PHP 7.3.0 raises E_NOTICE when compact() parameters do not refer to an existing variable

[ettoredn]

It appears that since PHP 7.3.0 compact() raises E_NOTICE when passed variable names are undefined.

PHP Notice: compact(): Undefined variable: post_status in wp-admin/includes/post.php on line 1059
PHP Notice: compact(): Undefined variable: perm in wp-admin/includes/post.php on line 1059
PHP Notice: compact(): Undefined variable: order in wp-admin/includes/post.php on line 1059
PHP Notice: compact(): Undefined variable: orderby in wp-admin/includes/post.php on line 1059

Steps to reproduce:

1. Install WP 5.0.0
2. set error_reporting = E_ALL
3. Log in the admin interface.

I get the feeling there a few other similar situations across the WP codebase.

[ocean90]

Duplicate of #45483.