wp-includes/class-wp-query.php:4496Determines whether the query is for the front page of the site.
bool public function is_front_page() { // Most likely case. if ( 'posts' === get_option( 'show_on_front' ) && $this->is_home() ) { return true; } elseif ( 'page' === get_option( 'show_on_front' ) && get_option( 'page_on_front' ) && $this->is_page( get_option( 'page_on_front' ) ) ) { return true; } else { return false; } }Introduced in 3.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-query.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.