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Avoid side-effects from try_coerce when suggesting borrowing LHS of cast

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This commit is contained in:
Michael Goulet 2023-08-15 02:23:49 +00:00
parent 6ef7d16be0
commit 822caa8b80
5 changed files with 12 additions and 72 deletions
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24
compiler/rustc_hir_typeck/src/cast.rs
View File

@ -389,34 +389,26 @@ impl<'a, 'tcx> CastCheck<'tcx> {
if let ty::Ref(reg, cast_ty, mutbl) = *self.cast_ty.kind() {
if let ty::RawPtr(TypeAndMut { ty: expr_ty, .. }) = *self.expr_ty.kind()
&& fcx
.try_coerce(
self.expr,
.can_coerce(
Ty::new_ref(fcx.tcx,
fcx.tcx.lifetimes.re_erased,
TypeAndMut { ty: expr_ty, mutbl },
),
self.cast_ty,
AllowTwoPhase::No,
None,
)
.is_ok()
{
sugg = Some((format!("&{}*", mutbl.prefix_str()), cast_ty == expr_ty));
} else if let ty::Ref(expr_reg, expr_ty, expr_mutbl) = *self.expr_ty.kind()
&& expr_mutbl == Mutability::Not
&& mutbl == Mutability::Mut
&& fcx
.try_coerce(
self.expr,
.can_coerce(
Ty::new_ref(fcx.tcx,
expr_reg,
TypeAndMut { ty: expr_ty, mutbl: Mutability::Mut },
),
self.cast_ty,
AllowTwoPhase::No,
None,
)
.is_ok()
{
sugg_mutref = true;
}
@ -424,30 +416,22 @@ impl<'a, 'tcx> CastCheck<'tcx> {
if !sugg_mutref
&& sugg == None
&& fcx
.try_coerce(
self.expr,
.can_coerce(
Ty::new_ref(fcx.tcx,reg, TypeAndMut { ty: self.expr_ty, mutbl }),
self.cast_ty,
AllowTwoPhase::No,
None,
)
.is_ok()
{
sugg = Some((format!("&{}", mutbl.prefix_str()), false));
}
} else if let ty::RawPtr(TypeAndMut { mutbl, .. }) = *self.cast_ty.kind()
&& fcx
.try_coerce(
self.expr,
.can_coerce(
Ty::new_ref(fcx.tcx,
fcx.tcx.lifetimes.re_erased,
TypeAndMut { ty: self.expr_ty, mutbl },
),
self.cast_ty,
AllowTwoPhase::No,
None,
)
.is_ok()
{
sugg = Some((format!("&{}", mutbl.prefix_str()), false));
}

20
tests/ui/traits/trait-upcasting/type-checking-test-1.current.stderr
View File

@ -2,22 +2,8 @@ error[E0605]: non-primitive cast: `&dyn Foo` as `&dyn Bar<_>`
--> $DIR/type-checking-test-1.rs:19:13
|
LL | let _ = x as &dyn Bar<_>; // Ambiguous
| ^^^^^^^^^^^^^^^^ invalid cast
|
help: consider borrowing the value
|
LL | let _ = &x as &dyn Bar<_>; // Ambiguous
| +
| ^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object
error[E0277]: the trait bound `&dyn Foo: Bar<_>` is not satisfied
--> $DIR/type-checking-test-1.rs:19:13
|
LL | let _ = x as &dyn Bar<_>; // Ambiguous
| ^ the trait `Bar<_>` is not implemented for `&dyn Foo`
|
= note: required for the cast from `&&dyn Foo` to `&dyn Bar<_>`
error: aborting due to previous error
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0277, E0605.
For more information about an error, try `rustc --explain E0277`.
For more information about this error, try `rustc --explain E0605`.

1
tests/ui/traits/trait-upcasting/type-checking-test-1.rs
View File

@ -18,7 +18,6 @@ fn test_specific(x: &dyn Foo) {
fn test_unknown_version(x: &dyn Foo) {
let _ = x as &dyn Bar<_>; // Ambiguous
//~^ ERROR non-primitive cast
//[current]~^^ ERROR the trait bound `&dyn Foo: Bar<_>` is not satisfied
}
fn test_infer_version(x: &dyn Foo) {

2
tests/ui/traits/trait-upcasting/type-checking-test-2.rs
View File

@ -18,13 +18,11 @@ fn test_specific2(x: &dyn Foo<u32>) {
fn test_specific3(x: &dyn Foo<i32>) {
let _ = x as &dyn Bar<u32>; // Error
//~^ ERROR non-primitive cast
//~^^ ERROR the trait bound `&dyn Foo<i32>: Bar<u32>` is not satisfied
}
fn test_infer_arg(x: &dyn Foo<u32>) {
let a = x as &dyn Bar<_>; // Ambiguous
//~^ ERROR non-primitive cast
//~^^ ERROR the trait bound `&dyn Foo<u32>: Bar<_>` is not satisfied
let _ = a.bar();
}

37
tests/ui/traits/trait-upcasting/type-checking-test-2.stderr
View File

@ -2,41 +2,14 @@ error[E0605]: non-primitive cast: `&dyn Foo<i32>` as `&dyn Bar<u32>`
--> $DIR/type-checking-test-2.rs:19:13
|
LL | let _ = x as &dyn Bar<u32>; // Error
| ^^^^^^^^^^^^^^^^^^ invalid cast
|
help: consider borrowing the value
|
LL | let _ = &x as &dyn Bar<u32>; // Error
| +
error[E0277]: the trait bound `&dyn Foo<i32>: Bar<u32>` is not satisfied
--> $DIR/type-checking-test-2.rs:19:13
|
LL | let _ = x as &dyn Bar<u32>; // Error
| ^ the trait `Bar<u32>` is not implemented for `&dyn Foo<i32>`
|
= note: required for the cast from `&&dyn Foo<i32>` to `&dyn Bar<u32>`
| ^^^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object
error[E0605]: non-primitive cast: `&dyn Foo<u32>` as `&dyn Bar<_>`
--> $DIR/type-checking-test-2.rs:25:13
--> $DIR/type-checking-test-2.rs:24:13
|
LL | let a = x as &dyn Bar<_>; // Ambiguous
| ^^^^^^^^^^^^^^^^ invalid cast
|
help: consider borrowing the value
|
LL | let a = &x as &dyn Bar<_>; // Ambiguous
| +
| ^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object
error[E0277]: the trait bound `&dyn Foo<u32>: Bar<_>` is not satisfied
--> $DIR/type-checking-test-2.rs:25:13
|
LL | let a = x as &dyn Bar<_>; // Ambiguous
| ^ the trait `Bar<_>` is not implemented for `&dyn Foo<u32>`
|
= note: required for the cast from `&&dyn Foo<u32>` to `&dyn Bar<_>`
error: aborting due to 2 previous errors
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0277, E0605.
For more information about an error, try `rustc --explain E0277`.
For more information about this error, try `rustc --explain E0605`.