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Don't warn an empty pattern unreachable if we're not sure the data is valid

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This commit is contained in:
Nadrieril 2023-11-18 21:39:57 +01:00
parent f5dbb54648
commit ddef5b61f1
9 changed files with 183 additions and 654 deletions
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44
compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
View File

@ -787,9 +787,6 @@ pub(super) enum Constructor<'tcx> {
}
impl<'tcx> Constructor<'tcx> {
pub(super) fn is_wildcard(&self) -> bool {
matches!(self, Wildcard)
}
pub(super) fn is_non_exhaustive(&self) -> bool {
matches!(self, NonExhaustive)
}
@ -973,15 +970,17 @@ pub(super) enum ConstructorSet {
/// constructors that exist in the type but are not present in the column.
///
/// More formally, if we discard wildcards from the column, this respects the following constraints:
/// 1. the union of `present` and `missing` covers the whole type
/// 1. the union of `present`, `missing` and `missing_empty` covers all the constructors of the type
/// 2. each constructor in `present` is covered by something in the column
/// 3. no constructor in `missing` is covered by anything in the column
/// 3. no constructor in `missing` or `missing_empty` is covered by anything in the column
/// 4. each constructor in the column is equal to the union of one or more constructors in `present`
/// 5. `missing` does not contain empty constructors (see discussion about emptiness at the top of
/// the file);
/// 6. constructors in `present` and `missing` are split for the column; in other words, they are
/// either fully included in or fully disjoint from each constructor in the column. In other
/// words, there are no non-trivial intersections like between `0..10` and `5..15`.
/// 6. `missing_empty` contains only empty constructors
/// 7. constructors in `present`, `missing` and `missing_empty` are split for the column; in other
/// words, they are either fully included in or fully disjoint from each constructor in the
/// column. In yet other words, there are no non-trivial intersections like between `0..10` and
/// `5..15`.
///
/// We must be particularly careful with weird constructors like `Opaque`: they're not formally part
/// of the `ConstructorSet` for the type, yet if we forgot to include them in `present` we would be
@ -990,6 +989,7 @@ pub(super) enum ConstructorSet {
pub(super) struct SplitConstructorSet<'tcx> {
pub(super) present: SmallVec<[Constructor<'tcx>; 1]>,
pub(super) missing: Vec<Constructor<'tcx>>,
pub(super) missing_empty: Vec<Constructor<'tcx>>,
}
impl ConstructorSet {
@ -1132,10 +1132,10 @@ pub(super) fn split<'a, 'tcx>(
// Constructors in `ctors`, except wildcards and opaques.
let mut seen = Vec::new();
for ctor in ctors.cloned() {
if let Constructor::Opaque(..) = ctor {
present.push(ctor);
} else if !ctor.is_wildcard() {
seen.push(ctor);
match ctor {
Opaque(..) => present.push(ctor),
Wildcard => {} // discard wildcards
_ => seen.push(ctor),
}
}
@ -1239,16 +1239,24 @@ pub(super) fn split<'a, 'tcx>(
missing.push(NonExhaustive);
}
ConstructorSet::NoConstructors => {
if !pcx.is_top_level {
missing_empty.push(NonExhaustive);
}
// 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);
}
}
if !pcx.cx.tcx.features().exhaustive_patterns {
missing.extend(missing_empty);
// We have now grouped all the constructors into 3 buckets: present, missing, missing_empty.
// In the absence of the `exhaustive_patterns` feature however, we don't count nested empty
// types as empty. Only non-nested `!` or `enum Foo {}` are considered empty.
if !pcx.cx.tcx.features().exhaustive_patterns
&& !(pcx.is_top_level && matches!(self, Self::NoConstructors))
{
// Treat all missing constructors as nonempty.
missing.extend(missing_empty.drain(..));
}
SplitConstructorSet { present, missing }
SplitConstructorSet { present, missing, missing_empty }
}
}

