Macro assign_solver 

macro_rules! assign_solver {
    ( $self:ident, $def:ident, $lang_item:ident, TraitId, solver ) => { ... };
    ( $self:ident, $def:ident, $lang_item:ident, TypeAliasId, solver ) => { ... };
    ( $self:ident, $def:ident, $lang_item:ident, StructId, solver ) => { ... };
    ( $self:ident, $def:ident, $lang_item:ident, EnumId, solver ) => { ... };
    ( $self:ident, $def:ident, $lang_item:ident, UnionId, solver ) => { ... };
    ( $self:ident, $def:ident, $lang_item:ident, $ty:ident ) => { ... };
}