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Auto merge of #51052 - nikomatsakis:obsolete-arrow, r=petrochenkov
restore emplacement syntax (obsolete) Fix #50832 r? @petrochenkov
2 parents 7a0e6a8 + 626818f commit 1594c6c

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11 files changed

+98
-6
lines changed

11 files changed

+98
-6
lines changed

‎src/librustc/hir/lowering.rs

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2906,7 +2906,10 @@ impl<'a> LoweringContext<'a> {
29062906
fn lower_expr(&mut self, e: &Expr) -> hir::Expr {
29072907
let kind = match e.node {
29082908
ExprKind::Box(ref inner) => hir::ExprBox(P(self.lower_expr(inner))),
2909-
2909+
ExprKind::ObsoleteInPlace(..) => {
2910+
self.sess.abort_if_errors();
2911+
span_bug!(e.span, "encountered ObsoleteInPlace expr during lowering");
2912+
}
29102913
ExprKind::Array(ref exprs) => {
29112914
hir::ExprArray(exprs.iter().map(|x| self.lower_expr(x)).collect())
29122915
}

‎src/librustc_passes/ast_validation.rs

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -172,6 +172,13 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
172172
ExprKind::InlineAsm(..) if !self.session.target.target.options.allow_asm => {
173173
span_err!(self.session, expr.span, E0472, "asm! is unsupported on this target");
174174
}
175+
ExprKind::ObsoleteInPlace(..) => {
176+
self.err_handler()
177+
.struct_span_err(expr.span, "emplacement syntax is obsolete (for now, anyway)")
178+
.note("for more information, see \
179+
<https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>")
180+
.emit();
181+
}
175182
_ => {}
176183
}
177184

‎src/libsyntax/ast.rs

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1010,6 +1010,7 @@ impl Expr {
10101010
pub fn precedence(&self) -> ExprPrecedence {
10111011
match self.node {
10121012
ExprKind::Box(_) => ExprPrecedence::Box,
1013+
ExprKind::ObsoleteInPlace(..) => ExprPrecedence::ObsoleteInPlace,
10131014
ExprKind::Array(_) => ExprPrecedence::Array,
10141015
ExprKind::Call(..) => ExprPrecedence::Call,
10151016
ExprKind::MethodCall(..) => ExprPrecedence::MethodCall,
@@ -1068,6 +1069,8 @@ pub enum RangeLimits {
10681069
pub enum ExprKind {
10691070
/// A `box x` expression.
10701071
Box(P<Expr>),
1072+
/// First expr is the place; second expr is the value.
1073+
ObsoleteInPlace(P<Expr>, P<Expr>),
10711074
/// An array (`[a, b, c, d]`)
10721075
Array(Vec<P<Expr>>),
10731076
/// A function call

‎src/libsyntax/feature_gate.rs

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1690,6 +1690,9 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
16901690
gate_feature_post!(&self, type_ascription, e.span,
16911691
"type ascription is experimental");
16921692
}
1693+
ast::ExprKind::ObsoleteInPlace(..) => {
1694+
// these get a hard error in ast-validation
1695+
}
16931696
ast::ExprKind::Yield(..) => {
16941697
gate_feature_post!(&self, generators,
16951698
e.span,

‎src/libsyntax/fold.rs

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1194,6 +1194,9 @@ pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mu
11941194
ExprKind::Box(e) => {
11951195
ExprKind::Box(folder.fold_expr(e))
11961196
}
1197+
ExprKind::ObsoleteInPlace(a, b) => {
1198+
ExprKind::ObsoleteInPlace(folder.fold_expr(a), folder.fold_expr(b))
1199+
}
11971200
ExprKind::Array(exprs) => {
11981201
ExprKind::Array(folder.fold_exprs(exprs))
11991202
}

