Rollup merge of #128934 - Nadrieril:fix-empty-non-exhaustive, r=compiler-errors

Non-exhaustive structs may be empty

This is a follow-up to a discrepancy noticed in https://github.com/rust-lang/rust/pull/122792: today, the following struct is considered inhabited (non-empty) outside its defining crate:
```rust
#[non_exhaustive]
pub struct UninhabitedStruct {
    pub never: !,
    // other fields
}
```

`#[non_exhaustive]` on a struct should mean that adding fields to it isn't a breaking change. There is no way that adding fields to this struct could make it non-empty since the `never` field must stay and is inconstructible. I suspect this was implemented this way due to confusion with `#[non_exhaustive]` enums, which indeed should be considered non-empty outside their defining crate.

I propose that we consider such a struct uninhabited (empty), just like it would be without the `#[non_exhaustive]` annotation.

Code that doesn't pass today and will pass after this:
```rust
// In a different crate
fn empty_match_on_empty_struct<T>(x: UninhabitedStruct) -> T {
    match x {}
}
```

This is not a breaking change.

r? ``@compiler-errors``
This commit is contained in:
Matthias Krüger 2024-09-03 19:13:24 +02:00 committed by GitHub
commit e7504ac704
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
16 changed files with 136 additions and 208 deletions

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@ -81,10 +81,6 @@ impl<'tcx> VariantDef {
adt: ty::AdtDef<'_>, adt: ty::AdtDef<'_>,
) -> InhabitedPredicate<'tcx> { ) -> InhabitedPredicate<'tcx> {
debug_assert!(!adt.is_union()); debug_assert!(!adt.is_union());
if self.is_field_list_non_exhaustive() && !self.def_id.is_local() {
// Non-exhaustive variants from other crates are always considered inhabited.
return InhabitedPredicate::True;
}
InhabitedPredicate::all( InhabitedPredicate::all(
tcx, tcx,
self.fields.iter().map(|field| { self.fields.iter().map(|field| {

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@ -229,17 +229,11 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
} else { } else {
let variant = let variant =
&adt.variant(RustcPatCtxt::variant_index_for_adt(&ctor, *adt)); &adt.variant(RustcPatCtxt::variant_index_for_adt(&ctor, *adt));
// In the cases of either a `#[non_exhaustive]` field list or a non-public
// field, we skip uninhabited fields in order not to reveal the
// uninhabitedness of the whole variant.
let is_non_exhaustive =
variant.is_field_list_non_exhaustive() && !adt.did().is_local();
let tys = cx.variant_sub_tys(ty, variant).map(|(field, ty)| { let tys = cx.variant_sub_tys(ty, variant).map(|(field, ty)| {
let is_visible = let is_visible =
adt.is_enum() || field.vis.is_accessible_from(cx.module, cx.tcx); adt.is_enum() || field.vis.is_accessible_from(cx.module, cx.tcx);
let is_uninhabited = cx.is_uninhabited(*ty); let is_uninhabited = cx.is_uninhabited(*ty);
let skip = is_uninhabited && (!is_visible || is_non_exhaustive); let skip = is_uninhabited && !is_visible;
(ty, PrivateUninhabitedField(skip)) (ty, PrivateUninhabitedField(skip))
}); });
cx.dropless_arena.alloc_from_iter(tys) cx.dropless_arena.alloc_from_iter(tys)

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@ -7,11 +7,17 @@ pub enum UninhabitedEnum {
#[non_exhaustive] #[non_exhaustive]
pub struct UninhabitedStruct { pub struct UninhabitedStruct {
_priv: !, pub never: !,
_priv: (),
} }
#[non_exhaustive] #[non_exhaustive]
pub struct UninhabitedTupleStruct(!); pub struct PrivatelyUninhabitedStruct {
never: !,
}
#[non_exhaustive]
pub struct UninhabitedTupleStruct(pub !);
pub enum UninhabitedVariants { pub enum UninhabitedVariants {
#[non_exhaustive] Tuple(!), #[non_exhaustive] Tuple(!),

