| //! Validation of patterns/matches. |
| |
| mod _match; |
| mod check_match; |
| |
| pub(crate) use self::check_match::check_match; |
| |
| use crate::const_eval::const_variant_index; |
| |
| use crate::hair::util::UserAnnotatedTyHelpers; |
| use crate::hair::constant::*; |
| |
| use rustc::mir::{Field, BorrowKind, Mutability}; |
| use rustc::mir::{UserTypeProjection}; |
| use rustc::mir::interpret::{GlobalId, ConstValue, sign_extend, AllocId, Pointer}; |
| use rustc::ty::{self, Region, TyCtxt, AdtDef, Ty, UserType, DefIdTree}; |
| use rustc::ty::{CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations}; |
| use rustc::ty::subst::{SubstsRef, Kind}; |
| use rustc::ty::layout::{VariantIdx, Size}; |
| use rustc::hir::{self, PatKind, RangeEnd}; |
| use rustc::hir::def::{CtorOf, Res, DefKind, CtorKind}; |
| use rustc::hir::pat_util::EnumerateAndAdjustIterator; |
| |
| use rustc_data_structures::indexed_vec::Idx; |
| |
| use std::cmp::Ordering; |
| use std::fmt; |
| use syntax::ast; |
| use syntax::ptr::P; |
| use syntax::symbol::sym; |
| use syntax_pos::Span; |
| |
| #[derive(Clone, Debug)] |
| pub enum PatternError { |
| AssocConstInPattern(Span), |
| StaticInPattern(Span), |
| FloatBug, |
| NonConstPath(Span), |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| pub enum BindingMode { |
| ByValue, |
| ByRef(BorrowKind), |
| } |
| |
| #[derive(Clone, Debug)] |
| pub struct FieldPattern<'tcx> { |
| pub field: Field, |
| pub pattern: Pattern<'tcx>, |
| } |
| |
| #[derive(Clone, Debug)] |
| pub struct Pattern<'tcx> { |
| pub ty: Ty<'tcx>, |
| pub span: Span, |
| pub kind: Box<PatternKind<'tcx>>, |
| } |
| |
| |
| #[derive(Copy, Clone, Debug, PartialEq)] |
| pub struct PatternTypeProjection<'tcx> { |
| pub user_ty: CanonicalUserType<'tcx>, |
| } |
| |
| impl<'tcx> PatternTypeProjection<'tcx> { |
| pub(crate) fn from_user_type(user_annotation: CanonicalUserType<'tcx>) -> Self { |
| Self { |
| user_ty: user_annotation, |
| } |
| } |
| |
| pub(crate) fn user_ty( |
| self, |
| annotations: &mut CanonicalUserTypeAnnotations<'tcx>, |
| inferred_ty: Ty<'tcx>, |
| span: Span, |
| ) -> UserTypeProjection { |
| UserTypeProjection { |
| base: annotations.push(CanonicalUserTypeAnnotation { |
| span, |
| user_ty: self.user_ty, |
| inferred_ty, |
| }), |
| projs: Vec::new(), |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, Debug, PartialEq)] |
| pub struct Ascription<'tcx> { |
| pub user_ty: PatternTypeProjection<'tcx>, |
| /// Variance to use when relating the type `user_ty` to the **type of the value being |
| /// matched**. Typically, this is `Variance::Covariant`, since the value being matched must |
| /// have a type that is some subtype of the ascribed type. |
| /// |
| /// Note that this variance does not apply for any bindings within subpatterns. The type |
| /// assigned to those bindings must be exactly equal to the `user_ty` given here. |
| /// |
| /// The only place where this field is not `Covariant` is when matching constants, where |
| /// we currently use `Contravariant` -- this is because the constant type just needs to |
| /// be "comparable" to the type of the input value. So, for example: |
| /// |
| /// ```text |
| /// match x { "foo" => .. } |
| /// ``` |
| /// |
| /// requires that `&'static str <: T_x`, where `T_x` is the type of `x`. Really, we should |
| /// probably be checking for a `PartialEq` impl instead, but this preserves the behavior |
| /// of the old type-check for now. See #57280 for details. |
| pub variance: ty::Variance, |
| pub user_ty_span: Span, |
| } |
| |
| #[derive(Clone, Debug)] |
| pub enum PatternKind<'tcx> { |
| Wild, |
| |
| AscribeUserType { |
| ascription: Ascription<'tcx>, |
| subpattern: Pattern<'tcx>, |
| }, |
| |
| /// `x`, `ref x`, `x @ P`, etc. |
| Binding { |
| mutability: Mutability, |
| name: ast::Name, |
| mode: BindingMode, |
| var: hir::HirId, |
| ty: Ty<'tcx>, |
| subpattern: Option<Pattern<'tcx>>, |
| }, |
| |
| /// `Foo(...)` or `Foo{...}` or `Foo`, where `Foo` is a variant name from an ADT with |
| /// multiple variants. |
| Variant { |
| adt_def: &'tcx AdtDef, |
| substs: SubstsRef<'tcx>, |
| variant_index: VariantIdx, |
| subpatterns: Vec<FieldPattern<'tcx>>, |
| }, |
| |
| /// `(...)`, `Foo(...)`, `Foo{...}`, or `Foo`, where `Foo` is a variant name from an ADT with |
| /// a single variant. |
| Leaf { |
| subpatterns: Vec<FieldPattern<'tcx>>, |
| }, |
| |
| /// `box P`, `&P`, `&mut P`, etc. |
| Deref { |
| subpattern: Pattern<'tcx>, |
| }, |
| |
| Constant { |
| value: &'tcx ty::Const<'tcx>, |
| }, |
| |
| Range(PatternRange<'tcx>), |
| |
| /// Matches against a slice, checking the length and extracting elements. |