85
compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
View File

@ -637,12 +637,18 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
}
}
/// In the matrix, tracks whether a given place (aka column) is known to contain a valid value or
/// not.
/// Serves two purposes:
/// - in a wildcard, tracks whether the wildcard matches only valid values (i.e. is a binding `_a`)
/// or also invalid values (i.e. is a true `_` pattern).
/// - in the matrix, track whether a given place (aka column) is known to contain a valid value or
/// not.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub(super) enum ValidityConstraint {
ValidOnly,
MaybeInvalid,
/// Option for backwards compatibility: the place is not known to be valid but we allow omitting
/// `useful && !reachable` arms anyway.
MaybeInvalidButAllowOmittingArms,
}
impl ValidityConstraint {
@ -650,19 +656,37 @@ pub(super) fn from_bool(is_valid_only: bool) -> Self {
if is_valid_only { ValidOnly } else { MaybeInvalid }
}
fn allow_omitting_side_effecting_arms(self) -> Self {
match self {
MaybeInvalid | MaybeInvalidButAllowOmittingArms => MaybeInvalidButAllowOmittingArms,
// There are no side-effecting empty arms here, nothing to do.
ValidOnly => ValidOnly,
}
}
pub(super) fn is_known_valid(self) -> bool {
matches!(self, ValidOnly)
}
pub(super) fn allows_omitting_empty_arms(self) -> bool {
matches!(self, ValidOnly | MaybeInvalidButAllowOmittingArms)
}
/// If the place has validity given by `self` and we read that the value at the place has
/// constructor `ctor`, this computes what we can assume about the validity of the constructor
/// fields.
///
/// Pending further opsem decisions, the current behavior is: validity is preserved, except
/// under `&` where validity is reset to `MaybeInvalid`.
/// inside `&` and union fields where validity is reset to `MaybeInvalid`.
pub(super) fn specialize<'tcx>(
self,
pcx: &PatCtxt<'_, '_, 'tcx>,
ctor: &Constructor<'tcx>,
) -> Self {
// We preserve validity except when we go under a reference.
if matches!(ctor, Constructor::Single) && matches!(pcx.ty.kind(), ty::Ref(..)) {
// We preserve validity except when we go inside a reference or a union field.
if matches!(ctor, Constructor::Single)
&& (matches!(pcx.ty.kind(), ty::Ref(..))
|| matches!(pcx.ty.kind(), ty::Adt(def, ..) if def.is_union()))
{
// Validity of `x: &T` does not imply validity of `*x: T`.
MaybeInvalid
} else {
@ -675,7 +699,7 @@ impl fmt::Display for ValidityConstraint {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let s = match self {
ValidOnly => "✓",
MaybeInvalid => "?",
MaybeInvalid | MaybeInvalidButAllowOmittingArms => "?",
};
write!(f, "{s}")
}
@ -1202,9 +1226,9 @@ fn compute_exhaustiveness_and_usefulness<'p, 'tcx>(
for row in matrix.rows_mut() {
// All rows are useful until they're not.
row.useful = true;
// When there's an unguarded row, the match is exhaustive and any subsequent row is not
// useful.
if !row.is_under_guard {
// There's an unguarded row, so the match is exhaustive, and any subsequent row is
// unreachable.
return WitnessMatrix::empty();
}
}
@ -1215,26 +1239,37 @@ fn compute_exhaustiveness_and_usefulness<'p, 'tcx>(
debug!("ty: {ty:?}");
let pcx = &PatCtxt { cx, ty, is_top_level };
// Whether the place/column we are inspecting is known to contain valid data.
