diff --git a/compiler/rustc_mir_build/src/errors.rs b/compiler/rustc_mir_build/src/errors.rs index 4f98932a88d..c09dd186418 100644 --- a/compiler/rustc_mir_build/src/errors.rs +++ b/compiler/rustc_mir_build/src/errors.rs @@ -1,6 +1,6 @@ use crate::{ fluent_generated as fluent, - thir::pattern::{deconstruct_pat::DeconstructedPat, MatchCheckCtxt}, + thir::pattern::{deconstruct_pat::WitnessPat, MatchCheckCtxt}, }; use rustc_errors::{ error_code, AddToDiagnostic, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, @@ -810,7 +810,7 @@ impl<'tcx> Uncovered<'tcx> { pub fn new<'p>( span: Span, cx: &MatchCheckCtxt<'p, 'tcx>, - witnesses: Vec>, + witnesses: Vec>, ) -> Self { let witness_1 = witnesses.get(0).unwrap().to_pat(cx); Self { 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 93434dd3cc2..f3568b682a4 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs @@ -1,4 +1,4 @@ -use super::deconstruct_pat::{Constructor, DeconstructedPat}; +use super::deconstruct_pat::{Constructor, DeconstructedPat, WitnessPat}; use super::usefulness::{ compute_match_usefulness, MatchArm, MatchCheckCtxt, Reachability, UsefulnessReport, }; @@ -661,8 +661,8 @@ fn report_arm_reachability<'p, 'tcx>( } } -fn collect_non_exhaustive_tys<'p, 'tcx>( - pat: &DeconstructedPat<'p, 'tcx>, +fn collect_non_exhaustive_tys<'tcx>( + pat: &WitnessPat<'tcx>, non_exhaustive_tys: &mut FxHashSet>, ) { if matches!(pat.ctor(), Constructor::NonExhaustive) { @@ -678,7 +678,7 @@ fn non_exhaustive_match<'p, 'tcx>( thir: &Thir<'tcx>, scrut_ty: Ty<'tcx>, sp: Span, - witnesses: Vec>, + witnesses: Vec>, arms: &[ArmId], expr_span: Span, ) -> ErrorGuaranteed { @@ -860,10 +860,10 @@ fn non_exhaustive_match<'p, 'tcx>( pub(crate) fn joined_uncovered_patterns<'p, 'tcx>( cx: &MatchCheckCtxt<'p, 'tcx>, - witnesses: &[DeconstructedPat<'p, 'tcx>], + witnesses: &[WitnessPat<'tcx>], ) -> String { const LIMIT: usize = 3; - let pat_to_str = |pat: &DeconstructedPat<'p, 'tcx>| pat.to_pat(cx).to_string(); + let pat_to_str = |pat: &WitnessPat<'tcx>| pat.to_pat(cx).to_string(); match witnesses { [] => bug!(), [witness] => format!("`{}`", witness.to_pat(cx)), @@ -880,7 +880,7 @@ pub(crate) fn joined_uncovered_patterns<'p, 'tcx>( } pub(crate) fn pattern_not_covered_label( - witnesses: &[DeconstructedPat<'_, '_>], + witnesses: &[WitnessPat<'_>], joined_patterns: &str, ) -> String { format!("pattern{} {} not covered", rustc_errors::pluralize!(witnesses.len()), joined_patterns) @@ -891,7 +891,7 @@ fn adt_defined_here<'p, 'tcx>( cx: &MatchCheckCtxt<'p, 'tcx>, err: &mut Diagnostic, ty: Ty<'tcx>, - witnesses: &[DeconstructedPat<'p, 'tcx>], + witnesses: &[WitnessPat<'tcx>], ) { let ty = ty.peel_refs(); if let ty::Adt(def, _) = ty.kind() { @@ -922,7 +922,7 @@ fn adt_defined_here<'p, 'tcx>( fn maybe_point_at_variant<'a, 'p: 'a, 'tcx: 'a>( cx: &MatchCheckCtxt<'p, 'tcx>, def: AdtDef<'tcx>, - patterns: impl Iterator>, + patterns: impl Iterator>, ) -> Vec { use Constructor::*; let mut covered = vec![]; diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs index a7a000ba31c..818a8ff27c8 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs @@ -1312,9 +1312,10 @@ pub(super) fn iter_patterns<'a>( /// Values and patterns can be represented as a constructor applied to some fields. This represents /// a pattern in this form. -/// This also keeps track of whether the pattern has been found reachable during analysis. For this -/// reason we should be careful not to