c# - Generic and non-generic method overload rules with type inference -

given following 2 overloaded method signatures:

public b dosomething<a,b>(a objone, b objtwo) public object dosomething(object objone, type objtype); 

i expect calling call second signature, not:

var obj = new sometype(); var type = typeof(someothertype);  dosomething(obj, type); 

it seems me looking @ spec, second overload more applicable (has 1 exact type , lesser arity). but, not called. instead, first overload called type object , b type type. why , there way call method aside either renaming method or using named parameters?

edit:

here parts of spec i'm referring in 7.5.3.2:

in case parameter type sequences {p1, p2, …, pn} , {q1, q2, …, qn} equivalent (i.e. each pi has identity conversion corresponding qi), following tie-breaking rules applied, in order, determine better function member.

• if mp non-generic method , mq generic method, mp better mq.
• ...
• otherwise, if mp has more specific parameter types mq, mp better mq. let {r1, r2, …, rn} , {s1, s2, …, sn} represent uninstantiated , unexpanded parameter types of mp , mq. mp’s parameter types more specific mq’s if, each parameter, rx not less specific sx, and, @ least 1 parameter, rx more specific sx:
  • a type parameter less specific non-type parameter.
  • ...

after edit here methods compiler choose between

dosomething<sometype,type>(sometype o, type t) dosomething(object o,type t); 

as specification says picking better function member:

given argument list set of argument expressions { e1, e2, ..., en } , 2 applicable function members mp , mq parameter types { p1, p2, ..., pn } , { q1, q2, ..., qn }, mp defined better function member mq if
• @ least 1 argument, conversion ex px better conversion ex qx.

generic method have better conversion sometype sometype non-generic's method conversion sometype object. if non-generic method defined

dosomething(sometype o, type t); 

then there not arguments better conversion, , you'll fall case:

in case parameter type sequences {p1, p2, …, pn} , {q1, q2, …, qn} equivalent

where first rule pick non-generic method:

• if mp non-generic method , mq generic method, mp better mq.

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note: before edited question, there first argument of type object, , generic method was

dosomething<object,type>(object o, type t) 

and again, parameter sequences equivalent in case, , non-generic method picked.