let place_validity = matrix.place_validity[0];
// For backwards compability we allow omitting some empty arms that we ideally shouldn't.
let place_validity = place_validity.allow_omitting_side_effecting_arms();
// Analyze the constructors present in this column.
let ctors = matrix.heads().map(|p| p.ctor());
let split_set = ConstructorSet::for_ty(pcx.cx, pcx.ty).split(pcx, ctors);
let split_set = ConstructorSet::for_ty(cx, ty).split(pcx, ctors);
let all_missing = split_set.present.is_empty();
let always_report_all = is_top_level && !IntRange::is_integral(pcx.ty);
// Whether we should report "Enum::A and Enum::C are missing" or "_ is missing".
let report_individual_missing_ctors = always_report_all || !all_missing;
// Build the set of constructors we will specialize with. It must cover the whole type.
let mut split_ctors = split_set.present;
let mut only_report_missing = false;
if !split_set.missing.is_empty() {
// We need to iterate over a full set of constructors, so we add `Missing` to represent the
// missing ones. This is explained under "Constructor Splitting" at the top of this file.
split_ctors.push(Constructor::Missing);
// For diagnostic purposes we choose to only report the constructors that are missing. Since
// `Missing` matches only the wildcard rows, it matches fewer rows than any normal
// constructor and is therefore guaranteed to result in more witnesses. So skipping the
// other constructors does not jeopardize correctness.
only_report_missing = true;
} else if !split_set.missing_empty.is_empty() && !place_validity.is_known_valid() {
// The missing empty constructors are reachable if the place can contain invalid data.
split_ctors.push(Constructor::Missing);
}
// Decide what constructors to report.
let always_report_all = is_top_level && !IntRange::is_integral(pcx.ty);
// Whether we should report "Enum::A and Enum::C are missing" or "_ is missing".
let report_individual_missing_ctors = always_report_all || !all_missing;
// Which constructors are considered missing. We ensure that `!missing_ctors.is_empty() =>
// split_ctors.contains(Missing)`. The converse usually holds except in the
// `MaybeInvalidButAllowOmittingArms` backwards-compatibility case.
let mut missing_ctors = split_set.missing;
if !place_validity.allows_omitting_empty_arms() {
missing_ctors.extend(split_set.missing_empty);
}
let mut ret = WitnessMatrix::empty();
@ -1246,11 +1281,19 @@ fn compute_exhaustiveness_and_usefulness<'p, 'tcx>(
compute_exhaustiveness_and_usefulness(cx, &mut spec_matrix, false)
});
if !only_report_missing || matches!(ctor, Constructor::Missing) {
let counts_for_exhaustiveness = match ctor {
Constructor::Missing => !missing_ctors.is_empty(),
// If there are missing constructors we'll report those instead. Since `Missing` matches
// only the wildcard rows, it matches fewer rows than this constructor, and is therefore
// guaranteed to result in the same or more witnesses. So skipping this does not
// jeopardize correctness.
_ => missing_ctors.is_empty(),
};
if counts_for_exhaustiveness {
// Transform witnesses for `spec_matrix` into witnesses for `matrix`.
witnesses.apply_constructor(
pcx,
&split_set.missing,
&missing_ctors,
&ctor,
report_individual_missing_ctors,
);

