//! Naming rules every dialect's schema producers share.
/// The columns that name a table-level (composite) foreign key: its first
/// column, or all of them when another foreign key on the same table would
/// otherwise get the same name.
#[must_use]pubfncomposite_foreign_key_name_columns<'a>(columns:&'a [&'astr],
collides:bool,
)->&'a[&'astr]{if collides || columns.is_empty(){
columns
}else{&columns[..1]}}