mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Suggest never pattern instead of _ for empty types

Browse Source
This commit is contained in:
Nadrieril 2024-02-28 22:37:11 +01:00
parent 1ec73d70fa
commit 9f2aa5b85a
6 changed files with 97 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
compiler/rustc_pattern_analysis/src/constructor.rs
View File

@ -1048,10 +1048,32 @@ impl<Cx: TypeCx> ConstructorSet<Cx> {
// In a `MaybeInvalid` place even an empty pattern may be reachable. We therefore
// add a dummy empty constructor here, which will be ignored if the place is
// `ValidOnly`.
missing_empty.push(NonExhaustive);
missing_empty.push(Never);
}
}
SplitConstructorSet { present, missing, missing_empty }
}
/// Whether this set only contains empty constructors.
pub(crate) fn all_empty(&self) -> bool {
match self {
ConstructorSet::Bool
| ConstructorSet::Integers { .. }
| ConstructorSet::Ref
| ConstructorSet::Union
| ConstructorSet::Unlistable => false,
ConstructorSet::NoConstructors => true,
ConstructorSet::Struct { empty } => *empty,
ConstructorSet::Variants { variants, non_exhaustive } => {
!*non_exhaustive
&& variants
.iter()
.all(|visibility| matches!(visibility, VariantVisibility::Empty))
}
ConstructorSet::Slice { array_len, subtype_is_empty } => {
*subtype_is_empty && matches!(array_len, Some(1..))
}
}
}
}

12
compiler/rustc_pattern_analysis/src/pat.rs
View File

@ -292,18 +292,24 @@ impl<Cx: TypeCx> WitnessPat<Cx> {
pub(crate) fn new(ctor: Constructor<Cx>, fields: Vec<Self>, ty: Cx::Ty) -> Self {
Self { ctor, fields, ty }
}
pub(crate) fn wildcard(ty: Cx::Ty) -> Self {
Self::new(Wildcard, Vec::new(), ty)
/// Create a wildcard pattern for this type. If the type is empty, we create a `!` pattern.
pub(crate) fn wildcard(cx: &Cx, ty: Cx::Ty) -> Self {
let is_empty = cx.ctors_for_ty(&ty).is_ok_and(|ctors| ctors.all_empty());
let ctor = if is_empty { Never } else { Wildcard };
Self::new(ctor, Vec::new(), ty)
}
/// Construct a pattern that matches everything that starts with this constructor.
/// For example, if `ctor` is a `Constructor::Variant` for `Option::Some`, we get the pattern
/// `Some(_)`.
pub(crate) fn wild_from_ctor(cx: &Cx, ctor: Constructor<Cx>, ty: Cx::Ty) -> Self {
if matches!(ctor, Wildcard) {
return Self::wildcard(cx, ty);
}
let fields = cx
.ctor_sub_tys(&ctor, &ty)
.filter(|(_, PrivateUninhabitedField(skip))| !skip)
.map(|(ty, _)| Self::wildcard(ty))
.map(|(ty, _)| Self::wildcard(cx, ty))
.collect();
Self::new(ctor, fields, ty)
}

