diff options
Diffstat (limited to 'compiler/rustc_pattern_analysis/src/usefulness.rs')
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/usefulness.rs | 177 |
1 files changed, 87 insertions, 90 deletions
diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs index 3300013805d..d52d9358b94 100644 --- a/compiler/rustc_pattern_analysis/src/usefulness.rs +++ b/compiler/rustc_pattern_analysis/src/usefulness.rs @@ -242,7 +242,7 @@ //! Therefore `usefulness(tp_1, tp_2, tq)` returns the single witness-tuple `[Variant2(Some(true), 0)]`. //! //! -//! Computing the set of constructors for a type is done in [`MatchCheckCtxt::ctors_for_ty`]. See +//! Computing the set of constructors for a type is done in [`MatchCx::ctors_for_ty`]. See //! the following sections for more accurate versions of the algorithm and corresponding links. //! //! @@ -557,40 +557,39 @@ use std::fmt; use rustc_arena::TypedArena; use rustc_data_structures::{captures::Captures, stack::ensure_sufficient_stack}; -use rustc_middle::ty::Ty; -use rustc_span::Span; use crate::constructor::{Constructor, ConstructorSet}; -use crate::cx::MatchCheckCtxt; use crate::pat::{DeconstructedPat, WitnessPat}; -use crate::MatchArm; +use crate::{MatchArm, MatchCx}; use self::ValidityConstraint::*; -#[derive(Copy, Clone)] -pub(crate) struct PatCtxt<'a, 'p, 'tcx> { - pub(crate) cx: &'a MatchCheckCtxt<'p, 'tcx>, +#[derive(Clone)] +pub(crate) struct PatCtxt<'a, 'p, Cx: MatchCx> { + pub(crate) cx: &'a Cx, /// Type of the current column under investigation. - pub(crate) ty: Ty<'tcx>, + pub(crate) ty: Cx::Ty, /// Whether the current pattern is the whole pattern as found in a match arm, or if it's a /// subpattern. pub(crate) is_top_level: bool, /// An arena to store the wildcards we produce during analysis. - pub(crate) wildcard_arena: &'a TypedArena<DeconstructedPat<'p, 'tcx>>, + pub(crate) wildcard_arena: &'a TypedArena<DeconstructedPat<'p, Cx>>, } -impl<'a, 'p, 'tcx> PatCtxt<'a, 'p, 'tcx> { +impl<'a, 'p, Cx: MatchCx> PatCtxt<'a, 'p, Cx> { /// A `PatCtxt` when code other than `is_useful` needs one. pub(crate) fn new_dummy( - cx: &'a MatchCheckCtxt<'p, 'tcx>, - ty: Ty<'tcx>, - wildcard_arena: &'a TypedArena<DeconstructedPat<'p, 'tcx>>, + cx: &'a Cx, + ty: Cx::Ty, + wildcard_arena: &'a TypedArena<DeconstructedPat<'p, Cx>>, ) -> Self { PatCtxt { cx, ty, is_top_level: false, wildcard_arena } } } -impl<'a, 'p, 'tcx> fmt::Debug for PatCtxt<'a, 'p, 'tcx> { +impl<'a, 'p, Cx: MatchCx> Copy for PatCtxt<'a, 'p, Cx> {} + +impl<'a, 'p, Cx: MatchCx> fmt::Debug for PatCtxt<'a, 'p, Cx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("PatCtxt").field("ty", &self.ty).finish() } @@ -602,7 +601,7 @@ impl<'a, 'p, 'tcx> fmt::Debug for PatCtxt<'a, 'p, 'tcx> { /// - 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)] -enum ValidityConstraint { +pub(crate) enum ValidityConstraint { ValidOnly, MaybeInvalid, /// Option for backwards compatibility: the place is not known to be valid but we allow omitting @@ -611,7 +610,7 @@ enum ValidityConstraint { } impl ValidityConstraint { - fn from_bool(is_valid_only: bool) -> Self { + pub(crate) fn