Solver.Magic_equalTakes a slow but type-correct Equal module and returns the magic version, which is faster. NOTE: for this to be sound, the function in the original module must be just %equal (up to runtime representation).
module X : Solver_intf.Equaltype ('a, 'b, 'c) t = ('a, 'b, 'c) X.tval equal :
('a0, 'b, 'l0 * 'r0) t ->
('a1, 'b, 'l1 * 'r1) t ->
('a0, 'a1) Ocaml_utils.Misc_stdlib.eq option