106
tests/ui/pattern/usefulness/empty-types.never_pats.stderr
View File

@ -74,11 +74,11 @@ error: unreachable pattern
LL | _ => {}
| ^
error[E0004]: non-exhaustive patterns: `Ok(_)` and `Err(_)` not covered
error[E0004]: non-exhaustive patterns: `Ok(_)` and `Err(!)` not covered
--> $DIR/empty-types.rs:91:11
|
LL | match res_u32_never {}
| ^^^^^^^^^^^^^ patterns `Ok(_)` and `Err(_)` not covered
| ^^^^^^^^^^^^^ patterns `Ok(_)` and `Err(!)` not covered
|
note: `Result<u32, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -92,15 +92,15 @@ note: `Result<u32, !>` defined here
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 res_u32_never {
LL + Ok(_) | Err(_) => todo!(),
LL + Ok(_) | Err(!) => todo!(),
LL + }
|
error[E0004]: non-exhaustive patterns: `Err(_)` not covered
error[E0004]: non-exhaustive patterns: `Err(!)` not covered
--> $DIR/empty-types.rs:93:11
|
LL | match res_u32_never {
| ^^^^^^^^^^^^^ pattern `Err(_)` not covered
| ^^^^^^^^^^^^^ pattern `Err(!)` not covered
|
note: `Result<u32, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -111,7 +111,7 @@ note: `Result<u32, !>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ Ok(_) => {},
LL + Err(_) => todo!()
LL + Err(!) => todo!()
|
error[E0004]: non-exhaustive patterns: `Ok(1_u32..=u32::MAX)` not covered
@ -136,7 +136,7 @@ error[E0005]: refutable pattern in local binding
--> $DIR/empty-types.rs:106:9
|
LL | let Ok(_x) = res_u32_never;
| ^^^^^^ pattern `Err(_)` not covered
| ^^^^^^ pattern `Err(!)` 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
@ -164,7 +164,7 @@ error[E0005]: refutable pattern in local binding
--> $DIR/empty-types.rs:112:9
|
LL | let Ok(_x) = &res_u32_never;
| ^^^^^^ pattern `&Err(_)` not covered
| ^^^^^^ pattern `&Err(!)` 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
@ -174,11 +174,11 @@ help: you might want to use `let else` to handle the variant that isn't matched
LL | let Ok(_x) = &res_u32_never else { todo!() };
| ++++++++++++++++
error[E0004]: non-exhaustive patterns: `Ok(_)` and `Err(_)` not covered
error[E0004]: non-exhaustive patterns: `Ok(!)` and `Err(!)` not covered
--> $DIR/empty-types.rs:116:11
|
LL | match result_never {}
| ^^^^^^^^^^^^ patterns `Ok(_)` and `Err(_)` not covered
| ^^^^^^^^^^^^ patterns `Ok(!)` and `Err(!)` not covered
|
note: `Result<!, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -192,15 +192,15 @@ note: `Result<!, !>` defined here
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 result_never {
LL + Ok(_) | Err(_) => todo!(),
LL + Ok(!) | Err(!) => todo!(),
LL + }
|
error[E0004]: non-exhaustive patterns: `Err(_)` not covered
error[E0004]: non-exhaustive patterns: `Err(!)` not covered
--> $DIR/empty-types.rs:121:11
|
LL | match result_never {
| ^^^^^^^^^^^^ pattern `Err(_)` not covered
| ^^^^^^^^^^^^ pattern `Err(!)` not covered
|
note: `Result<!, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -210,7 +210,7 @@ note: `Result<!, !>` defined here
= note: the matched value is of type `Result<!, !>`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL | Ok(_) => {}, Err(_) => todo!()
LL | Ok(_) => {}, Err(!) => todo!()
| +++++++++++++++++++
error: unreachable pattern
@ -225,11 +225,11 @@ error: unreachable pattern
LL | _ if false => {}
| ^
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
error[E0004]: non-exhaustive patterns: `Some(!)` not covered
--> $DIR/empty-types.rs:146:15
|
LL | match opt_void {
| ^^^^^^^^ pattern `Some(_)` not covered
| ^^^^^^^^ pattern `Some(!)` not covered
|
note: `Option<Void>` defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@ -240,14 +240,14 @@ note: `Option<Void>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ None => {},
LL + Some(_) => todo!()
LL + Some(!) => todo!()
|
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
error[E0004]: non-exhaustive patterns: `Some(!)` not covered
--> $DIR/empty-types.rs:165:15
|
LL | match *ref_opt_void {
| ^^^^^^^^^^^^^ pattern `Some(_)` not covered
| ^^^^^^^^^^^^^ pattern `Some(!)` not covered
|
note: `Option<Void>` defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@ -258,7 +258,7 @@ note: `Option<Void>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ None => {},
LL + Some(_) => todo!()
LL + Some(!) => todo!()
|
error: unreachable pattern
@ -325,11 +325,11 @@ LL + _ => todo!(),
LL ~ }
|
error[E0004]: non-exhaustive patterns: `Ok(_)` and `Err(_)` not covered
error[E0004]: non-exhaustive patterns: `Ok(!)` and `Err(!)` not covered
--> $DIR/empty-types.rs:320:11
|
LL | match *x {}
| ^^ patterns `Ok(_)` and `Err(_)` not covered
| ^^ patterns `Ok(!)` and `Err(!)` not covered
|
note: `Result<!, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -343,7 +343,7 @@ note: `Result<!, !>` defined here
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 + Ok(_) | Err(_) => todo!(),
LL + Ok(!) | Err(!) => todo!(),
LL ~ }
|
@ -375,44 +375,44 @@ LL + _ => todo!(),
LL + }
|
error[E0004]: non-exhaustive patterns: `&[_, ..]` not covered
error[E0004]: non-exhaustive patterns: `&[!, ..]` not covered
--> $DIR/empty-types.rs:329:11
|
LL | match slice_never {
| ^^^^^^^^^^^ pattern `&[_, ..]` not covered