| /// irrefutable when there is a slice pattern and both `prefix` and `suffix` are empty. |
| /// e.g., `&[ref xs..]`. |
| Slice { |
| prefix: Vec<Pattern<'tcx>>, |
| slice: Option<Pattern<'tcx>>, |
| suffix: Vec<Pattern<'tcx>>, |
| }, |
| |
| /// Fixed match against an array; irrefutable. |
| Array { |
| prefix: Vec<Pattern<'tcx>>, |
| slice: Option<Pattern<'tcx>>, |
| suffix: Vec<Pattern<'tcx>>, |
| }, |
| } |
| |
| #[derive(Copy, Clone, Debug, PartialEq)] |
| pub struct PatternRange<'tcx> { |
| pub lo: &'tcx ty::Const<'tcx>, |
| pub hi: &'tcx ty::Const<'tcx>, |
| pub ty: Ty<'tcx>, |
| pub end: RangeEnd, |
| } |
| |
| impl<'tcx> fmt::Display for Pattern<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| match *self.kind { |
| PatternKind::Wild => write!(f, "_"), |
| PatternKind::AscribeUserType { ref subpattern, .. } => |
| write!(f, "{}: _", subpattern), |
| PatternKind::Binding { mutability, name, mode, ref subpattern, .. } => { |
| let is_mut = match mode { |
| BindingMode::ByValue => mutability == Mutability::Mut, |
| BindingMode::ByRef(bk) => { |
| write!(f, "ref ")?; |
| match bk { BorrowKind::Mut { .. } => true, _ => false } |
| } |
| }; |
| if is_mut { |
| write!(f, "mut ")?; |
| } |
| write!(f, "{}", name)?; |
| if let Some(ref subpattern) = *subpattern { |
| write!(f, " @ {}", subpattern)?; |
| } |
| Ok(()) |
| } |
| PatternKind::Variant { ref subpatterns, .. } | |
| PatternKind::Leaf { ref subpatterns } => { |
| let variant = match *self.kind { |
| PatternKind::Variant { adt_def, variant_index, .. } => { |
| Some(&adt_def.variants[variant_index]) |
| } |
| _ => if let ty::Adt(adt, _) = self.ty.sty { |
| if !adt.is_enum() { |
| Some(&adt.variants[VariantIdx::new(0)]) |
| } else { |
| None |
| } |
| } else { |
| None |
| } |
| }; |
| |
| let mut first = true; |
| let mut start_or_continue = || if first { first = false; "" } else { ", " }; |
| |
| if let Some(variant) = variant { |
| write!(f, "{}", variant.ident)?; |
| |
| // Only for Adt we can have `S {...}`, |
| // which we handle separately here. |
| if variant.ctor_kind == CtorKind::Fictive { |
| write!(f, " {{ ")?; |
| |
| let mut printed = 0; |
| for p in subpatterns { |
| if let PatternKind::Wild = *p.pattern.kind { |
| continue; |
| } |
| let name = variant.fields[p.field.index()].ident; |
| write!(f, "{}{}: {}", start_or_continue(), name, p.pattern)?; |
| printed += 1; |
| } |
| |
| if printed < variant.fields.len() { |
| write!(f, "{}..", start_or_continue())?; |
| } |
| |
| return write!(f, " }}"); |
| } |
| } |
| |
| let num_fields = variant.map_or(subpatterns.len(), |v| v.fields.len()); |
| if num_fields != 0 || variant.is_none() { |
| write!(f, "(")?; |
| for i in 0..num_fields { |
| write!(f, "{}", start_or_continue())?; |
| |
| // Common case: the field is where we expect it. |
| if let Some(p) = subpatterns.get(i) { |
| if p.field.index() == i { |
| write!(f, "{}", p.pattern)?; |
| continue; |
| } |
| } |
| |
| // Otherwise, we have to go looking for it. |
| if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) { |
| write!(f, "{}", p.pattern)?; |
| } else { |
| write!(f, "_")?; |
| } |
| } |
| write!(f, ")")?; |
| } |
| |
| Ok(()) |
| } |
| PatternKind::Deref { ref subpattern } => { |
| match self.ty.sty { |
| ty::Adt(def, _) if def.is_box() => write!(f, "box ")?, |
| ty::Ref(_, _, mutbl) => { |
| write!(f, "&")?; |
| if mutbl == hir::MutMutable { |
| write!(f, "mut ")?; |
| } |
| } |
| _ => bug!("{} is a bad Deref pattern type", self.ty) |
| } |
| write!(f, "{}", subpattern) |
| } |
| PatternKind::Constant { value } => { |
| write!(f, "{}", value) |
| } |
| PatternKind::Range(PatternRange { lo, hi, ty: _, end }) => { |
| write!(f, "{}", lo)?; |
| match end { |
| RangeEnd::Included => write!(f, "..=")?, |
| RangeEnd::Excluded => write!(f, "..")?, |
| } |
| write!(f, "{}", hi) |
| } |
| PatternKind::Slice { ref prefix, ref slice, ref suffix } | |
| PatternKind::Array { ref prefix, ref slice, ref suffix } => { |
| let mut first = true; |
| let mut start_or_continue = || if first { first = false; "" } else { ", " }; |
| write!(f, "[")?; |
| for p in prefix { |
| write!(f, "{}{}", start_or_continue(), p)?; |
| } |
| if let Some(ref slice) = *slice { |
| write!(f, "{}", start_or_continue())?; |
| match *slice.kind { |
| PatternKind::Wild => {} |
| _ => write!(f, "{}", slice)? |
| } |
| write!(f, "..")?; |
| } |
| for p in suffix { |
| write!(f, "{}{}", start_or_continue(), p)?; |
| } |
| write!(f, "]") |
| } |
| } |
| } |
| } |
| |
| pub struct PatternContext<'a, 'tcx> { |
| pub tcx: TyCtxt<'tcx>, |
| pub param_env: ty::ParamEnv<'tcx>, |
| pub tables: &'a ty::TypeckTables<'tcx>, |