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@ -5,7 +5,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedEnum` defined here note: `IndirectUninhabitedEnum` defined here
--> $DIR/auxiliary/uninhabited.rs:26:1 --> $DIR/auxiliary/uninhabited.rs:32:1
| |
LL | pub struct IndirectUninhabitedEnum(UninhabitedEnum); LL | pub struct IndirectUninhabitedEnum(UninhabitedEnum);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -24,7 +24,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedStruct` defined here note: `IndirectUninhabitedStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:28:1 --> $DIR/auxiliary/uninhabited.rs:34:1
| |
LL | pub struct IndirectUninhabitedStruct(UninhabitedStruct); LL | pub struct IndirectUninhabitedStruct(UninhabitedStruct);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -43,7 +43,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedTupleStruct` defined here note: `IndirectUninhabitedTupleStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:30:1 --> $DIR/auxiliary/uninhabited.rs:36:1
| |
LL | pub struct IndirectUninhabitedTupleStruct(UninhabitedTupleStruct); LL | pub struct IndirectUninhabitedTupleStruct(UninhabitedTupleStruct);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -62,7 +62,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedVariants` defined here note: `IndirectUninhabitedVariants` defined here
--> $DIR/auxiliary/uninhabited.rs:32:1 --> $DIR/auxiliary/uninhabited.rs:38:1
| |
LL | pub struct IndirectUninhabitedVariants(UninhabitedVariants); LL | pub struct IndirectUninhabitedVariants(UninhabitedVariants);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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@ -5,7 +5,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedEnum` defined here note: `IndirectUninhabitedEnum` defined here
--> $DIR/auxiliary/uninhabited.rs:26:1 --> $DIR/auxiliary/uninhabited.rs:32:1
| |
LL | pub struct IndirectUninhabitedEnum(UninhabitedEnum); LL | pub struct IndirectUninhabitedEnum(UninhabitedEnum);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -24,7 +24,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedStruct` defined here note: `IndirectUninhabitedStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:28:1 --> $DIR/auxiliary/uninhabited.rs:34:1
| |
LL | pub struct IndirectUninhabitedStruct(UninhabitedStruct); LL | pub struct IndirectUninhabitedStruct(UninhabitedStruct);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -43,7 +43,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedTupleStruct` defined here note: `IndirectUninhabitedTupleStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:30:1 --> $DIR/auxiliary/uninhabited.rs:36:1
| |
LL | pub struct IndirectUninhabitedTupleStruct(UninhabitedTupleStruct); LL | pub struct IndirectUninhabitedTupleStruct(UninhabitedTupleStruct);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -62,7 +62,7 @@ LL | match x {}
| ^ | ^
| |
note: `IndirectUninhabitedVariants` defined here note: `IndirectUninhabitedVariants` defined here
--> $DIR/auxiliary/uninhabited.rs:32:1 --> $DIR/auxiliary/uninhabited.rs:38:1
| |
LL | pub struct IndirectUninhabitedVariants(UninhabitedVariants); LL | pub struct IndirectUninhabitedVariants(UninhabitedVariants);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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@ -11,11 +11,12 @@ use uninhabited::PartiallyInhabitedVariants;
pub fn foo(x: PartiallyInhabitedVariants) { pub fn foo(x: PartiallyInhabitedVariants) {
match x { match x {
PartiallyInhabitedVariants::Struct { .. } => {}, PartiallyInhabitedVariants::Struct { .. } => {}
PartiallyInhabitedVariants::Struct { .. } => {},
//~^ ERROR unreachable pattern //~^ ERROR unreachable pattern
_ => {}, PartiallyInhabitedVariants::Struct { .. } => {}
//~^ ERROR unreachable pattern
_ => {}
} }
} }
fn main() { } fn main() {}

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@ -1,16 +1,23 @@
error: unreachable pattern error: unreachable pattern
--> $DIR/issue-65157-repeated-match-arm.rs:15:9 --> $DIR/issue-65157-repeated-match-arm.rs:14:9
| |
LL | PartiallyInhabitedVariants::Struct { .. } => {}, LL | PartiallyInhabitedVariants::Struct { .. } => {}
| ----------------------------------------- matches all the relevant values | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ matches no values because `PartiallyInhabitedVariants` is uninhabited
LL | PartiallyInhabitedVariants::Struct { .. } => {},
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no value can reach this
| |
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
note: the lint level is defined here note: the lint level is defined here
--> $DIR/issue-65157-repeated-match-arm.rs:2:9 --> $DIR/issue-65157-repeated-match-arm.rs:2:9
| |
LL | #![deny(unreachable_patterns)] LL | #![deny(unreachable_patterns)]
| ^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 1 previous error error: unreachable pattern
--> $DIR/issue-65157-repeated-match-arm.rs:16:9
|
LL | PartiallyInhabitedVariants::Struct { .. } => {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ matches no values because `PartiallyInhabitedVariants` is uninhabited
|
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
error: aborting due to 2 previous errors

