ItemTupleStructBuilder::field() should return a StructFieldBuilder directly. An intermediary TyBuilder is unnecessary and prevents the ability to create a pub tuple struct field.
ItemTupleStructBuilder::field() should return a StructFieldBuilder directly. An intermediary TyBuilder is unnecessary and prevents the ability to create a pub tuple struct field.

Manishearth/aster,huonw/rust-aster,erickt/aster,erickt/rust-aster,fxleblanc/rust-aster