1 //! Validation of patterns/matches.
8 pub(crate) use self::check_match::check_match;
10 use crate::thir::util::UserAnnotatedTyHelpers;
12 use rustc_errors::struct_span_err;
14 use rustc_hir::def::{CtorOf, DefKind, Res};
15 use rustc_hir::pat_util::EnumerateAndAdjustIterator;
16 use rustc_hir::RangeEnd;
17 use rustc_index::vec::Idx;
18 use rustc_middle::mir::interpret::{get_slice_bytes, ConstValue};
19 use rustc_middle::mir::interpret::{ErrorHandled, LitToConstError, LitToConstInput};
20 use rustc_middle::mir::UserTypeProjection;
21 use rustc_middle::mir::{BorrowKind, Field, Mutability};
22 use rustc_middle::thir::{Ascription, BindingMode, FieldPat, Pat, PatKind, PatRange, PatTyProj};
23 use rustc_middle::ty::subst::{GenericArg, SubstsRef};
24 use rustc_middle::ty::{self, AdtDef, ConstKind, DefIdTree, Region, Ty, TyCtxt, UserType};
25 use rustc_span::{Span, Symbol};
27 use std::cmp::Ordering;
29 #[derive(Clone, Debug)]
30 crate enum PatternError {
31 AssocConstInPattern(Span),
32 ConstParamInPattern(Span),
33 StaticInPattern(Span),
37 crate struct PatCtxt<'a, 'tcx> {
38 crate tcx: TyCtxt<'tcx>,
39 crate param_env: ty::ParamEnv<'tcx>,
40 crate typeck_results: &'a ty::TypeckResults<'tcx>,
41 crate errors: Vec<PatternError>,
42 include_lint_checks: bool,
45 crate fn pat_from_hir<'a, 'tcx>(
47 param_env: ty::ParamEnv<'tcx>,
48 typeck_results: &'a ty::TypeckResults<'tcx>,
49 pat: &'tcx hir::Pat<'tcx>,
51 let mut pcx = PatCtxt::new(tcx, param_env, typeck_results);
52 let result = pcx.lower_pattern(pat);
53 if !pcx.errors.is_empty() {
54 let msg = format!("encountered errors lowering pattern: {:?}", pcx.errors);
55 tcx.sess.delay_span_bug(pat.span, &msg);
57 debug!("pat_from_hir({:?}) = {:?}", pat, result);
61 impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
64 param_env: ty::ParamEnv<'tcx>,
65 typeck_results: &'a ty::TypeckResults<'tcx>,
67 PatCtxt { tcx, param_env, typeck_results, errors: vec![], include_lint_checks: false }
70 crate fn include_lint_checks(&mut self) -> &mut Self {
71 self.include_lint_checks = true;
75 crate fn lower_pattern(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Pat<'tcx> {
76 // When implicit dereferences have been inserted in this pattern, the unadjusted lowered
77 // pattern has the type that results *after* dereferencing. For example, in this code:
80 // match &&Some(0i32) {
81 // Some(n) => { ... },
86 // the type assigned to `Some(n)` in `unadjusted_pat` would be `Option<i32>` (this is
87 // determined in rustc_typeck::check::match). The adjustments would be
89 // `vec![&&Option<i32>, &Option<i32>]`.
91 // Applying the adjustments, we want to instead output `&&Some(n)` (as a THIR pattern). So
92 // we wrap the unadjusted pattern in `PatKind::Deref` repeatedly, consuming the
93 // adjustments in *reverse order* (last-in-first-out, so that the last `Deref` inserted
94 // gets the least-dereferenced type).
95 let unadjusted_pat = self.lower_pattern_unadjusted(pat);
96 self.typeck_results.pat_adjustments().get(pat.hir_id).unwrap_or(&vec![]).iter().rev().fold(
99 debug!("{:?}: wrapping pattern with type {:?}", pat, ref_ty);
103 kind: Box::new(PatKind::Deref { subpattern: pat }),
111 expr: &'tcx hir::Expr<'tcx>,
112 ) -> (PatKind<'tcx>, Option<Ascription<'tcx>>) {
113 match self.lower_lit(expr) {
114 PatKind::AscribeUserType { ascription, subpattern: Pat { kind: box kind, .. } } => {
115 (kind, Some(ascription))
117 kind => (kind, None),
121 fn lower_pattern_range(
124 lo: &'tcx ty::Const<'tcx>,
125 hi: &'tcx ty::Const<'tcx>,
129 assert_eq!(lo.ty, ty);
130 assert_eq!(hi.ty, ty);
131 let cmp = compare_const_vals(self.tcx, lo, hi, self.param_env, ty);
133 // `x..y` where `x < y`.
134 // Non-empty because the range includes at least `x`.
