librustc: Ensure that no moves from the inside of @ or & boxes occur. rs=crashing-servo
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Patrick Walton
parent
e67190a0d2
commit
bdb2d659ae
@ -40,15 +40,29 @@ fn check_crate(tcx: ty::ctxt, method_map: method_map, crate: @crate) {
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tcx.sess.abort_if_errors();
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}
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fn expr_is_non_moving_lvalue(cx: @AltCheckCtxt, expr: @expr) -> bool {
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if !ty::expr_is_lval(cx.tcx, cx.method_map, expr) {
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return false;
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}
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match cx.tcx.value_modes.find(expr.id) {
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Some(MoveValue) => return false,
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Some(CopyValue) | Some(ReadValue) => return true,
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None => {
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cx.tcx.sess.span_bug(expr.span, ~"no entry in value mode map");
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}
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}
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}
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fn check_expr(cx: @AltCheckCtxt, ex: @expr, &&s: (), v: visit::vt<()>) {
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visit::visit_expr(ex, s, v);
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match ex.node {
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expr_match(scrut, ref arms) => {
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// First, check legality of move bindings.
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let is_lvalue = ty::expr_is_lval(cx.tcx, cx.method_map, scrut);
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let is_non_moving_lvalue = expr_is_non_moving_lvalue(cx, ex);
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for arms.each |arm| {
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check_legality_of_move_bindings(cx,
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is_lvalue,
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is_non_moving_lvalue,
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arm.guard.is_some(),
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arm.pats);
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}
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@ -524,7 +538,7 @@ fn check_local(cx: @AltCheckCtxt, loc: @local, &&s: (), v: visit::vt<()>) {
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// Check legality of move bindings.
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let is_lvalue = match loc.node.init {
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Some(init) => ty::expr_is_lval(cx.tcx, cx.method_map, init),
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Some(init) => expr_is_non_moving_lvalue(cx, init),
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None => true
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};
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check_legality_of_move_bindings(cx, is_lvalue, false, [ loc.node.pat ]);
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@ -616,40 +630,98 @@ fn check_legality_of_move_bindings(cx: @AltCheckCtxt,
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}
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}
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let check_move: &fn(@pat, Option<@pat>) = |p, sub| {
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// check legality of moving out of the enum
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if sub.is_some() {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move with sub-bindings");
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} else if has_guard {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move into a pattern guard");
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} else if by_ref_span.is_some() {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move and by-ref \
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in the same pattern");
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tcx.sess.span_note(
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by_ref_span.get(),
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~"by-ref binding occurs here");
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} else if is_lvalue {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move when \
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matching an lvalue");
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}
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};
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if !any_by_move { return; } // pointless micro-optimization
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for pats.each |pat| {
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do walk_pat(*pat) |p| {
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if pat_is_binding(def_map, p) {
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match p.node {
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pat_ident(bind_by_move, _, sub) => {
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// check legality of moving out of the enum
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if sub.is_some() {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move with sub-bindings");
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} else if has_guard {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move into a pattern guard");
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} else if by_ref_span.is_some() {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move and by-ref \
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in the same pattern");
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tcx.sess.span_note(
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by_ref_span.get(),
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~"by-ref binding occurs here");
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} else if is_lvalue {
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tcx.sess.span_err(
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p.span,
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~"cannot bind by-move when \
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matching an lvalue");
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pat_ident(bind_by_move, _, sub) => check_move(p, sub),
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pat_ident(bind_infer, _, sub) => {
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match tcx.value_modes.find(p.id) {
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Some(MoveValue) => check_move(p, sub),
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Some(CopyValue) | Some(ReadValue) => {}
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None => {
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cx.tcx.sess.span_bug(
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pat.span, ~"no mode for pat binding");
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}
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}
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}
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_ => {}
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}
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}
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}
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// Now check to ensure that any move binding is not behind an @ or &.
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// This is always illegal.
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let vt = visit::mk_vt(@{
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visit_pat: |pat, behind_bad_pointer, v| {
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let error_out = || {
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cx.tcx.sess.span_err(pat.span, ~"by-move pattern \
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bindings may not occur \
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behind @ or & bindings");
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};
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match pat.node {
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pat_ident(binding_mode, _, sub) => {
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debug!("(check legality of move) checking pat \
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ident with behind_bad_pointer %?",
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behind_bad_pointer);
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match binding_mode {
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bind_by_move if behind_bad_pointer => error_out(),
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bind_infer if behind_bad_pointer => {
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match cx.tcx.value_modes.find(pat.id) {
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Some(MoveValue) => error_out(),
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Some(CopyValue) |
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Some(ReadValue) => {}
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None => {
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cx.tcx.sess.span_bug(pat.span,
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~"no mode for pat binding");
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}
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}
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}
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_ => {}
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}
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match sub {
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None => {}
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Some(subpat) => {
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(v.visit_pat)(subpat, behind_bad_pointer, v);
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}
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}
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}
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pat_box(subpat) | pat_region(subpat) => {
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(v.visit_pat)(subpat, true, v);
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}
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_ => visit::visit_pat(pat, behind_bad_pointer, v)
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}
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},
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.. *visit::default_visitor::<bool>()
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});
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(vt.visit_pat)(*pat, false, vt);
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}
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}
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23
src/test/compile-fail/by-move-pattern-binding.rs
Normal file
23
src/test/compile-fail/by-move-pattern-binding.rs
Normal file
@ -0,0 +1,23 @@
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enum E {
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Foo,
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Bar(~str)
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}
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struct S {
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x: E
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}
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fn f(x: ~str) {}
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fn main() {
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let s = S { x: Bar(~"hello") };
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match &s.x {
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&Foo => {}
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&Bar(identifier) => f(copy identifier) //~ ERROR by-move pattern bindings may not occur
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};
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match &s.x {
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&Foo => {}
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&Bar(ref identifier) => io::println(*identifier)
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};
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}
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