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Capture scrutinee of if let guards correctly

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Previously we were always capturing by value.
This commit is contained in:
Matthew Jasper 2023-09-20 11:57:00 +00:00
parent 62d9034a0d
commit d4ffb3b08a
5 changed files with 164 additions and 4 deletions
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10
compiler/rustc_hir_typeck/src/expr_use_visitor.rs
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@ -664,10 +664,12 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
);
self.walk_pat(discr_place, arm.pat, arm.guard.is_some());
if let Some(hir::Guard::If(e)) = arm.guard {
self.consume_expr(e)
} else if let Some(hir::Guard::IfLet(ref l)) = arm.guard {
self.consume_expr(l.init)
match arm.guard {
Some(hir::Guard::If(ref e)) => self.consume_expr(e),
Some(hir::Guard::IfLet(ref l)) => {
self.walk_local(l.init, l.pat, None, |t| t.borrow_expr(l.init, ty::ImmBorrow))
}
None => {}
}
self.consume_expr(arm.body);

33
tests/ui/closures/2229_closure_analysis/match/if-let-guards-errors.e2018.stderr Normal file
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@ -0,0 +1,33 @@
error[E0505]: cannot move out of `value` because it is borrowed
--> $DIR/if-let-guards-errors.rs:16:13
|
LL | let f = |x: &E| {
| ------- borrow of `value` occurs here
LL | match &x {
LL | E::Number(_) if let E::Number(ref mut n) = *value => { }
| ------ borrow occurs due to use in closure
...
LL | let x = value;
| ^^^^^ move out of `value` occurs here
LL |
LL | drop(f);
| - borrow later used here
error[E0382]: use of moved value: `value`
--> $DIR/if-let-guards-errors.rs:28:13
|
LL | fn if_let_move(value: Box<E>) {
| ----- move occurs because `value` has type `Box<E>`, which does not implement the `Copy` trait
LL | let f = |x: &E| {
| ------- value moved into closure here
LL | match &x {
LL | E::Number(_) if let E::String(s) = *value => { }
| ------ variable moved due to use in closure
...
LL | let x = value;
| ^^^^^ value used here after move
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0382, E0505.
For more information about an error, try `rustc --explain E0382`.

33
tests/ui/closures/2229_closure_analysis/match/if-let-guards-errors.e2021.stderr Normal file
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@ -0,0 +1,33 @@
error[E0505]: cannot move out of `value` because it is borrowed
--> $DIR/if-let-guards-errors.rs:16:13
|
LL | let f = |x: &E| {
| ------- borrow of `*value` occurs here
LL | match &x {
LL | E::Number(_) if let E::Number(ref mut n) = *value => { }
| ------ borrow occurs due to use in closure
...
LL | let x = value;
| ^^^^^ move out of `value` occurs here
LL |
LL | drop(f);
| - borrow later used here
error[E0382]: use of moved value: `value`
--> $DIR/if-let-guards-errors.rs:28:13
|
LL | fn if_let_move(value: Box<E>) {
| ----- move occurs because `value` has type `Box<E>`, which does not implement the `Copy` trait
LL | let f = |x: &E| {
| ------- value moved into closure here
LL | match &x {
LL | E::Number(_) if let E::String(s) = *value => { }
| ------ variable moved due to use in closure
...
LL | let x = value;
| ^^^^^ value used here after move
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0382, E0505.
For more information about an error, try `rustc --explain E0382`.

37
tests/ui/closures/2229_closure_analysis/match/if-let-guards-errors.rs Normal file
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@ -0,0 +1,37 @@
// Check the if let guards don't force capture by value
// revisions: e2018 e2021
//[e2018] edition:2018
//[e2021] edition:2021
#![feature(if_let_guard)]
#![allow(irrefutable_let_patterns)]
fn if_let_ref_mut(mut value: Box<E>) {
let f = |x: &E| {
match &x {
E::Number(_) if let E::Number(ref mut n) = *value => { }
_ => {}
}
};
let x = value;
//~^ ERROR cannot move out of `value` because it is borrowed
drop(f);
}
fn if_let_move(value: Box<E>) {
let f = |x: &E| {
match &x {
E::Number(_) if let E::String(s) = *value => { }
_ => {}
}
};
let x = value;
//~^ ERROR use of moved value: `value`
}
enum E {
String(String),
Number(i32),
}
fn main() {}

55
tests/ui/closures/2229_closure_analysis/match/if-let-guards.rs Normal file
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@ -0,0 +1,55 @@
// Check the if let guards don't force capture by value
// revisions: e2018 e2021
// check-pass
//[e2018] edition:2018
//[e2021] edition:2021
#![feature(if_let_guard)]
#![allow(irrefutable_let_patterns)]
fn if_let_underscore(value: Box<E>) {
|x: &E| {
match &x {
E::Number(_) if let _ = *value => { }
_ => {}
}
};
let x = value;
}
fn if_let_copy(value: Box<E>) {
|x: &E| {
match &x {
E::Number(_) if let E::Number(n) = *value => { }
_ => {}
}
};
let x = value;
}
fn if_let_ref(value: Box<E>) {
|x: &E| {
match &x {
E::Number(_) if let E::Number(ref n) = *value => { }
_ => {}
}
};
let x = value;
}
fn if_let_ref_mut(mut value: Box<E>) {
|x: &E| {
match &x {
E::Number(_) if let E::Number(ref mut n) = *value => { }
_ => {}
}
};
let x = value;
}
enum E {
String(String),
Number(i32),
}
fn main() {}