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Disallow impl Trait in unsupported position
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@sinkuu
sinkuu committed Apr 10, 2018
1 parent 4b9b70c commit 378bd49
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Showing 2 changed files with 74 additions and 17 deletions.
53 changes: 36 additions & 17 deletions src/librustc/hir/lowering.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -780,8 +780,9 @@ impl<'a> LoweringContext<'a> {
_ => None,
}),
|this| {
let itctx = ImplTraitContext::Universal(parent_id);
this.collect_in_band_defs(parent_id, anonymous_lifetime_mode, |this| {
(this.lower_generics(generics), f(this))
(this.lower_generics(generics, itctx), f(this))
})
},
);
Expand Down Expand Up @@ -1043,7 +1044,11 @@ impl<'a> LoweringContext<'a> {
}),
|this| {
hir::TyBareFn(P(hir::BareFnTy {
generic_params: this.lower_generic_params(&f.generic_params, &NodeMap()),
generic_params: this.lower_generic_params(
&f.generic_params,
&NodeMap(),
ImplTraitContext::Disallowed,
),
unsafety: this.lower_unsafety(f.unsafety),
abi: f.abi,
decl: this.lower_fn_decl(&f.decl, None, false),
Expand Down Expand Up @@ -1784,7 +1789,12 @@ impl<'a> LoweringContext<'a> {
}
}

fn lower_ty_param(&mut self, tp: &TyParam, add_bounds: &[TyParamBound]) -> hir::TyParam {
fn lower_ty_param(
&mut self,
tp: &TyParam,
add_bounds: &[TyParamBound],
itctx: ImplTraitContext,
) -> hir::TyParam {
let mut name = self.lower_ident(tp.ident);

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

let itctx = ImplTraitContext::Universal(self.resolver.definitions().local_def_id(tp.id));
let mut bounds = self.lower_bounds(&tp.bounds, itctx);
if !add_bounds.is_empty() {
bounds = bounds
Expand Down Expand Up @@ -1879,6 +1888,7 @@ impl<'a> LoweringContext<'a> {
&mut self,
params: &Vec<GenericParam>,
add_bounds: &NodeMap<Vec<TyParamBound>>,
itctx: ImplTraitContext,
) -> hir::HirVec<hir::GenericParam> {
params
.iter()
Expand All @@ -1889,12 +1899,13 @@ impl<'a> LoweringContext<'a> {
GenericParam::Type(ref ty_param) => hir::GenericParam::Type(self.lower_ty_param(
ty_param,
add_bounds.get(&ty_param.id).map_or(&[][..], |x| &x),
itctx,
)),
})
.collect()
}