389
tests/ui/pattern/usefulness/empty-types.exhaustive_patterns.stderr
View File

@ -31,12 +31,6 @@ LL + _ => todo!(),
LL + }
|
error: unreachable pattern
--> $DIR/empty-types.rs:62:9
|
LL | &_ => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:69:9
|
@ -184,42 +178,6 @@ error: unreachable pattern
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:158:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:167:13
|
LL | Some(_) => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:171:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:175:13
|
LL | _a => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:180:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:185:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:204:13
|
@ -250,48 +208,6 @@ error: unreachable pattern
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:234:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:239:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:245:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:251:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:256:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:262:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:268:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:284:9
|
@ -316,18 +232,6 @@ error: unreachable pattern
LL | Err(_) => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:296:9
|
LL | &_ => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:299:9
|
LL | Uninit { value: _ } => {}
| ^^^^^^^^^^^^^^^^^^^
error[E0004]: non-exhaustive patterns: type `&[!]` is non-empty
--> $DIR/empty-types.rs:323:11
|
@ -342,24 +246,6 @@ LL + _ => todo!(),
LL + }
|
error: unreachable pattern
--> $DIR/empty-types.rs:331:9
|
LL | [_] => {}
| ^^^
error: unreachable pattern
--> $DIR/empty-types.rs:332:9
|
LL | [_, _, ..] => {}
| ^^^^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:337:9
|
LL | [_, _, _, ..] => {}
| ^^^^^^^^^^^^^
error[E0004]: non-exhaustive patterns: `&[]` not covered
--> $DIR/empty-types.rs:334:11
|
@ -369,20 +255,9 @@ LL | match slice_never {
= 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 | [_, _, _, ..] => {}, &[] => todo!()
| ++++++++++++++++
error: unreachable pattern
--> $DIR/empty-types.rs:341:9
LL ~ [_, _, _, ..] => {},
LL + &[] => todo!()
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:345:9
|
LL | _x => {}
| ^^
error[E0004]: non-exhaustive patterns: `&[]` not covered
--> $DIR/empty-types.rs:347:11
@ -430,18 +305,6 @@ error: unreachable pattern
LL | [_, ..] => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:375:9
|
LL | &[_, _, _] => {}
| ^^^^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:379:9
|
LL | &[_x, _, _] => {}
| ^^^^^^^^^^^
error[E0004]: non-exhaustive patterns: type `[!; 0]` is non-empty
--> $DIR/empty-types.rs:383:11
|
@ -500,186 +363,6 @@ error: unreachable pattern
LL | _a => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:436:9
|
LL | &_ => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:444:9
|
LL | &_a => {}
| ^^^
error: unreachable pattern
--> $DIR/empty-types.rs:453:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:458:9
|
LL | _a => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:463:9
|
LL | &_ => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:468:9
|
LL | &_a => {}
| ^^^
error: unreachable pattern
--> $DIR/empty-types.rs:475:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:479:9
|
LL | _a => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:485:9
|
LL | ref _a => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:494:9
|
LL | Some(_) => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:499:9
|
LL | Some(_a) => {}
| ^^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:504:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:509:9
|
LL | _a => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:514:14
|
LL | _a @ Some(_) => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:521:9
|
LL | ref _a => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:526:18
|
LL | ref _a @ Some(_) => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:531:18
|
LL | ref _a @ Some(_b) => {}
| ^^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:538:9
|
LL | Ok(_) => {}
| ^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:542:9
|
LL | Ok(_) => {}
| ^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:544:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:549:9
|
LL | Ok(_a) => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:553:9
|
LL | Ok(_a) => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:555:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:559:9
|
LL | Ok(_a) => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:561:9
|
LL | Err(_) => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:569:9
|
LL | (_, _) => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:573:9
|
LL | (_x, _) => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:577:9
|
LL | (_, _x) => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:581:9
|
LL | (0, _x) => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:583:9
|
LL | (1.., _) => {}
| ^^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:598:9
|
@ -704,73 +387,7 @@ error: unreachable pattern
LL | _x if false => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:613:9
|
LL | _ if false => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:615:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:622:9
|
LL | _a if false => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:624:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:629:9
|
LL | _a if false => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:634:9
|
LL | &_a if false => {}
| ^^^
error: unreachable pattern
--> $DIR/empty-types.rs:641:9
|
LL | Ok(_x) if false => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:643:9
|
LL | Ok(_) => {}
| ^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:645:9
|
LL | Err(_) => {}
| ^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:650:9
|
LL | (_, _x) if false => {}
| ^^^^^^^
error: unreachable pattern
--> $DIR/empty-types.rs:652:9
|
LL | (_, _) => {}
| ^^^^^^
error: aborting due to 113 previous errors
error: aborting due to 49 previous errors
Some errors have detailed explanations: E0004, E0005.
For more information about an error, try `rustc --explain E0004`.