| pub substs: SubstsRef<'tcx>, |
| pub errors: Vec<PatternError>, |
| } |
| |
| impl<'a, 'tcx> Pattern<'tcx> { |
| pub fn from_hir( |
| tcx: TyCtxt<'tcx>, |
| param_env_and_substs: ty::ParamEnvAnd<'tcx, SubstsRef<'tcx>>, |
| tables: &'a ty::TypeckTables<'tcx>, |
| pat: &'tcx hir::Pat, |
| ) -> Self { |
| let mut pcx = PatternContext::new(tcx, param_env_and_substs, tables); |
| let result = pcx.lower_pattern(pat); |
| if !pcx.errors.is_empty() { |
| let msg = format!("encountered errors lowering pattern: {:?}", pcx.errors); |
| tcx.sess.delay_span_bug(pat.span, &msg); |
| } |
| debug!("Pattern::from_hir({:?}) = {:?}", pat, result); |
| result |
| } |
| } |
| |
| impl<'a, 'tcx> PatternContext<'a, 'tcx> { |
| pub fn new( |
| tcx: TyCtxt<'tcx>, |
| param_env_and_substs: ty::ParamEnvAnd<'tcx, SubstsRef<'tcx>>, |
| tables: &'a ty::TypeckTables<'tcx>, |
| ) -> Self { |
| PatternContext { |
| tcx, |
| param_env: param_env_and_substs.param_env, |
| tables, |
| substs: param_env_and_substs.value, |
| errors: vec![] |
| } |
| } |
| |
| pub fn lower_pattern(&mut self, pat: &'tcx hir::Pat) -> Pattern<'tcx> { |
| // When implicit dereferences have been inserted in this pattern, the unadjusted lowered |
| // pattern has the type that results *after* dereferencing. For example, in this code: |
| // |
| // ``` |
| // match &&Some(0i32) { |
| // Some(n) => { ... }, |
| // _ => { ... }, |
| // } |
| // ``` |
| // |
| // the type assigned to `Some(n)` in `unadjusted_pat` would be `Option<i32>` (this is |
| // determined in rustc_typeck::check::match). The adjustments would be |
| // |
| // `vec![&&Option<i32>, &Option<i32>]`. |
| // |
| // Applying the adjustments, we want to instead output `&&Some(n)` (as a HAIR pattern). So |
| // we wrap the unadjusted pattern in `PatternKind::Deref` repeatedly, consuming the |
| // adjustments in *reverse order* (last-in-first-out, so that the last `Deref` inserted |
| // gets the least-dereferenced type). |
| let unadjusted_pat = self.lower_pattern_unadjusted(pat); |
| self.tables |
| .pat_adjustments() |
| .get(pat.hir_id) |
| .unwrap_or(&vec![]) |
| .iter() |
| .rev() |
| .fold(unadjusted_pat, |pat, ref_ty| { |
| debug!("{:?}: wrapping pattern with type {:?}", pat, ref_ty); |
| Pattern { |
| span: pat.span, |
| ty: ref_ty, |
| kind: Box::new(PatternKind::Deref { subpattern: pat }), |
| } |
| }, |
| ) |
| } |
| |
| fn lower_range_expr( |
| &mut self, |
| expr: &'tcx hir::Expr, |
| ) -> (PatternKind<'tcx>, Option<Ascription<'tcx>>) { |
| match self.lower_lit(expr) { |
| PatternKind::AscribeUserType { |
| ascription: lo_ascription, |
| subpattern: Pattern { kind: box kind, .. }, |
| } => (kind, Some(lo_ascription)), |
| kind => (kind, None), |
| } |
| } |
| |
| fn lower_pattern_unadjusted(&mut self, pat: &'tcx hir::Pat) -> Pattern<'tcx> { |
| let mut ty = self.tables.node_type(pat.hir_id); |
| |
| let kind = match pat.node { |
| PatKind::Wild => PatternKind::Wild, |
| |
| PatKind::Lit(ref value) => self.lower_lit(value), |
| |
| PatKind::Range(ref lo_expr, ref hi_expr, end) => { |
| let (lo, lo_ascription) = self.lower_range_expr(lo_expr); |
| let (hi, hi_ascription) = self.lower_range_expr(hi_expr); |
| |
| let mut kind = match (lo, hi) { |
| (PatternKind::Constant { value: lo }, PatternKind::Constant { value: hi }) => { |
| let cmp = compare_const_vals( |
| self.tcx, |
| lo, |
| hi, |
| self.param_env.and(ty), |
| ); |
| match (end, cmp) { |
| (RangeEnd::Excluded, Some(Ordering::Less)) => |
| PatternKind::Range(PatternRange { lo, hi, ty, end }), |
| (RangeEnd::Excluded, _) => { |
| span_err!( |
| self.tcx.sess, |
| lo_expr.span, |
| E0579, |
| "lower range bound must be less than upper", |
| ); |
| PatternKind::Wild |
| } |
| (RangeEnd::Included, Some(Ordering::Equal)) => { |
| PatternKind::Constant { value: lo } |
| } |
| (RangeEnd::Included, Some(Ordering::Less)) => { |
| PatternKind::Range(PatternRange { lo, hi, ty, end }) |
| } |
| (RangeEnd::Included, _) => { |
| let mut err = struct_span_err!( |
| self.tcx.sess, |
| lo_expr.span, |
| E0030, |
| "lower range bound must be less than or equal to upper" |
| ); |
| err.span_label( |
| lo_expr.span, |
| "lower bound larger than upper bound", |
| ); |
| if self.tcx.sess.teach(&err.get_code().unwrap()) { |
| err.note("When matching against a range, the compiler \ |
| verifies that the range is non-empty. Range \ |
| patterns include both end-points, so this is \ |
| equivalent to requiring the start of the range \ |
| to be less than or equal to the end of the range."); |
| } |
| err.emit(); |
| PatternKind::Wild |
| } |
| } |
| }, |
| ref pats => { |
| self.tcx.sess.delay_span_bug( |
