp\Identical $expr, Scope
}
}

// array_key_first($a) !== null
Copy link
Contributor

@VincentLanglet VincentLanglet Feb 9, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I thought you forgot null !== array_key_first($a) but seems like it works looking at the test.
I'm not familiar with this code to know why at first sight.

Copy link
Contributor Author

@staabm staabm Feb 10, 2026 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

we are in resolveNormalizedIdentical, which is invoked in both directions here:

phpstan-src/src/Analyser/TypeSpecifier.php

Lines 2258 to 2269 in eb4e247

// Normalize to: fn() === expr
if ($rightExpr instanceof FuncCall && !$leftExpr instanceof FuncCall) {
$specifiedTypes = $this->resolveNormalizedIdentical(new Expr\BinaryOp\Identical(
$rightExpr,
$leftExpr,
), $scope, $context);
} else {
$specifiedTypes = $this->resolveNormalizedIdentical(new Expr\BinaryOp\Identical(
$leftExpr,
$rightExpr,
), $scope, $context);
}

// array_key_last($a) !== null
if (
$unwrappedLeftExpr instanceof FuncCall
&& $unwrappedLeftExpr->name instanceof Name
&& in_array($unwrappedLeftExpr->name->toLowerString(), ['array_key_first', 'array_key_last'], true)
&& isset($unwrappedLeftExpr->getArgs()[0])
&& $rightType->isNull()->yes()
Copy link
Contributor

@VincentLanglet VincentLanglet Feb 9, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You're getting escaped mutant here, but if I understand correctly, it should be supported by

if (array_key_first($array) !== $nullOrInt) {
		assertType('list<string>', $array);
	}

Copy link
Contributor Author

@staabm staabm Feb 10, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

agree. I tested it locally and the test starts failling when I manually mutate the code.

) {
$args = $unwrappedLeftExpr->getArgs();
$argType = $scope->getType($args[0]->value);
if ($argType->isArray()->yes()) {
return $this->create($args[0]->value, new NonEmptyArrayType(), $context->negate(), $scope)->setRootExpr($expr);
}
}

// preg_match($a) === $b
if (
$context->true()
Expand Down
94 changes: 94 additions & 0 deletions tests/PHPStan/Analyser/nsrt/bug-13546.php
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,94 @@
<?php
namespace Bug13546;

use function PHPStan\Testing\assertType;

/** @param array<int> $array */
function first(array $array): void
{
if (array_key_first($array) !== null) {
assertType('non-empty-array<int>', $array);
} else {
assertType('array{}', $array);
}
assertType('array<int>', $array);
}

/** @param array<int> $array */
function firstReversed(array $array): void
{
if (null !== array_key_first($array)) {
assertType('non-empty-array<int>', $array);
} else {
assertType('array{}', $array);
}
assertType('array<int>', $array);
}

/** @param array<int> $array */
function last(array $array): void
{
if (array_key_last($array) !== null) {
assertType('non-empty-array<int>', $array);
} else {
assertType('array{}', $array);
}
assertType('array<int>', $array);
}

function maybeArray(array $array, $mixed): void
{
$arrayOrMixed = rand(0, 1) ? $array : $mixed;

if (array_key_last($arrayOrMixed) !== null) {
assertType('mixed', $arrayOrMixed);
} else {
assertType('mixed', $arrayOrMixed);
}
assertType('mixed', $arrayOrMixed);
}

function mixedLast($mixed): void
{
if (is_array($mixed)) {
return;
}

if (array_key_last($mixed) !== null) {
assertType('mixed~array<mixed, mixed>', $mixed);
} else {
assertType('mixed~array<mixed, mixed>', $mixed);
}
assertType('mixed~array<mixed, mixed>', $mixed);
}

/** @param list<string> $array */
function firstInCondition(array $array)
{
if (($key = array_key_first($array)) !== null) {
assertType('list<string>', $array); // could be 'non-empty-list<string>'
return $array[$key];
}
assertType('list<string>', $array);
return null;
}

/** @param list<string> $array */
function maybeNull(array $array, ?int $nullOrInt, ?string $nullOrString): void
{
if (array_key_first($array) !== $nullOrInt) {
assertType('list<string>', $array);
}
if (array_key_first($array) !== $nullOrString) {
assertType('list<string>', $array);
}
assertType('list<string>', $array);

if (array_key_last($array) !== $nullOrInt) {
assertType('list<string>', $array);
}
if (array_key_last($array) !== $nullOrString) {
assertType('list<string>', $array);
}
assertType('list<string>', $array);
}
Loading