diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_mir_build/src/thir/pattern/check_match.rs | 74 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/constructor.rs | 39 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/pat.rs | 21 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/rustc.rs | 7 |
4 files changed, 94 insertions, 47 deletions
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs index 20d3b3f98ce..cfa853417ca 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs @@ -938,9 +938,6 @@ fn report_non_exhaustive_match<'p, 'tcx>( }; // In the case of an empty match, replace the '`_` not covered' diagnostic with something more // informative. - let mut err; - let pattern; - let patterns_len; if is_empty_match && !non_empty_enum { return cx.tcx.dcx().emit_err(NonExhaustivePatternsTypeNotEmpty { cx, @@ -948,33 +945,23 @@ fn report_non_exhaustive_match<'p, 'tcx>( span: sp, ty: scrut_ty, }); - } else { - // FIXME: migration of this diagnostic will require list support - let joined_patterns = joined_uncovered_patterns(cx, &witnesses); - err = create_e0004( - cx.tcx.sess, - sp, - format!("non-exhaustive patterns: {joined_patterns} not covered"), - ); - err.span_label( - sp, - format!( - "pattern{} {} not covered", - rustc_errors::pluralize!(witnesses.len()), - joined_patterns - ), - ); - patterns_len = witnesses.len(); - pattern = if witnesses.len() < 4 { - witnesses - .iter() - .map(|witness| cx.hoist_witness_pat(witness).to_string()) - .collect::<Vec<String>>() - .join(" | ") - } else { - "_".to_string() - }; - }; + } + + // FIXME: migration of this diagnostic will require list support + let joined_patterns = joined_uncovered_patterns(cx, &witnesses); + let mut err = create_e0004( + cx.tcx.sess, + sp, + format!("non-exhaustive patterns: {joined_patterns} not covered"), + ); + err.span_label( + sp, + format!( + "pattern{} {} not covered", + rustc_errors::pluralize!(witnesses.len()), + joined_patterns + ), + ); // Point at the definition of non-covered `enum` variants. if let Some(AdtDefinedHere { adt_def_span, ty, variants }) = @@ -1021,6 +1008,23 @@ fn report_non_exhaustive_match<'p, 'tcx>( } } + // Whether we suggest the actual missing patterns or `_`. + let suggest_the_witnesses = witnesses.len() < 4; + let suggested_arm = if suggest_the_witnesses { + let pattern = witnesses + .iter() + .map(|witness| cx.hoist_witness_pat(witness).to_string()) + .collect::<Vec<String>>() + .join(" | "); + if witnesses.iter().all(|p| p.is_never_pattern()) && cx.tcx.features().never_patterns { + // Arms with a never pattern don't take a body. + pattern + } else { + format!("{pattern} => todo!()") + } + } else { + format!("_ => todo!()") + }; let mut suggestion = None; let sm = cx.tcx.sess.source_map(); match arms { @@ -1033,7 +1037,7 @@ fn report_non_exhaustive_match<'p, 'tcx>( }; suggestion = Some(( sp.shrink_to_hi().with_hi(expr_span.hi()), - format!(" {{{indentation}{more}{pattern} => todo!(),{indentation}}}",), + format!(" {{{indentation}{more}{suggested_arm},{indentation}}}",), )); } [only] => { @@ -1059,7 +1063,7 @@ fn report_non_exhaustive_match<'p, 'tcx>( }; suggestion = Some(( only.span.shrink_to_hi(), - format!("{comma}{pre_indentation}{pattern} => todo!()"), + format!("{comma}{pre_indentation}{suggested_arm}"), )); } [.., prev, last] => { @@ -1082,7 +1086,7 @@ fn report_non_exhaustive_match<'p, 'tcx>( if let Some(spacing) = spacing { suggestion = Some(( last.span.shrink_to_hi(), - format!("{comma}{spacing}{pattern} => todo!()"), + format!("{comma}{spacing}{suggested_arm}"), )); } } @@ -1093,13 +1097,13 @@ fn report_non_exhaustive_match<'p, 'tcx>( let msg = format!( "ensure that all possible cases are being handled by adding a match arm with a wildcard \ pattern{}{}", - if patterns_len > 1 && patterns_len < 4 && suggestion.is_some() { + if witnesses.len() > 1 && suggest_the_witnesses && suggestion.is_some() { ", a match arm with multiple or-patterns" } else { // we are either not suggesting anything, or suggesting `_` "" }, - match patterns_len { + match witnesses.len() { // non-exhaustive enum case 0 if suggestion.is_some() => " as shown", 0 => "", diff --git a/compiler/rustc_pattern_analysis/src/constructor.rs b/compiler/rustc_pattern_analysis/src/constructor.rs index bbb89576ef7..5b58d7f43b2 100644 --- a/compiler/rustc_pattern_analysis/src/constructor.rs +++ b/compiler/rustc_pattern_analysis/src/constructor.rs @@ -678,15 +678,19 @@ pub enum Constructor<Cx: PatCx> { Or, /// Wildcard pattern. Wildcard, + /// Never pattern. Only used in `WitnessPat`. An actual never pattern should be lowered as + /// `Wildcard`. + Never, /// Fake extra constructor for enums that aren't allowed to be matched exhaustively. Also used - /// for those types for which we cannot list constructors explicitly, like `f64` and `str`. + /// for those types for which we cannot list constructors explicitly, like `f64` and `str`. Only + /// used in `WitnessPat`. NonExhaustive, - /// Fake extra constructor for variants that should not be mentioned in diagnostics. - /// We use this for variants behind an unstable gate as well as - /// `#[doc(hidden)]` ones. + /// Fake extra constructor for variants that should not be mentioned in diagnostics. We use this + /// for variants behind an unstable gate as well as `#[doc(hidden)]` ones. Only used in + /// `WitnessPat`. Hidden, /// Fake extra constructor for constructors that are not seen in the matrix, as explained at the - /// top of the file. + /// top of the file. Only used for specialization. Missing, /// Fake extra constructor that indicates and empty field that is private. When we encounter one /// we skip the column entirely so we don't observe its emptiness. Only used for specialization. @@ -708,6 +712,7 @@ impl<Cx: PatCx> Clone for Constructor<Cx> { Constructor::Str(value) => Constructor::Str(value.clone()), Constructor::Opaque(inner) => Constructor::Opaque(inner.clone()), Constructor::Or => Constructor::Or, + Constructor::Never => Constructor::Never, Constructor::Wildcard => Constructor::Wildcard, Constructor::NonExhaustive => Constructor::NonExhaustive, Constructor::Hidden => Constructor::Hidden, @@ -1040,10 +1045,32 @@ impl<Cx: PatCx> 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..)) + } + } + } } diff --git a/compiler/rustc_pattern_analysis/src/pat.rs b/compiler/rustc_pattern_analysis/src/pat.rs index e3667d44bc9..e7eed673c94 100644 --- a/compiler/rustc_pattern_analysis/src/pat.rs +++ b/compiler/rustc_pattern_analysis/src/pat.rs @@ -208,6 +208,7 @@ impl<Cx: PatCx> fmt::Debug for DeconstructedPat<Cx> { } Ok(()) } + Never => write!(f, "!"), Wildcard | Missing | NonExhaustive | Hidden | PrivateUninhabited => { write!(f, "_ : {:?}", pat.ty()) } @@ -311,18 +312,24 @@ impl<Cx: PatCx> 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) } @@ -334,6 +341,14 @@ impl<Cx: PatCx> WitnessPat<Cx> { &self.ty } + pub fn is_never_pattern(&self) -> bool { + match self.ctor() { + Never => true, + Or => self.fields.iter().all(|p| p.is_never_pattern()), + _ => self.fields.iter().any(|p| p.is_never_pattern()), + } + } + pub fn iter_fields(&self) -> impl Iterator<Item = &WitnessPat<Cx>> { self.fields.iter() } diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs index fd51fbedeef..eedc00a5613 100644 --- a/compiler/rustc_pattern_analysis/src/rustc.rs +++ b/compiler/rustc_pattern_analysis/src/rustc.rs @@ -247,7 +247,7 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> { _ => bug!("bad slice pattern {:?} {:?}", ctor, ty), }, Bool(..) | IntRange(..) | F32Range(..) | F64Range(..) | Str(..) | Opaque(..) - | NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => &[], + | Never | NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => &[], Or => { bug!("called `Fields::wildcards` on an `Or` ctor") } @@ -275,7 +275,7 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> { Ref => 1, Slice(slice) => slice.arity(), Bool(..) | IntRange(..) | F32Range(..) | F64Range(..) | Str(..) | Opaque(..) - | NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => 0, + | Never | NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => 0, Or => bug!("The `Or` constructor doesn't have a fixed arity"), } } @@ -824,7 +824,8 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> { } } &Str(value) => PatKind::Constant { value }, - Wildcard | NonExhaustive | Hidden | PrivateUninhabited => PatKind::Wild, + Never if self.tcx.features().never_patterns => PatKind::Never, + Never | Wildcard | NonExhaustive | Hidden | PrivateUninhabited => PatKind::Wild, Missing { .. } => bug!( "trying to convert a `Missing` constructor into a `Pat`; this is probably a bug, `Missing` should have been processed in `apply_constructors`" |