//! Linear-solver return status — port of `ESymSolverStatus`
//! in `IpSymLinearSolver.hpp`.
/// Outcome of a single call into a [`crate::SymLinearSolver`] or
/// [`crate::SparseSymLinearSolverInterface`].
///
/// Variant order and semantics match upstream Ipopt's
/// `enum ESymSolverStatus` so the algorithm-side state machines port
/// 1:1.