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Fix GH-23576: array_keys() on an empty array returns a non-zero next index #23577

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Fix GH-23576: array_keys() on an empty array returns a non-zero next index #23577

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158316f
Fix GH-23576: array_keys() on an empty array returns a non-zero next …
lazerg Sep 4, 2026
457a21e
Add empty array cases to the GH-23576 test
lazerg Sep 5, 2026
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2 changes: 2 additions & 0 deletions NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,8 @@ PHP NEWS
. Fixed a memory leak in array_merge_recursive() when the recursive merge of
an object converted to an array fails. (David Carlier)
. Fixed read buffer compaction in php_stream_filter_flush(). (crystarm)
. Fixed bug GH-23576 (Next index for array returned from array_keys() is
wrong). (Lazizbek Ergashev)

- SimpleXML:
. Fixed writing to a dimension of the object returned by attributes() not
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2 changes: 1 addition & 1 deletion ext/standard/array.c
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Expand Up @@ -4504,7 +4504,7 @@ PHP_FUNCTION(array_keys)

/* Base case: empty input */
if (!elem_count) {
RETURN_COPY(input);
RETURN_EMPTY_ARRAY();
}

/* Initialize return array */
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58 changes: 58 additions & 0 deletions ext/standard/tests/array/gh23576.phpt
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@@ -0,0 +1,58 @@
--TEST--
GH-23576 (Next index for array returned from array_keys() is wrong)
--FILE--
<?php
$a = [123 => 123];

@devnexen devnexen Sep 5, 2026

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would be nice to also test an empty array ?

@lazerg lazerg Sep 5, 2026

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Good idea, thanks. Added in 457a21e. The test now also runs all three array_keys() forms on an empty array.

unset($a[123]);

$b = array_keys($a);
$b[] = 42;
var_dump($b);

$c = array_keys($a, 123);
$c[] = 42;
var_dump($c);

$d = array_keys($a, 123, true);
$d[] = 42;
var_dump($d);

$e = [];

$f = array_keys($e);
$f[] = 42;
var_dump($f);

$g = array_keys($e, 123);
$g[] = 42;
var_dump($g);

$h = array_keys($e, 123, true);
$h[] = 42;
var_dump($h);
?>
--EXPECT--
array(1) {
[0]=>
int(42)
}
array(1) {
[0]=>
int(42)
}
array(1) {
[0]=>
int(42)
}
array(1) {
[0]=>
int(42)
}
array(1) {
[0]=>
int(42)
}
array(1) {
[0]=>
int(42)
}