Prefer "0..MAX not covered" to "_ not covered"

rust-lang · bors · Feb 8, 2024 · Feb 7, 2024 · Feb 7, 2024 · Feb 7, 2024
commit 9dca6be7b83f4816f67ebaa11008348ce022eb60
diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs
@@ -1520,11 1520,9 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
  split_ctors.push(Constructor::Missing);
  }
 
- // Decide what constructors to report.
- let is_integers = matches!(ctors_for_ty, ConstructorSet::Integers { .. });
- let always_report_all = place.is_scrutinee && !is_integers;
- // Whether we should report "Enum::A and Enum::C are missing" or "_ is missing".
- let report_individual_missing_ctors = always_report_all || !all_missing;
  // Whether we should report "Enum::A and Enum::C are missing" or "_ is missing". At the top
  // level we prefer to list all constructors.
  let report_individual_missing_ctors = place.is_scrutinee || !all_missing;
  // Which constructors are considered missing. We ensure that `!missing_ctors.is_empty() =>
  // split_ctors.contains(Missing)`. The converse usually holds except when
  // `!place_validity.is_known_valid()`.

diff --git a/tests/ui/pattern/usefulness/empty-match-check-notes.exhaustive_patterns.stderr b/tests/ui/pattern/usefulness/empty-match-check-notes.exhaustive_patterns.stderr
@@ -43,18 43,18 @@ help: you might want to use `if let` to ignore the variant that isn't matched
 LL | if let None = x { todo!() };
  | 
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `0_u8..=u8::MAX` not covered
  --> $DIR/empty-match-check-notes.rs:45:11
  |
 LL | match 0u8 {
- | ^^^ pattern `_` not covered
  | ^^^ pattern `0_u8..=u8::MAX` not covered
  |
  = note: the matched value is of type `u8`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL 0_u8..=u8::MAX => todo!()
  |
 
 error: aborting due to 6 previous errors

diff --git a/tests/ui/pattern/usefulness/empty-match-check-notes.normal.stderr b/tests/ui/pattern/usefulness/empty-match-check-notes.normal.stderr
@@ -42,18 42,18 @@ help: you might want to use `if let` to ignore the variant that isn't matched
 LL | if let None = x { todo!() };
  | 
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `0_u8..=u8::MAX` not covered
  --> $DIR/empty-match-check-notes.rs:45:11
  |
 LL | match 0u8 {
- | ^^^ pattern `_` not covered
  | ^^^ pattern `0_u8..=u8::MAX` not covered
  |
  = note: the matched value is of type `u8`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL 0_u8..=u8::MAX => todo!()
  |
 
 error: aborting due to 6 previous errors

diff --git a/tests/ui/pattern/usefulness/empty-match-check-notes.rs b/tests/ui/pattern/usefulness/empty-match-check-notes.rs
@@ -43,10 43,10 @@ fn empty_foreign_enum_private(x: Option<empty::SecretlyUninhabitedForeignStruct>
 
 fn main() {
  match 0u8 {
- //~^ ERROR `_` not covered
  //~^ ERROR not covered
  //~| NOTE the matched value is of type
  //~| NOTE match arms with guards don't count towards exhaustivity
- //~| NOTE pattern `_` not covered
  //~| NOTE not covered
  _ if false => {}
  }
 }
diff --git a/tests/ui/pattern/usefulness/empty-match.exhaustive_patterns.stderr b/tests/ui/pattern/usefulness/empty-match.exhaustive_patterns.stderr
@@ -148,46 148,46 @@ LL | V5,
  = note: the matched value is of type `NonEmptyEnum5`
  = help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or multiple match arms
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `0_u8..=u8::MAX` not covered
  --> $DIR/empty-match.rs:58:24
  |
 LL | match_guarded_arm!(0u8);
- | ^^^ pattern `_` not covered
  | ^^^ pattern `0_u8..=u8::MAX` not covered
  |
  = note: the matched value is of type `u8`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL 0_u8..=u8::MAX => todo!()
  |
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `i8::MIN..=i8::MAX` not covered
  --> $DIR/empty-match.rs:59:24
  |
 LL | match_guarded_arm!(0i8);
- | ^^^ pattern `_` not covered
  | ^^^ pattern `i8::MIN..=i8::MAX` not covered
  |
  = note: the matched value is of type `i8`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL i8::MIN..=i8::MAX => todo!()
  |
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `0_usize..` not covered
  --> $DIR/empty-match.rs:60:24
  |
 LL | match_guarded_arm!(0usize);
- | ^^^^^^ pattern `_` not covered
  | ^^^^^^ pattern `0_usize..` not covered
  |
  = note: the matched value is of type `usize`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL 0_usize.. => todo!()
  |
 
