diff options
Diffstat (limited to 'compiler/rustc_pattern_analysis/src/constructor.rs')
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/constructor.rs | 278 |
1 files changed, 9 insertions, 269 deletions
diff --git a/compiler/rustc_pattern_analysis/src/constructor.rs b/compiler/rustc_pattern_analysis/src/constructor.rs index 4c12cb3b029..aa02ca27add 100644 --- a/compiler/rustc_pattern_analysis/src/constructor.rs +++ b/compiler/rustc_pattern_analysis/src/constructor.rs @@ -158,21 +158,16 @@ use rustc_apfloat::ieee::{DoubleS, IeeeFloat, SingleS}; use rustc_data_structures::fx::FxHashSet; use rustc_hir::RangeEnd; use rustc_index::IndexVec; -use rustc_middle::middle::stability::EvalResult; -use rustc_middle::mir; -use rustc_middle::mir::interpret::Scalar; -use rustc_middle::thir::{Pat, PatKind, PatRange, PatRangeBoundary}; +use rustc_middle::mir::Const; use rustc_middle::ty::layout::IntegerExt; use rustc_middle::ty::{self, Ty, TyCtxt}; -use rustc_span::DUMMY_SP; -use rustc_target::abi::{Integer, VariantIdx, FIRST_VARIANT}; +use rustc_target::abi::{Integer, VariantIdx}; use self::Constructor::*; use self::MaybeInfiniteInt::*; use self::SliceKind::*; -use crate::pat::Fields; -use crate::usefulness::{MatchCheckCtxt, PatCtxt}; +use crate::usefulness::PatCtxt; /// Whether we have seen a constructor in the column or not. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] @@ -196,7 +191,7 @@ pub enum MaybeInfiniteInt { impl MaybeInfiniteInt { // The return value of `signed_bias` should be XORed with a value to encode/decode it. - fn signed_bias(tcx: TyCtxt<'_>, ty: Ty<'_>) -> u128 { + pub(crate) fn signed_bias(tcx: TyCtxt<'_>, ty: Ty<'_>) -> u128 { match *ty.kind() { ty::Int(ity) => { let bits = Integer::from_int_ty(&tcx, ity).size().bits() as u128; @@ -206,58 +201,13 @@ impl MaybeInfiniteInt { } } - fn new_finite(tcx: TyCtxt<'_>, ty: Ty<'_>, bits: u128) -> Self { + pub fn new_finite(tcx: TyCtxt<'_>, ty: Ty<'_>, bits: u128) -> Self { let bias = Self::signed_bias(tcx, ty); // Perform a shift if the underlying types are signed, which makes the interval arithmetic // type-independent. let x = bits ^ bias; Finite(x) } - pub(crate) fn from_pat_range_bdy<'tcx>( - bdy: PatRangeBoundary<'tcx>, - ty: Ty<'tcx>, - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - ) -> Self { - match bdy { - PatRangeBoundary::NegInfinity => NegInfinity, - PatRangeBoundary::Finite(value) => { - let bits = value.eval_bits(tcx, param_env); - Self::new_finite(tcx, ty, bits) - } - PatRangeBoundary::PosInfinity => PosInfinity, - } - } - - /// Used only for diagnostics. - /// Note: it is possible to get `isize/usize::MAX+1` here, as explained in the doc for - /// [`IntRange::split`]. This cannot be represented as a `Const`, so we represent it with - /// `PosInfinity`. - fn to_diagnostic_pat_range_bdy<'tcx>( - self, - ty: Ty<'tcx>, - tcx: TyCtxt<'tcx>, - ) -> PatRangeBoundary<'tcx> { - match self { - NegInfinity => PatRangeBoundary::NegInfinity, - Finite(x) => { - let bias = Self::signed_bias(tcx, ty); - let bits = x ^ bias; - let size = ty.primitive_size(tcx); - match Scalar::try_from_uint(bits, size) { - Some(scalar) => { - let value = mir::Const::from_scalar(tcx, scalar, ty); - PatRangeBoundary::Finite(value) - } - // The