Struct DynSelect 

pub struct DynSelect<D, Output> { /* private fields */ }

The one unavoidable escape hatch in this design: a single static type cannot mean “this table is joined” in one branch of an if and “it isn’t” in another. Only the join skeleton is erased. Every column reference was already checked against a concrete Scope before .erase(), and predicates keep the same closed ExprKind/Value representation used everywhere else, with no Box<dyn _> involved.

Composition happens before erasure, which is why DynSelect offers no further .filter()/.join(). It exists only to let two fully-built branches with different join topology unify into one value.

Implementations

impl<D, Output> DynSelect<D, Output>

pub fn limit(self, n: impl IntoRowCount) -> Self

LIMIT/OFFSET survive erasure because they reference nothing: a row count needs no proof that a table is joined. order_by doesn’t follow them here. A sort key is a column reference, and the scope that would justify it is exactly what .erase() gave up.

pub fn offset(self, n: impl IntoRowCount) -> Self

impl<D: Dialect, Output> DynSelect<D, Output>

pub fn count_sql(&self, _dialect: D) -> (String, Vec<Value>)

The same total Select::count_sql renders. Paging is the reason LIMIT/OFFSET survive erasure, and a page needs a total.

pub fn to_sql(&self, _dialect: D) -> (String, Vec<Value>)