diff options
Diffstat (limited to 'compiler/rustc_pattern_analysis/src')
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/constructor.rs | 88 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/errors.rs | 12 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/lib.rs | 10 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/lints.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/pat.rs | 43 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/pat_column.rs | 6 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/rustc.rs | 79 | ||||
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/usefulness.rs | 129 |
8 files changed, 149 insertions, 220 deletions
diff --git a/compiler/rustc_pattern_analysis/src/constructor.rs b/compiler/rustc_pattern_analysis/src/constructor.rs index 4be564b1d7b..24824682b74 100644 --- a/compiler/rustc_pattern_analysis/src/constructor.rs +++ b/compiler/rustc_pattern_analysis/src/constructor.rs @@ -151,7 +151,6 @@ use std::cmp::{self, max, min, Ordering}; use std::fmt; use std::iter::once; -use std::mem; use smallvec::SmallVec; @@ -648,6 +647,7 @@ impl OpaqueId { /// `specialize_constructor` returns the list of fields corresponding to a pattern, given a /// constructor. `Constructor::apply` reconstructs the pattern from a pair of `Constructor` and /// `Fields`. +#[derive(Debug)] pub enum Constructor<Cx: TypeCx> { /// Tuples and structs. Struct, @@ -717,74 +717,6 @@ impl<Cx: TypeCx> Clone for Constructor<Cx> { } } -impl<Cx: TypeCx> fmt::Debug for Constructor<Cx> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match self { - Constructor::Struct => f.debug_tuple("Struct").finish(), - Constructor::Variant(idx) => f.debug_tuple("Variant").field(idx).finish(), - Constructor::Ref => f.debug_tuple("Ref").finish(), - Constructor::Slice(slice) => f.debug_tuple("Slice").field(slice).finish(), - Constructor::UnionField => f.debug_tuple("UnionField").finish(), - Constructor::Bool(b) => f.debug_tuple("Bool").field(b).finish(), - Constructor::IntRange(range) => f.debug_tuple("IntRange").field(range).finish(), - Constructor::F32Range(lo, hi, end) => { - f.debug_tuple("F32Range").field(lo).field(hi).field(end).finish() - } - Constructor::F64Range(lo, hi, end) => { - f.debug_tuple("F64Range").field(lo).field(hi).field(end).finish() - } - Constructor::Str(value) => f.debug_tuple("Str").field(value).finish(), - Constructor::Opaque(inner) => f.debug_tuple("Opaque").field(inner).finish(), - Constructor::Or => f.debug_tuple("Or").finish(), - Constructor::Wildcard => f.debug_tuple("Wildcard").finish(), - Constructor::NonExhaustive => f.debug_tuple("NonExhaustive").finish(), - Constructor::Hidden => f.debug_tuple("Hidden").finish(), - Constructor::Missing => f.debug_tuple("Missing").finish(), - } - } -} - -impl<Cx: TypeCx> PartialEq for Constructor<Cx> { - fn eq(&self, other: &Self) -> bool { - (mem::discriminant(self) == mem::discriminant(other)) - && match (self, other) { - (Constructor::Struct, Constructor::Struct) => true, - (Constructor::Variant(self_variant), Constructor::Variant(other_variant)) => { - self_variant == other_variant - } - (Constructor::Ref, Constructor::Ref) => true, - (Constructor::Slice(self_slice), Constructor::Slice(other_slice)) => { - self_slice == other_slice - } - (Constructor::UnionField, Constructor::UnionField) => true, - (Constructor::Bool(self_b), Constructor::Bool(other_b)) => self_b == other_b, - (Constructor::IntRange(self_range), Constructor::IntRange(other_range)) => { - self_range == other_range - } - ( - Constructor::F32Range(self_lo, self_hi, self_end), - Constructor::F32Range(other_lo, other_hi, other_end), - ) => self_lo == other_lo && self_hi == other_hi && self_end == other_end, - ( - Constructor::F64Range(self_lo, self_hi, self_end), - Constructor::F64Range(other_lo, other_hi, other_end), - ) => self_lo == other_lo && self_hi == other_hi && self_end == other_end, - (Constructor::Str(self_value), Constructor::Str(other_value)) => { - self_value == other_value - } - (Constructor::Opaque(self_inner), Constructor::Opaque(other_inner)) => { - self_inner == other_inner - } - (Constructor::Or, Constructor::Or) => true, - (Constructor::Wildcard, Constructor::Wildcard) => true, - (Constructor::NonExhaustive, Constructor::NonExhaustive) => true, - (Constructor::Hidden, Constructor::Hidden) => true, - (Constructor::Missing, Constructor::Missing) => true, - _ => unreachable!