1. A method of computer aided design of a product comprising a set of objects ( 11 - 51 ), said method comprising a step of: identifying (S 10 ) constraints ( 1121 - 4151 ) linking objects ( 11 - 51 ) of said set of objects, each of said constraints being oriented from a first object to a second object so as to ensure, upon solving (S 90 ) the constraints, that the first object is not moved provided that all other of said constraints are solved; if an impossibility of solving said constraints is detected, testing whether said constraints can be solved upon modifying one oriented constraint ( 4151 ) amongst said constraints; and returning a suggestion ( 110 ) for modifying said one oriented constraint ( 4151 ) including displaying the suggestion to a user.