from_bool(is_valid_only: bool) -> Self { if is_valid_only { ValidOnly } else { MaybeInvalid } } @@ -636,7 +635,7 @@ impl ValidityConstraint { /// /// Pending further opsem decisions, the current behavior is: validity is preserved, except /// inside `&` and union fields where validity is reset to `MaybeInvalid`. - fn specialize(self, ctor: &Constructor<'_>) -> Self { + fn specialize<Cx: MatchCx>(self, ctor: &Constructor<Cx>) -> Self { // We preserve validity except when we go inside a reference or a union field. if matches!(ctor, Constructor::Ref | Constructor::UnionField) { // Validity of `x: &T` does not imply validity of `*x: T`. @@ -661,15 +660,15 @@ impl fmt::Display for ValidityConstraint { // The three lifetimes are: // - 'a allocated by us // - 'p coming from the input -// - 'tcx global compilation context +// - Cx global compilation context #[derive(Clone)] -struct PatStack<'a, 'p, 'tcx> { +struct PatStack<'a, 'p, Cx: MatchCx> { // Rows of len 1 are very common, which is why `SmallVec[_; 2]` works well. - pats: SmallVec<[&'a DeconstructedPat<'p, 'tcx>; 2]>, + pats: SmallVec<[&'a DeconstructedPat<'p, Cx>; 2]>, } -impl<'a, 'p, 'tcx> PatStack<'a, 'p, 'tcx> { - fn from_pattern(pat: &'a DeconstructedPat<'p, 'tcx>) -> Self { +impl<'a, 'p, Cx: MatchCx> PatStack<'a, 'p, Cx> { + fn from_pattern(pat: &'a DeconstructedPat<'p, Cx>) -> Self { PatStack { pats: smallvec![pat] } } @@ -681,17 +680,17 @@ impl<'a, 'p, 'tcx> PatStack<'a, 'p, 'tcx> { self.pats.len() } - fn head(&self) -> &'a DeconstructedPat<'p, 'tcx> { + fn head(&self) -> &'a DeconstructedPat<'p, Cx> { self.pats[0] } - fn iter<'b>(&'b self) -> impl Iterator<Item = &'a DeconstructedPat<'p, 'tcx>> + Captures<'b> { + fn iter<'b>(&'b self) -> impl Iterator<Item = &'a DeconstructedPat<'p, Cx>> + Captures<'b> { self.pats.iter().copied() } // Recursively expand the first or-pattern into its subpatterns. Only useful if the pattern is // an or-pattern. Panics if `self` is empty. - fn expand_or_pat<'b>(&'b self) -> impl Iterator<Item = PatStack<'a, 'p, 'tcx>> + Captures<'b> { + fn expand_or_pat<'b>(&'b self) -> impl Iterator<Item = PatStack<'a, 'p, Cx>> + Captures<'b> { self.head().flatten_or_pat().into_iter().map(move |pat| { let mut new = self.clone(); new.pats[0] = pat; @@ -703,9 +702,9 @@ impl<'a, 'p, 'tcx> PatStack<'a, 'p, 'tcx> { /// Only call if `ctor.is_covered_by(self.head().ctor())` is true. fn pop_head_constructor( &self, - pcx: &PatCtxt<'a, 'p, 'tcx>, - ctor: &Constructor<'tcx>, - ) -> PatStack<'a, 'p, 'tcx> { + pcx: &PatCtxt<'a, 'p, Cx>, + ctor: &Constructor<Cx>, + ) -> PatStack<'a, 'p, Cx> { // We pop the head pattern and push the new fields extracted from the arguments of // `self.head()`. let mut new_pats = self.head().specialize(pcx, ctor); @@ -714,7 +713,7 @@ impl<'a, 'p, 'tcx> PatStack<'a, 'p, 'tcx> { } } -impl<'a, 'p, 'tcx> fmt::Debug for PatStack<'a, 'p, 'tcx> { +impl<'a, 'p, Cx: MatchCx> fmt::Debug for PatStack<'a, 'p, Cx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { // We pretty-print similarly to the `Debug` impl of `Matrix`. write!