value doesn't fit. Since `x >= 0` and 0 always encodes the minimum value - // for a type, the problem isn't that the value is too small. So it must be too - // large. - None => PatRangeBoundary::PosInfinity, - } - } - JustAfterMax | PosInfinity => PatRangeBoundary::PosInfinity, - } - } /// Note: this will not turn a finite value into an infinite one or vice-versa. pub fn minus_one(self) -> Self { @@ -290,16 +240,11 @@ impl MaybeInfiniteInt { /// space: i.e., `range.lo < range.hi`. #[derive(Clone, Copy, PartialEq, Eq)] pub struct IntRange { - pub(crate) lo: MaybeInfiniteInt, // Must not be `PosInfinity`. - pub(crate) hi: MaybeInfiniteInt, // Must not be `NegInfinity`. + pub lo: MaybeInfiniteInt, // Must not be `PosInfinity`. + pub hi: MaybeInfiniteInt, // Must not be `NegInfinity`. } impl IntRange { - #[inline] - pub(super) fn is_integral(ty: Ty<'_>) -> bool { - matches!(ty.kind(), ty::Char | ty::Int(_) | ty::Uint(_)) - } - /// Best effort; will not know that e.g. `255u8..` is a singleton. pub fn is_singleton(&self) -> bool { // Since `lo` and `hi` can't be the same `Infinity` and `plus_one` never changes from finite @@ -421,55 +366,6 @@ impl IntRange { (presence, range) }) } - - /// Whether the range denotes the fictitious values before `isize::MIN` or after - /// `usize::MAX`/`isize::MAX` (see doc of [`IntRange::split`] for why these exist). - pub fn is_beyond_boundaries<'tcx>(&self, ty: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> bool { - ty.is_ptr_sized_integral() && { - // The two invalid ranges are `NegInfinity..isize::MIN` (represented as - // `NegInfinity..0`), and `{u,i}size::MAX+1..PosInfinity`. `to_diagnostic_pat_range_bdy` - // converts `MAX+1` to `PosInfinity`, and we couldn't have `PosInfinity` in `self.lo` - // otherwise. - let lo = self.lo.to_diagnostic_pat_range_bdy(ty, tcx); - matches!(lo, PatRangeBoundary::PosInfinity) - || matches!(self.hi, MaybeInfiniteInt::Finite(0)) - } - } - /// Only used for displaying the range. - pub(super) fn to_diagnostic_pat<'tcx>(&self, ty: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Pat<'tcx> { - let kind = if matches!((self.lo, self.hi), (NegInfinity, PosInfinity)) { - PatKind::Wild - } else if self.is_singleton() { - let lo = self.lo.to_diagnostic_pat_range_bdy(ty, tcx); - let value = lo.as_finite().unwrap(); - PatKind::Constant { value } - } else { - // We convert to an inclusive range for diagnostics. - let mut end = RangeEnd::Included; - let mut lo = self.lo.to_diagnostic_pat_range_bdy(ty, tcx); - if matches!(lo, PatRangeBoundary::PosInfinity) { - // The only reason to get `PosInfinity` here is the special case where - // `to_diagnostic_pat_range_bdy` found `{u,i}size::MAX+1`. So the range denotes the - // fictitious values after `{u,i}size::MAX` (see [`IntRange::split`] for why we do - // this). We show this to the user as `usize::MAX..` which is slightly incorrect but - // probably clear enough. - let c = ty.numeric_max_val(tcx).unwrap(); - let value = mir::Const::from_ty_const(c, tcx); - lo = PatRangeBoundary::Finite(value); - } - let hi = if matches!