wp-includes/theme.php:1751Checks whether a custom header is set or not.
boolfunction has_custom_header() { if ( has_header_image() || ( has_header_video() && is_header_video_active() ) ) { return true; } return false;}Introduced in 4.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/theme.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.