130
tests/ui/pattern/usefulness/empty-types.normal.stderr
View File

@ -234,12 +234,6 @@ LL ~ None => {},
LL + Some(_) => todo!()
|
error: unreachable pattern
--> $DIR/empty-types.rs:158:13
|
LL | _ => {}
| ^
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
--> $DIR/empty-types.rs:161:15
|
@ -258,18 +252,6 @@ LL ~ None => {},
LL + Some(_) => todo!()
|
error: unreachable pattern
--> $DIR/empty-types.rs:180:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:185:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:204:13
|
@ -300,48 +282,6 @@ error: unreachable pattern
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:234:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:239:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:245:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:251:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:256:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:262:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:268:13
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:284:9
|
@ -448,8 +388,9 @@ LL | match slice_never {
= 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 | [_, _, _, ..] => {}, &[] | &[_] | &[_, _] => todo!()
| +++++++++++++++++++++++++++++++++
LL ~ [_, _, _, ..] => {},
LL + &[] | &[_] | &[_, _] => todo!()
|
error[E0004]: non-exhaustive patterns: `&[]` and `&[_, ..]` not covered
--> $DIR/empty-types.rs:347:11
@ -545,24 +486,6 @@ LL ~ &None => {},
LL + &Some(_) => todo!()
|
error: unreachable pattern
--> $DIR/empty-types.rs:475:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:479:9
|
LL | _a => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:485:9
|
LL | ref _a => {}
| ^^^^^^
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
--> $DIR/empty-types.rs:487:11
|
@ -595,8 +518,9 @@ 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(_) => {},
LL + Err(_) => todo!()
|
error[E0004]: non-exhaustive patterns: `Err(_)` not covered
--> $DIR/empty-types.rs:546:11
@ -612,8 +536,9 @@ 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(_a) => {}, Err(_) => todo!()
| +++++++++++++++++++
LL ~ Ok(_a) => {},
LL + Err(_) => todo!()
|
error[E0004]: non-exhaustive patterns: type `(u32, !)` is non-empty
--> $DIR/empty-types.rs:565:11
@ -653,36 +578,6 @@ error: unreachable pattern
LL | _x if false => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:613:9
|
LL | _ if false => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:615:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:622:9
|
LL | _a if false => {}
| ^^
error: unreachable pattern
--> $DIR/empty-types.rs:624:9
|
LL | _ => {}
| ^
error: unreachable pattern
--> $DIR/empty-types.rs:629:9
|
LL | _a if false => {}
| ^^
error[E0004]: non-exhaustive patterns: `&_` not covered
--> $DIR/empty-types.rs:631:11
|
@ -694,8 +589,9 @@ LL | match ref_never {
= 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 or an explicit pattern as shown
|
LL | &_a if false => {}, &_ => todo!()
| +++++++++++++++
LL ~ &_a if false => {},
LL + &_ => todo!()
|
error[E0004]: non-exhaustive patterns: `Some(_)` not covered
--> $DIR/empty-types.rs:659:11
@ -715,7 +611,7 @@ LL ~ None => {},
LL + Some(_) => todo!()
|
error: aborting due to 66 previous errors
error: aborting due to 48 previous errors
Some errors have detailed explanations: E0004, E0005.
For more information about an error, try `rustc --explain E0004`.