(self.hi, MaybeInfiniteInt::Finite(0)) { - // The range encodes `..ty::MIN`, so we can't convert it to an inclusive range. - end = RangeEnd::Excluded; - self.hi - } else { - self.hi.minus_one() - }; - let hi = hi.to_diagnostic_pat_range_bdy(ty, tcx); - PatKind::Range(Box::new(PatRange { lo, hi, end, ty })) - }; - - Pat { ty, span: DUMMY_SP, kind } - } } /// Note: this will render signed ranges incorrectly. To render properly, convert to a pattern @@ -742,7 +638,7 @@ pub enum Constructor<'tcx> { F32Range(IeeeFloat<SingleS>, IeeeFloat<SingleS>, RangeEnd), F64Range(IeeeFloat<DoubleS>, IeeeFloat<DoubleS>, RangeEnd), /// String literals. Strings are not quite the same as `&[u8]` so we treat them separately. - Str(mir::Const<'tcx>), + Str(Const<'tcx>), /// Array and slice patterns. Slice(Slice), /// Constants that must not be matched structurally. They are treated as black boxes for the @@ -797,49 +693,10 @@ impl<'tcx> Constructor<'tcx> { } } - pub(crate) fn variant_index_for_adt(&self, adt: ty::AdtDef<'tcx>) -> VariantIdx { - match *self { - Variant(idx) => idx, - Single => { - assert!(!adt.is_enum()); - FIRST_VARIANT - } - _ => bug!("bad constructor {:?} for adt {:?}", self, adt), - } - } - /// The number of fields for this constructor. This must be kept in sync with /// `Fields::wildcards`. pub(crate) fn arity(&self, pcx: &PatCtxt<'_, '_, 'tcx>) -> usize { - match self { - Single | Variant(_) => match pcx.ty.kind() { - ty::Tuple(fs) => fs.len(), - ty::Ref(..) => 1, - ty::Adt(adt, ..) => { - if adt.is_box() { - // The only legal patterns of type `Box` (outside `std`) are `_` and box - // patterns. If we're here we can assume this is a box pattern. - 1 - } else { - let variant = &adt.variant(self.variant_index_for_adt(*adt)); - Fields::list_variant_nonhidden_fields(pcx.cx, pcx.ty, variant).count() - } - } - _ => bug!("Unexpected type for `Single` constructor: {:?}", pcx.ty), - }, - Slice(slice) => slice.arity(), - Bool(..) - | IntRange(..) - | F32Range(..) - | F64Range(..) - | Str(..) - | Opaque(..) - | NonExhaustive - | Hidden - | Missing { .. } - | Wildcard => 0, - Or => bug!("The `Or` constructor doesn't have a fixed arity"), - } + pcx.cx.ctor_arity(self, pcx.ty) } /// Returns whether `self` is covered by `other`, i.e. whether `self` is a subset of `other`. @@ -974,123 +831,6 @@ pub(super) struct SplitConstructorSet<'tcx> { } impl ConstructorSet { - /// Creates a set that represents all the constructors of `ty`. - /// - /// See at the top of the file for considerations of emptiness. - #[instrument(level = "debug", skip(cx), ret)] - pub fn for_ty<'p, 'tcx>(cx: &MatchCheckCtxt<'p, 'tcx>, ty: Ty<'tcx>) -> Self { - let make_range = |start, end| { - IntRange::from_range( - MaybeInfiniteInt::new_finite(cx.tcx, ty, start), - MaybeInfiniteInt::new_finite(cx.tcx, ty, end), - RangeEnd::Included, - ) - }; - // This determines the set of all possible constructors for the type `ty`. For numbers, - // arrays and slices we use ranges and variable-length slices when appropriate. - match ty.kind() { - ty::Bool => Self::Bool, - ty::Char => { - // The valid Unicode Scalar Value ranges. - Self::Integers { - range_1: make_range('\u{0000}' as u128, '\u{D7FF}' as u128), - range_2: Some(make_range('\u{E000}' as u128, '\u{10FFFF}' as u128)), - } - } - &ty::Int(ity) => { - let range = if ty.is_ptr_sized_integral() { - // The min/max values of `isize` are not allowed to be