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Add underscore expressions for destructuring assignments

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Co-authored-by: varkor <github@varkor.com>
This commit is contained in:
Fabian Zaiser 2020-11-11 13:15:15 +00:00
parent a38f8fb674
commit 8cf3564310
27 changed files with 243 additions and 45 deletions
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3
src/test/ui/cross/cross-file-errors/main.rs
View file

@ -3,5 +3,6 @@ mod underscore;
fn main() {
underscore!();
//~^ ERROR expected expression, found reserved identifier `_`
//~^ ERROR `_` can only be used on the left-hand side of an assignment
//~| ERROR destructuring assignments are unstable
}

22
src/test/ui/cross/cross-file-errors/main.stderr
View file

@ -1,8 +1,23 @@
error: expected expression, found reserved identifier `_`
error[E0658]: destructuring assignments are unstable
--> $DIR/underscore.rs:8:9
|
LL | _
| ^ expected expression
| ^
|
::: $DIR/main.rs:5:5
|
LL | underscore!();
| -------------- in this macro invocation
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/underscore.rs:8:9
|
LL | _
| ^ `_` not allowed here
|
::: $DIR/main.rs:5:5
|
@ -11,5 +26,6 @@ LL | underscore!();
|
= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to previous error
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0658`.

3
src/test/ui/destructuring-assignment/nested_destructure.rs
View file

@ -14,4 +14,7 @@ fn main() {
Struct { a: TupleStruct((a, b), c), b: [d] } =
Struct { a: TupleStruct((0, 1), 2), b: [3] };
assert_eq!((a, b, c, d), (0, 1, 2, 3));
// unnested underscore: just discard
_ = 1;
}

2
src/test/ui/destructuring-assignment/slice_destructure.rs
View file

@ -9,6 +9,8 @@ fn main() {
let mut c;
[a, .., b, c] = [1, 2, 3, 4, 5];
assert_eq!((a, b, c), (1, 4, 5));
[_, a, _] = [1, 2, 3];
assert_eq!((a, b), (2, 4));
[..] = [1, 2, 3];
[c, ..] = [5, 6, 6];
assert_eq!(c, 5);

1
src/test/ui/destructuring-assignment/slice_destructure_fail.rs
View file

@ -4,4 +4,5 @@ fn main() {
let (mut a, mut b);
[a, .., b, ..] = [0, 1]; //~ ERROR `..` can only be used once per slice pattern
[a, a, b] = [1, 2]; //~ ERROR pattern requires 3 elements but array has 2
[_] = [1, 2]; //~ ERROR pattern requires 1 element but array has 2
}

8
src/test/ui/destructuring-assignment/slice_destructure_fail.stderr
View file

@ -12,6 +12,12 @@ error[E0527]: pattern requires 3 elements but array has 2
LL | [a, a, b] = [1, 2];
| ^^^^^^^^^ expected 2 elements
error: aborting due to 2 previous errors
error[E0527]: pattern requires 1 element but array has 2
--> $DIR/slice_destructure_fail.rs:7:3
|
LL | [_] = [1, 2];
| ^^^ expected 2 elements
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0527`.

6
src/test/ui/destructuring-assignment/struct_destructure.rs
View file

@ -12,8 +12,10 @@ fn main() {
assert_eq!((a, b), (0, 1));
Struct { a: b, b: a } = Struct { a: 1, b: 2 };
assert_eq!((a,b), (2, 1));
Struct { a: _, b } = Struct { a: 1, b: 2 };
assert_eq!((a, b), (2, 2));
Struct { a, .. } = Struct { a: 1, b: 3 };
assert_eq!((a, b), (1, 1));
assert_eq!((a, b), (1, 2));
Struct { .. } = Struct { a: 1, b: 4 };
assert_eq!((a, b), (1, 1));
assert_eq!((a, b), (1, 2));
}