(f, "+")?; @@ -727,9 +726,9 @@ impl<'a, 'p, 'tcx> fmt::Debug for PatStack<'a, 'p, 'tcx> { /// A row of the matrix. #[derive(Clone)] -struct MatrixRow<'a, 'p, 'tcx> { +struct MatrixRow<'a, 'p, Cx: MatchCx> { // The patterns in the row. - pats: PatStack<'a, 'p, 'tcx>, + pats: PatStack<'a, 'p, Cx>, /// Whether the original arm had a guard. This is inherited when specializing. is_under_guard: bool, /// When we specialize, we remember which row of the original matrix produced a given row of the @@ -742,7 +741,7 @@ struct MatrixRow<'a, 'p, 'tcx> { useful: bool, } -impl<'a, 'p, 'tcx> MatrixRow<'a, 'p, 'tcx> { +impl<'a, 'p, Cx: MatchCx> MatrixRow<'a, 'p, Cx> { fn is_empty(&self) -> bool { self.pats.is_empty() } @@ -751,17 +750,17 @@ impl<'a, 'p, 'tcx> MatrixRow<'a, 'p, 'tcx> { self.pats.len() } - fn head(&self) -> &'a DeconstructedPat<'p, 'tcx> { + fn head(&self) -> &'a DeconstructedPat<'p, Cx> { self.pats.head() } - fn iter<'b>(&'b self) -> impl Iterator<Item = &'a DeconstructedPat<'p, 'tcx>> + Captures<'b> { + fn iter<'b>(&'b self) -> impl Iterator<Item = &'a DeconstructedPat<'p, Cx>> + Captures<'b> { self.pats.iter() } // Recursively expand the first or-pattern into its subpatterns. Only useful if the pattern is // an or-pattern. Panics if `self` is empty. - fn expand_or_pat<'b>(&'b self) -> impl Iterator<Item = MatrixRow<'a, 'p, 'tcx>> + Captures<'b> { + fn expand_or_pat<'b>(&'b self) -> impl Iterator<Item = MatrixRow<'a, 'p, Cx>> + Captures<'b> { self.pats.expand_or_pat().map(|patstack| MatrixRow { pats: patstack, parent_row: self.parent_row, @@ -774,10 +773,10 @@ impl<'a, 'p, 'tcx> MatrixRow<'a, 'p, 'tcx> { /// Only call if `ctor.is_covered_by(self.head().ctor())` is true. fn pop_head_constructor( &self, - pcx: &PatCtxt<'a, 'p, 'tcx>, - ctor: &Constructor<'tcx>, + pcx: &PatCtxt<'a, 'p, Cx>, + ctor: &Constructor<Cx>, parent_row: usize, - ) -> MatrixRow<'a, 'p, 'tcx> { + ) -> MatrixRow<'a, 'p, Cx> { MatrixRow { pats: self.pats.pop_head_constructor(pcx, ctor), parent_row, @@ -787,7 +786,7 @@ impl<'a, 'p, 'tcx> MatrixRow<'a, 'p, 'tcx> { } } -impl<'a, 'p, 'tcx> fmt::Debug for MatrixRow<'a, 'p, 'tcx> { +impl<'a, 'p, Cx: MatchCx> fmt::Debug for MatrixRow<'a, 'p, Cx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { self.pats.fmt(f) } @@ -804,22 +803,22 @@ impl<'a, 'p, 'tcx> fmt::Debug for MatrixRow<'a, 'p, 'tcx> { /// specializing `(,)` and `Some` on a pattern of type `(Option<u32>, bool)`, the first column of /// the matrix will correspond to `scrutinee.0.Some.0` and the second column to `scrutinee.1`. #[derive(Clone)] -struct Matrix<'a, 'p, 'tcx> { +struct Matrix<'a, 'p, Cx: MatchCx> { /// Vector of rows. The rows must form a rectangular 2D array. Moreover, all the patterns of /// each column must have the same type. Each column corresponds to a place within the /// scrutinee. - rows: Vec<MatrixRow<'a, 'p, 'tcx>>, + rows: Vec<MatrixRow<'a, 'p, Cx>>, /// Stores an extra fictitious row full of wildcards. Mostly used to keep track of the type of /// each column. This must obey the same invariants as the real rows. - wildcard_row: PatStack<'a, 'p, 'tcx>, + wildcard_row: PatStack<'a, 'p, Cx>, /// Track