rust/src/rustc/middle/check_loop.rs

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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) {
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visit::visit_crate(*crate, {in_loop: false,can_ret: true}, visit::mk_vt(@{
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visit_item: |i, _cx, v| {
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visit::visit_item(i, {in_loop: false, can_ret: true}, v);
},
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visit_expr: |e: @expr, cx: ctx, v: visit::vt<ctx>| {
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alt e.node {
expr_while(e, b) {
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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);
}
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expr_fn_block(_, b, _) {
v.visit_block(b, {in_loop: false, can_ret: false}, v);
}
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expr_loop_body(@{node: expr_fn_block(_, b, _), _}) {
let blk = is_blockish(ty::ty_fn_proto(ty::expr_ty(tcx, e)));
v.visit_block(b, {in_loop: true, can_ret: blk}, v);
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}
expr_break {
if !cx.in_loop {
tcx.sess.span_err(e.span, "`break` outside of loop");
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}
}
expr_again {
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if !cx.in_loop {
tcx.sess.span_err(e.span, "`again` outside of loop");
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}
}
expr_ret(oe) {
if !cx.can_ret {
tcx.sess.span_err(e.span, "`ret` in block function");
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}
visit::visit_expr_opt(oe, cx, v);
}
_ { visit::visit_expr(e, cx, v); }
}
}
with *visit::default_visitor()
}));
}