Using the following code:

<?php
xdebug_start_code_coverage(XDEBUG_CC_UNUSED | XDEBUG_CC_DEAD_CODE);
$a = 1;
$options = [
'key1' => 'value1',
'key2' => 'value2',
'key3' => 'value3'
];
print_r(xdebug_get_code_coverage());
xdebug_stop_code_coverage();
?>

The result is:

Array
(
[/home/jaillet/coverage_missing.php] => Array
(
[3] => 1
[5] => 1
[6] => 1
[8] => 1
[9] => 1
)

)

Seems the line 4 (ie. $options = [) is missing.