| ^^^^^^^^^^^ pattern `&[!, ..]` not covered
|
= note: the matched value is of type `&[!]`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ [] => {},
LL + &[_, ..] => todo!()
LL + &[!, ..] => todo!()
|
error[E0004]: non-exhaustive patterns: `&[]`, `&[_]` and `&[_, _]` not covered
error[E0004]: non-exhaustive patterns: `&[]`, `&[!]` and `&[!, !]` not covered
--> $DIR/empty-types.rs:338:11
|
LL | match slice_never {
| ^^^^^^^^^^^ patterns `&[]`, `&[_]` and `&[_, _]` not covered
| ^^^^^^^^^^^ patterns `&[]`, `&[!]` and `&[!, !]` not covered
|
= note: the matched value is of type `&[!]`
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 ~ [_, _, _, ..] => {},
LL + &[] | &[_] | &[_, _] => todo!()
LL + &[] | &[!] | &[!, !] => todo!()
|
error[E0004]: non-exhaustive patterns: `&[]` and `&[_, ..]` not covered
error[E0004]: non-exhaustive patterns: `&[]` and `&[!, ..]` not covered
--> $DIR/empty-types.rs:352:11
|
LL | match slice_never {
| ^^^^^^^^^^^ patterns `&[]` and `&[_, ..]` not covered
| ^^^^^^^^^^^ patterns `&[]` and `&[!, ..]` not covered
|
= note: the matched value is of type `&[!]`
= note: match arms with guards don't count towards exhaustivity
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 ~ &[..] if false => {},
LL + &[] | &[_, ..] => todo!()
LL + &[] | &[!, ..] => todo!()
|
error[E0004]: non-exhaustive patterns: type `[!]` is non-empty
@ -477,11 +477,11 @@ LL ~ [..] if false => {},
LL + [] => todo!()
|
error[E0004]: non-exhaustive patterns: `&Some(_)` not covered
error[E0004]: non-exhaustive patterns: `&Some(!)` not covered
--> $DIR/empty-types.rs:452:11
|
LL | match ref_opt_never {
| ^^^^^^^^^^^^^ pattern `&Some(_)` not covered
| ^^^^^^^^^^^^^ pattern `&Some(!)` not covered
|
note: `Option<!>` defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@ -492,14 +492,14 @@ note: `Option<!>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ &None => {},
LL + &Some(_) => todo!()
LL + &Some(!) => todo!()
|
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
error[E0004]: non-exhaustive patterns: `Some(!)` not covered
--> $DIR/empty-types.rs:493:11
|
LL | match *ref_opt_never {
| ^^^^^^^^^^^^^^ pattern `Some(_)` not covered
| ^^^^^^^^^^^^^^ pattern `Some(!)` not covered
|
note: `Option<!>` defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@ -510,14 +510,14 @@ note: `Option<!>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ None => {},
LL + Some(_) => todo!()
LL + Some(!) => todo!()
|
error[E0004]: non-exhaustive patterns: `Err(_)` not covered
error[E0004]: non-exhaustive patterns: `Err(!)` not covered
--> $DIR/empty-types.rs:541:11
|
LL | match *ref_res_never {
| ^^^^^^^^^^^^^^ pattern `Err(_)` not covered
| ^^^^^^^^^^^^^^ pattern `Err(!)` not covered
|
note: `Result<!, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -528,14 +528,14 @@ note: `Result<!, !>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ Ok(_) => {},
LL + Err(_) => todo!()
LL + Err(!) => todo!()
|
error[E0004]: non-exhaustive patterns: `Err(_)` not covered
error[E0004]: non-exhaustive patterns: `Err(!)` not covered
--> $DIR/empty-types.rs:552:11
|
LL | match *ref_res_never {
| ^^^^^^^^^^^^^^ pattern `Err(_)` not covered
| ^^^^^^^^^^^^^^ pattern `Err(!)` not covered
|
note: `Result<!, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -546,7 +546,7 @@ note: `Result<!, !>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ Ok(_a) => {},
LL + Err(_) => todo!()
LL + Err(!) => todo!()
|
error[E0004]: non-exhaustive patterns: type `(u32, !)` is non-empty
@ -587,11 +587,11 @@ error: unreachable pattern
LL | _x if false => {}
| ^^
error[E0004]: non-exhaustive patterns: `&_` not covered
error[E0004]: non-exhaustive patterns: `&!` not covered
--> $DIR/empty-types.rs:638:11
|
LL | match ref_never {
| ^^^^^^^^^ pattern `&_` not covered
| ^^^^^^^^^ pattern `&!` not covered
|
= note: the matched value is of type `&!`
= note: references are always considered inhabited
@ -599,14 +599,14 @@ LL | match ref_never {
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ &_a if false => {},
LL + &_ => todo!()
LL + &! => todo!()
|
error[E0004]: non-exhaustive patterns: `Ok(_)` not covered
error[E0004]: non-exhaustive patterns: `Ok(!)` not covered
--> $DIR/empty-types.rs:654:11
|
LL | match *ref_result_never {
| ^^^^^^^^^^^^^^^^^ pattern `Ok(_)` not covered
| ^^^^^^^^^^^^^^^^^ pattern `Ok(!)` not covered
|
note: `Result<!, !>` defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@ -617,14 +617,14 @@ note: `Result<!, !>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ Err(_) => {},
LL + Ok(_) => todo!()
LL + Ok(!) => todo!()
|
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
error[E0004]: non-exhaustive patterns: `Some(!)` not covered
--> $DIR/empty-types.rs:674:11
|
LL | match *x {
| ^^ pattern `Some(_)` not covered
| ^^ pattern `Some(!)` not covered
|
note: `Option<Result<!, !>>` defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@ -635,7 +635,7 @@ note: `Option<Result<!, !>>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ None => {},
LL + Some(_) => todo!()
LL + Some(!) => todo!()
|
error: aborting due to 49 previous errors; 1 warning emitted