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@ -3,12 +3,7 @@
extern crate uninhabited; extern crate uninhabited;
use uninhabited::{ use uninhabited::*;
UninhabitedEnum,
UninhabitedStruct,
UninhabitedTupleStruct,
UninhabitedVariants,
};
struct A; struct A;
@ -19,16 +14,20 @@ fn cannot_empty_match_on_empty_enum_to_anything(x: UninhabitedEnum) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {} //~ ERROR non-exhaustive patterns
} }
fn cannot_empty_match_on_empty_struct_to_anything(x: UninhabitedStruct) -> A { fn empty_match_on_empty_struct(x: UninhabitedStruct) -> A {
match x {}
}
fn cannot_empty_match_on_privately_empty_struct(x: PrivatelyUninhabitedStruct) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {} //~ ERROR non-exhaustive patterns
} }
fn cannot_empty_match_on_empty_tuple_struct_to_anything(x: UninhabitedTupleStruct) -> A { fn empty_match_on_empty_tuple_struct(x: UninhabitedTupleStruct) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {}
} }
fn cannot_empty_match_on_enum_with_empty_variants_struct_to_anything(x: UninhabitedVariants) -> A { fn empty_match_on_enum_with_empty_variants_struct(x: UninhabitedVariants) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {}
} }
fn main() {} fn main() {}

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@ -1,15 +1,15 @@
error[E0004]: non-exhaustive patterns: type `UninhabitedEnum` is non-empty error[E0004]: non-exhaustive patterns: type `uninhabited::UninhabitedEnum` is non-empty
--> $DIR/match.rs:19:11 --> $DIR/match.rs:14:11
| |
LL | match x {} LL | match x {}
| ^ | ^
| |
note: `UninhabitedEnum` defined here note: `uninhabited::UninhabitedEnum` defined here
--> $DIR/auxiliary/uninhabited.rs:5:1 --> $DIR/auxiliary/uninhabited.rs:5:1
| |
LL | pub enum UninhabitedEnum { LL | pub enum UninhabitedEnum {
| ^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^
= note: the matched value is of type `UninhabitedEnum`, which is marked as non-exhaustive = note: the matched value is of type `uninhabited::UninhabitedEnum`, which is marked as non-exhaustive
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown
| |
LL ~ match x { LL ~ match x {
@ -17,18 +17,18 @@ LL + _ => todo!(),
LL ~ } LL ~ }
| |
error[E0004]: non-exhaustive patterns: type `UninhabitedStruct` is non-empty error[E0004]: non-exhaustive patterns: type `uninhabited::PrivatelyUninhabitedStruct` is non-empty
--> $DIR/match.rs:23:11 --> $DIR/match.rs:22:11
| |
LL | match x {} LL | match x {}
| ^ | ^
| |
note: `UninhabitedStruct` defined here note: `uninhabited::PrivatelyUninhabitedStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:9:1 --> $DIR/auxiliary/uninhabited.rs:15:1
| |
LL | pub struct UninhabitedStruct { LL | pub struct PrivatelyUninhabitedStruct {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: the matched value is of type `UninhabitedStruct` = note: the matched value is of type `uninhabited::PrivatelyUninhabitedStruct`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown
| |
LL ~ match x { LL ~ match x {
@ -36,48 +36,6 @@ LL + _ => todo!(),
LL ~ } LL ~ }
| |
error[E0004]: non-exhaustive patterns: type `UninhabitedTupleStruct` is non-empty error: aborting due to 2 previous errors
--> $DIR/match.rs:27:11
|
LL | match x {}
| ^
|
note: `UninhabitedTupleStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:14:1
|
LL | pub struct UninhabitedTupleStruct(!);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: the matched value is of type `UninhabitedTupleStruct`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown
|
LL ~ match x {
LL + _ => todo!(),
LL ~ }
|
error[E0004]: non-exhaustive patterns: `UninhabitedVariants::Tuple(_)` and `UninhabitedVariants::Struct { .. }` not covered
--> $DIR/match.rs:31:11
|
LL | match x {}
| ^ patterns `UninhabitedVariants::Tuple(_)` and `UninhabitedVariants::Struct { .. }` not covered
|
note: `UninhabitedVariants` defined here
--> $DIR/auxiliary/uninhabited.rs:16:1
|
LL | pub enum UninhabitedVariants {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | #[non_exhaustive] Tuple(!),
| ----- not covered
LL | #[non_exhaustive] Struct { x: ! }
| ------ not covered
= note: the matched value is of type `UninhabitedVariants`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern, a match arm with multiple or-patterns as shown, or multiple match arms
|
LL ~ match x {
LL + UninhabitedVariants::Tuple(_) | UninhabitedVariants::Struct { .. } => todo!(),
LL ~ }
|
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0004`. For more information about this error, try `rustc --explain E0004`.