clone patterns for which we care about that. Use -/// `clone_and_forget_reachability` if you're sure. +/// This also uses interior mutability to keep track of whether the pattern has been found reachable +/// during analysis. For this reason they cannot be cloned. +/// A `DeconstructedPat` will almost always come from user input; the only exception are some +/// `Wildcard`s introduced during specialization. pub(crate) struct DeconstructedPat<'p, 'tcx> { ctor: Constructor<'tcx>, fields: Fields<'p, 'tcx>, @@ -1337,20 +1338,6 @@ pub(super) fn new( DeconstructedPat { ctor, fields, ty, span, reachable: Cell::new(false) } } - /// 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(super) fn wild_from_ctor(pcx: &PatCtxt<'_, 'p, 'tcx>, ctor: Constructor<'tcx>) -> Self { - let fields = Fields::wildcards(pcx, &ctor); - DeconstructedPat::new(ctor, fields, pcx.ty, pcx.span) - } - - /// Clone this value. This method emphasizes that cloning loses reachability information and - /// should be done carefully. - pub(super) fn clone_and_forget_reachability(&self) -> Self { - DeconstructedPat::new(self.ctor.clone(), self.fields, self.ty, self.span) - } - pub(crate) fn from_pat(cx: &MatchCheckCtxt<'p, 'tcx>, pat: &Pat<'tcx>) -> Self { let mkpat = |pat| DeconstructedPat::from_pat(cx, pat); let ctor; @@ -1529,95 +1516,6 @@ pub(crate) fn from_pat(cx: &MatchCheckCtxt<'p, 'tcx>, pat: &Pat<'tcx>) -> Self { DeconstructedPat::new(ctor, fields, pat.ty, pat.span) } - pub(crate) fn to_pat(&self, cx: &MatchCheckCtxt<'p, 'tcx>) -> Pat<'tcx> { - let is_wildcard = |pat: &Pat<'_>| { - matches!(pat.kind, PatKind::Binding { subpattern: None, .. } | PatKind::Wild) - }; - let mut subpatterns = self.iter_fields().map(|p| Box::new(p.to_pat(cx))); - let kind = match &self.ctor { - Single | Variant(_) => match self.ty.kind() { - ty::Tuple(..) => PatKind::Leaf { - subpatterns: subpatterns - .enumerate() - .map(|(i, pattern)| FieldPat { field: FieldIdx::new(i), pattern }) - .collect(), - }, - ty::Adt(adt_def, _) if adt_def.is_box() => { - // Without `box_patterns`, the only legal pattern of type `Box` is `_` (outside - // of `std`). So this branch is only reachable when the feature is enabled and - // the pattern is a box pattern. - PatKind::Deref { subpattern: subpatterns.next().unwrap() } - } - ty::Adt(adt_def, args) => { - let variant_index = self.ctor.variant_index_for_adt(*adt_def); - let variant = &adt_def.variant(variant_index); - let subpatterns = Fields::list_variant_nonhidden_fields(cx, self.ty, variant) - .zip(subpatterns) - .map(|((field, _ty), pattern)| FieldPat { field, pattern }) - .collect(); - - if adt_def.is_enum() { - PatKind::Variant { adt_def: *adt_def, args, variant_index, subpatterns } - } else { - PatKind::Leaf { subpatterns } - } - } - // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should - // be careful to reconstruct the correct constant pattern here. However a string - // literal pattern will never be reported as a non-exhaustiveness witness, so we - // ignore this issue. - ty::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() }, - _ => bug!("unexpected ctor for type {:?} {:?}", self.ctor, self.ty), - }, - Slice(slice) => { - match slice.kind { - FixedLen(_) => PatKind::Slice { - prefix: subpatterns.collect(), - slice: None, - suffix: Box::new([]), - }, - VarLen(prefix, _) => { - let mut subpatterns = subpatterns.peekable(); - let mut prefix: Vec<_> = subpatterns.by_ref().take(prefix).collect(); - if slice.array_len.is_some() { - // Improves diagnostics a bit: if the type is a known-size array, instead - // of reporting `[x, _, .., _, y]`, we prefer to report `[x, .., y]`. - // This is incorrect if the size is not known, since `[_, ..]