‎src/libsyntax/parse/parser.rs

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2839,6 +2839,17 @@ impl<'a> Parser<'a> {
28392839
let (span, e) = self.interpolated_or_expr_span(e)?;
28402840
(lo.to(span), ExprKind::AddrOf(m, e))
28412841
}
2842+
token::Ident(..) if self.token.is_keyword(keywords::In) => {
2843+
self.bump();
2844+
let place = self.parse_expr_res(
2845+
Restrictions::NO_STRUCT_LITERAL,
2846+
None,
2847+
)?;
2848+
let blk = self.parse_block()?;
2849+
let span = blk.span;
2850+
let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new());
2851+
(lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr))
2852+
}
28422853
token::Ident(..) if self.token.is_keyword(keywords::Box) => {
28432854
self.bump();
28442855
let e = self.parse_prefix_expr(None);
@@ -3042,6 +3053,8 @@ impl<'a> Parser<'a> {
30423053
}
30433054
AssocOp::Assign =>
30443055
self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
3056+
AssocOp::ObsoleteInPlace =>
3057+
self.mk_expr(span, ExprKind::ObsoleteInPlace(lhs, rhs), ThinVec::new()),
30453058
AssocOp::AssignOp(k) => {
30463059
let aop = match k {
30473060
token::Plus => BinOpKind::Add,

‎src/libsyntax/print/pprust.rs

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2057,6 +2057,13 @@ impl<'a> State<'a> {
20572057
self.word_space("box")?;
20582058
self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)?;
20592059
}
2060+
ast::ExprKind::ObsoleteInPlace(ref place, ref expr) => {
2061+
let prec = AssocOp::ObsoleteInPlace.precedence() as i8;
2062+
self.print_expr_maybe_paren(place, prec + 1)?;
2063+
self.s.space()?;
2064+
self.word_space("<-")?;
2065+
self.print_expr_maybe_paren(expr, prec)?;
2066+
}
20602067
ast::ExprKind::Array(ref exprs) => {
20612068
self.print_expr_vec(&exprs[..], attrs)?;
20622069
}

‎src/libsyntax/util/parser.rs

Lines changed: 11 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -56,6 +56,8 @@ pub enum AssocOp {
5656
GreaterEqual,
5757
/// `=`
5858
Assign,
59+
/// `<-`
60+
ObsoleteInPlace,
5961
/// `?=` where ? is one of the BinOpToken
6062
AssignOp(BinOpToken),
6163
/// `as`
@@ -84,6 +86,7 @@ impl AssocOp {
8486
use self::AssocOp::*;
8587
match *t {
8688
Token::BinOpEq(k) => Some(AssignOp(k)),
89+
Token::LArrow => Some(ObsoleteInPlace),
8790
Token::Eq => Some(Assign),
8891
Token::BinOp(BinOpToken::Star) => Some(Multiply),
8992
Token::BinOp(BinOpToken::Slash) => Some(Divide),
@@ -153,6 +156,7 @@ impl AssocOp {
153156
LAnd => 6,
154157
LOr => 5,
155158
DotDot | DotDotEq => 4,
159+
ObsoleteInPlace => 3,
156160
Assign | AssignOp(_) => 2,
157161
}
158162
}
@@ -162,7 +166,7 @@ impl AssocOp {
162166
use self::AssocOp::*;
163167
// NOTE: it is a bug to have an operators that has same precedence but different fixities!
164168
match *self {
165-
Assign | AssignOp(_) => Fixity::Right,
169+
ObsoleteInPlace | Assign | AssignOp(_) => Fixity::Right,
166170
As | Multiply | Divide | Modulus | Add | Subtract | ShiftLeft | ShiftRight | BitAnd |
167171
BitXor | BitOr | Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual |
168172
LAnd | LOr | Colon => Fixity::Left,
@@ -174,16 +178,16 @@ impl AssocOp {
174178
use self::AssocOp::*;
175179
match *self {
176180
Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual => true,
177-
Assign | AssignOp(_) | As | Multiply | Divide | Modulus | Add | Subtract |
178-
ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd | LOr |
181+
ObsoleteInPlace | Assign | AssignOp(_) | As | Multiply | Divide | Modulus | Add |
182+
Subtract | ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd | LOr |
179183
DotDot | DotDotEq | Colon => false
180184
}
181185
}
182186