2
src/test/ui/destructuring-assignment/struct_destructure_fail.rs
View file

@ -9,6 +9,8 @@ fn main() {
let mut c;
let d = Struct { a: 0, b: 1 };
Struct { a, b, c } = Struct { a: 0, b: 1 }; //~ ERROR does not have a field named `c`
Struct { a, _ } = Struct { a: 1, b: 2 }; //~ ERROR pattern does not mention field `b`
//~| ERROR expected identifier, found reserved identifier `_`
Struct { a, ..d } = Struct { a: 1, b: 2 };
//~^ ERROR functional record updates are not allowed in destructuring assignments
Struct { a, .. }; //~ ERROR base expression required after `..`

32
src/test/ui/destructuring-assignment/struct_destructure_fail.stderr
View file

@ -1,11 +1,19 @@
error: expected identifier, found reserved identifier `_`
--> $DIR/struct_destructure_fail.rs:12:17
|
LL | Struct { a, _ } = Struct { a: 1, b: 2 };
| ------ ^ expected identifier, found reserved identifier
| |
| while parsing this struct
error: functional record updates are not allowed in destructuring assignments
--> $DIR/struct_destructure_fail.rs:12:19
--> $DIR/struct_destructure_fail.rs:14:19
|
LL | Struct { a, ..d } = Struct { a: 1, b: 2 };
| ^ help: consider removing the trailing pattern
error: base expression required after `..`
--> $DIR/struct_destructure_fail.rs:14:19
--> $DIR/struct_destructure_fail.rs:16:19
|
LL | Struct { a, .. };
| ^ add a base expression here
@ -16,6 +24,22 @@ error[E0026]: struct `Struct` does not have a field named `c`
LL | Struct { a, b, c } = Struct { a: 0, b: 1 };
| ^ struct `Struct` does not have this field
error: aborting due to 3 previous errors
error[E0027]: pattern does not mention field `b`
--> $DIR/struct_destructure_fail.rs:12:5
|
LL | Struct { a, _ } = Struct { a: 1, b: 2 };
| ^^^^^^^^^^^^^^^ missing field `b`
|
help: include the missing field in the pattern
|
LL | Struct { a, b, _ } = Struct { a: 1, b: 2 };
| ^^^
help: if you don't care about this missing field, you can explicitly ignore it
|
LL | Struct { a, .., _ } = Struct { a: 1, b: 2 };
| ^^^^
For more information about this error, try `rustc --explain E0026`.
error: aborting due to 5 previous errors
Some errors have detailed explanations: E0026, E0027.
For more information about an error, try `rustc --explain E0026`.

2
src/test/ui/destructuring-assignment/tuple_destructure.rs
View file

@ -16,6 +16,8 @@ fn main() {
assert_eq!((a, b), (2, 2));
(b, ..) = (5, 6, 7);
assert_eq!(b, 5);
(a, _) = (8, 9);
assert_eq!(a, 8);
// Test for a non-Copy type (String):
let (mut c, mut d);

1
src/test/ui/destructuring-assignment/tuple_destructure_fail.rs
View file

@ -7,4 +7,5 @@ fn main() {
(a, .., b, ..) = (0, 1); //~ ERROR `..` can only be used once per tuple pattern
(a, a, b) = (1, 2); //~ ERROR mismatched types
(C, ..) = (0,1); //~ ERROR invalid left-hand side of assignment
(_,) = (1, 2); //~ ERROR mismatched types
}

13
src/test/ui/destructuring-assignment/tuple_destructure_fail.stderr
View file

@ -25,7 +25,18 @@ LL | (C, ..) = (0,1);
| |
| cannot assign to this expression
error: aborting due to 3 previous errors
error[E0308]: mismatched types
--> $DIR/tuple_destructure_fail.rs:10:5
|
LL | (_,) = (1, 2);
| ^^^^ ------ this expression has type `({integer}, {integer})`
| |
| expected a tuple with 2 elements, found one with 1 element
|
= note: expected type `({integer}, {integer})`
found tuple `(_,)`
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0070, E0308.
For more information about an error, try `rustc --explain E0070`.

