import syntax::ast::*; import syntax::visit; import driver::session::session; type ctx = {in_loop: bool, can_ret: bool}; fn check_crate(tcx: ty::ctxt, crate: @crate) { visit::visit_crate(*crate, {in_loop: false,can_ret: true}, visit::mk_vt(@{ visit_item: |i, _cx, v| { visit::visit_item(i, {in_loop: false, can_ret: true}, v); }, visit_expr: |e: @expr, cx: ctx, v: visit::vt| { match e.node { expr_while(e, b) => { v.visit_expr(e, cx, v); v.visit_block(b, {in_loop: true with cx}, v); } expr_loop(b, _) => { v.visit_block(b, {in_loop: true with cx}, v); } expr_fn(_, _, _, _) => { visit::visit_expr(e, {in_loop: false, can_ret: true}, v); } expr_fn_block(_, b, _) => { v.visit_block(b, {in_loop: false, can_ret: false}, v); } expr_loop_body(@{node: expr_fn_block(_, b, _), _}) => { let blk = ty::is_blockish(ty::ty_fn_proto(ty::expr_ty(tcx, e))); v.visit_block(b, {in_loop: true, can_ret: blk}, v); } expr_break(_) => { if !cx.in_loop { tcx.sess.span_err(e.span, ~"`break` outside of loop"); } } expr_again(_) => { if !cx.in_loop { tcx.sess.span_err(e.span, ~"`again` outside of loop"); } } expr_ret(oe) => { if !cx.can_ret { tcx.sess.span_err(e.span, ~"`return` in block function"); } visit::visit_expr_opt(oe, cx, v); } _ => visit::visit_expr(e, cx, v) } } with *visit::default_visitor() })); }