` captures - // arrays of lengths `>= 1` whereas `[..]` captures any length. - while !prefix.is_empty() && is_wildcard(prefix.last().unwrap()) { - prefix.pop(); - } - while subpatterns.peek().is_some() - && is_wildcard(subpatterns.peek().unwrap()) - { - subpatterns.next(); - } - } - let suffix: Box<[_]> = subpatterns.collect(); - let wild = Pat::wildcard_from_ty(self.ty); - PatKind::Slice { - prefix: prefix.into_boxed_slice(), - slice: Some(Box::new(wild)), - suffix, - } - } - } - } - &Str(value) => PatKind::Constant { value }, - IntRange(range) => return range.to_pat(cx.tcx, self.ty), - Wildcard | NonExhaustive | Hidden => 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`" - ), - F32Range(..) | F64Range(..) | Opaque | Or => { - bug!("can't convert to pattern: {:?}", self) - } - }; - - Pat { ty: self.ty, span: DUMMY_SP, kind } - } - pub(super) fn is_or_pat(&self) -> bool { matches!(self.ctor, Or) } @@ -1800,3 +1698,131 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { } } } + +/// Same idea as `DeconstructedPat`, except this is a fictitious pattern built up for diagnostics +/// purposes. As such they don't use interning and can be cloned. +#[derive(Debug, Clone)] +pub(crate) struct WitnessPat<'tcx> { + ctor: Constructor<'tcx>, + fields: Vec>, + ty: Ty<'tcx>, +} + +impl<'tcx> WitnessPat<'tcx> { + pub(super) fn new(ctor: Constructor<'tcx>, fields: Vec, ty: Ty<'tcx>) -> Self { + Self { ctor, fields, ty } + } + pub(super) fn wildcard(ty: Ty<'tcx>) -> Self { + Self::new(Wildcard, 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(super) fn wild_from_ctor(pcx: &PatCtxt<'_, '_, 'tcx>, ctor: Constructor<'tcx>) -> Self { + // Reuse `Fields::wildcards` to get the types. + let fields = Fields::wildcards(pcx, &ctor) + .iter_patterns() + .map(|deco_pat| Self::wildcard(deco_pat.ty())) + .collect(); + Self::new(ctor, fields, pcx.ty) + } + + pub(super) fn ctor(&self) -> &Constructor<'tcx> { + &self.ctor + } + pub(super) fn ty(&self) -> Ty<'tcx> { + self.ty + } + + pub(crate) fn to_pat(&self, cx: &MatchCheckCtxt<'_, 'tcx>) -> Pat<'tcx> { + let is_wildcard = |pat: &Pat<'_>| matches!(pat.kind, PatKind::Wild); + let mut subpatterns = self.iter_fields().map(|p| Box::new(p.to_pat(cx))); + let kind = match &self.ctor { + Single | Variant(_) => match self.ty.kind() { + ty::Tuple(..) => PatKind::Leaf { + subpatterns: subpatterns + .enumerate() + .map(|(i, pattern)| FieldPat { field: FieldIdx::new(i), pattern }) + .collect(), + }, + ty::Adt(adt_def, _) if adt_def.is_box() => { + // Without `box_patterns`, the only legal pattern of type `Box` is `_` (outside + // of `std`). So this branch is only reachable when the feature is enabled and + // the pattern is a box pattern. + PatKind::Deref { subpattern: subpatterns.next().unwrap() } + } + ty::Adt(adt_def, args) => { + let variant_index = self.ctor.variant_index_for_adt(*adt_def); + let variant = &adt_def.variant(variant_index); + let subpatterns = Fields::list_variant_nonhidden_fields(cx, self.ty, variant) + .zip(subpatterns) + .map(|((field, _ty), pattern)| FieldPat { field, pattern }) + .collect(); + + if adt_def.is_enum() { + PatKind::Variant { adt_def: *adt_def, args, variant_index, subpatterns } + } else { + PatKind::Leaf { subpatterns } + } + } + // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should + // be careful to reconstruct the correct constant pattern here. However a string + // literal pattern will never be reported as a non-exhaustiveness witness, so we + // ignore this issue. + ty::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() }, + _ => bug!