4
src/test/ui/destructuring-assignment/tuple_struct_destructure.rs
View file

@ -23,8 +23,10 @@ fn main() {
assert_eq!((a, b), (0, 1));
TupleStruct(a, .., b) = TupleStruct(1, 2);
assert_eq!((a, b), (1, 2));
TupleStruct(_, a) = TupleStruct(2, 2);
assert_eq!((a, b), (2, 2));
TupleStruct(..) = TupleStruct(3, 4);
assert_eq!((a, b), (1, 2));
assert_eq!((a, b), (2, 2));
TupleStruct(5,6).assign(&mut a, &mut b);
assert_eq!((a, b), (5, 6));
Enum::SingleVariant(a, b) = Enum::SingleVariant(7, 8);

4
src/test/ui/destructuring-assignment/tuple_struct_destructure_fail.rs
View file

@ -29,8 +29,12 @@ fn main() {
TupleStruct(a, a, b) = TupleStruct(1, 2);
//~^ ERROR this pattern has 3 fields, but the corresponding tuple struct has 2 fields
TupleStruct(_) = TupleStruct(1, 2);
//~^ ERROR this pattern has 1 field, but the corresponding tuple struct has 2 fields
Enum::SingleVariant(a, a, b) = Enum::SingleVariant(1, 2);
//~^ ERROR this pattern has 3 fields, but the corresponding tuple variant has 2 fields
Enum::SingleVariant(_) = Enum::SingleVariant(1, 2);
//~^ ERROR this pattern has 1 field, but the corresponding tuple variant has 2 fields
// Check if `test` is recognized as not a tuple struct but a function call:
test() = TupleStruct(0, 0);

28
src/test/ui/destructuring-assignment/tuple_struct_destructure_fail.stderr
View file

@ -23,17 +23,35 @@ LL | struct TupleStruct<S, T>(S, T);
LL | TupleStruct(a, a, b) = TupleStruct(1, 2);
| ^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 3
error[E0023]: this pattern has 3 fields, but the corresponding tuple variant has 2 fields
error[E0023]: this pattern has 1 field, but the corresponding tuple struct has 2 fields
--> $DIR/tuple_struct_destructure_fail.rs:32:5
|
LL | struct TupleStruct<S, T>(S, T);
| ------------------------------- tuple struct defined here
...
LL | TupleStruct(_) = TupleStruct(1, 2);
| ^^^^^^^^^^^^^^ expected 2 fields, found 1
error[E0023]: this pattern has 3 fields, but the corresponding tuple variant has 2 fields
--> $DIR/tuple_struct_destructure_fail.rs:34:5
|
LL | SingleVariant(S, T)
| ------------------- tuple variant defined here
...
LL | Enum::SingleVariant(a, a, b) = Enum::SingleVariant(1, 2);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 3
error[E0023]: this pattern has 1 field, but the corresponding tuple variant has 2 fields
--> $DIR/tuple_struct_destructure_fail.rs:36:5
|
LL | SingleVariant(S, T)
| ------------------- tuple variant defined here
...
LL | Enum::SingleVariant(_) = Enum::SingleVariant(1, 2);
| ^^^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 1
error[E0070]: invalid left-hand side of assignment
--> $DIR/tuple_struct_destructure_fail.rs:36:12
--> $DIR/tuple_struct_destructure_fail.rs:40:12
|
LL | test() = TupleStruct(0, 0);
| ------ ^
@ -41,7 +59,7 @@ LL | test() = TupleStruct(0, 0);
| cannot assign to this expression
error[E0070]: invalid left-hand side of assignment
--> $DIR/tuple_struct_destructure_fail.rs:38:14
--> $DIR/tuple_struct_destructure_fail.rs:42:14
|
LL | (test)() = TupleStruct(0, 0);
| -------- ^
@ -49,14 +67,14 @@ LL | (test)() = TupleStruct(0, 0);
| cannot assign to this expression
error[E0070]: invalid left-hand side of assignment
--> $DIR/tuple_struct_destructure_fail.rs:40:38
--> $DIR/tuple_struct_destructure_fail.rs:44:38
|
LL | <Alias::<isize> as Test>::test() = TupleStruct(0, 0);
| -------------------------------- ^
| |
| cannot assign to this expression
error: aborting due to 7 previous errors
error: aborting due to 9 previous errors
Some errors have detailed explanations: E0023, E0070.
For more information about an error, try `rustc --explain E0023`.

