Skip to content

Commit 9908711

Browse files
eddybeddyb
committed
Implement field shorthands in struct literal expressions.
1 parent a5b6a9f commit 9908711

15 files changed

+179
-18
lines changed

‎src/librustc/hir/lowering.rs

+2
Original file line numberDiff line numberDiff line change
@@ -543,6 +543,7 @@ impl<'a> LoweringContext<'a> {
543543
name: respan(f.ident.span, f.ident.node.name),
544544
expr: self.lower_expr(&f.expr),
545545
span: f.span,
546+
is_shorthand: f.is_shorthand,
546547
}
547548
}
548549

@@ -1682,6 +1683,7 @@ impl<'a> LoweringContext<'a> {
16821683
},
16831684
span: span,
16841685
expr: expr,
1686+
is_shorthand: false,
16851687
}
16861688
}
16871689

‎src/librustc/hir/mod.rs

+1
Original file line numberDiff line numberDiff line change
@@ -817,6 +817,7 @@ pub struct Field {
817817
pub name: Spanned<Name>,
818818
pub expr: P<Expr>,
819819
pub span: Span,
820+
pub is_shorthand: bool,
820821
}
821822

822823
#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]

‎src/librustc/hir/print.rs

+4-2
Original file line numberDiff line numberDiff line change
@@ -1229,8 +1229,10 @@ impl<'a> State<'a> {
12291229
&fields[..],
12301230
|s, field| {
12311231
s.ibox(indent_unit)?;
1232-
s.print_name(field.name.node)?;
1233-
s.word_space(":")?;
1232+
if !field.is_shorthand {
1233+
s.print_name(field.name.node)?;
1234+
s.word_space(":")?;
1235+
}
12341236
s.print_expr(&field.expr)?;
12351237
s.end()
12361238
},

‎src/libsyntax/ast.rs

+1
Original file line numberDiff line numberDiff line change
@@ -900,6 +900,7 @@ pub struct Field {
900900
pub ident: SpannedIdent,
901901
pub expr: P<Expr>,
902902
pub span: Span,
903+
pub is_shorthand: bool,
903904
}
904905

905906
pub type SpannedIdent = Spanned<Ident>;

‎src/libsyntax/ext/build.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -713,7 +713,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
713713
self.expr(b.span, ast::ExprKind::Block(b))
714714
}
715715
fn field_imm(&self, span: Span, name: Ident, e: P<ast::Expr>) -> ast::Field {
716-
ast::Field { ident: respan(span, name), expr: e, span: span }
716+
ast::Field { ident: respan(span, name), expr: e, span: span, is_shorthand: false }
717717
}
718718
fn expr_struct(&self, span: Span, path: ast::Path, fields: Vec<ast::Field>) -> P<ast::Expr> {
719719
self.expr(span, ast::ExprKind::Struct(path, fields, None))

‎src/libsyntax/feature_gate.rs

+11
Original file line numberDiff line numberDiff line change
@@ -306,6 +306,9 @@ declare_features! (
306306

307307
// Allows attributes on lifetime/type formal parameters in generics (RFC 1327)
308308
(active, generic_param_attrs, "1.11.0", Some(34761)),
309+
310+
// Allows field shorthands (`x` meaning `x: x`) in struct literal expressions.
311+
(active, field_init_shorthand, "1.14.0", Some(37340)),
309312
);
310313

311314
declare_features! (
@@ -1087,6 +1090,14 @@ impl<'a> Visitor for PostExpansionVisitor<'a> {
10871090
ast::ExprKind::InPlace(..) => {
10881091
gate_feature_post!(&self, placement_in_syntax, e.span, EXPLAIN_PLACEMENT_IN);
10891092
}
1093+
ast::ExprKind::Struct(_, ref fields, _) => {
1094+
for field in fields {
1095+
if field.is_shorthand {
1096+
gate_feature_post!(&self, field_init_shorthand, field.span,
1097+
"struct field shorthands are unstable");
1098+
}
1099+
}
1100+
}
10901101
_ => {}
10911102
}
10921103
visit::walk_expr(self, e);

‎src/libsyntax/fold.rs

+5-4
Original file line numberDiff line numberDiff line change
@@ -823,11 +823,12 @@ pub fn noop_fold_struct_field<T: Folder>(f: StructField, fld: &mut T) -> StructF
823823
}
824824
}
825825

826-
pub fn noop_fold_field<T: Folder>(Field {ident, expr, span}: Field, folder: &mut T) -> Field {
826+
pub fn noop_fold_field<T: Folder>(f: Field, folder: &mut T) -> Field {
827827
Field {
828-
ident: respan(ident.span, folder.fold_ident(ident.node)),
829-
expr: folder.fold_expr(expr),
830-
span: folder.new_span(span)
828+
ident: respan(f.ident.span, folder.fold_ident(f.ident.node)),
829+
expr: folder.fold_expr(f.expr),
830+
span: folder.new_span(f.span),
831+
is_shorthand: f.is_shorthand,
831832
}
832833
}
833834

‎src/libsyntax/parse/parser.rs

+21-8
Original file line numberDiff line numberDiff line change
@@ -2007,17 +2007,30 @@ impl<'a> Parser<'a> {
20072007
}
20082008
}
20092009