| pat.span, |
| &format!( |
| "found bad range pattern `{:?}` outside of error recovery", |
| pats, |
| ), |
| ); |
| |
| PatternKind::Wild |
| }, |
| }; |
| |
| // If we are handling a range with associated constants (e.g. |
| // `Foo::<'a>::A..=Foo::B`), we need to put the ascriptions for the associated |
| // constants somewhere. Have them on the range pattern. |
| for ascription in &[lo_ascription, hi_ascription] { |
| if let Some(ascription) = ascription { |
| kind = PatternKind::AscribeUserType { |
| ascription: *ascription, |
| subpattern: Pattern { span: pat.span, ty, kind: Box::new(kind), }, |
| }; |
| } |
| } |
| |
| kind |
| } |
| |
| PatKind::Path(ref qpath) => { |
| return self.lower_path(qpath, pat.hir_id, pat.span); |
| } |
| |
| PatKind::Ref(ref subpattern, _) | |
| PatKind::Box(ref subpattern) => { |
| PatternKind::Deref { subpattern: self.lower_pattern(subpattern) } |
| } |
| |
| PatKind::Slice(ref prefix, ref slice, ref suffix) => { |
| match ty.sty { |
| ty::Ref(_, ty, _) => |
| PatternKind::Deref { |
| subpattern: Pattern { |
| ty, |
| span: pat.span, |
| kind: Box::new(self.slice_or_array_pattern( |
| pat.span, ty, prefix, slice, suffix)) |
| }, |
| }, |
| ty::Slice(..) | |
| ty::Array(..) => |
| self.slice_or_array_pattern(pat.span, ty, prefix, slice, suffix), |
| ty::Error => { // Avoid ICE |
| return Pattern { span: pat.span, ty, kind: Box::new(PatternKind::Wild) }; |
| } |
| _ => |
| span_bug!( |
| pat.span, |
| "unexpanded type for vector pattern: {:?}", |
| ty), |
| } |
| } |
| |
| PatKind::Tuple(ref subpatterns, ddpos) => { |
| match ty.sty { |
| ty::Tuple(ref tys) => { |
| let subpatterns = |
| subpatterns.iter() |
| .enumerate_and_adjust(tys.len(), ddpos) |
| .map(|(i, subpattern)| FieldPattern { |
| field: Field::new(i), |
| pattern: self.lower_pattern(subpattern) |
| }) |
| .collect(); |
| |
| PatternKind::Leaf { subpatterns } |
| } |
| ty::Error => { // Avoid ICE (#50577) |
| return Pattern { span: pat.span, ty, kind: Box::new(PatternKind::Wild) }; |
| } |
| _ => span_bug!(pat.span, "unexpected type for tuple pattern: {:?}", ty), |
| } |
| } |
| |
| PatKind::Binding(_, id, ident, ref sub) => { |
| let var_ty = self.tables.node_type(pat.hir_id); |
| if let ty::Error = var_ty.sty { |
| // Avoid ICE |
| return Pattern { span: pat.span, ty, kind: Box::new(PatternKind::Wild) }; |
| }; |
| let bm = *self.tables.pat_binding_modes().get(pat.hir_id) |
| .expect("missing binding mode"); |
| let (mutability, mode) = match bm { |
| ty::BindByValue(hir::MutMutable) => |
| (Mutability::Mut, BindingMode::ByValue), |
| ty::BindByValue(hir::MutImmutable) => |
| (Mutability::Not, BindingMode::ByValue), |
| ty::BindByReference(hir::MutMutable) => |
| (Mutability::Not, BindingMode::ByRef( |
| BorrowKind::Mut { allow_two_phase_borrow: false })), |
| ty::BindByReference(hir::MutImmutable) => |
| (Mutability::Not, BindingMode::ByRef( |
| BorrowKind::Shared)), |
| }; |
| |
| // A ref x pattern is the same node used for x, and as such it has |
| // x's type, which is &T, where we want T (the type being matched). |
| if let ty::BindByReference(_) = bm { |
| if let ty::Ref(_, rty, _) = ty.sty { |
| ty = rty; |
| } else { |
| bug!("`ref {}` has wrong type {}", ident, ty); |
| } |
| } |
| |
| PatternKind::Binding { |
| mutability, |
| mode, |
| name: ident.name, |
| var: id, |
| ty: var_ty, |
| subpattern: self.lower_opt_pattern(sub), |
| } |
| } |
| |
| PatKind::TupleStruct(ref qpath, ref subpatterns, ddpos) => { |
| let res = self.tables.qpath_res(qpath, pat.hir_id); |
| let adt_def = match ty.sty { |
| ty::Adt(adt_def, _) => adt_def, |
| ty::Error => { // Avoid ICE (#50585) |
| return Pattern { span: pat.span, ty, kind: Box::new(PatternKind::Wild) }; |
| } |
| _ => span_bug!(pat.span, |
| "tuple struct pattern not applied to an ADT {:?}", |
| ty), |
| }; |
| let variant_def = adt_def.variant_of_res(res); |
| |
| let subpatterns = |
| subpatterns.iter() |
| .enumerate_and_adjust(variant_def.fields.len(), ddpos) |
| .map(|(i, field)| FieldPattern { |
| field: Field::new(i), |
| pattern: self.lower_pattern(field), |
| }) |
| .collect(); |
| |
| self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns) |
| } |
| |
| PatKind::Struct(ref qpath, ref fields, _) => { |
| let res = self.tables.qpath_res(qpath, pat.hir_id); |
| let subpatterns = |
| fields.iter() |
| .map(|field| { |
| FieldPattern { |
| field: Field::new(self.tcx.field_index(field.node.hir_id, |
| self.tables)), |
| pattern: self.lower_pattern(&field.node.pat), |
| } |
| }) |
| .collect(); |
| |
| self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns) |
| } |
| }; |
| |
| Pattern { |
