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librustc: Ensure that no moves from the inside of @ or & boxes occur. rs=crashing-servo

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This commit is contained in:
Patrick Walton 2012-12-14 17:50:48 -08:00
parent e67190a0d2
commit bdb2d659ae
2 changed files with 121 additions and 26 deletions
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124
src/librustc/middle/check_alt.rs
View File

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

23
src/test/compile-fail/by-move-pattern-binding.rs Normal file
View File

@ -0,0 +1,23 @@
enum E {
Foo,
Bar(~str)
}
struct S {
x: E
}
fn f(x: ~str) {}
fn main() {
let s = S { x: Bar(~"hello") };
match &s.x {
&Foo => {}
&Bar(identifier) => f(copy identifier) //~ ERROR by-move pattern bindings may not occur
};
match &s.x {
&Foo => {}
&Bar(ref identifier) => io::println(*identifier)
};
}