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@ -5,32 +5,28 @@
extern crate uninhabited; extern crate uninhabited;
use uninhabited::{ use uninhabited::{
UninhabitedEnum, UninhabitedEnum, UninhabitedStruct, UninhabitedTupleStruct, UninhabitedVariants,
UninhabitedStruct,
UninhabitedTupleStruct,
UninhabitedVariants,
}; };
struct A; struct A;
// This test checks that an empty match on a non-exhaustive uninhabited type from an extern crate // This test checks that non-exhaustive enums are never considered uninhabited outside their
// will not compile. In particular, this enables the `exhaustive_patterns` feature as this can // defining crate, and non-exhaustive structs are considered uninhabited the same way as normal
// change the branch used in the compiler to determine this. // ones.
fn cannot_empty_match_on_non_exhaustive_empty_enum(x: UninhabitedEnum) -> A {
fn cannot_empty_match_on_empty_enum_to_anything(x: UninhabitedEnum) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {} //~ ERROR non-exhaustive patterns
} }
fn cannot_empty_match_on_empty_struct_to_anything(x: UninhabitedStruct) -> A { fn empty_match_on_empty_struct(x: UninhabitedStruct) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {}
} }
fn cannot_empty_match_on_empty_tuple_struct_to_anything(x: UninhabitedTupleStruct) -> A { fn empty_match_on_empty_tuple_struct(x: UninhabitedTupleStruct) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {}
} }
fn cannot_empty_match_on_enum_with_empty_variants_struct_to_anything(x: UninhabitedVariants) -> A { fn empty_match_on_enum_with_empty_variants_struct(x: UninhabitedVariants) -> A {
match x {} //~ ERROR non-exhaustive patterns match x {}
} }
fn main() {} fn main() {}

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@ -1,5 +1,5 @@
error[E0004]: non-exhaustive patterns: type `UninhabitedEnum` is non-empty error[E0004]: non-exhaustive patterns: type `UninhabitedEnum` is non-empty
--> $DIR/match_with_exhaustive_patterns.rs:21:11 --> $DIR/match_with_exhaustive_patterns.rs:17:11
| |
LL | match x {} LL | match x {}
| ^ | ^
@ -17,67 +17,6 @@ LL + _ => todo!(),
LL ~ } LL ~ }
| |
error[E0004]: non-exhaustive patterns: type `UninhabitedStruct` is non-empty error: aborting due to 1 previous error
--> $DIR/match_with_exhaustive_patterns.rs:25:11
|
LL | match x {}
| ^
|
note: `UninhabitedStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:9:1
|
LL | pub struct UninhabitedStruct {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: the matched value is of type `UninhabitedStruct`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown
|
LL ~ match x {
LL + _ => todo!(),
LL ~ }
|
error[E0004]: non-exhaustive patterns: type `UninhabitedTupleStruct` is non-empty
--> $DIR/match_with_exhaustive_patterns.rs:29:11
|
LL | match x {}
| ^
|
note: `UninhabitedTupleStruct` defined here
--> $DIR/auxiliary/uninhabited.rs:14:1
|
LL | pub struct UninhabitedTupleStruct(!);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: the matched value is of type `UninhabitedTupleStruct`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown
|
LL ~ match x {
LL + _ => todo!(),
LL ~ }
|
error[E0004]: non-exhaustive patterns: `UninhabitedVariants::Tuple(_)` and `UninhabitedVariants::Struct { .. }` not covered
--> $DIR/match_with_exhaustive_patterns.rs:33:11
|
LL | match x {}
| ^ patterns `UninhabitedVariants::Tuple(_)` and `UninhabitedVariants::Struct { .. }` not covered
|
note: `UninhabitedVariants` defined here
--> $DIR/auxiliary/uninhabited.rs:16:1
|
LL | pub enum UninhabitedVariants {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | #[non_exhaustive] Tuple(!),
| ----- not covered
LL | #[non_exhaustive] Struct { x: ! }
| ------ not covered
= note: the matched value is of type `UninhabitedVariants`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern, a match arm with multiple or-patterns as shown, or multiple match arms
|
LL ~ match x {
LL + UninhabitedVariants::Tuple(_) | UninhabitedVariants::Struct { .. } => todo!(),
LL ~ }
|
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0004`. For more information about this error, try `rustc --explain E0004`.