135 (RangeEnd::Excluded, Some(Ordering::Less)) => PatKind::Range(PatRange { lo, hi, end }),
136 // `x..y` where `x >= y`. The range is empty => error.
137 (RangeEnd::Excluded, _) => {
142 "lower range bound must be less than upper"
147 // `x..=y` where `x == y`.
148 (RangeEnd::Included, Some(Ordering::Equal)) => PatKind::Constant { value: lo },
149 // `x..=y` where `x < y`.
150 (RangeEnd::Included, Some(Ordering::Less)) => PatKind::Range(PatRange { lo, hi, end }),
151 // `x..=y` where `x > y` hence the range is empty => error.
152 (RangeEnd::Included, _) => {
153 let mut err = struct_span_err!(
157 "lower range bound must be less than or equal to upper"
159 err.span_label(span, "lower bound larger than upper bound");
160 if self.tcx.sess.teach(&err.get_code().unwrap()) {
162 "When matching against a range, the compiler \
163 verifies that the range is non-empty. Range \
164 patterns include both end-points, so this is \
165 equivalent to requiring the start of the range \
166 to be less than or equal to the end of the range.",
175 fn normalize_range_pattern_ends(
178 lo: Option<&PatKind<'tcx>>,
179 hi: Option<&PatKind<'tcx>>,
180 ) -> Option<(&'tcx ty::Const<'tcx>, &'tcx ty::Const<'tcx>)> {
182 (Some(PatKind::Constant { value: lo }), Some(PatKind::Constant { value: hi })) => {
185 (Some(PatKind::Constant { value: lo }), None) => {
186 Some((lo, ty.numeric_max_val(self.tcx)?))
188 (None, Some(PatKind::Constant { value: hi })) => {
189 Some((ty.numeric_min_val(self.tcx)?, hi))
195 fn lower_pattern_unadjusted(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Pat<'tcx> {
196 let mut ty = self.typeck_results.node_type(pat.hir_id);
198 let kind = match pat.kind {
199 hir::PatKind::Wild => PatKind::Wild,
201 hir::PatKind::Lit(ref value) => self.lower_lit(value),
203 hir::PatKind::Range(ref lo_expr, ref hi_expr, end) => {
204 let (lo_expr, hi_expr) = (lo_expr.as_deref(), hi_expr.as_deref());
205 let lo_span = lo_expr.map_or(pat.span, |e| e.span);
206 let lo = lo_expr.map(|e| self.lower_range_expr(e));
207 let hi = hi_expr.map(|e| self.lower_range_expr(e));
209 let (lp, hp) = (lo.as_ref().map(|x| &x.0), hi.as_ref().map(|x| &x.0));
210 let mut kind = match self.normalize_range_pattern_ends(ty, lp, hp) {
211 Some((lc, hc)) => self.lower_pattern_range(ty, lc, hc, end, lo_span),
214 "found bad range pattern `{:?}` outside of error recovery",
217 self.tcx.sess.delay_span_bug(pat.span, msg);
222 // If we are handling a range with associated constants (e.g.
223 // `Foo::<'a>::A..=Foo::B`), we need to put the ascriptions for the associated
224 // constants somewhere. Have them on the range pattern.
225 for end in &[lo, hi] {
226 if let Some((_, Some(ascription))) = end {
227 let subpattern = Pat { span: pat.span, ty, kind: Box::new(kind) };
228 kind = PatKind::AscribeUserType { ascription: *ascription, subpattern };
235 hir::PatKind::Path(ref qpath) => {
236 return self.lower_path(qpath, pat.hir_id, pat.span);
239 hir::PatKind::Ref(ref subpattern, _) | hir::PatKind::Box(ref subpattern) => {
240 PatKind::Deref { subpattern: self.lower_pattern(subpattern) }
243 hir::PatKind::Slice(ref prefix, ref slice, ref suffix) => {
244 self.slice_or_array_pattern(pat.span, ty, prefix, slice, suffix)
247 hir::PatKind::Tuple(ref pats, ddpos) => {
248 let tys = match ty.kind() {
249 ty::Tuple(ref tys) => tys,
250 _ => span_bug!(pat.span, "unexpected type for tuple pattern: {:?}", ty),
252 let subpatterns = self.lower_tuple_subpats(pats, tys.len(), ddpos);
253 PatKind::Leaf { subpatterns }
256 hir::PatKind::Binding(_, id, ident, ref sub) => {
261 .expect("missing binding mode");
262 let (mutability, mode) = match bm {
263 ty::BindByValue(mutbl) => (mutbl, BindingMode::ByValue),
264 ty::BindByReference(hir::Mutability::Mut) => (
266 BindingMode::ByRef(BorrowKind::Mut { allow_two_phase_borrow: false }),
268 ty::BindByReference(hir::Mutability::Not) => {
269 (Mutability::Not, BindingMode::ByRef(BorrowKind::Shared))
273 // A ref x pattern is the same node used for x, and as such it has
274 // x's type, which is &T, where we want T (the type being matched).