("unexpected ctor for type {:?} {:?}", self.ctor, self.ty), + }, + Slice(slice) => { + match slice.kind { + FixedLen(_) => PatKind::Slice { + prefix: subpatterns.collect(), + slice: None, + suffix: Box::new([]), + }, + VarLen(prefix, _) => { + let mut subpatterns = subpatterns.peekable(); + let mut prefix: Vec<_> = subpatterns.by_ref().take(prefix).collect(); + if slice.array_len.is_some() { + // Improves diagnostics a bit: if the type is a known-size array, instead + // of reporting `[x, _, .., _, y]`, we prefer to report `[x, .., y]`. + // This is incorrect if the size is not known, since `[_, ..]` captures + // arrays of lengths `>= 1` whereas `[..]` captures any length. + while !prefix.is_empty() && is_wildcard(prefix.last().unwrap()) { + prefix.pop(); + } + while subpatterns.peek().is_some() + && is_wildcard(subpatterns.peek().unwrap()) + { + subpatterns.next(); + } + } + let suffix: Box<[_]> = subpatterns.collect(); + let wild = Pat::wildcard_from_ty(self.ty); + PatKind::Slice { + prefix: prefix.into_boxed_slice(), + slice: Some(Box::new(wild)), + suffix, + } + } + } + } + &Str(value) => PatKind::Constant { value }, + IntRange(range) => return range.to_pat(cx.tcx, self.ty), + Wildcard | NonExhaustive | Hidden => 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`" + ), + F32Range(..) | F64Range(..) | Opaque | Or => { + bug!("can't convert to pattern: {:?}", self) + } + }; + + Pat { ty: self.ty, span: DUMMY_SP, kind } + } + + pub(super) fn iter_fields<'a>(&'a self) -> impl Iterator> { + self.fields.iter() + } +} diff --git a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs index 6cd73c7eaa9..e60349be3ba 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs @@ -213,7 +213,7 @@ //! or-patterns in the first column are expanded before being stored in the matrix. Specialization //! for a single patstack is done from a combination of [`Constructor::is_covered_by`] and //! [`PatStack::pop_head_constructor`]. The internals of how it's done mostly live in the -//! [`Fields`] struct. +//! [`super::deconstruct_pat::Fields`] struct. //! //! //! # Computing usefulness @@ -307,7 +307,7 @@ use self::ArmType::*; use self::Usefulness::*; -use super::deconstruct_pat::{Constructor, ConstructorSet, DeconstructedPat, Fields}; +use super::deconstruct_pat::{Constructor, ConstructorSet, DeconstructedPat, WitnessPat}; use crate::errors::{NonExhaustiveOmittedPattern, Uncovered}; use rustc_data_structures::captures::Captures; @@ -322,7 +322,6 @@ use smallvec::{smallvec, SmallVec}; use std::fmt; -use std::iter::once; pub(crate) struct MatchCheckCtxt<'p, 'tcx> { pub(crate) tcx: TyCtxt<'tcx>, @@ -555,20 +554,20 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { /// exhaustiveness of a whole match, we use the `WithWitnesses` variant, which carries a list of /// witnesses of non-exhaustiveness when there are any. /// Which variant to use is dictated by `ArmType`. -#[derive(Debug)] -enum Usefulness<'p, 'tcx> { +#[derive(Debug, Clone)] +enum Usefulness<'tcx> { /// If we don't care about witnesses, simply