(), - } - } -} - impl<Cx: TypeCx> Constructor<Cx> { pub(crate) fn is_non_exhaustive(&self) -> bool { matches!(self, NonExhaustive) @@ -826,10 +758,12 @@ impl<Cx: TypeCx> Constructor<Cx> { /// this checks for inclusion. // We inline because this has a single call site in `Matrix::specialize_constructor`. #[inline] - pub(crate) fn is_covered_by(&self, cx: &Cx, other: &Self) -> bool { - match (self, other) { + pub(crate) fn is_covered_by(&self, cx: &Cx, other: &Self) -> Result<bool, Cx::Error> { + Ok(match (self, other) { (Wildcard, _) => { - cx.bug(format_args!("Constructor splitting should not have returned `Wildcard`")) + return Err(cx.bug(format_args!( + "Constructor splitting should not have returned `Wildcard`" + ))); } // Wildcards cover anything (_, Wildcard) => true, @@ -871,10 +805,12 @@ impl<Cx: TypeCx> Constructor<Cx> { (Opaque(self_id), Opaque(other_id)) => self_id == other_id, (Opaque(..), _) | (_, Opaque(..)) => false, - _ => cx.bug(format_args!( - "trying to compare incompatible constructors {self:?} and {other:?}" - )), - } + _ => { + return Err(cx.bug(format_args!( + "trying to compare incompatible constructors {self:?} and {other:?}" + ))); + } + }) } } diff --git a/compiler/rustc_pattern_analysis/src/errors.rs b/compiler/rustc_pattern_analysis/src/errors.rs index 88770b0c43b..2dffdc9846c 100644 --- a/compiler/rustc_pattern_analysis/src/errors.rs +++ b/compiler/rustc_pattern_analysis/src/errors.rs @@ -1,4 +1,4 @@ -use rustc_errors::{AddToDiagnostic, Diagnostic, SubdiagnosticMessage}; +use rustc_errors::{AddToDiagnostic, Diagnostic, SubdiagnosticMessageOp}; use rustc_macros::{LintDiagnostic, Subdiagnostic}; use rustc_middle::thir::Pat; use rustc_middle::ty::Ty; @@ -23,7 +23,10 @@ impl<'tcx> Uncovered<'tcx> { span: Span, cx: &RustcMatchCheckCtxt<'p, 'tcx>, witnesses: Vec<WitnessPat<'p, 'tcx>>, - ) -> Self { + ) -> Self + where + 'tcx: 'p, + { let witness_1 = cx.hoist_witness_pat(witnesses.get(0).unwrap()); Self { span, @@ -59,10 +62,7 @@ pub struct Overlap<'tcx> { } impl<'tcx> AddToDiagnostic for Overlap<'tcx> { - fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F) - where - F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage, - { + fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, _: F) { let Overlap { span, range } = self; // FIXME(mejrs) unfortunately `#[derive(LintDiagnostic)]` diff --git a/compiler/rustc_pattern_analysis/src/lib.rs b/compiler/rustc_pattern_analysis/src/lib.rs index fe347231e12..164dc36b679 100644 --- a/compiler/rustc_pattern_analysis/src/lib.rs +++ b/compiler/rustc_pattern_analysis/src/lib.rs @@ -122,20 +122,20 @@ pub trait TypeCx: Sized + fmt::Debug { /// `DeconstructedPat`. Only invoqued when `pat.ctor()` is `Struct | Variant(_) | UnionField`. fn write_variant_name( f: &mut fmt::Formatter<'_>, - pat: &crate::pat::DeconstructedPat<'_, Self>, + pat: &crate::pat::DeconstructedPat<Self>, ) -> fmt::Result; /// Raise a bug. - fn bug(&self, fmt: fmt::Arguments<'_>) -> !; + fn bug(&self, fmt: fmt::Arguments<'_>) -> Self::Error; /// Lint that the range `pat` overlapped with all the ranges in `overlaps_with`, where the range /// they overlapped over is `overlaps_on`. We only detect singleton overlaps. /// The default implementation does nothing. fn lint_overlapping_range_endpoints( &self, - _pat: &DeconstructedPat<'_, Self>, + _pat: &DeconstructedPat<Self>, _overlaps_on: IntRange, - _overlaps_with: &[&DeconstructedPat<'_, Self>], + _overlaps_with: &[&DeconstructedPat<Self>], ) { } } @@ -143,7 +143,7 @@ pub trait TypeCx: Sized + fmt::Debug { /// The arm of a match expression. #[derive(Debug)] pub struct MatchArm<'p, Cx: TypeCx> { - pub pat: &'p DeconstructedPat<'p, Cx>, + pub pat: &'p DeconstructedPat<Cx>, pub has_guard: bool, pub arm_data: Cx::ArmData, } diff --git a/compiler/rustc_pattern_analysis/src/lints.rs b/compiler/rustc_pattern_analysis/src/lints.rs index 3f1497540d2..30e775733de 100644 --- a/compiler/rustc_pattern_analysis/src/lints.rs +++ b/compiler/rustc_pattern_analysis/src/lints.rs @@ -10,7 +10,7 @@ use crate::MatchArm; /// Traverse the patterns to collect any variants of a non_exhaustive enum that fail to be mentioned /// in a given column. #[instrument(level = "debug", skip(cx), ret)] -fn collect_nonexhaustive_missing_variants<'a, 'p, 'tcx>( +fn