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Implement empty struct with braces (RFC 218)

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This commit is contained in:
Vadim Petrochenkov 2015-09-10 22:46:52 +03:00
parent cff0411706
commit 5fa6e857c9
11 changed files with 114 additions and 133 deletions
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50
src/librustc_front/print/pprust.rs
View file

@ -1218,34 +1218,34 @@ impl<'a> State<'a> {
fields: &[hir::Field],
wth: &Option<P<hir::Expr>>) -> io::Result<()> {
try!(self.print_path(path, true, 0));
if !(fields.is_empty() && wth.is_none()) {
try!(word(&mut self.s, "{"));
try!(self.commasep_cmnt(
Consistent,
&fields[..],
|s, field| {
try!(s.ibox(indent_unit));
try!(s.print_ident(field.ident.node));
try!(s.word_space(":"));
try!(s.print_expr(&*field.expr));
s.end()
},
|f| f.span));
match *wth {
Some(ref expr) => {
try!(self.ibox(indent_unit));
if !fields.is_empty() {
try!(word(&mut self.s, ","));
try!(space(&mut self.s));
}
try!(word(&mut self.s, ".."));
try!(self.print_expr(&**expr));
try!(self.end());
try!(word(&mut self.s, "{"));
try!(self.commasep_cmnt(
Consistent,
&fields[..],
|s, field| {
try!(s.ibox(indent_unit));
try!(s.print_ident(field.ident.node));
try!(s.word_space(":"));
try!(s.print_expr(&*field.expr));
s.end()
},
|f| f.span));
match *wth {
Some(ref expr) => {
try!(self.ibox(indent_unit));
if !fields.is_empty() {
try!(word(&mut self.s, ","));
try!(space(&mut self.s));
}
_ => try!(word(&mut self.s, ",")),
try!(word(&mut self.s, ".."));
try!(self.print_expr(&**expr));
try!(self.end());
}
_ => if !fields.is_empty() {
try!(word(&mut self.s, ","))
}
try!(word(&mut self.s, "}"));
}
try!(word(&mut self.s, "}"));
Ok(())
}

4
src/librustc_typeck/check/mod.rs
View file

@ -1473,14 +1473,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
_ => return None
};
if let ty::VariantKind::Dict = variant.kind() {
let var_kind = variant.kind();
if var_kind == ty::VariantKind::Dict || var_kind == ty::VariantKind::Unit {
Some((adt, variant))
} else {
None
}
}
pub fn write_nil(&self, node_id: ast::NodeId) {
self.write_ty(node_id, self.tcx().mk_nil());
}

21
src/libsyntax/parse/parser.rs
View file

@ -2231,14 +2231,6 @@ impl<'a> Parser<'a> {
&[token::CloseDelim(token::Brace)]));
}
if fields.is_empty() && base.is_none() {
let last_span = self.last_span;
self.span_err(last_span,
"structure literal must either \
have at least one field or use \
structure update syntax");
}
hi = self.span.hi;
try!(self.expect(&token::CloseDelim(token::Brace)));
ex = ExprStruct(pth, fields, base);
@ -4713,14 +4705,14 @@ impl<'a> Parser<'a> {
(Vec::new(), Some(ast::DUMMY_NODE_ID))
} else {
// If we see: `struct Foo<T> where T: Copy { ... }`
(try!(self.parse_record_struct_body(&class_name)), None)
(try!(self.parse_record_struct_body()), None)
}
// No `where` so: `struct Foo<T>;`
} else if try!(self.eat(&token::Semi) ){
(Vec::new(), Some(ast::DUMMY_NODE_ID))
// Record-style struct definition
} else if self.token == token::OpenDelim(token::Brace) {
let fields = try!(self.parse_record_struct_body(&class_name));
let fields = try!(self.parse_record_struct_body());
(fields, None)
// Tuple-style struct definition with optional where-clause.
} else if self.token == token::OpenDelim(token::Paren) {
@ -4740,20 +4732,13 @@ impl<'a> Parser<'a> {
None))
}
pub fn parse_record_struct_body(&mut self,
class_name: &ast::Ident) -> PResult<Vec<StructField>> {
pub fn parse_record_struct_body(&mut self) -> PResult<Vec<StructField>> {
let mut fields = Vec::new();
if try!(self.eat(&token::OpenDelim(token::Brace)) ){
while self.token != token::CloseDelim(token::Brace) {
fields.push(try!(self.parse_struct_decl_field(true)));
}
if fields.is_empty() {
return Err(self.fatal(&format!("unit-like struct definition should be \
written as `struct {};`",
class_name)));
}
try!(self.bump());
} else {
let token_str = self.this_token_to_string();