for each column/place whether it contains a known valid value. place_validity: SmallVec<[ValidityConstraint; 2]>, } -impl<'a, 'p, 'tcx> Matrix<'a, 'p, 'tcx> { +impl<'a, 'p, Cx: MatchCx> Matrix<'a, 'p, Cx> { /// Pushes a new row to the matrix. If the row starts with an or-pattern, this recursively /// expands it. Internal method, prefer [`Matrix::new`]. - fn expand_and_push(&mut self, row: MatrixRow<'a, 'p, 'tcx>) { + fn expand_and_push(&mut self, row: MatrixRow<'a, 'p, Cx>) { if !row.is_empty() && row.head().is_or_pat() { // Expand nested or-patterns. for new_row in row.expand_or_pat() { @@ -832,13 +831,13 @@ impl<'a, 'p, 'tcx> Matrix<'a, 'p, 'tcx> { /// Build a new matrix from an iterator of `MatchArm`s. fn new( - wildcard_arena: &'a TypedArena<DeconstructedPat<'p, 'tcx>>, - arms: &'a [MatchArm<'p, 'tcx>], - scrut_ty: Ty<'tcx>, + wildcard_arena: &'a TypedArena<DeconstructedPat<'p, Cx>>, + arms: &'a [MatchArm<'p, Cx>], + scrut_ty: Cx::Ty, scrut_validity: ValidityConstraint, ) -> Self { let wild_pattern = - wildcard_arena.alloc(DeconstructedPat::wildcard(scrut_ty, Span::default())); + wildcard_arena.alloc(DeconstructedPat::wildcard(scrut_ty, Cx::Span::default())); let wildcard_row = PatStack::from_pattern(wild_pattern); let mut matrix = Matrix { rows: Vec::with_capacity(arms.len()), @@ -857,7 +856,7 @@ impl<'a, 'p, 'tcx> Matrix<'a, 'p, 'tcx> { matrix } - fn head_ty(&self) -> Option<Ty<'tcx>> { + fn head_ty(&self) -> Option<Cx::Ty> { if self.column_count() == 0 { return None; } @@ -865,10 +864,10 @@ impl<'a, 'p, 'tcx> Matrix<'a, 'p, 'tcx> { let mut ty = self.wildcard_row.head().ty(); // If the type is opaque and it is revealed anywhere in the column, we take the revealed // version. Otherwise we could encounter constructors for the revealed type and crash. - if MatchCheckCtxt::is_opaque(ty) { + if Cx::is_opaque_ty(ty) { for pat in self.heads() { let pat_ty = pat.ty(); - if !MatchCheckCtxt::is_opaque(pat_ty) { + if !Cx::is_opaque_ty(pat_ty) { ty = pat_ty; break; } @@ -882,15 +881,13 @@ impl<'a, 'p, 'tcx> Matrix<'a, 'p, 'tcx> { fn rows<'b>( &'b self, - ) -> impl Iterator<Item = &'b MatrixRow<'a, 'p, 'tcx>> - + Clone - + DoubleEndedIterator - + ExactSizeIterator { + ) -> impl Iterator<Item = &'b MatrixRow<'a, 'p, Cx>> + Clone + DoubleEndedIterator + ExactSizeIterator + { self.rows.iter() } fn rows_mut<'b>( &'b mut self, - ) -> impl Iterator<Item = &'b mut MatrixRow<'a, 'p, 'tcx>> + DoubleEndedIterator + ExactSizeIterator + ) -> impl Iterator<Item = &'b mut MatrixRow<'a, 'p, Cx>> + DoubleEndedIterator + ExactSizeIterator { self.rows.iter_mut() } @@ -898,16 +895,16 @@ impl<'a, 'p, 'tcx> Matrix<'a, 'p, 'tcx> { /// Iterate over the first pattern of each row. fn heads<'b>( &'b self, - ) -> impl Iterator<Item = &'b DeconstructedPat<'p, 'tcx>> + Clone + Captures<'a> { + ) -> impl Iterator<Item = &'b DeconstructedPat<'p, Cx>> + Clone + Captures<'a> { self.rows().map(|r| r.head()) } /// This computes `specialize(ctor, self)`. See top of the file for explanations. fn specialize_constructor( &self, - pcx: &PatCtxt<'a, 'p, 'tcx>, - ctor: &Constructor<'tcx>, - ) -> Matrix<'a, 