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

hir::Generics {
params: self.lower_generic_params(&g.params, &add_bounds),
params: self.lower_generic_params(&g.params, &add_bounds, itctx),
where_clause: self.lower_where_clause(&g.where_clause),
span: g.span,
}
Expand Down Expand Up @@ -1981,6 +1992,7 @@ impl<'a> LoweringContext<'a> {
bound_generic_params: this.lower_generic_params(
bound_generic_params,
&NodeMap(),
ImplTraitContext::Disallowed,
),
bounded_ty: this.lower_ty(bounded_ty, ImplTraitContext::Disallowed),
bounds: bounds
Expand Down Expand Up @@ -2064,7 +2076,8 @@ impl<'a> LoweringContext<'a> {
p: &PolyTraitRef,
itctx: ImplTraitContext,
) -> hir::PolyTraitRef {
let bound_generic_params = self.lower_generic_params(&p.bound_generic_params, &NodeMap());
let bound_generic_params =
self.lower_generic_params(&p.bound_generic_params, &NodeMap(), itctx);
let trait_ref = self.with_parent_impl_lifetime_defs(
&bound_generic_params
.iter()
Expand Down Expand Up @@ -2216,7 +2229,7 @@ impl<'a> LoweringContext<'a> {
ItemKind::GlobalAsm(ref ga) => hir::ItemGlobalAsm(self.lower_global_asm(ga)),
ItemKind::Ty(ref t, ref generics) => hir::ItemTy(
self.lower_ty(t, ImplTraitContext::Disallowed),
self.lower_generics(generics),
self.lower_generics(generics, ImplTraitContext::Disallowed),
),
ItemKind::Enum(ref enum_definition, ref generics) => hir::ItemEnum(
hir::EnumDef {
Expand All @@ -2226,15 +2239,21 @@ impl<'a> LoweringContext<'a> {
.map(|x| self.lower_variant(x))
.collect(),
},
self.lower_generics(generics),
self.lower_generics(generics, ImplTraitContext::Disallowed),
),
ItemKind::Struct(ref struct_def, ref generics) => {
let struct_def = self.lower_variant_data(struct_def);
hir::ItemStruct(struct_def, self.lower_generics(generics))
hir::ItemStruct(
struct_def,
self.lower_generics(generics, ImplTraitContext::Disallowed),
)
}
ItemKind::Union(ref vdata, ref generics) => {
let vdata = self.lower_variant_data(vdata);
hir::ItemUnion(vdata, self.lower_generics(generics))
hir::ItemUnion(
vdata,
self.lower_generics(generics, ImplTraitContext::Disallowed),
)
}
ItemKind::Impl(
unsafety,
Expand Down Expand Up @@ -2313,13 +2332,13 @@ impl<'a> LoweringContext<'a> {
hir::ItemTrait(
self.lower_is_auto(is_auto),
self.lower_unsafety(unsafety),
self.lower_generics(generics),
self.lower_generics(generics, ImplTraitContext::Disallowed),
bounds,
items,
)
}
ItemKind::TraitAlias(ref generics, ref bounds) => hir::ItemTraitAlias(
self.lower_generics(generics),
self.lower_generics(generics, ImplTraitContext::Disallowed),
self.lower_bounds(bounds, ImplTraitContext::Disallowed),
),
ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
Expand Down Expand Up @@ -2454,7 +2473,7 @@ impl<'a> LoweringContext<'a> {

let (generics, node) = match i.node {
TraitItemKind::Const(ref ty, ref default) => (
this.lower_generics(&i.generics),
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
hir::TraitItemKind::Const(
this.lower_ty(ty, ImplTraitContext::Disallowed),
default
Expand Down Expand Up @@ -2495,7 +2514,7 @@ impl<'a> LoweringContext<'a> {
)
}
TraitItemKind::Type(ref bounds, ref default) => (
this.lower_generics(&i.generics),
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
hir::TraitItemKind::Type(
this.lower_bounds(bounds, ImplTraitContext::Disallowed),
default
Expand Down Expand Up @@ -2552,7 +2571,7 @@ impl<'a> LoweringContext<'a> {
ImplItemKind::Const(ref ty, ref expr) => {
let body_id = this.lower_body(None, |this| this.lower_expr(expr));
(
this.lower_generics(&i.generics),
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
hir::ImplItemKind::Const(
this.lower_ty(ty, ImplTraitContext::Disallowed),
body_id,
Expand Down Expand Up @@ -2583,7 +2602,7 @@ impl<'a> LoweringContext<'a> {
)
}
ImplItemKind::Type(ref ty) => (
this.lower_generics(&i.generics),
this.lower_generics(&i.generics, ImplTraitContext::Disallowed),
hir::ImplItemKind::Type(this.lower_ty(ty, ImplTraitContext::Disallowed)),
),
ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),
Expand Down
38 changes: 38 additions & 0 deletions src/test/compile-fail/issue-47715.rs
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,38 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

trait Foo {}

trait Bar<T> {}

trait Iterable {
type Item;
}

struct Container<T: Iterable<Item = impl Foo>> {
//~^ ERROR `impl Trait` not allowed
field: T
}

enum Enum<T: Iterable<Item = impl Foo>> {
//~^ ERROR `impl Trait` not allowed
A(T),
}

union Union<T: Iterable<Item = impl Foo> + Copy> {
//~^ ERROR `impl Trait` not allowed
x: T,
}

type Type<T: Iterable<Item = impl Foo>> = T;
//~^ ERROR `impl Trait` not allowed

fn main() {
}

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