50
src/libsyntax/print/pprust.rs
View file

@ -1855,34 +1855,34 @@ impl<'a> State<'a> {
fields: &[ast::Field],
wth: &Option<P<ast::Expr>>) -> io::Result<()> {
try!(self.print_path(path, true, 0));
if !(fields.is_empty() && wth.is_none()) {
try!(word(&mut self.s, "{"));
try!(self.commasep_cmnt(
Consistent,
&fields[..],
|s, field| {
try!(s.ibox(indent_unit));
try!(s.print_ident(field.ident.node));
try!(s.word_space(":"));
try!(s.print_expr(&*field.expr));
s.end()
},
|f| f.span));
match *wth {
Some(ref expr) => {
try!(self.ibox(indent_unit));
if !fields.is_empty() {
try!(word(&mut self.s, ","));
try!(space(&mut self.s));
}
try!(word(&mut self.s, ".."));
try!(self.print_expr(&**expr));
try!(self.end());
try!(word(&mut self.s, "{"));
try!(self.commasep_cmnt(
Consistent,
&fields[..],
|s, field| {
try!(s.ibox(indent_unit));
try!(s.print_ident(field.ident.node));
try!(s.word_space(":"));
try!(s.print_expr(&*field.expr));
s.end()
},
|f| f.span));
match *wth {
Some(ref expr) => {
try!(self.ibox(indent_unit));
if !fields.is_empty() {
try!(word(&mut self.s, ","));
try!(space(&mut self.s));
}
_ => try!(word(&mut self.s, ",")),
try!(word(&mut self.s, ".."));
try!(self.print_expr(&**expr));
try!(self.end());
}
_ => if !fields.is_empty() {
try!(word(&mut self.s, ","))
}
try!(word(&mut self.s, "}"));
}
try!(word(&mut self.s, "}"));
Ok(())
}

13
src/test/parse-fail/struct-no-fields-2.rs → src/test/compile-fail/empty-struct-with-braces-1.rs
View file

@ -1,4 +1,4 @@
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
@ -8,13 +8,10 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// compile-flags: -Z parse-only
// Empty struct defined with braces shouldn't add names into value namespace
struct Foo;
struct Empty {}
fn f2() {
let _end_stmt = Foo { };
//~^ ERROR: structure literal must either have at least one field
fn main() {
let e = Empty; //~ ERROR `Empty` is the name of a struct or struct variant
}
fn main() {}

20
src/test/parse-fail/struct-no-fields-3.rs → src/test/compile-fail/empty-struct-with-braces-2.rs
View file

@ -1,4 +1,4 @@
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
@ -8,13 +8,17 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// compile-flags: -Z parse-only
// Empty struct defined with braces shouldn't add names into value namespace
struct Foo;
#![deny(warnings)]
fn g3() {
let _mid_tuple = (Foo { }, 2);
//~^ ERROR: structure literal must either have at least one field
struct Empty {}
fn main() {
let e = Empty {};
match e {
Empty => () //~ ERROR unused variable: `Empty`
//~^ ERROR variable `Empty` should have a snake case name such as `empty`
}
}
fn main() {}

4
src/test/compile-fail/issue-27831.rs
View file

@ -22,8 +22,8 @@ fn main() {
let Foo { .. } = x; //~ ERROR `Foo` does not name a struct
let x = Bar;
Bar { ..x }; //~ ERROR `Bar` does not name a structure
let Bar { .. } = x; //~ ERROR `Bar` does not name a struct
Bar { ..x };
let Bar { .. } = x;
match Enum::Bar {
Enum::Bar { .. } //~ ERROR `Enum::Bar` does not name a struct

20
src/test/parse-fail/struct-no-fields-4.rs
View file

@ -1,20 +0,0 @@
// Copyright 2013 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.
// compile-flags: -Z parse-only
struct Foo;
fn h4() {
let _end_of_tuple = (3, Foo { });
//~^ ERROR: structure literal must either have at least one field
}
fn main() {}

20
src/test/parse-fail/struct-no-fields-5.rs
View file

@ -1,20 +0,0 @@
// Copyright 2013 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.
// compile-flags: -Z parse-only
struct Foo;
fn i5() {
let _end_of_block = { Foo { } };
//~^ ERROR: structure literal must either have at least one field
}
fn main() {}

31
src/test/run-pass/empty-struct-with-braces.rs Normal file
View file

@ -0,0 +1,31 @@
// Copyright 2015 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.
// Empty struct defined with braces add names into type namespace
// Empty struct defined without braces add names into both type and value namespaces
struct Empty1 {}
struct Empty2;
fn main() {
let e1: Empty1 = Empty1 {};
let e2: Empty2 = Empty2 {};
let e2: Empty2 = Empty2;
match e1 {
Empty1 {} => ()
}
match e2 {
Empty2 {} => ()
}
match e2 {
Empty2 => ()
}
}

14
src/test/parse-fail/struct-no-fields.rs → src/test/run-pass/issue-16819.rs
View file

@ -1,4 +1,4 @@
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
@ -8,9 +8,13 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// compile-flags: -Z parse-only
//`#[cfg]` on struct field permits empty unusable struct
struct Foo {}
//~^ ERROR: unit-like struct definition should be written as `struct Foo;`
struct S {
#[cfg(untrue)]
a: int,
}
fn main() {}
fn main() {
let s = S {};
}