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Parse auto traits the same as traits.
This moves the well formedness checks to the AST validation pass. Tests were adjusted. The auto keyword should be back-compat now.
1 parent 9d181ac commit 97de8ca

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7 files changed

+83
-110
lines changed

7 files changed

+83
-110
lines changed

‎src/librustc_passes/ast_validation.rs‎

Lines changed: 16 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -229,7 +229,22 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
229229
}
230230
}
231231
}
232-
ItemKind::Trait(.., ref bounds, ref trait_items) => {
232+
ItemKind::Trait(is_auto, _, ref generics, ref bounds, ref trait_items) => {
233+
if is_auto == IsAuto::Yes {
234+
// Auto traits cannot have generics, super traits nor contain items.
235+
if !generics.ty_params.is_empty() {
236+
self.err_handler().span_err(item.span,
237+
"auto traits cannot have generics");
238+
}
239+
if !bounds.is_empty() {
240+
self.err_handler().span_err(item.span,
241+
"auto traits cannot have super traits");
242+
}
243+
if !trait_items.is_empty() {
244+
self.err_handler().span_err(item.span,
245+
"auto traits cannot contain items");
246+
}
247+
}
233248
self.no_questions_in_bounds(bounds, "supertraits", true);
234249
for trait_item in trait_items {
235250
if let TraitItemKind::Method(ref sig, ref block) = trait_item.node {

‎src/libsyntax/parse/parser.rs‎

Lines changed: 32 additions & 49 deletions
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,6 @@ use ast::{Mod, Arg, Arm, Attribute, BindingMode, TraitItemKind};
1616
use ast::Block;
1717
use ast::{BlockCheckMode, CaptureBy};
1818
use ast::{Constness, Crate};
19-
use ast::Generics;
2019
use ast::Defaultness;
2120
use ast::EnumDef;
2221
use ast::{Expr, ExprKind, RangeLimits};
@@ -3874,6 +3873,16 @@ impl<'a> Parser<'a> {
38743873
self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
38753874
}
38763875

3876+
fn eat_auto_trait(&mut self) -> bool {
3877+
if self.token.is_keyword(keywords::Auto)
3878+
&& self.look_ahead(1, |t| t.is_keyword(keywords::Trait))
3879+
{
3880+
self.eat_keyword(keywords::Auto) && self.eat_keyword(keywords::Trait)
3881+
} else {
3882+
false
3883+
}
3884+
}
3885+
38773886
fn is_defaultness(&self) -> bool {
38783887
// `pub` is included for better error messages
38793888
self.token.is_keyword(keywords::Default) &&
@@ -5052,7 +5061,7 @@ impl<'a> Parser<'a> {
50525061
}
50535062

50545063
/// Parse trait Foo { ... }
5055-
fn parse_item_trait(&mut self, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5064+
fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
50565065
let ident = self.parse_ident()?;
50575066
let mut tps = self.parse_generics()?;
50585067

@@ -5079,17 +5088,7 @@ impl<'a> Parser<'a> {
50795088
}
50805089
}
50815090
}
5082-
Ok((ident, ItemKind::Trait(IsAuto::No, unsafety, tps, bounds, trait_items), None))
5083-
}
5084-
5085-
fn parse_item_auto_trait(&mut self, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
5086-
let ident = self.parse_ident()?;
5087-
self.expect(&token::OpenDelim(token::Brace))?;
5088-
self.expect(&token::CloseDelim(token::Brace))?;
5089-
// Auto traits cannot have generics, super traits nor contain items.
5090-
Ok((ident,
5091-
ItemKind::Trait(IsAuto::Yes, unsafety, Generics::default(), Vec::new(), Vec::new()),
5092-
None))
5091+
Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
50935092
}
50945093