276 if let ty::BindByReference(_) = bm {
277 if let ty::Ref(_, rty, _) = ty.kind() {
280 bug!("`ref {}` has wrong type {}", ident, ty);
290 subpattern: self.lower_opt_pattern(sub),
291 is_primary: id == pat.hir_id,
295 hir::PatKind::TupleStruct(ref qpath, ref pats, ddpos) => {
296 let res = self.typeck_results.qpath_res(qpath, pat.hir_id);
297 let adt_def = match ty.kind() {
298 ty::Adt(adt_def, _) => adt_def,
299 _ => span_bug!(pat.span, "tuple struct pattern not applied to an ADT {:?}", ty),
301 let variant_def = adt_def.variant_of_res(res);
302 let subpatterns = self.lower_tuple_subpats(pats, variant_def.fields.len(), ddpos);
303 self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns)
306 hir::PatKind::Struct(ref qpath, ref fields, _) => {
307 let res = self.typeck_results.qpath_res(qpath, pat.hir_id);
308 let subpatterns = fields
310 .map(|field| FieldPat {
311 field: Field::new(self.tcx.field_index(field.hir_id, self.typeck_results)),
312 pattern: self.lower_pattern(&field.pat),
316 self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns)
319 hir::PatKind::Or(ref pats) => PatKind::Or { pats: self.lower_patterns(pats) },
322 Pat { span: pat.span, ty, kind: Box::new(kind) }
325 fn lower_tuple_subpats(
327 pats: &'tcx [hir::Pat<'tcx>],
329 gap_pos: Option<usize>,
330 ) -> Vec<FieldPat<'tcx>> {
332 .enumerate_and_adjust(expected_len, gap_pos)
333 .map(|(i, subpattern)| FieldPat {
334 field: Field::new(i),
335 pattern: self.lower_pattern(subpattern),
340 fn lower_patterns(&mut self, pats: &'tcx [hir::Pat<'tcx>]) -> Vec<Pat<'tcx>> {
341 pats.iter().map(|p| self.lower_pattern(p)).collect()
344 fn lower_opt_pattern(&mut self, pat: &'tcx Option<&'tcx hir::Pat<'tcx>>) -> Option<Pat<'tcx>> {
345 pat.as_ref().map(|p| self.lower_pattern(p))
348 fn slice_or_array_pattern(
352 prefix: &'tcx [hir::Pat<'tcx>],
353 slice: &'tcx Option<&'tcx hir::Pat<'tcx>>,
354 suffix: &'tcx [hir::Pat<'tcx>],
356 let prefix = self.lower_patterns(prefix);
357 let slice = self.lower_opt_pattern(slice);
358 let suffix = self.lower_patterns(suffix);
360 // Matching a slice, `[T]`.
361 ty::Slice(..) => PatKind::Slice { prefix, slice, suffix },
362 // Fixed-length array, `[T; len]`.
363 ty::Array(_, len) => {
364 let len = len.eval_usize(self.tcx, self.param_env);
365 assert!(len >= prefix.len() as u64 + suffix.len() as u64);
366 PatKind::Array { prefix, slice, suffix }
368 _ => span_bug!(span, "bad slice pattern type {:?}", ty),
372 fn lower_variant_or_leaf(
378 subpatterns: Vec<FieldPat<'tcx>>,
380 let res = match res {
381 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_id) => {
382 let variant_id = self.tcx.parent(variant_ctor_id).unwrap();
383 Res::Def(DefKind::Variant, variant_id)
388 let mut kind = match res {
389 Res::Def(DefKind::Variant, variant_id) => {
390 let enum_id = self.tcx.parent(variant_id).unwrap();
391 let adt_def = self.tcx.adt_def(enum_id);
392 if adt_def.is_enum() {
393 let substs = match ty.kind() {
394 ty::Adt(_, substs) | ty::FnDef(_, substs) => substs,
396 // Avoid ICE (#50585)
397 return PatKind::Wild;
399 _ => bug!("inappropriate type for def: {:?}", ty),
404 variant_index: adt_def.variant_index_with_id(variant_id),
408 PatKind::Leaf { subpatterns }
414 | DefKind::Ctor(CtorOf::Struct, ..)