| span: pat.span, |
| ty, |
| kind: Box::new(kind), |
| } |
| } |
| |
| fn lower_patterns(&mut self, pats: &'tcx [P<hir::Pat>]) -> Vec<Pattern<'tcx>> { |
| pats.iter().map(|p| self.lower_pattern(p)).collect() |
| } |
| |
| fn lower_opt_pattern(&mut self, pat: &'tcx Option<P<hir::Pat>>) -> Option<Pattern<'tcx>> |
| { |
| pat.as_ref().map(|p| self.lower_pattern(p)) |
| } |
| |
| fn flatten_nested_slice_patterns( |
| &mut self, |
| prefix: Vec<Pattern<'tcx>>, |
| slice: Option<Pattern<'tcx>>, |
| suffix: Vec<Pattern<'tcx>>) |
| -> (Vec<Pattern<'tcx>>, Option<Pattern<'tcx>>, Vec<Pattern<'tcx>>) |
| { |
| let orig_slice = match slice { |
| Some(orig_slice) => orig_slice, |
| None => return (prefix, slice, suffix) |
| }; |
| let orig_prefix = prefix; |
| let orig_suffix = suffix; |
| |
| // dance because of intentional borrow-checker stupidity. |
| let kind = *orig_slice.kind; |
| match kind { |
| PatternKind::Slice { prefix, slice, mut suffix } | |
| PatternKind::Array { prefix, slice, mut suffix } => { |
| let mut orig_prefix = orig_prefix; |
| |
| orig_prefix.extend(prefix); |
| suffix.extend(orig_suffix); |
| |
| (orig_prefix, slice, suffix) |
| } |
| _ => { |
| (orig_prefix, Some(Pattern { |
| kind: box kind, ..orig_slice |
| }), orig_suffix) |
| } |
| } |
| } |
| |
| fn slice_or_array_pattern( |
| &mut self, |
| span: Span, |
| ty: Ty<'tcx>, |
| prefix: &'tcx [P<hir::Pat>], |
| slice: &'tcx Option<P<hir::Pat>>, |
| suffix: &'tcx [P<hir::Pat>]) |
| -> PatternKind<'tcx> |
| { |
| let prefix = self.lower_patterns(prefix); |
| let slice = self.lower_opt_pattern(slice); |
| let suffix = self.lower_patterns(suffix); |
| let (prefix, slice, suffix) = |
| self.flatten_nested_slice_patterns(prefix, slice, suffix); |
| |
| match ty.sty { |
| ty::Slice(..) => { |
| // matching a slice or fixed-length array |
| PatternKind::Slice { prefix: prefix, slice: slice, suffix: suffix } |
| } |
| |
| ty::Array(_, len) => { |
| // fixed-length array |
| let len = len.unwrap_usize(self.tcx); |
| assert!(len >= prefix.len() as u64 + suffix.len() as u64); |
| PatternKind::Array { prefix: prefix, slice: slice, suffix: suffix } |
| } |
| |
| _ => { |
| span_bug!(span, "bad slice pattern type {:?}", ty); |
| } |
| } |
| } |
| |
| fn lower_variant_or_leaf( |
| &mut self, |
| res: Res, |
| hir_id: hir::HirId, |
| span: Span, |
| ty: Ty<'tcx>, |
| subpatterns: Vec<FieldPattern<'tcx>>, |
| ) -> PatternKind<'tcx> { |
| let res = match res { |
| Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_id) => { |
| let variant_id = self.tcx.parent(variant_ctor_id).unwrap(); |
| Res::Def(DefKind::Variant, variant_id) |
| }, |
| res => res, |
| }; |
| |
| let mut kind = match res { |
| Res::Def(DefKind::Variant, variant_id) => { |
| let enum_id = self.tcx.parent(variant_id).unwrap(); |
| let adt_def = self.tcx.adt_def(enum_id); |
| if adt_def.is_enum() { |
| let substs = match ty.sty { |
| ty::Adt(_, substs) | |
| ty::FnDef(_, substs) => substs, |
| ty::Error => { // Avoid ICE (#50585) |
| return PatternKind::Wild; |
| } |
| _ => bug!("inappropriate type for def: {:?}", ty), |
| }; |
| PatternKind::Variant { |
| adt_def, |
| substs, |
| variant_index: adt_def.variant_index_with_id(variant_id), |
| subpatterns, |
| } |
| } else { |
| PatternKind::Leaf { subpatterns } |
| } |
| } |
| |
| Res::Def(DefKind::Struct, _) |
| | Res::Def(DefKind::Ctor(CtorOf::Struct, ..), _) |
| | Res::Def(DefKind::Union, _) |
| | Res::Def(DefKind::TyAlias, _) |
| | Res::Def(DefKind::AssocTy, _) |
| | Res::SelfTy(..) |
| | Res::SelfCtor(..) => { |
| PatternKind::Leaf { subpatterns } |
| } |
| |
| _ => { |
| self.errors.push(PatternError::NonConstPath(span)); |
| PatternKind::Wild |
| } |
| }; |
| |
| if let Some(user_ty) = self.user_substs_applied_to_ty_of_hir_id(hir_id) { |
| debug!("lower_variant_or_leaf: kind={:?} user_ty={:?} span={:?}", kind, user_ty, span); |
| kind = PatternKind::AscribeUserType { |
| subpattern: Pattern { |
| span, |
| ty, |
| kind: Box::new(kind), |
| }, |
| ascription: Ascription { |
| user_ty: PatternTypeProjection::from_user_type(user_ty), |
| user_ty_span: span, |
| variance: ty::Variance::Covariant, |
| }, |
| }; |
| } |
| |
| kind |
| } |
| |
| /// Takes a HIR Path. If the path is a constant, evaluates it and feeds |
| /// it to `const_to_pat`. Any other path (like enum variants without fields) |
| /// is converted to the corresponding pattern via `lower_variant_or_leaf`. |
| fn lower_path(&mut self, |
| qpath: &hir::QPath, |
| id: hir::HirId, |
| span: Span) |
| -> Pattern<'tcx> { |
| let ty = self.tables.node_type(id); |
| let res = self.tables.qpath_res(qpath, id); |
| let is_associated_const = match res { |
