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qnighyqnighy
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Add unsized tuple coercions.
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18 files changed

+549
-18
lines changed

18 files changed

+549
-18
lines changed

‎src/librustc/traits/error_reporting.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1060,7 +1060,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
10601060
err.note("slice and array elements must have `Sized` type");
10611061
}
10621062
ObligationCauseCode::TupleElem => {
1063-
err.note("tuple elements must have `Sized` type");
1063+
err.note("only the last element of a tuple may have a dynamically sized type");
10641064
}
10651065
ObligationCauseCode::ProjectionWf(data) => {
10661066
err.note(&format!("required so that the projection `{}` is well-formed",

‎src/librustc/traits/select.rs‎

Lines changed: 36 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1651,6 +1651,11 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
16511651
def_id_a == def_id_b
16521652
}
16531653

1654+
// (.., T) -> (.., U).
1655+
(&ty::TyTuple(tys_a, _), &ty::TyTuple(tys_b, _)) => {
1656+
tys_a.len() == tys_b.len()
1657+
}
1658+
16541659
_ => false
16551660
};
16561661

@@ -2617,6 +2622,37 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
26172622
&[inner_target]));
26182623
}
26192624

2625+
// (.., T) -> (.., U).
2626+
(&ty::TyTuple(tys_a, _), &ty::TyTuple(tys_b, _)) => {
2627+
assert_eq!(tys_a.len(), tys_b.len());
2628+
2629+
// The last field of the tuple has to exist.
2630+
let (a_last, a_mid) = if let Some(x) = tys_a.split_last() {
2631+
x
2632+
} else {
2633+
return Err(Unimplemented);
2634+
};
2635+
let b_last = tys_b.last().unwrap();
2636+
2637+
// Check that the source tuple with the target's
2638+
// last element is a subtype of the target.
2639+
let new_tuple = tcx.mk_tup(a_mid.iter().chain(Some(b_last)), false);
2640+
let InferOk { obligations, .. } =
2641+
self.infcx.at(&obligation.cause, obligation.param_env)
2642+
.eq(target, new_tuple)
2643+
.map_err(|_| Unimplemented)?;
2644+
self.inferred_obligations.extend(obligations);
2645+
2646+
// Construct the nested T: Unsize<U> predicate.
2647+
nested.push(tcx.predicate_for_trait_def(
2648+
obligation.param_env,
2649+
obligation.cause.clone(),
2650+
obligation.predicate.def_id(),
2651+
obligation.recursion_depth + 1,
2652+
a_last,
2653+
&[b_last]));
2654+
}
2655+
26202656
_ => bug!()
26212657
};
26222658

‎src/librustc/ty/layout.rs‎

Lines changed: 7 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1220,12 +1220,16 @@ impl<'a, 'tcx> Layout {
12201220
}
12211221

12221222
ty::TyTuple(tys, _) => {
1223-
// FIXME(camlorn): if we ever allow unsized tuples, this needs to be checked.
1224-
// See the univariant case below to learn how.
1223+
let kind = if tys.len() == 0 {
1224+
StructKind::AlwaysSizedUnivariant
1225+
} else {
1226+
StructKind::MaybeUnsizedUnivariant
1227+
};
1228+
12251229
let st = Struct::new(dl,
12261230
&tys.iter().map(|ty| ty.layout(tcx, param_env))
12271231
.collect::<Result<Vec<_>, _>>()?,
1228-
&ReprOptions::default(), StructKind::AlwaysSizedUnivariant, ty)?;
1232+
&ReprOptions::default(), kind, ty)?;
12291233
Univariant { variant: st, non_zero: false }
12301234
}
12311235

‎src/librustc/ty/util.rs‎

Lines changed: 20 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -317,15 +317,26 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
317317
target: Ty<'tcx>)
318318
-> (Ty<'tcx>, Ty<'tcx>) {
319319
let (mut a, mut b) = (source, target);
320-
while let (&TyAdt(a_def, a_substs), &TyAdt(b_def, b_substs)) = (&a.sty, &b.sty) {
321-
if a_def != b_def || !a_def.is_struct() {
322-
break;
323-
}
324-
match a_def.struct_variant().fields.last() {
325-
Some(f) => {
326-
a = f.ty(self, a_substs);
327-
b = f.ty(self, b_substs);
328-
}
320+
loop {
321+
match (&a.sty, &b.sty) {
322+
(&TyAdt(a_def, a_substs), &TyAdt(b_def, b_substs))
323+
if a_def == b_def && a_def.is_struct() => {
324+
if let Some(f) = a_def.struct_variant().fields.last() {
325+
a = f.ty(self, a_substs);
326+
b = f.ty(self, b_substs);
327+
} else {
328+
break;
329+
}
330+
},
331+
(&TyTuple(a_tys, _), &TyTuple(b_tys, _))
332+
if a_tys.len() == b_tys.len() => {
333+
if let Some(a_last) = a_tys.last() {
334+
a = a_last;
335+
b = b_tys.last().unwrap();
336+
} else {
337+
break;
338+
}
339+
},
329340
_ => break,
330341
}
331342
}

‎src/librustc_trans/glue.rs‎

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -76,7 +76,7 @@ pub fn size_and_align_of_dst<'a, 'tcx>(bcx: &Builder<'a, 'tcx>, t: Ty<'tcx>, inf
7676
}
7777
assert!(!info.is_null());
7878
match t.sty {
79-
ty::TyAdt(def, substs) => {
79+
ty::TyAdt(..) | ty::TyTuple(..) => {
8080
let ccx = bcx.ccx;
8181
// First get the size of all statically known fields.
8282
// Don't use size_of because it also rounds up to alignment, which we
@@ -101,8 +101,14 @@ pub fn size_and_align_of_dst<'a, 'tcx>(bcx: &Builder<'a, 'tcx>, t: Ty<'tcx>, inf
101101