128
tests/ui/pattern/usefulness/empty-types.rs
View File

@ -59,7 +59,7 @@ fn basic(x: NeverBundle) {
}
match ref_never {
// useful, reachable
&_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&_ => {}
}
let tuple_half_never: (u32, !) = x.tuple_half_never;
@ -155,7 +155,7 @@ fn void_same_as_never(x: NeverBundle) {
let ref_void: &Void = &x.void;
match *ref_void {}
match *ref_void {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
let ref_opt_void: &Option<Void> = &None;
match *ref_opt_void {
@ -164,25 +164,25 @@ fn void_same_as_never(x: NeverBundle) {
}
match *ref_opt_void {
None => {}
Some(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Some(_) => {}
}
match *ref_opt_void {
None => {}
_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_ => {}
}
match *ref_opt_void {
None => {}
_a => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_a => {}
}
let union_void = Uninit::<Void>::new();
match union_void.value {}
match union_void.value {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
let ptr_void: *const Void = std::ptr::null();
match *ptr_void {}
match *ptr_void {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
}
}
@ -231,41 +231,41 @@ fn invalid_scrutinees(x: NeverBundle) {
// A pointer may point to a place with an invalid value.
match *ptr_never {}
match *ptr_never {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// A reference may point to a place with an invalid value.
match *ref_never {}
match *ref_never {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// This field access is a dereference.
let ref_x: &NeverBundle = &x;
match ref_x.never {}
match ref_x.never {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// This nested field access is a dereference.
let nested_ref_x: &NestedNeverBundle = &nested_x;
match nested_ref_x.0.never {}
match nested_ref_x.0.never {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// A cast does not load.
match (*ptr_never as Void) {}
match (*ptr_never as Void) {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// A union field may contain invalid data.
let union_never = Uninit::<!>::new();
match union_never.value {}
match union_never.value {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// Indexing is like a field access. This one accesses behind a reference.
let slice_never: &[!] = &[];
match slice_never[0] {}
match slice_never[0] {
_ => {} //~ ERROR unreachable pattern
_ => {}
}
}
}
@ -293,10 +293,10 @@ fn nested_validity_tracking(bundle: NeverBundle) {
// These should be considered !known_valid and not warn unreachable.
match ref_never {
&_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&_ => {}
}
match union_never {
Uninit { value: _ } => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Uninit { value: _ } => {}
}
}
@ -328,21 +328,21 @@ fn arrays_and_slices(x: NeverBundle) {
}
match slice_never {
[] => {}
[_] => {} //[exhaustive_patterns]~ ERROR unreachable pattern
[_, _, ..] => {} //[exhaustive_patterns]~ ERROR unreachable pattern
[_] => {}
[_, _, ..] => {}
}
match slice_never {
//[normal]~^ ERROR `&[]`, `&[_]` and `&[_, _]` not covered
//[exhaustive_patterns]~^^ ERROR `&[]` not covered
[_, _, _, ..] => {} //[exhaustive_patterns]~ ERROR unreachable pattern
[_, _, _, ..] => {}
}
match slice_never {
[] => {}
_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_ => {}
}
match slice_never {
[] => {}
_x => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_x => {}
}
match slice_never {
//[normal]~^ ERROR `&[]` and `&[_, ..]` not covered
@ -372,11 +372,11 @@ fn arrays_and_slices(x: NeverBundle) {
let ref_array_3_never: &[!; 3] = &array_3_never;
match ref_array_3_never {
// useful, reachable
&[_, _, _] => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&[_, _, _] => {}
}
match ref_array_3_never {
// useful, !reachable
&[_x, _, _] => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&[_x, _, _] => {}
}
let array_0_never: [!; 0] = [];
@ -433,7 +433,7 @@ fn bindings(x: NeverBundle) {
}
match ref_never {
// useful, reachable
&_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&_ => {}
}
match ref_never {
// useful, reachable
@ -441,7 +441,7 @@ fn bindings(x: NeverBundle) {
}
match ref_never {
// useful, !reachable
&_a => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&_a => {}
}
match ref_opt_never {
//[normal]~^ ERROR non-exhaustive
@ -450,39 +450,39 @@ fn bindings(x: NeverBundle) {
match ref_opt_never {
&None => {}
// useful, reachable
_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_ => {}
}
match ref_opt_never {
&None => {}
// useful, reachable
_a => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_a => {}
}
match ref_opt_never {
&None => {}
// useful, reachable
&_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&_ => {}
}
match ref_opt_never {
&None => {}
// useful, !reachable
&_a => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&_a => {}
}
// On a !known_valid place.
match *ref_never {}
match *ref_never {
// useful, reachable
_ => {} //~ ERROR unreachable pattern
_ => {}
}
match *ref_never {
// useful, !reachable
_a => {} //~ ERROR unreachable pattern
_a => {}
}