collect_nonexhaustive_missing_variants<'p, 'tcx>( cx: &RustcMatchCheckCtxt<'p, 'tcx>, column: &PatternColumn<'p, RustcMatchCheckCtxt<'p, 'tcx>>, ) -> Result<Vec<WitnessPat<'p, 'tcx>>, ErrorGuaranteed> { diff --git a/compiler/rustc_pattern_analysis/src/pat.rs b/compiler/rustc_pattern_analysis/src/pat.rs index c94d8b93535..9bde23c7bf1 100644 --- a/compiler/rustc_pattern_analysis/src/pat.rs +++ b/compiler/rustc_pattern_analysis/src/pat.rs @@ -6,7 +6,7 @@ use std::fmt; use smallvec::{smallvec, SmallVec}; use crate::constructor::{Constructor, Slice, SliceKind}; -use crate::{Captures, TypeCx}; +use crate::TypeCx; use self::Constructor::*; @@ -21,9 +21,9 @@ use self::Constructor::*; /// This happens if a private or `non_exhaustive` field is uninhabited, because the code mustn't /// observe that it is uninhabited. In that case that field is not included in `fields`. Care must /// be taken when converting to/from `thir::Pat`. -pub struct DeconstructedPat<'p, Cx: TypeCx> { +pub struct DeconstructedPat<Cx: TypeCx> { ctor: Constructor<Cx>, - fields: &'p [DeconstructedPat<'p, Cx>], + fields: Vec<DeconstructedPat<Cx>>, ty: Cx::Ty, /// Extra data to store in a pattern. `None` if the pattern is a wildcard that does not /// correspond to a user-supplied pattern. @@ -32,14 +32,20 @@ pub struct DeconstructedPat<'p, Cx: TypeCx> { useful: Cell<bool>, } -impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> { +impl<Cx: TypeCx> DeconstructedPat<Cx> { pub fn wildcard(ty: Cx::Ty) -> Self { - DeconstructedPat { ctor: Wildcard, fields: &[], ty, data: None, useful: Cell::new(false) } + DeconstructedPat { + ctor: Wildcard, + fields: Vec::new(), + ty, + data: None, + useful: Cell::new(false), + } } pub fn new( ctor: Constructor<Cx>, - fields: &'p [DeconstructedPat<'p, Cx>], + fields: Vec<DeconstructedPat<Cx>>, ty: Cx::Ty, data: Cx::PatData, ) -> Self { @@ -62,17 +68,17 @@ impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> { self.data.as_ref() } - pub fn iter_fields(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'_> { + pub fn iter_fields<'a>(&'a self) -> impl Iterator<Item = &'a DeconstructedPat<Cx>> { self.fields.iter() } /// Specialize this pattern with a constructor. /// `other_ctor` can be different from `self.ctor`, but must be covered by it. - pub(crate) fn specialize( - &self, + pub(crate) fn specialize<'a>( + &'a self, other_ctor: &Constructor<Cx>, ctor_arity: usize, - ) -> SmallVec<[PatOrWild<'p, Cx>; 2]> { + ) -> SmallVec<[PatOrWild<'a, Cx>; 2]> { let wildcard_sub_tys = || (0..ctor_arity).map(|_| PatOrWild::Wild).collect(); match (&self.ctor, other_ctor) { // Return a wildcard for each field of `other_ctor`. @@ -139,7 +145,7 @@ impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> { } /// This is best effort and not good enough for a `Display` impl. -impl<'p, Cx: TypeCx> fmt::Debug for DeconstructedPat<'p, Cx> { +impl<Cx: TypeCx> fmt::Debug for DeconstructedPat<Cx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let pat = self; let mut first = true; @@ -221,7 +227,7 @@ pub(crate) enum PatOrWild<'p, Cx: TypeCx> { /// A non-user-provided wildcard, created during specialization. Wild, /// A user-provided pattern. - Pat(&'p DeconstructedPat<'p, Cx>), + Pat(&'p DeconstructedPat<Cx>), } impl<'p, Cx: TypeCx> Clone for PatOrWild<'p, Cx> { @@ -236,7 +242,7 @@ impl<'p, Cx: TypeCx> Clone for PatOrWild<'p, Cx> { impl<'p, Cx: TypeCx> Copy for PatOrWild<'p, Cx> {} impl<'p, Cx: TypeCx> PatOrWild<'p, Cx> { - pub(crate) fn as_pat(&self) -> Option<&'p DeconstructedPat<'p, Cx>> { + pub(crate) fn as_pat(&self) -> Option<&'p DeconstructedPat<Cx>> { match self { PatOrWild::Wild => None, PatOrWild::Pat(pat) => Some(pat), @@ -297,6 +303,7 @@ impl<'p, Cx: TypeCx> fmt::Debug for PatOrWild<'p, Cx> { /// 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)] pub struct WitnessPat<Cx: TypeCx> { ctor: Constructor<Cx>, pub(crate) fields: Vec<WitnessPat<Cx>>, @@ -309,16 +316,6 @@ impl<Cx: TypeCx> Clone for WitnessPat<Cx> { } } -impl<Cx: TypeCx> fmt::Debug for WitnessPat<Cx> { - fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt.debug_struct("WitnessPat") - .field("ctor", &self.ctor) - .field("fields", &self.fields) - .field("ty", &self.ty) - .finish() - } -} - impl<Cx: TypeCx> WitnessPat<Cx> { pub(crate) fn new(ctor: Constructor<Cx>, fields: Vec<Self>, ty: Cx::Ty) -> Self { Self { ctor, fields, ty } diff --git a/compiler/rustc_pattern_analysis/src/pat_column.rs b/compiler/rustc_pattern_analysis/src/pat_column.rs index 3cacfc491b9..ce14fdc364f 100644 --- a/compiler/rustc_pattern_analysis/src/pat_column.rs +++ b/compiler/rustc_pattern_analysis/src/pat_column.rs @@ -13,7 +13,7 @@ use crate::{Captures, MatchArm, TypeCx}; #[derive(Debug)] pub struct PatternColumn<'p, Cx: TypeCx> { /// This must not contain an or-pattern. `expand_and_push` takes care to expand them. - patterns: Vec<&'p DeconstructedPat<'p, Cx>>, + patterns: Vec<&'p DeconstructedPat<Cx>>, } impl<'p, Cx: TypeCx> PatternColumn<'p, Cx> { @@ -41,7 +41,7 @@ impl<'p, Cx: TypeCx> PatternColumn<'p, Cx> { pub fn head_ty(&self) -> Option<&Cx::Ty> { self.patterns.first().map(|pat| pat.ty()) } - pub fn iter<'a>(&'a self) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'a> { + pub fn iter<'a>(&'a self) -> impl Iterator<Item = &'p DeconstructedPat<Cx>> + Captures<'a> { self.patterns.iter().copied() } @@ -78,7 +78,7 @@ impl<'p, Cx: TypeCx> PatternColumn<'p, Cx> { let mut specialized_columns: Vec<_> = (0..arity).map(|_| Self { patterns: Vec::new() }).collect(); let relevant_patterns = - self.patterns.iter().filter(|pat| ctor.is_covered_by(cx, pat.ctor())); + self.patterns.iter().filter(|pat| ctor.is_covered_by(cx, pat.ctor()).unwrap_or(false)); for pat in relevant_patterns { let specialized = pat.specialize(ctor, arity); for (subpat, column) in specialized.into_iter().zip(&mut specialized_columns) { diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs index ec37e202118..a8fe0cb6a1d 100644 --- a/compiler/rustc_pattern_analysis/src/rustc.rs +++ b/compiler/rustc_pattern_analysis/src/rustc.rs @@ -1,8 +1,7 @@ -use smallvec::SmallVec; use std::fmt; use std::iter::once; -use rustc_arena::{DroplessArena, TypedArena}; +use rustc_arena::DroplessArena; use rustc_hir::def_id::DefId; use rustc_hir::HirId; use rustc_index::{Idx, IndexVec}; @@ -27,8 +26,7 @@ use crate::constructor::Constructor::*; pub type Constructor<'p, 'tcx> = crate::constructor::Constructor<RustcMatchCheckCtxt<'p, 'tcx>>; pub type ConstructorSet<'p, 'tcx> = crate::constructor::ConstructorSet<RustcMatchCheckCtxt<'p, 'tcx>>; -pub type DeconstructedPat<'p, 'tcx> = - crate::pat::DeconstructedPat<'p, RustcMatchCheckCtxt<'p, 'tcx>>; +pub type DeconstructedPat<'p, 'tcx> = crate::pat::DeconstructedPat<RustcMatchCheckCtxt<'p, 'tcx>>; pub type MatchArm<'p, 'tcx> = crate::MatchArm<'p, RustcMatchCheckCtxt<'p, 'tcx>>; pub type Usefulness<'p, 'tcx> = crate::usefulness::Usefulness<'p, RustcMatchCheckCtxt<'p, 'tcx>>; pub type UsefulnessReport<'p, 'tcx> = @@ -64,7 +62,7 @@ impl<'tcx> RevealedTy<'tcx> { } #[derive(Clone)] -pub struct RustcMatchCheckCtxt<'p, 'tcx> { +pub struct RustcMatchCheckCtxt<'p, 'tcx: 'p> { pub tcx: TyCtxt<'tcx>, pub typeck_results: &'tcx ty::TypeckResults<'tcx>, /// The module in which the match occurs. This is necessary for @@ -74,8 +72,6 @@ pub struct RustcMatchCheckCtxt<'p, 'tcx> { /// outside its module and should not be matchable with an empty match statement. pub module: DefId, pub param_env: ty::ParamEnv<'tcx>, - /// To allocate lowered patterns - pub pattern_arena: &'p TypedArena<DeconstructedPat<'p, 'tcx>>, /// To allocate the result of `self.ctor_sub_tys()` pub dropless_arena: &'p DroplessArena, /// Lint level at the match. @@ -91,13 +87,13 @@ pub struct RustcMatchCheckCtxt<'p, 'tcx> { pub known_valid_scrutinee: bool, } -impl<'p, 'tcx> fmt::Debug for RustcMatchCheckCtxt<'p, 'tcx> { +impl<'p, 'tcx: 'p> fmt::Debug for RustcMatchCheckCtxt<'p, 'tcx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("RustcMatchCheckCtxt").finish() } } -impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { +impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> { /// Type inference occasionally gives us opaque types in places where corresponding patterns /// have more specific types. To avoid inconsistencies as well as detect opaque uninhabited /// types, we use the corresponding concrete type if possible. @@ -423,7 +419,8 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { | ty::FnDef(_, _) | ty::FnPtr(_) | ty::Dynamic(_, _, _) - | ty::Closure(_, _) + | ty::Closure(..) + | ty::CoroutineClosure(..) | ty::Coroutine(_, _) | ty::Alias(_, _) | ty::Param(_) @@ -458,21 +455,20 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { /// Note: the input patterns must have been lowered through /// `rustc_mir_build::thir::pattern::check_match::MatchVisitor::lower_pattern`. pub fn lower_pat(&self, pat: &'p Pat<'tcx>) -> DeconstructedPat<'p, 'tcx> { - let singleton = |pat| std::slice::from_ref(self.pattern_arena.alloc(pat)); let cx = self; let ty = cx.reveal_opaque_ty(pat.ty); let ctor; - let fields: &[_]; + let mut fields: Vec<_>; match &pat.kind { PatKind::AscribeUserType { subpattern, .. } | PatKind::InlineConstant { subpattern, .. } => return self.lower_pat(subpattern), PatKind::Binding { subpattern: Some(subpat), .. } => return self.lower_pat(subpat), PatKind::Binding { subpattern: None, .. } | PatKind::Wild => { ctor = Wildcard; - fields = &[]; + fields = vec![]; } PatKind::Deref { subpattern } => { - fields = singleton(self.lower_pat(subpattern)); + fields = vec![self.lower_pat(subpattern)]; ctor = match ty.kind() { // This is a box pattern. ty::Adt(adt, ..) if adt.is_box() => Struct, @@ -484,15 +480,14 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { match ty.kind() { ty::Tuple(fs) => { ctor = Struct; - let mut wilds: SmallVec<[_; 2]> = fs + fields = fs .iter() .map(|ty| cx.reveal_opaque_ty(ty)) .map(|ty| DeconstructedPat::wildcard(ty)) .collect(); for pat in subpatterns { - wilds[pat.field.index()] = self.lower_pat(&pat.pattern); + fields[pat.field.index()] = self.lower_pat(&pat.pattern); } - fields = cx.pattern_arena.alloc_from_iter(wilds); } ty::Adt(adt, args) if adt.is_box() => { // The only legal patterns of type `Box` (outside `std`) are `_` and box @@ -514,7 +509,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { DeconstructedPat::wildcard(self.reveal_opaque_ty(args.type_at(0))) }; ctor = Struct; - fields = singleton(pat); + fields = vec![pat]; } ty::Adt(adt, _) => { ctor = match pat.kind { @@ -534,14 +529,12 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { ty }, ); - let mut wilds: SmallVec<[_; 2]> = - tys.map(|ty| DeconstructedPat::wildcard(ty)).collect(); + fields = tys.map(|ty| DeconstructedPat::wildcard(ty)).collect(); for pat in subpatterns { if let Some(i) = field_id_to_id[pat.field.index()] { - wilds[i] = self.lower_pat(&pat.pattern); + fields[i] = self.lower_pat(&pat.pattern); } } - fields = cx.pattern_arena.alloc_from_iter(wilds); } _ => bug!("pattern has unexpected type: pat: {:?}, ty: {:?}", pat, ty), } @@ -553,7 +546,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { Some(b) => Bool(b), None => Opaque(OpaqueId::new()), }; - fields = &[]; + fields = vec![]; } ty::Char | ty::Int(_) | ty::Uint(_) => { ctor = match value.try_eval_bits(cx.tcx, cx.param_env) { @@ -569,7 +562,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { } None => Opaque(OpaqueId::new()), }; - fields = &[]; + fields = vec![]; } ty::Float(ty::FloatTy::F32) => { ctor = match value.try_eval_bits(cx.tcx, cx.param_env) { @@ -580,7 +573,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { } None => Opaque(OpaqueId::new()), }; - fields = &[]; + fields = vec![]; } ty::Float(ty::FloatTy::F64) => { ctor = match value.try_eval_bits(cx.tcx, cx.param_env) { @@ -591,7 +584,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { } None => Opaque(OpaqueId::new()), }; - fields = &[]; + fields = vec![]; } ty::Ref(_, t, _) if t.is_str() => { // We want a `&str` constant to behave like a `Deref` pattern, to be compatible @@ -602,16 +595,16 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { // subfields. // Note: `t` is `str`, not `&str`. let ty = self.reveal_opaque_ty(*t); - let subpattern = DeconstructedPat::new(Str(*value), &[], ty, pat); + let subpattern = DeconstructedPat::new(Str(*value), Vec::new(), ty, pat); ctor = Ref; - fields = singleton(subpattern) + fields = vec![subpattern] } // All constants that can be structurally matched have already been expanded // into the corresponding `Pat`s by `const_to_pat`. Constants that remain are // opaque. _ => { ctor = Opaque(OpaqueId::new()); - fields = &[]; + fields = vec![]; } } } @@ -648,7 +641,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { } _ => bug!