2010-
/// Parse ident COLON expr
2010+
/// Parse ident (COLON expr)?
20112011
pub fn parse_field(&mut self) -> PResult<'a, Field> {
20122012
let lo = self.span.lo;
2013-
let i = self.parse_field_name()?;
2014-
let hi = self.prev_span.hi;
2015-
self.expect(&token::Colon)?;
2016-
let e = self.parse_expr()?;
2013+
let hi;
2014+
2015+
// Check if a colon exists one ahead. This means we're parsing a fieldname.
2016+
let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
2017+
let fieldname = self.parse_field_name()?;
2018+
self.bump();
2019+
hi = self.prev_span.hi;
2020+
(fieldname, self.parse_expr()?, false)
2021+
} else {
2022+
let fieldname = self.parse_ident()?;
2023+
hi = self.prev_span.hi;
2024+
2025+
// Mimic `x: x` for the `x` field shorthand.
2026+
let path = ast::Path::from_ident(mk_sp(lo, hi), fieldname);
2027+
(fieldname, self.mk_expr(lo, hi, ExprKind::Path(None, path), ThinVec::new()), true)
2028+
};
20172029
Ok(ast::Field {
2018-
ident: spanned(lo, hi, i),
2019-
span: mk_sp(lo, e.span.hi),
2020-
expr: e,
2030+
ident: spanned(lo, hi, fieldname),
2031+
span: mk_sp(lo, expr.span.hi),
2032+
expr: expr,
2033+
is_shorthand: is_shorthand,
20212034
})
20222035
}
20232036

‎src/libsyntax/print/pprust.rs

+4-2
Original file line numberDiff line numberDiff line change
@@ -1893,8 +1893,10 @@ impl<'a> State<'a> {
18931893
&fields[..],
18941894
|s, field| {
18951895
try!(s.ibox(INDENT_UNIT));
1896-
try!(s.print_ident(field.ident.node));
1897-
try!(s.word_space(":"));
1896+
if !field.is_shorthand {
1897+
try!(s.print_ident(field.ident.node));
1898+
try!(s.word_space(":"));
1899+
}
18981900
try!(s.print_expr(&field.expr));
18991901
s.end()
19001902
},

‎src/test/compile-fail/feature-gate-field-init-shorthand.rs

+24
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
// Copyright 2016 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+
struct Foo {
12+
x: i32,
13+
y: bool,
14+
z: i32
15+
}
16+
17+
fn main() {
18+
let (x, y, z) = (1, true, 2);
19+
let _ = Foo {
20+
x, //~ ERROR struct field shorthands are unstable
21+
y: y,
22+
z //~ ERROR struct field shorthands are unstable
23+
};
24+
}

‎src/test/compile-fail/struct-fields-shorthand-unresolved.rs

+24
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
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+
#![feature(field_init_shorthand)]
12+
13+
struct Foo {
14+
x: i32,
15+
y: i32
16+
}
17+
18+
fn main() {
19+
let x = 0;
20+
let foo = Foo {
21+
x,
22+
y //~ ERROR unresolved name `y`
23+
};
24+
}

‎src/test/compile-fail/struct-fields-shorthand.rs

+24
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
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+
#![feature(field_init_shorthand)]
12+
13+
struct Foo {
14+
x: i32,
15+
y: i32
16+
}
17+
18+
fn main() {
19+
let (x, y, z) = (0, 1, 2);
20+
let foo = Foo {
21+
x, y, z //~ ERROR struct `Foo` has no field named `z`
22+
};
23+
}
24+

‎src/test/parse-fail/removed-syntax-with-2.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -18,5 +18,5 @@ fn removed_with() {
1818

1919
let a = S { foo: (), bar: () };
2020
let b = S { foo: (), with a };
21-
//~^ ERROR expected `:`, found `a`
21+
//~^ ERROR expected one of `,` or `}`, found `a`
2222
}

‎src/test/parse-fail/struct-field-numeric-shorthand.rs

+19
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
1+
// Copyright 2016 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+
// compile-flags: -Z parse-only
12+
13+
#![feature(field_init_shorthand)]
14+
15+
struct Rgb(u8, u8, u8);
16+
17+
fn main() {
18+
let _ = Rgb { 0, 1, 2 }; //~ ERROR expected identifier, found `0`
19+
}

‎src/test/run-pass/struct-field-shorthand.rs

+37
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,37 @@
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+
#![feature(field_init_shorthand)]
12+
13+
struct Foo {
14+
x: i32,
15+
y: bool,
16+
z: i32
17+
}
18+
19+
struct Bar {
20+
x: i32
21+
}
22+
23+
pub fn main() {
24+
let (x, y, z) = (1, true, 2);
25+
let a = Foo { x, y: y, z };
26+
assert_eq!(a.x, x);
27+
assert_eq!(a.y, y);
28+
assert_eq!(a.z, z);
29+
30+
let b = Bar { x, };
31+
assert_eq!(b.x, x);
32+
33+
let c = Foo { z, y, x };
34+
assert_eq!(c.x, x);
35+
assert_eq!(c.y, y);
36+
assert_eq!(c.z, z);
37+
}

0 commit comments

Comments
 (0)