50955094
/// Parses items implementations variants
@@ -5999,44 +5998,19 @@ impl<'a> Parser<'a> {
59995998
return Ok(Some(item));
60005999
}
60016000
if self.check_keyword(keywords::Unsafe) &&
6002-
self.look_ahead(1, |t| t.is_keyword(keywords::Trait))
6001+
(self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) ||
6002+
self.look_ahead(1, |t| t.is_keyword(keywords::Auto)))
60036003
{
60046004
// UNSAFE TRAIT ITEM
60056005
self.expect_keyword(keywords::Unsafe)?;
6006-
self.expect_keyword(keywords::Trait)?;
6006+
let is_auto = if self.eat_keyword(keywords::Trait) {
6007+
IsAuto::No
6008+
} else {
6009+
self.eat_auto_trait();
6010+
IsAuto::Yes
6011+
};
60076012
let (ident, item_, extra_attrs) =
6008-
self.parse_item_trait(ast::Unsafety::Unsafe)?;
6009-
let prev_span = self.prev_span;
6010-
let item = self.mk_item(lo.to(prev_span),
6011-
ident,
6012-
item_,
6013-
visibility,
6014-
maybe_append(attrs, extra_attrs));
6015-
return Ok(Some(item));
6016-
}
6017-
if self.eat_keyword(keywords::Auto) {
6018-
self.expect_keyword(keywords::Trait)?;
6019-
// AUTO TRAIT ITEM
6020-
let (ident,
6021-
item_,
6022-
extra_attrs) = self.parse_item_auto_trait(ast::Unsafety::Normal)?;
6023-
let prev_span = self.prev_span;
6024-
let item = self.mk_item(lo.to(prev_span),
6025-
ident,
6026-
item_,
6027-
visibility,
6028-
maybe_append(attrs, extra_attrs));
6029-
return Ok(Some(item));
6030-
}
6031-
if self.check_keyword(keywords::Unsafe) &&
6032-
self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) {
6033-
self.expect_keyword(keywords::Unsafe)?;
6034-
self.expect_keyword(keywords::Auto)?;
6035-
self.expect_keyword(keywords::Trait)?;
6036-
// UNSAFE AUTO TRAIT ITEM
6037-
let (ident,
6038-
item_,
6039-
extra_attrs) = self.parse_item_auto_trait(ast::Unsafety::Unsafe)?;
6013+
self.parse_item_trait(is_auto, ast::Unsafety::Unsafe)?;
60406014
let prev_span = self.prev_span;
60416015
let item = self.mk_item(lo.to(prev_span),
60426016
ident,
@@ -6139,10 +6113,19 @@ impl<'a> Parser<'a> {
61396113
maybe_append(attrs, extra_attrs));
61406114
return Ok(Some(item));
61416115
}
6142-
if self.eat_keyword(keywords::Trait) {
6116+
if self.check_keyword(keywords::Trait)
6117+
|| (self.check_keyword(keywords::Auto)
6118+
&& self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
6119+
{
6120+
let is_auto = if self.eat_keyword(keywords::Trait) {
6121+
IsAuto::No
6122+
} else {
6123+
self.eat_auto_trait();
6124+
IsAuto::Yes
6125+
};
61436126
// TRAIT ITEM
61446127
let (ident, item_, extra_attrs) =
6145-
self.parse_item_trait(ast::Unsafety::Normal)?;
6128+
self.parse_item_trait(is_auto, ast::Unsafety::Normal)?;
61466129
let prev_span = self.prev_span;
61476130
let item = self.mk_item(lo.to(prev_span),
61486131
ident,

‎src/test/compile-fail/auto-is-contextual.rs‎

Lines changed: 0 additions & 29 deletions
This file was deleted.

‎src/test/compile-fail/auto-trait-validation.rs‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
1+
// Copyright 2017 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+
#![feature(optin_builtin_traits)]
12+
13+
auto trait Generic<T> {}
14+
//~^ ERROR auto traits cannot have generics
15+
//~^^ traits with auto impls (`e.g. impl Trait for ..`) can not have type parameters
16+
auto trait Bound : Copy {}
17+
//~^ ERROR auto traits cannot have super traits
18+
//~^^ traits with auto impls (`e.g. impl Trait for ..`) cannot have predicates
19+
auto trait MyTrait { fn foo() {} }
20+
//~^ ERROR auto traits cannot contain items
21+
//~^^ traits with default impls (`e.g. impl Trait for ..`) must have no methods or associated items
22+
fn main() {}

‎src/test/parse-fail/auto-trait-no-rename.rs‎

Lines changed: 0 additions & 14 deletions
This file was deleted.

‎src/test/parse-fail/auto-trait-no-super.rs‎

Lines changed: 0 additions & 14 deletions
This file was deleted.

‎src/test/parse-fail/auto-trait-no-generics.rs‎ renamed to ‎src/test/run-pass/auto-is-contextual.rs‎

Lines changed: 13 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,17 @@
88
// option. This file may not be copied, modified, or distributed
99
// except according to those terms.
1010

11-
// compile-flags: -Z parse-only
11+
macro_rules! auto {
12+
() => (struct S;)
13+
}
1214

13-
auto trait Auto<T> { }
14-
//~^ ERROR: expected `{`, found `<`
15+
auto!();
16+
17+
fn auto() {}
18+
19+
fn main() {
20+
auto();
21+
let auto = 10;
22+
auto;
23+
auto as u8;
24+
}

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