102102
// Recurse to get the size of the dynamically sized field (must be
103103
// the last field).
104-
let last_field = def.struct_variant().fields.last().unwrap();
105-
let field_ty = monomorphize::field_ty(bcx.tcx(), substs, last_field);
104+
let field_ty = match t.sty {
105+
ty::TyAdt(def, substs) => {
106+
let last_field = def.struct_variant().fields.last().unwrap();
107+
monomorphize::field_ty(bcx.tcx(), substs, last_field)
108+
},
109+
ty::TyTuple(tys, _) => tys.last().unwrap(),
110+
_ => unreachable!(),
111+
};
106112
let (unsized_size, unsized_align) = size_and_align_of_dst(bcx, field_ty, info);
107113

108114
// FIXME (#26403, #27023): We should be adding padding

‎src/test/compile-fail/dst-bad-assign-3.rs‎

Lines changed: 48 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,48 @@
1+
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2+
// file at the top-level directory of this distribution and at
3+
// http://rust-lang.org/COPYRIGHT.
4+
//
5+
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6+
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7+
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8+
// option. This file may not be copied, modified, or distributed
9+
// except according to those terms.
10+
11+
// Forbid assignment into a dynamically sized type.
12+
13+
type Fat<T: ?Sized> = (isize, &'static str, T);
14+
//~^ WARNING trait bounds are not (yet) enforced
15+
16+
#[derive(PartialEq,Eq)]
17+
struct Bar;
18+
19+
#[derive(PartialEq,Eq)]
20+
struct Bar1 {
21+
f: isize
22+
}
23+
24+
trait ToBar {
25+
fn to_bar(&self) -> Bar;
26+
fn to_val(&self) -> isize;
27+
}
28+
29+
impl ToBar for Bar1 {
30+
fn to_bar(&self) -> Bar {
31+
Bar
32+
}
33+
fn to_val(&self) -> isize {
34+
self.f
35+
}
36+
}
37+
38+
pub fn main() {
39+
// Assignment.
40+
let f5: &mut Fat<ToBar> = &mut (5, "some str", Bar1 {f :42});
41+
let z: Box<ToBar> = Box::new(Bar1 {f: 36});
42+
f5.2 = Bar1 {f: 36};
43+
//~^ ERROR mismatched types
44+
//~| expected type `ToBar`
45+
//~| found type `Bar1`
46+
//~| expected trait ToBar, found struct `Bar1`
47+
//~| ERROR `ToBar: std::marker::Sized` is not satisfied
48+
}

‎src/test/compile-fail/dst-bad-coerce1.rs‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -29,4 +29,16 @@ pub fn main() {
2929
let f2: &Fat<Foo> = &f1;
3030
let f3: &Fat<Bar> = f2;
3131
//~^ ERROR `Foo: Bar` is not satisfied
32+
33+
// Tuple with a vec of isize.
34+
let f1 = ([1, 2, 3],);
35+
let f2: &([isize; 3],) = &f1;
36+
let f3: &([usize],) = f2;
37+
//~^ ERROR mismatched types
38+
39+
// Tuple with a trait.
40+
let f1 = (Foo,);
41+
let f2: &(Foo,) = &f1;
42+
let f3: &(Bar,) = f2;
43+
//~^ ERROR `Foo: Bar` is not satisfied
3244
}

‎src/test/compile-fail/dst-bad-coerce2.rs‎

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -28,4 +28,14 @@ pub fn main() {
2828
let f1 = Fat { ptr: Foo };
2929
let f2: &Fat<Foo> = &f1;
3030
let f3: &mut Fat<Bar> = f2; //~ ERROR mismatched types
31+
32+
// Tuple with a vec of ints.
33+
let f1 = ([1, 2, 3],);
34+
let f2: &([isize; 3],) = &f1;
35+
let f3: &mut ([isize],) = f2; //~ ERROR mismatched types
36+
37+
// Tuple with a trait.
38+
let f1 = (Foo,);
39+
let f2: &(Foo,) = &f1;
40+
let f3: &mut (Bar,) = f2; //~ ERROR mismatched types
3141
}

‎src/test/compile-fail/dst-bad-coerce3.rs‎

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -28,6 +28,16 @@ fn baz<'a>() {
2828
let f1 = Fat { ptr: Foo };
2929
let f2: &Fat<Foo> = &f1; //~ ERROR `f1` does not live long enough
3030
let f3: &'a Fat<Bar> = f2;
31+
32+
// Tuple with a vec of ints.
33+
let f1 = ([1, 2, 3],);
34+
let f2: &([isize; 3],) = &f1; //~ ERROR `f1` does not live long enough
35+
let f3: &'a ([isize],) = f2;
36+
37+
// Tuple with a trait.
38+
let f1 = (Foo,);
39+
let f2: &(Foo,) = &f1; //~ ERROR `f1` does not live long enough
40+
let f3: &'a (Bar,) = f2;
3141
}
3242

3343
pub fn main() {

‎src/test/compile-fail/dst-bad-coerce4.rs‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -22,4 +22,12 @@ pub fn main() {
2222
//~| expected type `&Fat<[isize; 3]>`
2323
//~| found type `&Fat<[isize]>`
2424
//~| expected array of 3 elements, found slice
25+
26+
// Tuple with a vec of isizes.
27+
let f1: &([isize],) = &([1, 2, 3],);
28+
let f2: &([isize; 3],) = f1;
29+
//~^ ERROR mismatched types
30+
//~| expected type `&([isize; 3],)`
31+
//~| found type `&([isize],)`
32+
//~| expected array of 3 elements, found slice
2533
}

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