("invalid type for range pattern: {}", ty.inner()), }; - fields = &[]; + fields = vec![]; } PatKind::Array { prefix, slice, suffix } | PatKind::Slice { prefix, slice, suffix } => { let array_len = match ty.kind() { @@ -664,25 +657,23 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { SliceKind::FixedLen(prefix.len() + suffix.len()) }; ctor = Slice(Slice::new(array_len, kind)); - fields = cx.pattern_arena.alloc_from_iter( - prefix.iter().chain(suffix.iter()).map(|p| self.lower_pat(&*p)), - ) + fields = prefix.iter().chain(suffix.iter()).map(|p| self.lower_pat(&*p)).collect(); } PatKind::Or { .. } => { ctor = Or; let pats = expand_or_pat(pat); - fields = - cx.pattern_arena.alloc_from_iter(pats.into_iter().map(|p| self.lower_pat(p))) + fields = pats.into_iter().map(|p| self.lower_pat(p)).collect(); } PatKind::Never => { - // FIXME(never_patterns): handle `!` in exhaustiveness. This is a sane default - // in the meantime. + // A never pattern matches all the values of its type (namely none). Moreover it + // must be compatible with other constructors, since we can use `!` on a type like + // `Result<!, !>` which has other constructors. Hence we lower it as a wildcard. ctor = Wildcard; - fields = &[]; + fields = vec![]; } PatKind::Error(_) => { ctor = Opaque(OpaqueId::new()); - fields = &[]; + fields = vec![]; } } DeconstructedPat::new(ctor, fields, ty, pat) @@ -853,7 +844,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> { } } -impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> { +impl<'p, 'tcx: 'p> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> { type Ty = RevealedTy<'tcx>; type Error = ErrorGuaranteed; type VariantIdx = VariantIdx; @@ -887,7 +878,7 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> { fn write_variant_name( f: &mut fmt::Formatter<'_>, - pat: &crate::pat::DeconstructedPat<'_, Self>, + pat: &crate::pat::DeconstructedPat<Self>, ) -> fmt::Result { if let ty::Adt(adt, _) = pat.ty().kind() { if adt.is_box() { @@ -900,15 +891,15 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> { Ok(()) } - fn bug(&self, fmt: fmt::Arguments<'_>) -> ! { + fn bug(&self, fmt: fmt::Arguments<'_>) -> Self::Error { span_bug!(self.scrut_span, "{}", fmt) } fn lint_overlapping_range_endpoints( &self, - pat: &crate::pat::DeconstructedPat<'_, Self>, + pat: &crate::pat::DeconstructedPat<Self>, overlaps_on: IntRange, - overlaps_with: &[&crate::pat::DeconstructedPat<'_, Self>], + overlaps_with: &[&crate::pat::DeconstructedPat<Self>], ) { let overlap_as_pat = self.hoist_pat_range(&overlaps_on, *pat.ty()); let overlaps: Vec<_> = overlaps_with diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs index 3d45d032a99..80a807b4f27 100644 --- a/compiler/rustc_pattern_analysis/src/usefulness.rs +++ b/compiler/rustc_pattern_analysis/src/usefulness.rs @@ -767,12 +767,6 @@ impl<'a, Cx: TypeCx> PlaceCtxt<'a, Cx> { fn ctor_arity(&self, ctor: &Constructor<Cx>) -> usize { self.cx.ctor_arity(ctor, self.ty) } - fn ctor_sub_tys( - &'a self, - ctor: &'a Constructor<Cx>, - ) -> impl Iterator<Item = Cx::Ty> + ExactSizeIterator + Captures<'a> { - self.cx.ctor_sub_tys(ctor, self.ty) - } fn ctors_for_ty(&self) -> Result<ConstructorSet<Cx>, Cx::Error> { self.cx.ctors_for_ty(self.ty) } @@ -828,6 +822,38 @@ impl fmt::Display for ValidityConstraint { } } +/// Data about a place under investigation. +struct PlaceInfo<Cx: TypeCx> { + /// The type of the place. + ty: Cx::Ty, + /// Whether the place is known to contain valid data. + validity: ValidityConstraint, + /// Whether the place is the scrutinee itself or a subplace of it. + is_scrutinee: bool, +} + +impl<Cx: TypeCx> PlaceInfo<Cx> { + fn specialize<'a>( + &'a self, + cx: &'a Cx, + ctor: &'a Constructor<Cx>, + ) -> impl Iterator<Item = Self> + ExactSizeIterator + Captures<'a> { + let ctor_sub_tys = cx.ctor_sub_tys(ctor, &self.ty); + let ctor_sub_validity = self.validity.specialize(ctor); + ctor_sub_tys.map(move |ty| PlaceInfo { + ty, + validity: ctor_sub_validity, + is_scrutinee: false, + }) + } +} + +impl<Cx: TypeCx> Clone for PlaceInfo<Cx> { + fn clone(&self) -> Self { + Self { ty: self.ty.clone(), validity: self.validity, is_scrutinee: self.is_scrutinee } + } +} + /// Represents a pattern-tuple under investigation. // The three lifetimes are: // - 'p coming from the input @@ -848,7 +874,7 @@ impl<'p, Cx: TypeCx> Clone for PatStack<'p, Cx> { } impl<'p, Cx: TypeCx> PatStack<'p, Cx> { - fn from_pattern(pat: &'p DeconstructedPat<'p, Cx>) -> Self { + fn from_pattern(pat: &'p DeconstructedPat<Cx>) -> Self { PatStack { pats: smallvec![PatOrWild::Pat(pat)], relevant: true } } @@ -1001,10 +1027,9 @@ struct Matrix<'p, Cx: TypeCx> { /// each