| Res::Def(DefKind::AssocConst, _) => true, |
| _ => false, |
| }; |
| let kind = match res { |
| Res::Def(DefKind::Const, def_id) | Res::Def(DefKind::AssocConst, def_id) => { |
| let substs = self.tables.node_substs(id); |
| match ty::Instance::resolve( |
| self.tcx, |
| self.param_env, |
| def_id, |
| substs, |
| ) { |
| Some(instance) => { |
| let cid = GlobalId { |
| instance, |
| promoted: None, |
| }; |
| match self.tcx.at(span).const_eval(self.param_env.and(cid)) { |
| Ok(value) => { |
| let pattern = self.const_to_pat(instance, value, id, span); |
| if !is_associated_const { |
| return pattern; |
| } |
| |
| let user_provided_types = self.tables().user_provided_types(); |
| return if let Some(u_ty) = user_provided_types.get(id) { |
| let user_ty = PatternTypeProjection::from_user_type(*u_ty); |
| Pattern { |
| span, |
| kind: Box::new( |
| PatternKind::AscribeUserType { |
| subpattern: pattern, |
| ascription: Ascription { |
| /// Note that use `Contravariant` here. See the |
| /// `variance` field documentation for details. |
| variance: ty::Variance::Contravariant, |
| user_ty, |
| user_ty_span: span, |
| }, |
| } |
| ), |
| ty: value.ty, |
| } |
| } else { |
| pattern |
| } |
| }, |
| Err(_) => { |
| self.tcx.sess.span_err( |
| span, |
| "could not evaluate constant pattern", |
| ); |
| PatternKind::Wild |
| } |
| } |
| }, |
| None => { |
| self.errors.push(if is_associated_const { |
| PatternError::AssocConstInPattern(span) |
| } else { |
| PatternError::StaticInPattern(span) |
| }); |
| PatternKind::Wild |
| }, |
| } |
| } |
| _ => self.lower_variant_or_leaf(res, id, span, ty, vec![]), |
| }; |
| |
| Pattern { |
| span, |
| ty, |
| kind: Box::new(kind), |
| } |
| } |
| |
| /// Converts literals, paths and negation of literals to patterns. |
| /// The special case for negation exists to allow things like `-128_i8` |
| /// which would overflow if we tried to evaluate `128_i8` and then negate |
| /// afterwards. |
| fn lower_lit(&mut self, expr: &'tcx hir::Expr) -> PatternKind<'tcx> { |
| match expr.node { |
| hir::ExprKind::Lit(ref lit) => { |
| let ty = self.tables.expr_ty(expr); |
| match lit_to_const(&lit.node, self.tcx, ty, false) { |
| Ok(val) => { |
| let instance = ty::Instance::new( |
| self.tables.local_id_root.expect("literal outside any scope"), |
| self.substs, |
| ); |
| *self.const_to_pat(instance, val, expr.hir_id, lit.span).kind |
| }, |
| Err(LitToConstError::UnparseableFloat) => { |
| self.errors.push(PatternError::FloatBug); |
| PatternKind::Wild |
| }, |
| Err(LitToConstError::Reported) => PatternKind::Wild, |
| } |
| }, |
| hir::ExprKind::Path(ref qpath) => *self.lower_path(qpath, expr.hir_id, expr.span).kind, |
| hir::ExprKind::Unary(hir::UnNeg, ref expr) => { |
| let ty = self.tables.expr_ty(expr); |
| let lit = match expr.node { |
| hir::ExprKind::Lit(ref lit) => lit, |
| _ => span_bug!(expr.span, "not a literal: {:?}", expr), |
| }; |
| match lit_to_const(&lit.node, self.tcx, ty, true) { |
| Ok(val) => { |
| let instance = ty::Instance::new( |
| self.tables.local_id_root.expect("literal outside any scope"), |
| self.substs, |
| ); |
| *self.const_to_pat(instance, val, expr.hir_id, lit.span).kind |
| }, |
| Err(LitToConstError::UnparseableFloat) => { |
| self.errors.push(PatternError::FloatBug); |
| PatternKind::Wild |
| }, |
| Err(LitToConstError::Reported) => PatternKind::Wild, |
| } |
| } |
| _ => span_bug!(expr.span, "not a literal: {:?}", expr), |
| } |
| } |
| |
| /// Converts an evaluated constant to a pattern (if possible). |
| /// This means aggregate values (like structs and enums) are converted |
| /// to a pattern that matches the value (as if you'd compared via equality). |
| fn const_to_pat( |
| &self, |
| instance: ty::Instance<'tcx>, |
| cv: &'tcx ty::Const<'tcx>, |
| id: hir::HirId, |
| span: Span, |
| ) -> Pattern<'tcx> { |
| debug!("const_to_pat: cv={:#?} id={:?}", cv, id); |
| let adt_subpattern = |i, variant_opt| { |
| let field = Field::new(i); |
| let val = crate::const_eval::const_field( |
| self.tcx, self.param_env, variant_opt, field, cv |
| ); |
| self.const_to_pat(instance, val, id, span) |
| }; |
| let adt_subpatterns = |n, variant_opt| { |
| (0..n).map(|i| { |
| let field = Field::new(i); |
| FieldPattern { |
| field, |
| pattern: adt_subpattern(i, variant_opt), |
| } |
| }).collect::<Vec<_>>() |
| }; |
| debug!("const_to_pat: cv.ty={:?} span={:?}", cv.ty, span); |
| let kind = match cv.ty.sty { |
| ty::Float(_) => { |
| self.tcx.lint_hir( |
| ::rustc::lint::builtin::ILLEGAL_FLOATING_POINT_LITERAL_PATTERN, |
| id, |
| span, |
| "floating-point types cannot be used in patterns", |