observed. - IntRange { lo: NegInfinity, hi: PosInfinity } - } else { - let bits = Integer::from_int_ty(&cx.tcx, ity).size().bits() as u128; - let min = 1u128 << (bits - 1); - let max = min - 1; - make_range(min, max) - }; - Self::Integers { range_1: range, range_2: None } - } - &ty::Uint(uty) => { - let range = if ty.is_ptr_sized_integral() { - // The max value of `usize` is not allowed to be observed. - let lo = MaybeInfiniteInt::new_finite(cx.tcx, ty, 0); - IntRange { lo, hi: PosInfinity } - } else { - let size = Integer::from_uint_ty(&cx.tcx, uty).size(); - let max = size.truncate(u128::MAX); - make_range(0, max) - }; - Self::Integers { range_1: range, range_2: None } - } - ty::Slice(sub_ty) => { - Self::Slice { array_len: None, subtype_is_empty: cx.is_uninhabited(*sub_ty) } - } - ty::Array(sub_ty, len) => { - // We treat arrays of a constant but unknown length like slices. - Self::Slice { - array_len: len.try_eval_target_usize(cx.tcx, cx.param_env).map(|l| l as usize), - subtype_is_empty: cx.is_uninhabited(*sub_ty), - } - } - ty::Adt(def, args) if def.is_enum() => { - let is_declared_nonexhaustive = cx.is_foreign_non_exhaustive_enum(ty); - if def.variants().is_empty() && !is_declared_nonexhaustive { - Self::NoConstructors - } else { - let mut variants = - IndexVec::from_elem(VariantVisibility::Visible, def.variants()); - for (idx, v) in def.variants().iter_enumerated() { - let variant_def_id = def.variant(idx).def_id; - // Visibly uninhabited variants. - let is_inhabited = v - .inhabited_predicate(cx.tcx, *def) - .instantiate(cx.tcx, args) - .apply(cx.tcx, cx.param_env, cx.module); - // Variants that depend on a disabled unstable feature. - let is_unstable = matches!( - cx.tcx.eval_stability(variant_def_id, None, DUMMY_SP, None), - EvalResult::Deny { .. } - ); - // Foreign `#[doc(hidden)]` variants. - let is_doc_hidden = - cx.tcx.is_doc_hidden(variant_def_id) && !variant_def_id.is_local(); - let visibility = if !is_inhabited { - // FIXME: handle empty+hidden - VariantVisibility::Empty - } else if is_unstable || is_doc_hidden { - VariantVisibility::Hidden - } else { - VariantVisibility::Visible - }; - variants[idx] = visibility; - } - - Self::Variants { variants, non_exhaustive: is_declared_nonexhaustive } - } - } - ty::Adt(..) | ty::Tuple(..) | ty::Ref(..) => { - Self::Single { empty: cx.is_uninhabited(ty) } - } - ty::Never => Self::NoConstructors, - // This type is one for which we cannot list constructors, like `str` or `f64`. - // FIXME(Nadrieril): which of these are actually allowed? - ty::Float(_) - | ty::Str - | ty::Foreign(_) - | ty::RawPtr(_) - | ty::FnDef(_, _) - | ty::FnPtr(_) - | ty::Dynamic(_, _, _) - | ty::Closure(_, _) - | ty::Coroutine(_, _, _) - | ty::Alias(_, _) - | ty::Param(_) - | ty::Error(_) => Self::Unlistable, - ty::CoroutineWitness(_, _) | ty::Bound(_, _) | ty::Placeholder(_) | ty::Infer(_) => { - bug!("Encountered unexpected type in `ConstructorSet::for_ty`: {ty:?}") - } - } - } - /// This analyzes a column of constructors to 1/ determine which constructors of the type (if /// any) are missing; 2/ split constructors to handle non-trivial intersections e.g. on ranges /// or slices. This can get subtle; see [`SplitConstructorSet`] for details of this operation |