// This is equivalent to `match ref_never { _a => {} }`. In other words, it asserts validity of
// `ref_never` but says nothing of the data at `*ref_never`.
match *ref_never {
// useful, reachable
ref _a => {} //~ ERROR unreachable pattern
ref _a => {}
}
match *ref_opt_never {
//[normal]~^ ERROR non-exhaustive
@ -491,74 +491,74 @@ fn bindings(x: NeverBundle) {
match *ref_opt_never {
None => {}
// useful, reachable
Some(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Some(_) => {}
}
match *ref_opt_never {
None => {}
// useful, !reachable
Some(_a) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Some(_a) => {}
}
match *ref_opt_never {
None => {}
// useful, reachable
_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_ => {}
}
match *ref_opt_never {
None => {}
// useful, !reachable
_a => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_a => {}
}
match *ref_opt_never {
None => {}
// useful, !reachable
_a @ Some(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_a @ Some(_) => {}
}
// This is equivalent to `match ref_opt_never { None => {}, _a => {} }`. In other words, it
// asserts validity of `ref_opt_never` but says nothing of the data at `*ref_opt_never`.
match *ref_opt_never {
None => {}
// useful, reachable
ref _a => {} //[exhaustive_patterns]~ ERROR unreachable pattern
ref _a => {}
}
match *ref_opt_never {
None => {}
// useful, reachable
ref _a @ Some(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
ref _a @ Some(_) => {}
}
match *ref_opt_never {
None => {}
// useful, !reachable
ref _a @ Some(_b) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
ref _a @ Some(_b) => {}
}
let ref_res_never: &Result<!, !> = &x.result_never;
match *ref_res_never {
//[normal]~^ ERROR non-exhaustive
// useful, reachable
Ok(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Ok(_) => {}
}
match *ref_res_never {
// useful, reachable
Ok(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Ok(_) => {}
// useful, reachable
_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_ => {}
}
match *ref_res_never {
//[normal]~^ ERROR non-exhaustive
// useful, !reachable
Ok(_a) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Ok(_a) => {}
}
match *ref_res_never {
// useful, !reachable
Ok(_a) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Ok(_a) => {}
// useful, reachable
_ => {} //[exhaustive_patterns]~ ERROR unreachable pattern
_ => {}
}
match *ref_res_never {
// useful, !reachable
Ok(_a) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Ok(_a) => {}
// useful, reachable
Err(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Err(_) => {}
}
let ref_tuple_half_never: &(u32, !) = &x.tuple_half_never;
@ -566,21 +566,21 @@ fn bindings(x: NeverBundle) {
//[normal]~^ ERROR non-empty
match *ref_tuple_half_never {
// useful, reachable
(_, _) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
(_, _) => {}
}
match *ref_tuple_half_never {
// useful, reachable
(_x, _) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
(_x, _) => {}
}
match *ref_tuple_half_never {
// useful, !reachable
(_, _x) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
(_, _x) => {}
}
match *ref_tuple_half_never {
// useful, !reachable
(0, _x) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
(0, _x) => {}
// useful, reachable
(1.., _) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
(1.., _) => {}
}
}
@ -610,46 +610,46 @@ fn guards_and_validity(x: NeverBundle) {
// If the pattern under the guard doesn't load, all is normal.
match *ref_never {
// useful, reachable
_ if false => {} //~ ERROR unreachable pattern
_ if false => {}
// useful, reachable
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// Now the madness commences. The guard caused a load of the value thus asserting validity. So
// there's no invalid value for `_` to catch. So the second pattern is unreachable despite the
// guard not being taken.
match *ref_never {
// useful, !reachable
_a if false => {} //~ ERROR unreachable pattern
_a if false => {}
// !useful, !reachable
_ => {} //~ ERROR unreachable pattern
_ => {}
}
// The above still applies to the implicit `_` pattern used for exhaustiveness.
match *ref_never {
// useful, !reachable
_a if false => {} //~ ERROR unreachable pattern
_a if false => {}
}
match ref_never {
//[normal]~^ ERROR non-exhaustive
// useful, !reachable
&_a if false => {} //[exhaustive_patterns]~ ERROR unreachable pattern
&_a if false => {}
}
// Same but with subpatterns.
let ref_result_never: &Result<!, !> = &x.result_never;
match *ref_result_never {
// useful, !reachable
Ok(_x) if false => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Ok(_x) if false => {}
// !useful, !reachable
Ok(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Ok(_) => {}
// useful, !reachable
Err(_) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
Err(_) => {}
}
let ref_tuple_never: &(!, !) = &x.tuple_never;
match *ref_tuple_never {
// useful, !reachable
(_, _x) if false => {} //[exhaustive_patterns]~ ERROR unreachable pattern
(_, _x) if false => {}
// !useful, !reachable
(_, _) => {} //[exhaustive_patterns]~ ERROR unreachable pattern
(_, _) => {}
}
}