8
tests/ui/pattern/usefulness/empty-types.rs
View File

@ -338,7 +338,7 @@ fn arrays_and_slices(x: NeverBundle) {
match slice_never {
//[normal,min_exh_pats]~^ ERROR `&[]`, `&[_]` and `&[_, _]` not covered
//[exhaustive_patterns]~^^ ERROR `&[]` not covered
//[never_pats]~^^^ ERROR `&[]`, `&[_]` and `&[_, _]` not covered
//[never_pats]~^^^ ERROR `&[]`, `&[!]` and `&[!, !]` not covered
[_, _, _, ..] => {}
}
match slice_never {
@ -352,7 +352,7 @@ fn arrays_and_slices(x: NeverBundle) {
match slice_never {
//[normal,min_exh_pats]~^ ERROR `&[]` and `&[_, ..]` not covered
//[exhaustive_patterns]~^^ ERROR `&[]` not covered
//[never_pats]~^^^ ERROR `&[]` and `&[_, ..]` not covered
//[never_pats]~^^^ ERROR `&[]` and `&[!, ..]` not covered
&[..] if false => {}
}
@ -653,7 +653,7 @@ fn guards_and_validity(x: NeverBundle) {
}
match *ref_result_never {
//[normal,min_exh_pats]~^ ERROR `Ok(_)` not covered
//[never_pats]~^^ ERROR `Ok(_)` not covered
//[never_pats]~^^ ERROR `Ok(!)` not covered
// useful, reachable
Ok(_) if false => {}
// useful, reachable
@ -673,7 +673,7 @@ fn diagnostics_subtlety(x: NeverBundle) {
let x: &Option<Result<!, !>> = &None;
match *x {
//[normal,min_exh_pats]~^ ERROR `Some(_)` not covered
//[never_pats]~^^ ERROR `Some(_)` not covered
//[never_pats]~^^ ERROR `Some(!)` not covered
None => {}
}
}

4
tests/ui/rfcs/rfc-0000-never_patterns/check.rs
View File

@ -15,12 +15,12 @@ fn no_arms_or_guards(x: Void) {
//~^ ERROR a never pattern is always unreachable
None => {}
}
match None::<Void> { //~ ERROR: `Some(_)` not covered
match None::<Void> { //~ ERROR: `Some(!)` not covered
Some(!) if true,
//~^ ERROR guard on a never pattern
None => {}
}
match None::<Void> { //~ ERROR: `Some(_)` not covered
match None::<Void> { //~ ERROR: `Some(!)` not covered
Some(!) if true => {}
//~^ ERROR a never pattern is always unreachable
None => {}

12
tests/ui/rfcs/rfc-0000-never_patterns/check.stderr
View File

@ -31,11 +31,11 @@ LL | Some(never!()) => {}
| this will never be executed
| help: remove this expression
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
error[E0004]: non-exhaustive patterns: `Some(!)` not covered
--> $DIR/check.rs:18:11
|
LL | match None::<Void> {
| ^^^^^^^^^^^^ pattern `Some(_)` not covered
| ^^^^^^^^^^^^ pattern `Some(!)` not covered
|
note: `Option<Void>` defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@ -46,14 +46,14 @@ note: `Option<Void>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ None => {},
LL + Some(_) => todo!()
LL + Some(!) => todo!()
|
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
error[E0004]: non-exhaustive patterns: `Some(!)` not covered
--> $DIR/check.rs:23:11
|
LL | match None::<Void> {
| ^^^^^^^^^^^^ pattern `Some(_)` not covered
| ^^^^^^^^^^^^ pattern `Some(!)` not covered
|
note: `Option<Void>` defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@ -64,7 +64,7 @@ note: `Option<Void>` defined here
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL ~ None => {},
LL + Some(_) => todo!()
LL + Some(!) => todo!()
|
error: aborting due to 6 previous errors