183187
pub fn is_assign_like(&self) -> bool {
184188
use self::AssocOp::*;
185189
match *self {
186-
Assign | AssignOp(_) => true,
190+
Assign | AssignOp(_) | ObsoleteInPlace => true,
187191
Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual | As | Multiply | Divide |
188192
Modulus | Add | Subtract | ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd |
189193
LOr | DotDot | DotDotEq | Colon => false
@@ -211,7 +215,7 @@ impl AssocOp {
211215
BitOr => Some(BinOpKind::BitOr),
212216
LAnd => Some(BinOpKind::And),
213217
LOr => Some(BinOpKind::Or),
214-
Assign | AssignOp(_) | As | DotDot | DotDotEq | Colon => None
218+
ObsoleteInPlace | Assign | AssignOp(_) | As | DotDot | DotDotEq | Colon => None
215219
}
216220
}
217221
}
@@ -238,6 +242,7 @@ pub enum ExprPrecedence {
238242

239243
Binary(BinOpKind),
240244

245+
ObsoleteInPlace,
241246
Cast,
242247
Type,
243248

@@ -304,6 +309,7 @@ impl ExprPrecedence {
304309

305310
// Binop-like expr kinds, handled by `AssocOp`.
306311
ExprPrecedence::Binary(op) => AssocOp::from_ast_binop(op).precedence() as i8,
312+
ExprPrecedence::ObsoleteInPlace => AssocOp::ObsoleteInPlace.precedence() as i8,
307313
ExprPrecedence::Cast => AssocOp::As.precedence() as i8,
308314
ExprPrecedence::Type => AssocOp::Colon.precedence() as i8,
309315

‎src/libsyntax/visit.rs

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -660,6 +660,10 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
660660
ExprKind::Box(ref subexpression) => {
661661
visitor.visit_expr(subexpression)
662662
}
663+
ExprKind::ObsoleteInPlace(ref place, ref subexpression) => {
664+
visitor.visit_expr(place);
665+
visitor.visit_expr(subexpression)
666+
}
663667
ExprKind::Array(ref subexpressions) => {
664668
walk_list!(visitor, visit_expr, subexpressions);
665669
}

‎src/test/ui/obsolete-in-place/bad.bad.stderr

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
error: emplacement syntax is obsolete (for now, anyway)
2+
--> $DIR/bad.rs:19:5
3+
|
4+
LL | x <- y; //[bad]~ ERROR emplacement syntax is obsolete
5+
| ^^^^^^
6+
|
7+
= note: for more information, see <https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>
8+
9+
error: emplacement syntax is obsolete (for now, anyway)
10+
--> $DIR/bad.rs:20:5
11+
|
12+
LL | in(foo) { bar }; //[bad]~ ERROR emplacement syntax is obsolete
13+
| ^^^^^^^^^^^^^^^
14+
|
15+
= note: for more information, see <https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>
16+
17+
error: aborting due to 2 previous errors
18+

‎src/test/ui/obsolete-in-place/bad.rs

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,25 @@
1+
// Copyright 2015 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+
// Check that `<-` and `in` syntax gets a hard error.
12+
13+
// revisions: good bad
14+
//[good] run-pass
15+
16+
#[cfg(bad)]
17+
fn main() {
18+
let (x, y, foo, bar);
19+
x <- y; //[bad]~ ERROR emplacement syntax is obsolete
20+
in(foo) { bar }; //[bad]~ ERROR emplacement syntax is obsolete
21+
}
22+
23+
#[cfg(good)]
24+
fn main() {
25+
}

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