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@ -1,5 +1,4 @@
//@ check-pass //@ check-pass
#![deny(unreachable_patterns)] #![deny(unreachable_patterns)]
#![feature(never_type)] #![feature(never_type)]
@ -9,11 +8,12 @@ pub enum UninhabitedEnum {
#[non_exhaustive] #[non_exhaustive]
pub struct UninhabitedStruct { pub struct UninhabitedStruct {
_priv: !, pub never: !,
_priv: (),
} }
#[non_exhaustive] #[non_exhaustive]
pub struct UninhabitedTupleStruct(!); pub struct UninhabitedTupleStruct(pub !);
pub enum UninhabitedVariants { pub enum UninhabitedVariants {
#[non_exhaustive] Tuple(!), #[non_exhaustive] Tuple(!),
@ -22,24 +22,21 @@ pub enum UninhabitedVariants {
struct A; struct A;
// This test checks that an empty match on a non-exhaustive uninhabited type from the defining crate // This checks that `non_exhaustive` annotations do not affect exhaustiveness checking within the
// will compile. In particular, this enables the `exhaustive_patterns` feature as this can // defining crate.
// change the branch used in the compiler to determine this. fn empty_match_on_empty_enum(x: UninhabitedEnum) -> A {
// Codegen is skipped because tests with long names can cause issues on Windows CI, see #60648.
fn cannot_empty_match_on_empty_enum_to_anything(x: UninhabitedEnum) -> A {
match x {} match x {}
} }
fn cannot_empty_match_on_empty_struct_to_anything(x: UninhabitedStruct) -> A { fn empty_match_on_empty_struct(x: UninhabitedStruct) -> A {
match x {} match x {}
} }
fn cannot_empty_match_on_empty_tuple_struct_to_anything(x: UninhabitedTupleStruct) -> A { fn empty_match_on_empty_tuple_struct(x: UninhabitedTupleStruct) -> A {
match x {} match x {}
} }
fn cannot_empty_match_on_enum_with_empty_variants_struct_to_anything(x: UninhabitedVariants) -> A { fn empty_match_on_enum_with_empty_variants_struct(x: UninhabitedVariants) -> A {
match x {} match x {}
} }

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@ -1,14 +1,10 @@
//@ aux-build:uninhabited.rs //@ aux-build:uninhabited.rs
//@ build-pass (FIXME(62277): could be check-pass?)
#![deny(unreachable_patterns)] #![deny(unreachable_patterns)]
extern crate uninhabited; extern crate uninhabited;
use uninhabited::{ use uninhabited::{
PartiallyInhabitedVariants, PartiallyInhabitedVariants, UninhabitedEnum, UninhabitedStruct, UninhabitedTupleStruct,
UninhabitedEnum,
UninhabitedStruct,
UninhabitedTupleStruct,
UninhabitedVariants, UninhabitedVariants,
}; };
@ -32,27 +28,26 @@ fn uninhabited_tuple_struct() -> Option<UninhabitedTupleStruct> {
None None
} }
// This test checks that non-exhaustive types that would normally be considered uninhabited within // This test checks that non-exhaustive enums are never considered uninhabited outside their
// the defining crate are not considered uninhabited from extern crates. // defining crate, and non-exhaustive structs are considered uninhabited the same way as normal
// ones.
fn main() { fn main() {
match uninhabited_enum() { match uninhabited_enum() {
Some(_x) => (), // This line would normally error. Some(_x) => (), // This would error without `non_exhaustive`
None => (), None => (),
} }
match uninhabited_variant() { match uninhabited_variant() {
Some(_x) => (), // This line would normally error. Some(_x) => (), //~ ERROR unreachable
None => (), None => (),
} }
// This line would normally error. // This line would normally error.
while let PartiallyInhabitedVariants::Struct { x, .. } = partially_inhabited_variant() { while let PartiallyInhabitedVariants::Struct { x, .. } = partially_inhabited_variant() {} //~ ERROR unreachable
while let Some(_x) = uninhabited_struct() { //~ ERROR unreachable
} }
while let Some(_x) = uninhabited_struct() { // This line would normally error. while let Some(_x) = uninhabited_tuple_struct() { //~ ERROR unreachable
}
while let Some(_x) = uninhabited_tuple_struct() { // This line would normally error.
} }
} }

