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Rollup merge of #118759 - compiler-errors:bare-unit-structs, r=petroc…
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…henkov

Support bare unit structs in destructuring assignments

We should be allowed to use destructuring assignments on *bare* unit structs, not just unit structs that are located within other pattern constructors.

Fixes #118753

r? petrochenkov since you reviewed #95380, reassign if you're busy or don't want to review this.
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matthiaskrgr authored Dec 13, 2023
2 parents c3def26 + d473bdf commit dbc6ec6
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Showing 9 changed files with 42 additions and 24 deletions.
2 changes: 2 additions & 0 deletions compiler/rustc_ast_lowering/src/expr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1222,6 +1222,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
| ExprKind::Struct(..)
| ExprKind::Tup(..)
| ExprKind::Underscore => false,
// Check for unit struct constructor.
ExprKind::Path(..) => lower_ctx.extract_unit_struct_path(lhs).is_none(),
// Check for tuple struct constructor.
ExprKind::Call(callee, ..) => lower_ctx.extract_tuple_struct_path(callee).is_none(),
ExprKind::Paren(e) => {
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2 changes: 0 additions & 2 deletions tests/ui/destructuring-assignment/bad-expr-lhs.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,4 @@ fn main() {
(1, 2) = (3, 4);
//~^ ERROR invalid left-hand side of assignment
//~| ERROR invalid left-hand side of assignment

None = Some(3); //~ ERROR invalid left-hand side of assignment
}
10 changes: 1 addition & 9 deletions tests/ui/destructuring-assignment/bad-expr-lhs.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -30,15 +30,7 @@ LL | (1, 2) = (3, 4);
| |
| cannot assign to this expression

error[E0070]: invalid left-hand side of assignment
--> $DIR/bad-expr-lhs.rs:8:10
|
LL | None = Some(3);
| ---- ^
| |
| cannot assign to this expression

error: aborting due to 5 previous errors
error: aborting due to 4 previous errors

Some errors have detailed explanations: E0067, E0070.
For more information about an error, try `rustc --explain E0067`.
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
fn main() {
None = Some(3);
//~^ ERROR refutable pattern in local binding
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
error[E0005]: refutable pattern in local binding
--> $DIR/non-exhaustive-destructure.rs:2:5
|
LL | None = Some(3);
| ^^^^ pattern `Some(_)` not covered
|
= note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
= note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html
= note: the matched value is of type `Option<i32>`
help: you might want to use `if let` to ignore the variant that isn't matched
|
LL | if None = Some(3) { todo!() };
| ++ +++++++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0005`.
Original file line number Diff line number Diff line change
Expand Up @@ -11,24 +11,30 @@ type A = E;
fn main() {
let mut a;

S = S;
(S, a) = (S, ());

E::V = E::V;
(E::V, a) = (E::V, ());

<E>::V = E::V;
(<E>::V, a) = (E::V, ());
A::V = A::V;
(A::V, a) = (E::V, ());
}

impl S {
fn check() {
let a;
Self = S;
(Self, a) = (S, ());
}
}

impl E {
fn check() {
let a;
Self::V = E::V;
(Self::V, a) = (E::V, ());
}
}
6 changes: 1 addition & 5 deletions tests/ui/inference/issue-103587.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -26,14 +26,10 @@ error[E0308]: mismatched types
LL | if None = x { }
| ^^^^^^^^ expected `bool`, found `()`
|
help: you might have meant to use pattern matching
help: consider adding `let`
|
LL | if let None = x { }
| +++
help: you might have meant to compare for equality
|
LL | if None == x { }
| +

error: aborting due to 3 previous errors

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4 changes: 2 additions & 2 deletions tests/ui/issues/issue-13407.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,6 @@ mod A {

fn main() {
A::C = 1;
//~^ ERROR: invalid left-hand side of assignment
//~| ERROR: struct `C` is private
//~^ ERROR: mismatched types
//~| ERROR: unit struct `C` is private
}
15 changes: 9 additions & 6 deletions tests/ui/issues/issue-13407.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -10,15 +10,18 @@ note: the unit struct `C` is defined here
LL | struct C;
| ^^^^^^^^^

error[E0070]: invalid left-hand side of assignment
--> $DIR/issue-13407.rs:6:10
error[E0308]: mismatched types
--> $DIR/issue-13407.rs:6:5
|
LL | struct C;
| -------- unit struct defined here
...
LL | A::C = 1;
| ---- ^
| ^^^^ - this expression has type `{integer}`
| |
| cannot assign to this expression
| expected integer, found `C`

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0070, E0603.
For more information about an error, try `rustc --explain E0070`.
Some errors have detailed explanations: E0308, E0603.
For more information about an error, try `rustc --explain E0308`.

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