 error[E0004]: non-exhaustive patterns: `_` not covered

diff --git a/tests/ui/pattern/usefulness/empty-match.normal.stderr b/tests/ui/pattern/usefulness/empty-match.normal.stderr
@@ -148,46 148,46 @@ LL | V5,
  = note: the matched value is of type `NonEmptyEnum5`
  = help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or multiple match arms
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `0_u8..=u8::MAX` not covered
  --> $DIR/empty-match.rs:58:24
  |
 LL | match_guarded_arm!(0u8);
- | ^^^ pattern `_` not covered
  | ^^^ pattern `0_u8..=u8::MAX` not covered
  |
  = note: the matched value is of type `u8`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL 0_u8..=u8::MAX => todo!()
  |
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `i8::MIN..=i8::MAX` not covered
  --> $DIR/empty-match.rs:59:24
  |
 LL | match_guarded_arm!(0i8);
- | ^^^ pattern `_` not covered
  | ^^^ pattern `i8::MIN..=i8::MAX` not covered
  |
  = note: the matched value is of type `i8`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL i8::MIN..=i8::MAX => todo!()
  |
 
-error[E0004]: non-exhaustive patterns: `_` not covered
 error[E0004]: non-exhaustive patterns: `0_usize..` not covered
  --> $DIR/empty-match.rs:60:24
  |
 LL | match_guarded_arm!(0usize);
- | ^^^^^^ pattern `_` not covered
  | ^^^^^^ pattern `0_usize..` not covered
  |
  = note: the matched value is of type `usize`
  = 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 ~ _ if false => {},
-LL _ => todo!()
 LL 0_usize.. => todo!()
  |
 
 error[E0004]: non-exhaustive patterns: `_` not covered

diff --git a/tests/ui/pattern/usefulness/empty-match.rs b/tests/ui/pattern/usefulness/empty-match.rs
@@ -55,9 55,9 @@ fn nonempty() {
  match_no_arms!(NonEmptyEnum2::Foo(true)); //~ ERROR `NonEmptyEnum2::Foo(_)` and `NonEmptyEnum2::Bar` not covered
  match_no_arms!(NonEmptyEnum5::V1); //~ ERROR `NonEmptyEnum5::V1`, `NonEmptyEnum5::V2`, `NonEmptyEnum5::V3` and 2 more not covered
 
- match_guarded_arm!(0u8); //~ ERROR `_` not covered
- match_guarded_arm!(0i8); //~ ERROR `_` not covered
- match_guarded_arm!(0usize); //~ ERROR `_` not covered
  match_guarded_arm!(0u8); //~ ERROR `0_u8..=u8::MAX` not covered
  match_guarded_arm!(0i8); //~ ERROR `i8::MIN..=i8::MAX` not covered
  match_guarded_arm!(0usize); //~ ERROR `0_usize..` not covered
  match_guarded_arm!(0isize); //~ ERROR `_` not covered
  match_guarded_arm!(NonEmptyStruct1); //~ ERROR `NonEmptyStruct1` not covered
  match_guarded_arm!(NonEmptyStruct2(true)); //~ ERROR `NonEmptyStruct2(_)` not covered