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@ -0,0 +1,39 @@
error: unreachable pattern
--> $DIR/patterns.rs:41:9
|
LL | Some(_x) => (),
| ^^^^^^^^ matches no values because `UninhabitedVariants` is uninhabited
|
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
note: the lint level is defined here
--> $DIR/patterns.rs:2:9
|
LL | #![deny(unreachable_patterns)]
| ^^^^^^^^^^^^^^^^^^^^
error: unreachable pattern
--> $DIR/patterns.rs:46:15
|
LL | while let PartiallyInhabitedVariants::Struct { x, .. } = partially_inhabited_variant() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ matches no values because `!` is uninhabited
|
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
error: unreachable pattern
--> $DIR/patterns.rs:48:15
|
LL | while let Some(_x) = uninhabited_struct() {
| ^^^^^^^^ matches no values because `UninhabitedStruct` is uninhabited
|
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
error: unreachable pattern
--> $DIR/patterns.rs:51:15
|
LL | while let Some(_x) = uninhabited_tuple_struct() {
| ^^^^^^^^ matches no values because `UninhabitedTupleStruct` is uninhabited
|
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
error: aborting due to 4 previous errors

View File

@ -6,11 +6,12 @@ pub enum UninhabitedEnum {
} }
#[non_exhaustive] #[non_exhaustive]
pub struct UninhabitedTupleStruct(!); pub struct UninhabitedTupleStruct(pub !);
#[non_exhaustive] #[non_exhaustive]
pub struct UninhabitedStruct { pub struct UninhabitedStruct {
_priv: !, pub never: !,
_priv: (),
} }
pub enum UninhabitedVariants { pub enum UninhabitedVariants {

View File

@ -1,5 +1,5 @@
error: unreachable pattern error: unreachable pattern
--> $DIR/patterns_same_crate.rs:51:9 --> $DIR/patterns_same_crate.rs:52:9
| |
LL | Some(_x) => (), LL | Some(_x) => (),
| ^^^^^^^^ matches no values because `UninhabitedEnum` is uninhabited | ^^^^^^^^ matches no values because `UninhabitedEnum` is uninhabited
@ -12,7 +12,7 @@ LL | #![deny(unreachable_patterns)]
| ^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^
error: unreachable pattern error: unreachable pattern
--> $DIR/patterns_same_crate.rs:56:9 --> $DIR/patterns_same_crate.rs:57:9
| |
LL | Some(_x) => (), LL | Some(_x) => (),
| ^^^^^^^^ matches no values because `UninhabitedVariants` is uninhabited | ^^^^^^^^ matches no values because `UninhabitedVariants` is uninhabited
@ -20,7 +20,7 @@ LL | Some(_x) => (),
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
error: unreachable pattern error: unreachable pattern
--> $DIR/patterns_same_crate.rs:60:15 --> $DIR/patterns_same_crate.rs:61:15
| |
LL | while let PartiallyInhabitedVariants::Struct { x } = partially_inhabited_variant() { LL | while let PartiallyInhabitedVariants::Struct { x } = partially_inhabited_variant() {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ matches no values because `!` is uninhabited | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ matches no values because `!` is uninhabited
@ -28,7 +28,7 @@ LL | while let PartiallyInhabitedVariants::Struct { x } = partially_inhabite
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
error: unreachable pattern error: unreachable pattern
--> $DIR/patterns_same_crate.rs:64:15 --> $DIR/patterns_same_crate.rs:65:15
| |
LL | while let Some(_x) = uninhabited_struct() { LL | while let Some(_x) = uninhabited_struct() {
| ^^^^^^^^ matches no values because `UninhabitedStruct` is uninhabited | ^^^^^^^^ matches no values because `UninhabitedStruct` is uninhabited
@ -36,7 +36,7 @@ LL | while let Some(_x) = uninhabited_struct() {
= note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types = note: to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
error: unreachable pattern error: unreachable pattern
--> $DIR/patterns_same_crate.rs:67:15 --> $DIR/patterns_same_crate.rs:68:15
| |
LL | while let Some(_x) = uninhabited_tuple_struct() { LL | while let Some(_x) = uninhabited_tuple_struct() {
| ^^^^^^^^ matches no values because `UninhabitedTupleStruct` is uninhabited | ^^^^^^^^ matches no values because `UninhabitedTupleStruct` is uninhabited