'p, 'tcx> { + pcx: &PatCtxt<'a, 'p, Cx>, + ctor: &Constructor<Cx>, + ) -> Matrix<'a, 'p, Cx> { let wildcard_row = self.wildcard_row.pop_head_constructor(pcx, ctor); let new_validity = self.place_validity[0].specialize(ctor); let new_place_validity = std::iter::repeat(new_validity) @@ -936,7 +933,7 @@ impl<'a, 'p, 'tcx> Matrix<'a, 'p, 'tcx> { /// + _ + [_, _, tail @ ..] + /// | ✓ | ? | // column validity /// ``` -impl<'a, 'p, 'tcx> fmt::Debug for Matrix<'a, 'p, 'tcx> { +impl<'a, 'p, Cx: MatchCx> fmt::Debug for Matrix<'a, 'p, Cx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "\n")?; @@ -1027,17 +1024,17 @@ impl<'a, 'p, 'tcx> fmt::Debug for Matrix<'a, 'p, 'tcx> { /// /// See the top of the file for more detailed explanations and examples. #[derive(Debug, Clone)] -struct WitnessStack<'tcx>(Vec<WitnessPat<'tcx>>); +struct WitnessStack<Cx: MatchCx>(Vec<WitnessPat<Cx>>); -impl<'tcx> WitnessStack<'tcx> { +impl<Cx: MatchCx> WitnessStack<Cx> { /// Asserts that the witness contains a single pattern, and returns it. - fn single_pattern(self) -> WitnessPat<'tcx> { + fn single_pattern(self) -> WitnessPat<Cx> { assert_eq!(self.0.len(), 1); self.0.into_iter().next().unwrap() } /// Reverses specialization by the `Missing` constructor by pushing a whole new pattern. - fn push_pattern(&mut self, pat: WitnessPat<'tcx>) { + fn push_pattern(&mut self, pat: WitnessPat<Cx>) { self.0.push(pat); } @@ -1055,7 +1052,7 @@ impl<'tcx> WitnessStack<'tcx> { /// pats: [(false, "foo"), _, true] /// result: [Enum::Variant { a: (false, "foo"), b: _ }, true] /// ``` - fn apply_constructor(&mut self, pcx: &PatCtxt<'_, '_, 'tcx>, ctor: &Constructor<'tcx>) { + fn apply_constructor(&mut self, pcx: &PatCtxt<'_, '_, Cx>, ctor: &Constructor<Cx>) { let len = self.0.len(); let arity = ctor.arity(pcx); let fields = self.0.drain((len - arity)..).rev().collect(); @@ -1074,9 +1071,9 @@ impl<'tcx> WitnessStack<'tcx> { /// Just as the `Matrix` starts with a single column, by the end of the algorithm, this has a single /// column, which contains the patterns that are missing for the match to be exhaustive. #[derive(Debug, Clone)] -struct WitnessMatrix<'tcx>(Vec<WitnessStack<'tcx>>); +struct WitnessMatrix<Cx: MatchCx>(Vec<WitnessStack<Cx>>); -impl<'tcx> WitnessMatrix<'tcx> { +impl<Cx: MatchCx> WitnessMatrix<Cx> { /// New matrix with no witnesses. fn empty() -> Self { WitnessMatrix(vec![]) @@ -1091,12 +1088,12 @@ impl<'tcx> WitnessMatrix<'tcx> { self.0.is_empty() } /// Asserts that there is a single column and returns the patterns in it. - fn single_column(self) -> Vec<WitnessPat<'tcx>> { + fn single_column(self) -> Vec<WitnessPat<Cx>> { self.0.into_iter().map(|w| w.single_pattern()).collect() } /// Reverses specialization by the `Missing` constructor by pushing a whole new pattern. - fn push_pattern(&mut self, pat: WitnessPat<'tcx>) { + fn push_pattern(&mut self, pat: WitnessPat<Cx>) { for witness in self.0.iter_mut() { witness.push_pattern(pat.clone()) } @@ -1105,9 +1102,9 @@ impl<'tcx> WitnessMatrix<'tcx> { /// Reverses specialization by `ctor`. See the section on `unspecialize` at