2
src/test/ui/destructuring-assignment/underscore-range-expr-gating.rs
View file

@ -4,5 +4,7 @@ struct S { x : u32 }
#[cfg(FALSE)]
fn foo() {
_; //~ ERROR destructuring assignments are unstable
S { x: 5, .. }; //~ ERROR destructuring assignments are unstable
}

13
src/test/ui/destructuring-assignment/underscore-range-expr-gating.stderr
View file

@ -1,5 +1,14 @@
error[E0658]: destructuring assignments are unstable
--> $DIR/underscore-range-expr-gating.rs:7:15
--> $DIR/underscore-range-expr-gating.rs:7:5
|
LL | _;
| ^
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error[E0658]: destructuring assignments are unstable
--> $DIR/underscore-range-expr-gating.rs:9:15
|
LL | S { x: 5, .. };
| ^^
@ -7,6 +16,6 @@ LL | S { x: 5, .. };
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error: aborting due to previous error
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0658`.

18
src/test/ui/suggestions/fn-or-tuple-struct-with-underscore-args.rs
View file

@ -8,12 +8,18 @@ trait T {
fn main() {
let _: usize = foo(_, _);
//~^ ERROR expected expression
//~| ERROR expected expression
//~^ ERROR `_` can only be used on the left-hand side of an assignment
//~| ERROR `_` can only be used on the left-hand side of an assignment
//~| ERROR destructuring assignments are unstable
//~| ERROR destructuring assignments are unstable
let _: S = S(_, _);
//~^ ERROR expected expression
//~| ERROR expected expression
//~^ ERROR `_` can only be used on the left-hand side of an assignment
//~| ERROR `_` can only be used on the left-hand side of an assignment
//~| ERROR destructuring assignments are unstable
//~| ERROR destructuring assignments are unstable
let _: usize = T::baz(_, _);
//~^ ERROR expected expression
//~| ERROR expected expression
//~^ ERROR `_` can only be used on the left-hand side of an assignment
//~| ERROR `_` can only be used on the left-hand side of an assignment
//~| ERROR destructuring assignments are unstable
//~| ERROR destructuring assignments are unstable
}

89
src/test/ui/suggestions/fn-or-tuple-struct-with-underscore-args.stderr
View file

@ -1,38 +1,93 @@
error: expected expression, found reserved identifier `_`
error[E0658]: destructuring assignments are unstable
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:10:24
|
LL | let _: usize = foo(_, _);
| ^ expected expression
| ^
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error: expected expression, found reserved identifier `_`
error[E0658]: destructuring assignments are unstable
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:10:27
|
LL | let _: usize = foo(_, _);
| ^ expected expression
| ^
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error: expected expression, found reserved identifier `_`
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:13:18
error[E0658]: destructuring assignments are unstable
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:15:18
|
LL | let _: S = S(_, _);
| ^ expected expression
| ^
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error: expected expression, found reserved identifier `_`
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:13:21
error[E0658]: destructuring assignments are unstable
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:15:21
|
LL | let _: S = S(_, _);
| ^ expected expression
| ^
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error: expected expression, found reserved identifier `_`
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:16:27
error[E0658]: destructuring assignments are unstable
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:20:27
|
LL | let _: usize = T::baz(_, _);
| ^ expected expression
| ^
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error: expected expression, found reserved identifier `_`
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:16:30
error[E0658]: destructuring assignments are unstable
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:20:30
|
LL | let _: usize = T::baz(_, _);
| ^ expected expression
| ^
|
= note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
= help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
error: aborting due to 6 previous errors
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:10:24
|
LL | let _: usize = foo(_, _);
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:10:27
|
LL | let _: usize = foo(_, _);
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:15:18
|
LL | let _: S = S(_, _);
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:15:21
|
LL | let _: S = S(_, _);
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:20:27
|
LL | let _: usize = T::baz(_, _);
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/fn-or-tuple-struct-with-underscore-args.rs:20:30
|
LL | let _: usize = T::baz(_, _);
| ^ `_` not allowed here
error: aborting due to 12 previous errors
For more information about this error, try `rustc --explain E0658`.