  We study a pointwise tracking optimal control problem for the stationary
Navier--Stokes equations; control constraints are also considered. The problem
entails the minimization of a cost functional involving point evaluations of
the state velocity field, thus leading to an adjoint problem with a linear
combination of Dirac measures as a forcing term in the momentum equation, and
whose solution has reduced regularity properties. We analyze the existence of
optimal solutions and derive first and, necessary and sufficient, second order
optimality conditions in the framework of regular solutions for the
Navier--Stokes equations. We develop two discretization strategies: a
semidiscrete strategy in which the control variable is not discretized, and a
fully discrete scheme in which the control variable is discretized with
piecewise constant functions. For each solution technique, we analyze
convergence properties of discretizations and derive a priori error estimates.
