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Disallow impl Trait in unsupported position
1 parent 4b9b70c commit 378bd49

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2 files changed

+74
-17
lines changed

2 files changed

+74
-17
lines changed

‎src/librustc/hir/lowering.rs‎

Lines changed: 36 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -780,8 +780,9 @@ impl<'a> LoweringContext<'a> {
780780
_ => None,
781781
}),
782782
|this| {
783+
let itctx = ImplTraitContext::Universal(parent_id);
783784
this.collect_in_band_defs(parent_id, anonymous_lifetime_mode, |this| {
784-
(this.lower_generics(generics), f(this))
785+
(this.lower_generics(generics, itctx), f(this))
785786
})
786787
},
787788
);
@@ -1043,7 +1044,11 @@ impl<'a> LoweringContext<'a> {
10431044
}),
10441045
|this| {
10451046
hir::TyBareFn(P(hir::BareFnTy {
1046-
generic_params: this.lower_generic_params(&f.generic_params, &NodeMap()),
1047+
generic_params: this.lower_generic_params(
1048+
&f.generic_params,
1049+
&NodeMap(),
1050+
ImplTraitContext::Disallowed,
1051+
),
10471052
unsafety: this.lower_unsafety(f.unsafety),
10481053
abi: f.abi,
10491054
decl: this.lower_fn_decl(&f.decl, None, false),
@@ -1784,7 +1789,12 @@ impl<'a> LoweringContext<'a> {
17841789
}
17851790
}
17861791

1787-
fn lower_ty_param(&mut self, tp: &TyParam, add_bounds: &[TyParamBound]) -> hir::TyParam {
1792+
fn lower_ty_param(
1793+
&mut self,
1794+
tp: &TyParam,
1795+
add_bounds: &[TyParamBound],
1796+
itctx: ImplTraitContext,
1797+
) -> hir::TyParam {
17881798
let mut name = self.lower_ident(tp.ident);
17891799

17901800
// Don't expose `Self` (recovered "keyword used as ident" parse error).
@@ -1794,7 +1804,6 @@ impl<'a> LoweringContext<'a> {
17941804
name = Symbol::gensym("Self");
17951805
}
17961806

1797-
let itctx = ImplTraitContext::Universal(self.resolver.definitions().local_def_id(tp.id));
17981807
let mut bounds = self.lower_bounds(&tp.bounds, itctx);
17991808
if !add_bounds.is_empty() {
18001809
bounds = bounds
@@ -1879,6 +1888,7 @@ impl<'a> LoweringContext<'a> {
18791888
&mut self,
18801889
params: &Vec<GenericParam>,
18811890
add_bounds: &NodeMap<Vec<TyParamBound>>,
1891+
itctx: ImplTraitContext,
18821892
) -> hir::HirVec<hir::GenericParam> {
18831893
params
18841894
.iter()
@@ -1889,12 +1899,13 @@ impl<'a> LoweringContext<'a> {
18891899
GenericParam::Type(ref ty_param) => hir::GenericParam::Type(self.lower_ty_param(
18901900
ty_param,
18911901
add_bounds.get(&ty_param.id).map_or(&[][..], |x| &x),
1902+
itctx,
18921903
)),
18931904
})
18941905
.collect()
18951906
}
18961907

1897-
fn lower_generics(&mut self, g: &Generics) -> hir::Generics {
1908+
fn lower_generics(&mut self, g: &Generics, itctx: ImplTraitContext) -> hir::Generics {
18981909
// Collect `?Trait` bounds in where clause and move them to parameter definitions.
18991910
// FIXME: This could probably be done with less rightward drift. Also looks like two control
19001911
// paths where report_error is called are also the only paths that advance to after
@@ -1947,7 +1958,7 @@ impl<'a> LoweringContext<'a> {
19471958
}
19481959