6
tests/ui/pattern/usefulness/slice_of_empty.rs
View File

@ -11,12 +11,12 @@ fn foo(nevers: &[!]) {
match nevers {
&[] => (),
&[_] => (), //~ ERROR unreachable pattern
&[_, _, ..] => (), //~ ERROR unreachable pattern
&[_] => (),
&[_, _, ..] => (),
};
match nevers {
//~^ ERROR non-exhaustive patterns: `&[]` not covered
&[_] => (), //~ ERROR unreachable pattern
&[_] => (),
};
}

31
tests/ui/pattern/usefulness/slice_of_empty.stderr
View File

@ -1,27 +1,3 @@
error: unreachable pattern
--> $DIR/slice_of_empty.rs:14:9
|
LL | &[_] => (),
| ^^^^
|
note: the lint level is defined here
--> $DIR/slice_of_empty.rs:3:9
|
LL | #![deny(unreachable_patterns)]
| ^^^^^^^^^^^^^^^^^^^^
error: unreachable pattern
--> $DIR/slice_of_empty.rs:15:9
|
LL | &[_, _, ..] => (),
| ^^^^^^^^^^^
error: unreachable pattern
--> $DIR/slice_of_empty.rs:20:9
|
LL | &[_] => (),
| ^^^^
error[E0004]: non-exhaustive patterns: `&[]` not covered
--> $DIR/slice_of_empty.rs:18:11
|
@ -31,9 +7,10 @@ LL | match nevers {
= 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 | &[_] => (), &[] => todo!(),
| ++++++++++++++++
LL ~ &[_] => (),
LL ~ &[] => todo!(),
|
error: aborting due to 4 previous errors
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0004`.

4
tests/ui/uninhabited/uninhabited-patterns.rs
View File

@ -22,14 +22,14 @@ fn main() {
match x {
&[] => (),
&[..] => (), //~ ERROR unreachable pattern
&[..] => (),
};
let x: Result<Box<NotSoSecretlyEmpty>, &[Result<!, !>]> = Err(&[]);
match x {
Ok(box _) => (), //~ ERROR unreachable pattern
Err(&[]) => (),
Err(&[..]) => (), //~ ERROR unreachable pattern
Err(&[..]) => (),
}
let x: Result<foo::SecretlyEmpty, Result<NotSoSecretlyEmpty, u32>> = Err(Err(123));

20
tests/ui/uninhabited/uninhabited-patterns.stderr
View File

@ -1,8 +1,8 @@
error: unreachable pattern
--> $DIR/uninhabited-patterns.rs:25:9
--> $DIR/uninhabited-patterns.rs:30:9
|
LL | &[..] => (),
| ^^^^^
LL | Ok(box _) => (),
| ^^^^^^^^^
|
note: the lint level is defined here
--> $DIR/uninhabited-patterns.rs:4:9
@ -10,18 +10,6 @@ note: the lint level is defined here
LL | #![deny(unreachable_patterns)]
| ^^^^^^^^^^^^^^^^^^^^
error: unreachable pattern
--> $DIR/uninhabited-patterns.rs:30:9
|
LL | Ok(box _) => (),
| ^^^^^^^^^
error: unreachable pattern
--> $DIR/uninhabited-patterns.rs:32:9
|
LL | Err(&[..]) => (),
| ^^^^^^^^^^
error: unreachable pattern
--> $DIR/uninhabited-patterns.rs:39:9
|
@ -34,5 +22,5 @@ error: unreachable pattern
LL | while let Some(_y) = foo() {
| ^^^^^^^^
error: aborting due to 5 previous errors
error: aborting due to 3 previous errors