boehm::ffi::GC_bitmap
type GC_bitmap = *mut GC_word;
type GC_bitmap = *mut GC_word;
                Prefix searches with a type followed by a colon (e.g.
                fn:) to restrict the search to a given type.
            
                Accepted types are: fn, mod,
                struct (or str), enum,
                trait, typedef (or
                tdef).