Fix unconstrained type parameter checks

This patch removes our old method of checking for unconstrained type
parameters which only worked for the basic cases such as:

  impl<T> Foo { }

But checking for unconstrained types is more complex, we need to handle
covariant types such as:

  impl<T> *T { }

Or

  struct foo<X,Y>(X,Y);
  impl<T> foo<&T,*T> {}

This rewrites the algorithm to take advantage of our substition
abstractions and HirIds so we can map the ids of the type-params to be
constrained and look at the trait-references used-arguments when the
generics are applied (or they may be empty) and then do the same for any
used arguments on an algebraic data type.

Fixes #1019

0 files changed, 0 insertions, 0 deletions