remember if the pattern was useful. NoWitnesses { useful: bool }, /// Carries a list of witnesses of non-exhaustiveness. If empty, indicates that the whole /// pattern is unreachable. - WithWitnesses(Vec>), + WithWitnesses(Vec>), } -impl<'p, 'tcx> Usefulness<'p, 'tcx> { +impl<'tcx> Usefulness<'tcx> { fn new_useful(preference: ArmType) -> Self { match preference { // A single (empty) witness of reachability. - FakeExtraWildcard => WithWitnesses(vec![Witness(vec![])]), + FakeExtraWildcard => WithWitnesses(vec![WitnessStack(vec![])]), RealArm => NoWitnesses { useful: true }, } } @@ -605,8 +604,8 @@ fn extend(&mut self, other: Self) { /// with the results of specializing with the other constructors. fn apply_constructor( self, - pcx: &PatCtxt<'_, 'p, 'tcx>, - matrix: &Matrix<'p, 'tcx>, // used to compute missing ctors + pcx: &PatCtxt<'_, '_, 'tcx>, + matrix: &Matrix<'_, 'tcx>, // used to compute missing ctors ctor: &Constructor<'tcx>, ) -> Self { match self { @@ -627,25 +626,18 @@ fn apply_constructor( // wildcards for fields, i.e. that matches everything that can be built with it. // For example, if `ctor` is a `Constructor::Variant` for `Option::Some`, we get // the pattern `Some(_)`. - let new_patterns: Vec> = missing + let new_patterns: Vec> = missing .into_iter() - .map(|missing_ctor| { - DeconstructedPat::wild_from_ctor(pcx, missing_ctor.clone()) - }) + .map(|missing_ctor| WitnessPat::wild_from_ctor(pcx, missing_ctor.clone())) .collect(); witnesses .into_iter() .flat_map(|witness| { new_patterns.iter().map(move |pat| { - Witness( - witness - .0 - .iter() - .chain(once(pat)) - .map(DeconstructedPat::clone_and_forget_reachability) - .collect(), - ) + let mut stack = witness.clone(); + stack.0.push(pat.clone()); + stack }) }) .collect() @@ -667,15 +659,17 @@ enum ArmType { RealArm, } -/// A witness of non-exhaustiveness for error reporting, represented -/// as a list of patterns (in reverse order of construction) with -/// wildcards inside to represent elements that can take any inhabitant -/// of the type as a value. +/// A witness-tuple of non-exhaustiveness for error reporting, represented as a list of patterns (in +/// reverse order of construction) with wildcards inside to represent elements that can take any +/// inhabitant of the type as a value. /// -/// A witness against a list of patterns should have the same types -/// and length as the pattern matched against. Because Rust `match` -/// is always against a single pattern, at the end the witness will -/// have length 1, but in the middle of the algorithm, it can contain +/// This mirrors `PatStack`: they function similarly, except `PatStack` contains user patterns we +/// are inspecting, and `WitnessStack` contains witnesses we are constructing. +/// FIXME(Nadrieril): use the same order of patterns for both +/// +/// A `WitnessStack` should have the same types and length as the `PatStacks` we are inspecting +/// (except we store the patterns in reverse order). Because Rust `match` is always against a single +/// pattern, at the end the stack will have length 1. In the middle of the algorithm, it can contain /// multiple patterns. /// /// For example, if we are constructing a witness for the match against @@ -690,23 +684,37 @@ enum ArmType { /// # } /// ``` /// -/// We'll perform the following steps: -/// 1. Start with an empty witness -/// `Witness(vec![])` -/// 2. Push a witness `true` against the `false` -/// `Witness(vec![true])` -/// 3. Push a witness `Some(_)` against the `None` -/// `Witness(vec![true, Some(_)])` -/// 4. Apply the `Pair` constructor to the witnesses -/// `Witness(vec![Pair(Some(_), true)])` +/// We'll perform the following steps (among others): +/// - Start with a matrix representing the match +/// `PatStack(vec![Pair(None, _)])` +/// `PatStack(vec![Pair(_, false)])` +/// - Specialize with `Pair` +/// `PatStack(vec![None, _])` +/// `PatStack(vec![_, false])` +/// - Specialize with `Some` +/// `PatStack(vec![_, false])` +/// - Specialize with `_` +/// `PatStack(vec![false])` +/// - Specialize with `true` +/// // no patstacks left +/// - This is a non-exhaustive match: we have the empty witness stack as a witness. +/// `WitnessStack(vec![])` +/// - Apply `true` +/// `WitnessStack(vec![true])` +/// - Apply `_` +/// `WitnessStack(vec![true, _])` +/// - Apply `Some` +/// `WitnessStack(vec![true, Some(_)])` +/// - Apply `Pair` +/// `WitnessStack(vec![Pair(Some(_), true)])` /// /// The final `Pair(Some(_), true)` is then the resulting witness. -#[derive(Debug)] -pub(crate) struct Witness<'p, 'tcx>(Vec>); +#[derive(Debug, Clone)] +pub(crate) struct WitnessStack<'tcx>(Vec>); -impl<'p, 'tcx> Witness<'p, 'tcx> { +impl<'tcx> WitnessStack<'tcx> { /// Asserts that the witness contains a single pattern, and returns it. - fn single_pattern(self) -> DeconstructedPat<'p, 'tcx> { + fn single_pattern(self) -> WitnessPat<'tcx> { assert_eq!(self.0.len(), 1); self.0.into_iter().next().unwrap() } @@ -724,13 +732,12 @@ fn single_pattern(self) -> DeconstructedPat<'p, 'tcx> { /// /// left_ty: struct X { a: (bool, &'static str), b: usize} /// pats: [(false, "foo"), 42] => X { a: (false, "foo"), b: 42 } - fn apply_constructor(mut self, pcx: &PatCtxt<'_, 'p, 'tcx>, ctor: &Constructor<'tcx>) -> Self { + fn apply_constructor(mut self, pcx: &PatCtxt<'_, '_, 'tcx>, ctor: &Constructor<'tcx>) -> Self { let pat = { let len = self.0.len(); let arity = ctor.arity(pcx); - let pats = self.0.drain((len - arity)..).rev(); - let fields = Fields::from_iter(pcx.cx, pats); - DeconstructedPat::new(ctor.clone(), fields, pcx.ty, pcx.span) + let fields = self.0.drain((len - arity)..).rev().collect(); + WitnessPat::new(ctor.clone(), fields, pcx.ty) }; self.0.push(pat); @@ -770,7 +777,7 @@ fn is_useful<'p, 'tcx>( lint_root: HirId, is_under_guard: bool, is_top_level: bool, -) -> Usefulness<'p, 'tcx> { +) -> Usefulness<'tcx> { debug!(?matrix, ?v); let Matrix { patterns: rows, .. } = matrix; @@ -885,7 +892,7 @@ fn is_useful<'p, 'tcx>( // Because of how we computed `nonexhaustive_enum_missing_visible_variants`, // this will not return an empty `Vec`. .filter(|c| !(matches!(c, Constructor::NonExhaustive | Constructor::Hidden))) - .map(|missing_ctor| DeconstructedPat::wild_from_ctor(pcx, missing_ctor)) + .map(|missing_ctor| WitnessPat::wild_from_ctor(pcx, missing_ctor)) .collect::>(); // Report that a match of a `non_exhaustive` enum marked with `non_exhaustive_omitted_patterns` @@ -940,7 +947,7 @@ pub(crate) struct UsefulnessReport<'p, 'tcx> { pub(crate) arm_usefulness: Vec<(MatchArm<'p, 'tcx>, Reachability)>, /// If the match is exhaustive, this is empty. If not, this contains witnesses for the lack of /// exhaustiveness. - pub(crate) non_exhaustiveness_witnesses: Vec>, + pub(crate) non_exhaustiveness_witnesses: Vec>, } /// The entrypoint for the usefulness algorithm. Computes whether a match is exhaustive and which