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Rollup merge of rust-lang#68120 - Centril:ban-range-to-dotdotdot, r=oli-obk
Ban `...X` pats, harden tests, and improve diagnostics Follow up to rust-lang#67258 (comment) and rust-lang#67258 (comment). r? @cramertj @oli-obk
2 parents b00abbe + 883932c commit b8f6eb9

19 files changed

+260
-121
lines changed

‎src/librustc_parse/parser/expr.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -1966,7 +1966,7 @@ impl<'a> Parser<'a> {
19661966
limits: RangeLimits,
19671967
) -> PResult<'a, ExprKind> {
19681968
if end.is_none() && limits == RangeLimits::Closed {
1969-
self.error_inclusive_range_with_no_end(self.token.span);
1969+
self.error_inclusive_range_with_no_end(self.prev_span);
19701970
Ok(ExprKind::Err)
19711971
} else {
19721972
Ok(ExprKind::Range(start, end, limits))

‎src/librustc_parse/parser/pat.rs

+23-3
Original file line numberDiff line numberDiff line change
@@ -661,14 +661,34 @@ impl<'a> Parser<'a> {
661661
pub(super) fn error_inclusive_range_with_no_end(&self, span: Span) {
662662
use rustc_error_codes::E0586;
663663
struct_span_err!(self.sess.span_diagnostic, span, E0586, "inclusive range with no end")
664-
.help("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)")
664+
.span_suggestion_short(
665+
span,
666+
"use `..` instead",
667+
"..".to_string(),
668+
Applicability::MachineApplicable,
669+
)
670+
.note("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)")
665671
.emit();
666672
}
667673

668-
/// Parse a range-to pattern, e.g. `..X` and `..=X` where `X` remains to be parsed.
669-
fn parse_pat_range_to(&mut self, re: Spanned<RangeEnd>) -> PResult<'a, PatKind> {
674+
/// Parse a range-to pattern, `..X` or `..=X` where `X` remains to be parsed.
675+
///
676+
/// The form `...X` is prohibited to reduce confusion with the potential
677+
/// expression syntax `...expr` for splatting in expressions.
678+
fn parse_pat_range_to(&mut self, mut re: Spanned<RangeEnd>) -> PResult<'a, PatKind> {
670679
let end = self.parse_pat_range_end()?;
671680
self.sess.gated_spans.gate(sym::half_open_range_patterns, re.span.to(self.prev_span));
681+
if let RangeEnd::Included(ref mut syn @ RangeSyntax::DotDotDot) = &mut re.node {
682+
*syn = RangeSyntax::DotDotEq;
683+
self.struct_span_err(re.span, "range-to patterns with `...` are not allowed")
684+
.span_suggestion_short(
685+
re.span,
686+
"use `..=` instead",
687+
"..=".to_string(),
688+
Applicability::MachineApplicable,
689+
)
690+
.emit();
691+
}
672692
Ok(PatKind::Range(None, Some(end), re))
673693
}
674694

‎src/test/ui/error-codes/E0586.stderr

+3-3
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,10 @@
11
error[E0586]: inclusive range with no end
2-
--> $DIR/E0586.rs:3:22
2+
--> $DIR/E0586.rs:3:19
33
|
44
LL | let x = &tmp[1..=];
5-
| ^
5+
| ^^^ help: use `..` instead
66
|
7-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
7+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
88

99
error: aborting due to previous error
1010

‎src/test/ui/half-open-range-patterns/feature-gate-half-open-range-patterns.rs

+1
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,7 @@ fn foo() {
88
//~^ ERROR half-open range patterns are unstable
99
if let ...5 = 0 {}
1010
//~^ ERROR half-open range patterns are unstable
11+
//~| ERROR range-to patterns with `...` are not allowed
1112
if let ..5 = 0 {}
1213
//~^ ERROR half-open range patterns are unstable
1314
if let 5.. = 0 {}

‎src/test/ui/half-open-range-patterns/feature-gate-half-open-range-patterns.stderr