column must have the same type. Each column corresponds to a place within the /// scrutinee. rows: Vec<MatrixRow<'p, Cx>>, - /// Track the type of each column/place. - place_ty: SmallVec<[Cx::Ty; 2]>, - /// Track for each column/place whether it contains a known valid value. - place_validity: SmallVec<[ValidityConstraint; 2]>, + /// Track info about each place. Each place corresponds to a column in `rows`, and their types + /// must match. + place_info: SmallVec<[PlaceInfo<Cx>; 2]>, /// Track whether the virtual wildcard row used to compute exhaustiveness is relevant. See top /// of the file for details on relevancy. wildcard_row_is_relevant: bool, @@ -1032,10 +1057,10 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> { scrut_ty: Cx::Ty, scrut_validity: ValidityConstraint, ) -> Self { + let place_info = PlaceInfo { ty: scrut_ty, validity: scrut_validity, is_scrutinee: true }; let mut matrix = Matrix { rows: Vec::with_capacity(arms.len()), - place_ty: smallvec![scrut_ty], - place_validity: smallvec![scrut_validity], + place_info: smallvec![place_info], wildcard_row_is_relevant: true, }; for (row_id, arm) in arms.iter().enumerate() { @@ -1051,11 +1076,11 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> { matrix } - fn head_ty(&self) -> Option<&Cx::Ty> { - self.place_ty.first() + fn head_place(&self) -> Option<&PlaceInfo<Cx>> { + self.place_info.first() } fn column_count(&self) -> usize { - self.place_ty.len() + self.place_info.len() } fn rows( @@ -1082,28 +1107,23 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> { pcx: &PlaceCtxt<'_, Cx>, ctor: &Constructor<Cx>, ctor_is_relevant: bool, - ) -> Matrix<'p, Cx> { - let ctor_sub_tys = pcx.ctor_sub_tys(ctor); - let arity = ctor_sub_tys.len(); - let specialized_place_ty = ctor_sub_tys.chain(self.place_ty[1..].iter().cloned()).collect(); - let ctor_sub_validity = self.place_validity[0].specialize(ctor); - let specialized_place_validity = std::iter::repeat(ctor_sub_validity) - .take(arity) - .chain(self.place_validity[1..].iter().copied()) - .collect(); + ) -> Result<Matrix<'p, Cx>, Cx::Error> { + let subfield_place_info = self.place_info[0].specialize(pcx.cx, ctor); + let arity = subfield_place_info.len(); + let specialized_place_info = + subfield_place_info.chain(self.place_info[1..].iter().cloned()).collect(); let mut matrix = Matrix { rows: Vec::new(), - place_ty: specialized_place_ty, - place_validity: specialized_place_validity, + place_info: specialized_place_info, wildcard_row_is_relevant: self.wildcard_row_is_relevant && ctor_is_relevant, }; for (i, row) in self.rows().enumerate() { - if ctor.is_covered_by(pcx.cx, row.head().ctor()) { + if ctor.is_covered_by(pcx.cx, row.head().ctor())? { let new_row = row.pop_head_constructor(ctor, arity, ctor_is_relevant, i); matrix.expand_and_push(new_row); } } - matrix + Ok(matrix) } } @@ -1127,11 +1147,11 @@ impl<'p, Cx: TypeCx> fmt::Debug for Matrix<'p, Cx> { .map(|row| row.iter().map(|pat| format!("{pat:?}")).collect()) .collect(); pretty_printed_matrix - .push(self.place_validity.iter().map(|validity| format!("{validity}")).collect()); + .push(self.place_info.iter().map(|place| format!("{}", place.validity)).collect()); let column_count = self.column_count(); assert!(self.rows.iter().all(|row| row.len() == column_count)); - assert!(self.place_validity.len() == column_count); + assert!(self.place_info.len() == column_count); let column_widths: Vec<usize> = (0..column_count) .map(|col| pretty_printed_matrix.iter().map(|row| row[col].len()).max().unwrap_or(0)) .collect(); @@ -1207,6 +1227,7 @@ impl<'p, Cx: TypeCx> fmt::Debug for Matrix<'p, Cx> { /// The final `Pair(Some(_), true)` is then the resulting witness. /// /// See the top of the file for more detailed explanations and examples. +#[derive(Debug)] struct WitnessStack<Cx: TypeCx>(Vec<WitnessPat<Cx>>); impl<Cx: TypeCx> Clone for WitnessStack<Cx> { @@ -1215,12 +1236,6 @@ impl<Cx: TypeCx> Clone for WitnessStack<Cx> { } } -impl<Cx: TypeCx> fmt::Debug for WitnessStack<Cx> { - fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt.debug_tuple("WitnessStack").field(&self.0).finish() - } -} - impl<Cx: TypeCx> WitnessStack<Cx> { /// Asserts that the witness contains a single pattern, and returns it. fn single_pattern(self) -> WitnessPat<Cx> { @@ -1265,6 +1280,7 @@ impl<Cx: TypeCx> WitnessStack<Cx> { /// /// 