| ); |
| PatternKind::Constant { |
| value: cv, |
| } |
| } |
| ty::Adt(adt_def, _) if adt_def.is_union() => { |
| // Matching on union fields is unsafe, we can't hide it in constants |
| self.tcx.sess.span_err(span, "cannot use unions in constant patterns"); |
| PatternKind::Wild |
| } |
| ty::Adt(adt_def, _) if !self.tcx.has_attr(adt_def.did, sym::structural_match) => { |
| let path = self.tcx.def_path_str(adt_def.did); |
| let msg = format!( |
| "to use a constant of type `{}` in a pattern, \ |
| `{}` must be annotated with `#[derive(PartialEq, Eq)]`", |
| path, |
| path, |
| ); |
| self.tcx.sess.span_err(span, &msg); |
| PatternKind::Wild |
| } |
| ty::Ref(_, ty::TyS { sty: ty::Adt(adt_def, _), .. }, _) |
| if !self.tcx.has_attr(adt_def.did, sym::structural_match) => { |
| // HACK(estebank): Side-step ICE #53708, but anything other than erroring here |
| // would be wrong. Returnging `PatternKind::Wild` is not technically correct. |
| let path = self.tcx.def_path_str(adt_def.did); |
| let msg = format!( |
| "to use a constant of type `{}` in a pattern, \ |
| `{}` must be annotated with `#[derive(PartialEq, Eq)]`", |
| path, |
| path, |
| ); |
| self.tcx.sess.span_err(span, &msg); |
| PatternKind::Wild |
| } |
| ty::Adt(adt_def, substs) if adt_def.is_enum() => { |
| let variant_index = const_variant_index(self.tcx, self.param_env, cv); |
| let subpatterns = adt_subpatterns( |
| adt_def.variants[variant_index].fields.len(), |
| Some(variant_index), |
| ); |
| PatternKind::Variant { |
| adt_def, |
| substs, |
| variant_index, |
| subpatterns, |
| } |
| } |
| ty::Adt(adt_def, _) => { |
| let struct_var = adt_def.non_enum_variant(); |
| PatternKind::Leaf { |
| subpatterns: adt_subpatterns(struct_var.fields.len(), None), |
| } |
| } |
| ty::Tuple(fields) => { |
| PatternKind::Leaf { |
| subpatterns: adt_subpatterns(fields.len(), None), |
| } |
| } |
| ty::Array(_, n) => { |
| PatternKind::Array { |
| prefix: (0..n.unwrap_usize(self.tcx)) |
| .map(|i| adt_subpattern(i as usize, None)) |
| .collect(), |
| slice: None, |
| suffix: Vec::new(), |
| } |
| } |
| _ => { |
| PatternKind::Constant { |
| value: cv, |
| } |
| } |
| }; |
| |
| Pattern { |
| span, |
| ty: cv.ty, |
| kind: Box::new(kind), |
| } |
| } |
| } |
| |
| impl UserAnnotatedTyHelpers<'tcx> for PatternContext<'_, 'tcx> { |
| fn tcx(&self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| |
| fn tables(&self) -> &ty::TypeckTables<'tcx> { |
| self.tables |
| } |
| } |
| |
| |
| pub trait PatternFoldable<'tcx> : Sized { |
| fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| self.super_fold_with(folder) |
| } |
| |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self; |
| } |
| |
| pub trait PatternFolder<'tcx> : Sized { |
| fn fold_pattern(&mut self, pattern: &Pattern<'tcx>) -> Pattern<'tcx> { |
| pattern.super_fold_with(self) |
| } |
| |
| fn fold_pattern_kind(&mut self, kind: &PatternKind<'tcx>) -> PatternKind<'tcx> { |
| kind.super_fold_with(self) |
| } |
| } |
| |
| |
| impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Box<T> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| let content: T = (**self).fold_with(folder); |
| box content |
| } |
| } |
| |
| impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Vec<T> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| self.iter().map(|t| t.fold_with(folder)).collect() |
| } |
| } |
| |
| impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Option<T> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self{ |
| self.as_ref().map(|t| t.fold_with(folder)) |
| } |
| } |
| |
| macro_rules! CloneImpls { |
| (<$lt_tcx:tt> $($ty:ty),+) => { |
| $( |
| impl<$lt_tcx> PatternFoldable<$lt_tcx> for $ty { |
| fn super_fold_with<F: PatternFolder<$lt_tcx>>(&self, _: &mut F) -> Self { |
| Clone::clone(self) |
| } |
| } |
| )+ |
| } |
| } |
| |
| CloneImpls!{ <'tcx> |
| Span, Field, Mutability, ast::Name, hir::HirId, usize, ty::Const<'tcx>, |
| Region<'tcx>, Ty<'tcx>, BindingMode, &'tcx AdtDef, |
| SubstsRef<'tcx>, &'tcx Kind<'tcx>, UserType<'tcx>, |
| UserTypeProjection, PatternTypeProjection<'tcx> |
| } |
| |
| impl<'tcx> PatternFoldable<'tcx> for FieldPattern<'tcx> { |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| FieldPattern { |
| field: self.field.fold_with(folder), |
| pattern: self.pattern.fold_with(folder) |
| } |
| } |
| } |
| |
| impl<'tcx> PatternFoldable<'tcx> for Pattern<'tcx> { |
| fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| folder.fold_pattern(self) |
| } |
| |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| Pattern { |
| ty: self.ty.fold_with(folder), |
| span: self.span.fold_with(folder), |