+17-11
Original file line numberDiff line numberDiff line change
@@ -1,18 +1,24 @@
1+
error: range-to patterns with `...` are not allowed
2+
--> $DIR/feature-gate-half-open-range-patterns.rs:9:12
3+
|
4+
LL | if let ...5 = 0 {}
5+
| ^^^ help: use `..=` instead
6+
17
error[E0586]: inclusive range with no end
2-
--> $DIR/feature-gate-half-open-range-patterns.rs:15:13
8+
--> $DIR/feature-gate-half-open-range-patterns.rs:16:13
39
|
410
LL | if let 5..= = 0 {}
5-
| ^^^
11+
| ^^^ help: use `..` instead
612
|
7-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
13+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
814

915
error[E0586]: inclusive range with no end
10-
--> $DIR/feature-gate-half-open-range-patterns.rs:18:13
16+
--> $DIR/feature-gate-half-open-range-patterns.rs:19:13
1117
|
1218
LL | if let 5... = 0 {}
13-
| ^^^
19+
| ^^^ help: use `..` instead
1420
|
15-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
21+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
1622

1723
error[E0658]: half-open range patterns are unstable
1824
--> $DIR/feature-gate-half-open-range-patterns.rs:7:12
@@ -33,7 +39,7 @@ LL | if let ...5 = 0 {}
3339
= help: add `#![feature(half_open_range_patterns)]` to the crate attributes to enable
3440

3541
error[E0658]: half-open range patterns are unstable
36-
--> $DIR/feature-gate-half-open-range-patterns.rs:11:12
42+
--> $DIR/feature-gate-half-open-range-patterns.rs:12:12
3743
|
3844
LL | if let ..5 = 0 {}
3945
| ^^^
@@ -42,7 +48,7 @@ LL | if let ..5 = 0 {}
4248
= help: add `#![feature(half_open_range_patterns)]` to the crate attributes to enable
4349

4450
error[E0658]: half-open range patterns are unstable
45-
--> $DIR/feature-gate-half-open-range-patterns.rs:13:12
51+
--> $DIR/feature-gate-half-open-range-patterns.rs:14:12
4652
|
4753
LL | if let 5.. = 0 {}
4854
| ^^^
@@ -51,7 +57,7 @@ LL | if let 5.. = 0 {}
5157
= help: add `#![feature(half_open_range_patterns)]` to the crate attributes to enable
5258

5359
error[E0658]: half-open range patterns are unstable
54-
--> $DIR/feature-gate-half-open-range-patterns.rs:15:12
60+
--> $DIR/feature-gate-half-open-range-patterns.rs:16:12
5561
|
5662
LL | if let 5..= = 0 {}
5763
| ^^^^
@@ -60,15 +66,15 @@ LL | if let 5..= = 0 {}
6066
= help: add `#![feature(half_open_range_patterns)]` to the crate attributes to enable
6167

6268
error[E0658]: half-open range patterns are unstable
63-
--> $DIR/feature-gate-half-open-range-patterns.rs:18:12
69+
--> $DIR/feature-gate-half-open-range-patterns.rs:19:12
6470
|
6571
LL | if let 5... = 0 {}
6672
| ^^^^
6773
|
6874
= note: for more information, see https://github.com/rust-lang/rust/issues/67264
6975
= help: add `#![feature(half_open_range_patterns)]` to the crate attributes to enable
7076

71-
error: aborting due to 8 previous errors
77+
error: aborting due to 9 previous errors
7278

7379
Some errors have detailed explanations: E0586, E0658.
7480
For more information about an error, try `rustc --explain E0586`.

‎src/test/ui/half-open-range-patterns/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs

+32
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,32 @@
1+
// Test that `...X` range-to patterns are syntactically invalid.
2+
//
3+
// See https://github.com/rust-lang/rust/pull/67258#issuecomment-565656155
4+
// for the reason why. To summarize, we might want to introduce `...expr` as
5+
// an expression form for splatting (or "untupling") in an expression context.
6+
// While there is no syntactic ambiguity with `...X` in a pattern context,
7+
// there's a potential confusion factor here, and we would prefer to keep patterns
8+
// and expressions in-sync. As such, we do not allow `...X` in patterns either.
9+
10+
#![feature(half_open_range_patterns)]
11+
12+
fn main() {}
13+
14+
#[cfg(FALSE)]
15+
fn syntax() {
16+
match scrutinee {
17+
...X => {} //~ ERROR range-to patterns with `...` are not allowed
18+
...0 => {} //~ ERROR range-to patterns with `...` are not allowed
19+
...'a' => {} //~ ERROR range-to patterns with `...` are not allowed
20+
...0.0f32 => {} //~ ERROR range-to patterns with `...` are not allowed
21+
}
22+
}
23+
24+
fn syntax2() {
25+
macro_rules! mac {
26+
($e:expr) => {
27+
let ...$e; //~ ERROR range-to patterns with `...` are not allowed
28+
}
29+
}
30+
31+
mac!(0);
32+
}