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)] struct WitnessMatrix<Cx: TypeCx>(Vec<WitnessStack<Cx>>); impl<Cx: TypeCx> Clone for WitnessMatrix<Cx> { @@ -1273,12 +1289,6 @@ impl<Cx: TypeCx> Clone for WitnessMatrix<Cx> { } } -impl<Cx: TypeCx> fmt::Debug for WitnessMatrix<Cx> { - fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt.debug_tuple("WitnessMatrix").field(&self.0).finish() - } -} - impl<Cx: TypeCx> WitnessMatrix<Cx> { /// New matrix with no witnesses. fn empty() -> Self { @@ -1442,11 +1452,10 @@ fn collect_overlapping_range_endpoints<'p, Cx: TypeCx>( /// - unspecialization, where we lift the results from the previous step into results for this step /// (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(mcx, is_top_level), ret)] +#[instrument(level = "debug", skip(mcx), ret)] fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>( mcx: UsefulnessCtxt<'a, Cx>, matrix: &mut Matrix<'p, Cx>, - is_top_level: bool, ) -> Result<WitnessMatrix<Cx>, Cx::Error> { debug_assert!(matrix.rows().all(|r| r.len() == matrix.column_count())); @@ -1457,7 +1466,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>( return Ok(WitnessMatrix::empty()); } - let Some(ty) = matrix.head_ty().cloned() else { + let Some(place) = matrix.head_place() else { // The base case: there are no columns in the matrix. We are morally pattern-matching on (). // A row is useful iff it has no (unguarded) rows above it. let mut useful = true; // Whether the next row is useful. @@ -1477,18 +1486,17 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>( }; }; - debug!("ty: {ty:?}"); - let pcx = &PlaceCtxt { cx: mcx.tycx, ty: &ty }; + let ty = &place.ty.clone(); // Clone it out so we can mutate `matrix` later. + let pcx = &PlaceCtxt { cx: mcx.tycx, ty }; + debug!("ty: {:?}", pcx.ty); let ctors_for_ty = pcx.ctors_for_ty()?; - // Whether the place/column we are inspecting is known to contain valid data. - let place_validity = matrix.place_validity[0]; // We treat match scrutinees of type `!` or `EmptyEnum` differently. let is_toplevel_exception = - is_top_level && matches!(ctors_for_ty, ConstructorSet::NoConstructors); + place.is_scrutinee && matches!(ctors_for_ty, ConstructorSet::NoConstructors); // Whether empty patterns are counted as useful or not. We only warn an empty arm unreachable if // it is guaranteed unreachable by the opsem (i.e. if the place is `known_valid`). - let empty_arms_are_unreachable = place_validity.is_known_valid() + let empty_arms_are_unreachable = place.validity.is_known_valid() && (is_toplevel_exception || mcx.tycx.is_exhaustive_patterns_feature_on() || mcx.tycx.is_min_exhaustive_patterns_feature_on()); @@ -1512,11 +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 = is_top_level && !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()`. @@ -1533,9 +1539,9 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>( // strictly fewer rows. In that case we can sometimes skip it. See the top of the file for // details. let ctor_is_relevant = matches!(ctor, Constructor::Missing) || missing_ctors.is_empty(); - let mut spec_matrix = matrix.specialize_constructor(pcx, &ctor, ctor_is_relevant); + let mut spec_matrix = matrix.specialize_constructor(pcx, &ctor, ctor_is_relevant)?; let mut witnesses = ensure_sufficient_stack(|| { - compute_exhaustiveness_and_usefulness(mcx, &mut spec_matrix, false) + compute_exhaustiveness_and_usefulness(mcx, &mut spec_matrix) })?; // Transform witnesses for `spec_matrix` into witnesses for `matrix`. @@ -1585,7 +1591,7 @@ pub enum Usefulness<'p, Cx: TypeCx> { /// 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. - Useful(Vec<&'p DeconstructedPat<'p, Cx>>), + Useful(Vec<&'p DeconstructedPat<Cx>>), /// The arm is redundant and can be removed without changing the behavior of the match /// expression. Redundant, @@ -1610,8 +1616,7 @@ pub fn compute_match_usefulness<'p, Cx: TypeCx>( ) -> Result<UsefulnessReport<'p, Cx>, Cx::Error> { let cx = UsefulnessCtxt { tycx }; let mut matrix = Matrix::new(arms, scrut_ty, scrut_validity); - let non_exhaustiveness_witnesses = - compute_exhaustiveness_and_usefulness(cx, &mut matrix, true)?; + let non_exhaustiveness_witnesses = compute_exhaustiveness_and_usefulness(cx, &mut matrix)?; let non_exhaustiveness_witnesses: Vec<_> = non_exhaustiveness_witnesses.single_column(); let arm_usefulness: Vec<_> = arms |