19491960
hir::Generics {
1950-
params: self.lower_generic_params(&g.params, &add_bounds),
1961+
params: self.lower_generic_params(&g.params, &add_bounds, itctx),
19511962
where_clause: self.lower_where_clause(&g.where_clause),
19521963
span: g.span,
19531964
}
@@ -1981,6 +1992,7 @@ impl<'a> LoweringContext<'a> {
19811992
bound_generic_params: this.lower_generic_params(
19821993
bound_generic_params,
19831994
&NodeMap(),
1995+
ImplTraitContext::Disallowed,
19841996
),
19851997
bounded_ty: this.lower_ty(bounded_ty, ImplTraitContext::Disallowed),
19861998
bounds: bounds
@@ -2064,7 +2076,8 @@ impl<'a> LoweringContext<'a> {
20642076
p: &PolyTraitRef,
20652077
itctx: ImplTraitContext,
20662078
) -> hir::PolyTraitRef {
2067-
let bound_generic_params = self.lower_generic_params(&p.bound_generic_params, &NodeMap());
2079+
let bound_generic_params =
2080+
self.lower_generic_params(&p.bound_generic_params, &NodeMap(), itctx);
20682081
let trait_ref = self.with_parent_impl_lifetime_defs(
20692082
&bound_generic_params
20702083
.iter()
@@ -2216,7 +2229,7 @@ impl<'a> LoweringContext<'a> {
22162229
ItemKind::GlobalAsm(ref ga) => hir::ItemGlobalAsm(self.lower_global_asm(ga)),
22172230
ItemKind::Ty(ref t, ref generics) => hir::ItemTy(
22182231
self.lower_ty(t, ImplTraitContext::Disallowed),
2219-
self.lower_generics(generics),
2232+
self.lower_generics(generics, ImplTraitContext::Disallowed),
22202233
),
22212234
ItemKind::Enum(ref enum_definition, ref generics) => hir::ItemEnum(
22222235
hir::EnumDef {
@@ -2226,15 +2239,21 @@ impl<'a> LoweringContext<'a> {
22262239
.map(|x| self.lower_variant(x))
22272240
.collect(),
22282241
},
2229-
self.lower_generics(generics),
2242+
self.lower_generics(generics, ImplTraitContext::Disallowed),
22302243
),
22312244
ItemKind::Struct(ref struct_def, ref generics) => {
22322245
let struct_def = self.lower_variant_data(struct_def);
2233-
hir::ItemStruct(struct_def, self.lower_generics(generics))
2246+
hir::ItemStruct(
2247+
struct_def,
2248+
self.lower_generics(generics, ImplTraitContext::Disallowed),
2249+
)
22342250
}
22352251
ItemKind::Union(ref vdata, ref generics) => {
22362252
let vdata = self.lower_variant_data(vdata);
2237-
hir::ItemUnion(vdata, self.lower_generics(generics))
2253+
hir::ItemUnion(
2254+
vdata,
2255+
self.lower_generics(generics, ImplTraitContext::Disallowed),
2256+
)
22382257
}
22392258
ItemKind::Impl(
22402259
unsafety,
@@ -2313,13 +2332,13 @@ impl<'a> LoweringContext<'a> {
23132332
hir::ItemTrait(
23142333
self.lower_is_auto(is_auto),
23152334
self.lower_unsafety(unsafety),
2316-
self.lower_generics(generics),
2335+
self.lower_generics(generics, ImplTraitContext::Disallowed),
23172336
bounds,
23182337
items,
23192338
)
23202339
}
23212340
ItemKind::TraitAlias(ref generics, ref bounds) => hir::ItemTraitAlias(
2322-
self.lower_generics(generics),
2341+
self.lower_generics(generics, ImplTraitContext::Disallowed),
23232342
self.lower_bounds(bounds, ImplTraitContext::Disallowed),
23242343
),
23252344
ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
@@ -2454,7 +2473,7 @@ impl<'a> LoweringContext<'a> {
24542473

24552474
let (generics, node) = match i.node {
24562475
TraitItemKind::Const(ref ty, ref default) => (
2457-
this.lower_generics(&i.generics),
2476+
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
24582477
hir::TraitItemKind::Const(
24592478
this.lower_ty(ty, ImplTraitContext::Disallowed),
24602479
default
@@ -2495,7 +2514,7 @@ impl<'a> LoweringContext<'a> {
24952514
)
24962515
}
24972516
TraitItemKind::Type(ref bounds, ref default) => (
2498-
this.lower_generics(&i.generics),
2517+
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
24992518
hir::TraitItemKind::Type(
25002519
this.lower_bounds(bounds, ImplTraitContext::Disallowed),
25012520
default
@@ -2552,7 +2571,7 @@ impl<'a> LoweringContext<'a> {
25522571
ImplItemKind::Const(ref ty, ref expr) => {
25532572
let body_id = this.lower_body(None, |this| this.lower_expr(expr));
25542573
(
2555-
this.lower_generics(&i.generics),
2574+
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
25562575
hir::ImplItemKind::Const(
25572576
this.lower_ty(ty, ImplTraitContext::Disallowed),
25582577
body_id,
@@ -2583,7 +2602,7 @@ impl<'a> LoweringContext<'a> {
25832602
)
25842603
}
25852604
ImplItemKind::Type(ref ty) => (
2586-
this.lower_generics(&i.generics),
2605+
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
25872606
hir::ImplItemKind::Type(this.lower_ty(ty, ImplTraitContext::Disallowed)),
25882607
),
25892608
ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),

‎src/test/compile-fail/issue-47715.rs‎

Lines changed: 38 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,38 @@
1+
// Copyright 2018 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+
trait Foo {}
12+
13+
trait Bar<T> {}
14+
15+
trait Iterable {
16+
type Item;
17+
}
18+
19+
struct Container<T: Iterable<Item = impl Foo>> {
20+
//~^ ERROR `impl Trait` not allowed
21+
field: T
22+
}
23+
24+
enum Enum<T: Iterable<Item = impl Foo>> {
25+
//~^ ERROR `impl Trait` not allowed
26+
A(T),
27+
}
28+
29+
union Union<T: Iterable<Item = impl Foo> + Copy> {
30+
//~^ ERROR `impl Trait` not allowed
31+
x: T,
32+
}
33+
34+
type Type<T: Iterable<Item = impl Foo>> = T;
35+
//~^ ERROR `impl Trait` not allowed
36+
37+
fn main() {
38+
}

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