Linearity not preserved across function/method boundaries

[mukul-rathi]

consider:

class Bar = linear... {....} 
function int foo(Bar x, Bar y){
   x.f + y.f
}
let z = new Bar();
foo(z,z); // here have passed same object in, so not linear.

[mukul-rathi]

Solution: check all linear variables are not owned - have been consumed when entering a function scope.

[mukul-rathi]

This is stale - new version of the type system will have borrowing for function args