Function block_over 

pub fn block_over(
    source: BoundSource,
    filter: Option<BoundExpr>,
    columns: Vec<BoundResultColumn>,
) -> BoundSelect

Returns a block that reads one FROM term and nothing else.

Everything a SELECT can carry is empty here on purpose: this exists to wrap a term the binder has already produced so the compiler can iterate it, not to stand in for a query somebody wrote.