the top of the file. fn apply_constructor( &mut self, - pcx: &PatCtxt<'_, '_, 'tcx>, - missing_ctors: &[Constructor<'tcx>], - ctor: &Constructor<'tcx>, + pcx: &PatCtxt<'_, '_, Cx>, + missing_ctors: &[Constructor<Cx>], + ctor: &Constructor<Cx>, report_individual_missing_ctors: bool, ) { if self.is_empty() { @@ -1168,12 +1165,12 @@ impl<'tcx> WitnessMatrix<'tcx> { /// (using `apply_constructor` and by updating `row.useful` for each parent row). /// This is all explained at the top of the file. #[instrument(level = "debug", skip(cx, is_top_level, wildcard_arena), ret)] -fn compute_exhaustiveness_and_usefulness<'a, 'p, 'tcx>( - cx: &'a MatchCheckCtxt<'p, 'tcx>, - matrix: &mut Matrix<'a, 'p, 'tcx>, - wildcard_arena: &'a TypedArena<DeconstructedPat<'p, 'tcx>>, +fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: MatchCx>( + cx: &'a Cx, + matrix: &mut Matrix<'a, 'p, Cx>, + wildcard_arena: &'a TypedArena<DeconstructedPat<'p, Cx>>, is_top_level: bool, -) -> WitnessMatrix<'tcx> { +) -> WitnessMatrix<Cx> { debug_assert!(matrix.rows().all(|r| r.len() == matrix.column_count())); let Some(ty) = matrix.head_ty() else { @@ -1278,7 +1275,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, 'tcx>( /// Indicates whether or not a given arm is useful. #[derive(Clone, Debug)] -pub enum Usefulness { +pub enum Usefulness<Span> { /// The arm is useful. This additionally carries a set of or-pattern branches that have been /// found to be redundant despite the overall arm being useful. Used only in the presence of /// or-patterns, otherwise it stays empty. @@ -1289,23 +1286,23 @@ pub enum Usefulness { } /// The output of checking a match for exhaustiveness and arm usefulness. -pub struct UsefulnessReport<'p, 'tcx> { +pub struct UsefulnessReport<'p, Cx: MatchCx> { /// For each arm of the input, whether that arm is useful after the arms above it. - pub arm_usefulness: Vec<(MatchArm<'p, 'tcx>, Usefulness)>, + pub arm_usefulness: Vec<(MatchArm<'p, Cx>, Usefulness<Cx::Span>)>, /// If the match is exhaustive, this is empty. If not, this contains witnesses for the lack of /// exhaustiveness. - pub non_exhaustiveness_witnesses: Vec<WitnessPat<'tcx>>, + pub non_exhaustiveness_witnesses: Vec<WitnessPat<Cx>>, } /// Computes whether a match is exhaustive and which of its arms are useful. #[instrument(skip(cx, arms, wildcard_arena), level = "debug")] -pub(crate) fn compute_match_usefulness<'p, 'tcx>( - cx: &MatchCheckCtxt<'p, 'tcx>, - arms: &[MatchArm<'p, 'tcx>], - scrut_ty: Ty<'tcx>, - wildcard_arena: &TypedArena<DeconstructedPat<'p, 'tcx>>, -) -> UsefulnessReport<'p, 'tcx> { - let scrut_validity = ValidityConstraint::from_bool(cx.known_valid_scrutinee); +pub(crate) fn compute_match_usefulness<'p, Cx: MatchCx>( + cx: &Cx, + arms: &[MatchArm<'p, Cx>], + scrut_ty: Cx::Ty, + scrut_validity: ValidityConstraint, + wildcard_arena: &TypedArena<DeconstructedPat<'p, Cx>>, +) -> UsefulnessReport<'p, Cx> { let mut matrix = Matrix::new(wildcard_arena, arms, scrut_ty, scrut_validity); let non_exhaustiveness_witnesses = compute_exhaustiveness_and_usefulness(cx, &mut matrix, wildcard_arena, true); |