‎src/test/ui/half-open-range-patterns/half-open-range-pats-inclusive-dotdotdot-bad-syntax.stderr

+35
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,35 @@
1+
error: range-to patterns with `...` are not allowed
2+
--> $DIR/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs:17:9
3+
|
4+
LL | ...X => {}
5+
| ^^^ help: use `..=` instead
6+
7+
error: range-to patterns with `...` are not allowed
8+
--> $DIR/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs:18:9
9+
|
10+
LL | ...0 => {}
11+
| ^^^ help: use `..=` instead
12+
13+
error: range-to patterns with `...` are not allowed
14+
--> $DIR/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs:19:9
15+
|
16+
LL | ...'a' => {}
17+
| ^^^ help: use `..=` instead
18+
19+
error: range-to patterns with `...` are not allowed
20+
--> $DIR/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs:20:9
21+
|
22+
LL | ...0.0f32 => {}
23+
| ^^^ help: use `..=` instead
24+
25+
error: range-to patterns with `...` are not allowed
26+
--> $DIR/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs:27:17
27+
|
28+
LL | let ...$e;
29+
| ^^^ help: use `..=` instead
30+
...
31+
LL | mac!(0);
32+
| -------- in this macro invocation
33+
34+
error: aborting due to 5 previous errors
35+

‎src/test/ui/half-open-range-patterns/half-open-range-pats-inclusive-no-end.rs

+11
Original file line numberDiff line numberDiff line change
@@ -13,3 +13,14 @@ fn foo() {
1313
if let X... = 1 {} //~ ERROR inclusive range with no end
1414
if let X..= = 1 {} //~ ERROR inclusive range with no end
1515
}
16+
17+
fn bar() {
18+
macro_rules! mac {
19+
($e:expr) => {
20+
let $e...; //~ ERROR inclusive range with no end
21+
let $e..=; //~ ERROR inclusive range with no end
22+
}
23+
}
24+
25+
mac!(0);
26+
}

‎src/test/ui/half-open-range-patterns/half-open-range-pats-inclusive-no-end.stderr

+31-9
Original file line numberDiff line numberDiff line change
@@ -2,34 +2,56 @@ error[E0586]: inclusive range with no end
22
--> $DIR/half-open-range-pats-inclusive-no-end.rs:10:13
33
|
44
LL | if let 0... = 1 {}
5-
| ^^^
5+
| ^^^ help: use `..` instead
66
|
7-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
7+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
88

99
error[E0586]: inclusive range with no end
1010
--> $DIR/half-open-range-pats-inclusive-no-end.rs:11:13
1111
|
1212
LL | if let 0..= = 1 {}
13-
| ^^^
13+
| ^^^ help: use `..` instead
1414
|
15-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
15+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
1616

1717
error[E0586]: inclusive range with no end
1818
--> $DIR/half-open-range-pats-inclusive-no-end.rs:13:13
1919
|
2020
LL | if let X... = 1 {}
21-
| ^^^
21+
| ^^^ help: use `..` instead
2222
|
23-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
23+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
2424

2525
error[E0586]: inclusive range with no end
2626
--> $DIR/half-open-range-pats-inclusive-no-end.rs:14:13
2727
|
2828
LL | if let X..= = 1 {}
29-
| ^^^
29+
| ^^^ help: use `..` instead
3030
|
31-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
31+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
3232

33-
error: aborting due to 4 previous errors
33+
error[E0586]: inclusive range with no end
34+
--> $DIR/half-open-range-pats-inclusive-no-end.rs:20:19
35+
|
36+
LL | let $e...;
37+
| ^^^ help: use `..` instead
38+
...
39+
LL | mac!(0);
40+
| -------- in this macro invocation
41+
|
42+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
43+
44+
error[E0586]: inclusive range with no end
45+
--> $DIR/half-open-range-pats-inclusive-no-end.rs:21:19
46+
|
47+
LL | let $e..=;
48+
| ^^^ help: use `..` instead
49+
...
50+
LL | mac!(0);
51+
| -------- in this macro invocation
52+
|
53+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
54+
55+
error: aborting due to 6 previous errors
3456