| kind: self.kind.fold_with(folder) |
| } |
| } |
| } |
| |
| impl<'tcx> PatternFoldable<'tcx> for PatternKind<'tcx> { |
| fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| folder.fold_pattern_kind(self) |
| } |
| |
| fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self { |
| match *self { |
| PatternKind::Wild => PatternKind::Wild, |
| PatternKind::AscribeUserType { |
| ref subpattern, |
| ascription: Ascription { |
| variance, |
| ref user_ty, |
| user_ty_span, |
| }, |
| } => PatternKind::AscribeUserType { |
| subpattern: subpattern.fold_with(folder), |
| ascription: Ascription { |
| user_ty: user_ty.fold_with(folder), |
| variance, |
| user_ty_span, |
| }, |
| }, |
| PatternKind::Binding { |
| mutability, |
| name, |
| mode, |
| var, |
| ty, |
| ref subpattern, |
| } => PatternKind::Binding { |
| mutability: mutability.fold_with(folder), |
| name: name.fold_with(folder), |
| mode: mode.fold_with(folder), |
| var: var.fold_with(folder), |
| ty: ty.fold_with(folder), |
| subpattern: subpattern.fold_with(folder), |
| }, |
| PatternKind::Variant { |
| adt_def, |
| substs, |
| variant_index, |
| ref subpatterns, |
| } => PatternKind::Variant { |
| adt_def: adt_def.fold_with(folder), |
| substs: substs.fold_with(folder), |
| variant_index, |
| subpatterns: subpatterns.fold_with(folder) |
| }, |
| PatternKind::Leaf { |
| ref subpatterns, |
| } => PatternKind::Leaf { |
| subpatterns: subpatterns.fold_with(folder), |
| }, |
| PatternKind::Deref { |
| ref subpattern, |
| } => PatternKind::Deref { |
| subpattern: subpattern.fold_with(folder), |
| }, |
| PatternKind::Constant { |
| value |
| } => PatternKind::Constant { |
| value, |
| }, |
| PatternKind::Range(PatternRange { |
| lo, |
| hi, |
| ty, |
| end, |
| }) => PatternKind::Range(PatternRange { |
| lo, |
| hi, |
| ty: ty.fold_with(folder), |
| end, |
| }), |
| PatternKind::Slice { |
| ref prefix, |
| ref slice, |
| ref suffix, |
| } => PatternKind::Slice { |
| prefix: prefix.fold_with(folder), |
| slice: slice.fold_with(folder), |
| suffix: suffix.fold_with(folder) |
| }, |
| PatternKind::Array { |
| ref prefix, |
| ref slice, |
| ref suffix |
| } => PatternKind::Array { |
| prefix: prefix.fold_with(folder), |
| slice: slice.fold_with(folder), |
| suffix: suffix.fold_with(folder) |
| }, |
| } |
| } |
| } |
| |
| pub fn compare_const_vals<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| a: &'tcx ty::Const<'tcx>, |
| b: &'tcx ty::Const<'tcx>, |
| ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, |
| ) -> Option<Ordering> { |
| trace!("compare_const_vals: {:?}, {:?}", a, b); |
| |
| let from_bool = |v: bool| { |
| if v { |
| Some(Ordering::Equal) |
| } else { |
| None |
| } |
| }; |
| |
| let fallback = || from_bool(a == b); |
| |
| // Use the fallback if any type differs |
| if a.ty != b.ty || a.ty != ty.value { |
| return fallback(); |
| } |
| |
| // FIXME: This should use assert_bits(ty) instead of use_bits |
| // but triggers possibly bugs due to mismatching of arrays and slices |
| if let (Some(a), Some(b)) = (a.to_bits(tcx, ty), b.to_bits(tcx, ty)) { |
| use ::rustc_apfloat::Float; |
| return match ty.value.sty { |
| ty::Float(ast::FloatTy::F32) => { |
| let l = ::rustc_apfloat::ieee::Single::from_bits(a); |
| let r = ::rustc_apfloat::ieee::Single::from_bits(b); |
| l.partial_cmp(&r) |
| } |
| ty::Float(ast::FloatTy::F64) => { |
| let l = ::rustc_apfloat::ieee::Double::from_bits(a); |
| let r = ::rustc_apfloat::ieee::Double::from_bits(b); |
| l.partial_cmp(&r) |
| } |
| ty::Int(ity) => { |
| use rustc::ty::layout::{Integer, IntegerExt}; |
| use syntax::attr::SignedInt; |
| let size = Integer::from_attr(&tcx, SignedInt(ity)).size(); |
| let a = sign_extend(a, size); |
| let b = sign_extend(b, size); |
| Some((a as i128).cmp(&(b as i128))) |
| } |
| _ => Some(a.cmp(&b)), |
| } |
| } |
| |
| if let ty::Str = ty.value.sty { |
| match (a.val, b.val) { |
| ( |
| ConstValue::Slice { data: alloc_a, start: offset_a, end: end_a }, |
| ConstValue::Slice { data: alloc_b, start: offset_b, end: end_b }, |
| ) => { |
| let len_a = end_a - offset_a; |
| let len_b = end_b - offset_b; |
| let a = alloc_a.get_bytes( |
| &tcx, |
| // invent a pointer, only the offset is relevant anyway |
| Pointer::new(AllocId(0), Size::from_bytes(offset_a as u64)), |
| Size::from_bytes(len_a as u64), |
| ); |
| let b = alloc_b.get_bytes( |
| &tcx, |
| // invent a pointer, only the offset is relevant anyway |
| Pointer::new(AllocId(0), Size::from_bytes(offset_b as u64)), |
| Size::from_bytes(len_b as u64), |
| ); |
| if let (Ok(a), Ok(b)) = (a, b) { |
| return from_bool(a == b); |
| } |
| } |
| _ => (), |
| } |
| } |
| |
| fallback() |
| } |