3557
For more information about this error, try `rustc --explain E0586`.

‎src/test/ui/half-open-range-patterns/half-open-range-pats-ref-ambiguous-interp.rs

+2
Original file line numberDiff line numberDiff line change
@@ -20,5 +20,7 @@ fn syntax() {
2020
&..=0 | _ => {}
2121
//~^ ERROR the range pattern here has ambiguous interpretation
2222
&...0 | _ => {}
23+
//~^ ERROR the range pattern here has ambiguous interpretation
24+
//~| ERROR range-to patterns with `...` are not allowed
2325
}
2426
}

‎src/test/ui/half-open-range-patterns/half-open-range-pats-ref-ambiguous-interp.stderr

+17-5
Original file line numberDiff line numberDiff line change
@@ -8,9 +8,9 @@ error[E0586]: inclusive range with no end
88
--> $DIR/half-open-range-pats-ref-ambiguous-interp.rs:10:11
99
|
1010
LL | &0..= | _ => {}
11-
| ^^^
11+
| ^^^ help: use `..` instead
1212
|
13-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
13+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
1414

1515
error: the range pattern here has ambiguous interpretation
1616
--> $DIR/half-open-range-pats-ref-ambiguous-interp.rs:10:10
@@ -22,9 +22,9 @@ error[E0586]: inclusive range with no end
2222
--> $DIR/half-open-range-pats-ref-ambiguous-interp.rs:13:11
2323
|
2424
LL | &0... | _ => {}
25-
| ^^^
25+
| ^^^ help: use `..` instead
2626
|
27-
= help: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
27+
= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
2828

2929
error: the range pattern here has ambiguous interpretation
3030
--> $DIR/half-open-range-pats-ref-ambiguous-interp.rs:18:10
@@ -38,6 +38,18 @@ error: the range pattern here has ambiguous interpretation
3838
LL | &..=0 | _ => {}
3939
| ^^^^ help: add parentheses to clarify the precedence: `(..=0)`
4040

41-
error: aborting due to 6 previous errors
41+
error: range-to patterns with `...` are not allowed
42+
--> $DIR/half-open-range-pats-ref-ambiguous-interp.rs:22:10
43+
|
44+
LL | &...0 | _ => {}
45+
| ^^^ help: use `..=` instead
46+
47+
error: the range pattern here has ambiguous interpretation
48+
--> $DIR/half-open-range-pats-ref-ambiguous-interp.rs:22:10
49+
|
50+
LL | &...0 | _ => {}
51+
| ^^^^ help: add parentheses to clarify the precedence: `(..=0)`
52+
53+
error: aborting due to 8 previous errors
4254

4355
For more information about this error, try `rustc --explain E0586`.

‎src/test/ui/half-open-range-patterns/half-open-range-pats-syntactic-pass.rs

+10-12
Original file line numberDiff line numberDiff line change
@@ -11,22 +11,20 @@ fn main() {}
1111
fn syntax() {
1212
match scrutinee {
1313
X.. | 0.. | 'a'.. | 0.0f32.. => {}
14-
..=X | ...X | ..X => {}
15-
..=0 | ...0 | ..0 => {}
16-
..='a' | ...'a' | ..'a' => {}
17-
..=0.0f32 | ...0.0f32 | ..0.0f32 => {}
14+
..=X | ..X => {}
15+
..=0 | ..0 => {}
16+
..='a' | ..'a' => {}
17+
..=0.0f32 | ..0.0f32 => {}
1818
}
19+
}
1920

21+
fn syntax2() {
2022
macro_rules! mac {
2123
($e:expr) => {
22-
let ..$e;
23-
let ...$e;
24-
let ..=$e;
25-
let $e..;
26-
let $e...;
27-
let $e..=;
24+
match 0u8 { ..$e => {}, _ => {} }
25+
match 0u8 { ..=$e => {}, _ => {} }
26+
match 0u8 { $e.. => {}, _ => {} }
2827
}
2928
}
30-
31-
mac!(0);
29+
mac!(42u8);
3230
}

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