421 | Res::SelfCtor(..) => PatKind::Leaf { subpatterns },
423 let pattern_error = match res {
424 Res::Def(DefKind::ConstParam, _) => PatternError::ConstParamInPattern(span),
425 Res::Def(DefKind::Static, _) => PatternError::StaticInPattern(span),
426 _ => PatternError::NonConstPath(span),
428 self.errors.push(pattern_error);
433 if let Some(user_ty) = self.user_substs_applied_to_ty_of_hir_id(hir_id) {
434 debug!("lower_variant_or_leaf: kind={:?} user_ty={:?} span={:?}", kind, user_ty, span);
435 kind = PatKind::AscribeUserType {
436 subpattern: Pat { span, ty, kind: Box::new(kind) },
437 ascription: Ascription {
438 user_ty: PatTyProj::from_user_type(user_ty),
440 variance: ty::Variance::Covariant,
448 /// Takes a HIR Path. If the path is a constant, evaluates it and feeds
449 /// it to `const_to_pat`. Any other path (like enum variants without fields)
450 /// is converted to the corresponding pattern via `lower_variant_or_leaf`.
451 fn lower_path(&mut self, qpath: &hir::QPath<'_>, id: hir::HirId, span: Span) -> Pat<'tcx> {
452 let ty = self.typeck_results.node_type(id);
453 let res = self.typeck_results.qpath_res(qpath, id);
455 let pat_from_kind = |kind| Pat { span, ty, kind: Box::new(kind) };
457 let (def_id, is_associated_const) = match res {
458 Res::Def(DefKind::Const, def_id) => (def_id, false),
459 Res::Def(DefKind::AssocConst, def_id) => (def_id, true),
461 _ => return pat_from_kind(self.lower_variant_or_leaf(res, id, span, ty, vec![])),
464 // Use `Reveal::All` here because patterns are always monomorphic even if their function
466 let param_env_reveal_all = self.param_env.with_reveal_all_normalized(self.tcx);
467 let substs = self.typeck_results.node_substs(id);
468 let instance = match ty::Instance::resolve(self.tcx, param_env_reveal_all, def_id, substs) {
471 // It should be assoc consts if there's no error but we cannot resolve it.
472 debug_assert!(is_associated_const);
474 self.errors.push(PatternError::AssocConstInPattern(span));
476 return pat_from_kind(PatKind::Wild);
480 self.tcx.sess.span_err(span, "could not evaluate constant pattern");
481 return pat_from_kind(PatKind::Wild);
485 // `mir_const_qualif` must be called with the `DefId` of the item where the const is
486 // defined, not where it is declared. The difference is significant for associated
488 let mir_structural_match_violation = self.tcx.mir_const_qualif(instance.def_id()).custom_eq;
489 debug!("mir_structural_match_violation({:?}) -> {}", qpath, mir_structural_match_violation);
491 match self.tcx.const_eval_instance(param_env_reveal_all, instance, Some(span)) {
494 ty::Const::from_value(self.tcx, value, self.typeck_results.node_type(id));
496 let pattern = self.const_to_pat(&const_, id, span, mir_structural_match_violation);
498 if !is_associated_const {
502 let user_provided_types = self.typeck_results().user_provided_types();
503 if let Some(u_ty) = user_provided_types.get(id) {
504 let user_ty = PatTyProj::from_user_type(*u_ty);
507 kind: Box::new(PatKind::AscribeUserType {
509 ascription: Ascription {
510 /// Note that use `Contravariant` here. See the
511 /// `variance` field documentation for details.
512 variance: ty::Variance::Contravariant,
523 Err(ErrorHandled::TooGeneric) => {
524 // While `Reported | Linted` cases will have diagnostics emitted already
525 // it is not true for TooGeneric case, so we need to give user more information.
526 self.tcx.sess.span_err(span, "constant pattern depends on a generic parameter");
527 pat_from_kind(PatKind::Wild)
530 self.tcx.sess.span_err(span, "could not evaluate constant pattern");
531 pat_from_kind(PatKind::Wild)
536 /// Converts literals, paths and negation of literals to patterns.
537 /// The special case for negation exists to allow things like `-128_i8`
538 /// which would overflow if we tried to evaluate `128_i8` and then negate
540 fn lower_lit(&mut self, expr: &'tcx hir::Expr<'tcx>) -> PatKind<'tcx> {
541 if let hir::ExprKind::Path(ref qpath) = expr.kind {
542 *self.lower_path(qpath, expr.hir_id, expr.span).kind
544 let (lit, neg) = match expr.kind {
545 hir::ExprKind::ConstBlock(ref anon_const) => {
546 let anon_const_def_id = self.tcx.hir().local_def_id(anon_const.hir_id);
547 let value = ty::Const::from_anon_const(self.tcx, anon_const_def_id);
548 if matches!(value.val, ConstKind::Param(_)) {
549 let span = self.tcx.hir().span(anon_const.hir_id);
550 self.errors.push(PatternError::ConstParamInPattern(span));
551 return PatKind::Wild;
553 return *self.const_to_pat(value, expr.hir_id, expr.span, false).kind;
555 hir::ExprKind::Lit(ref lit) => (lit, false),
556 hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => {
557 let lit = match expr.kind {
558 hir::ExprKind::Lit(ref lit) => lit,
559 _ => span_bug!(expr.span, "not a literal: {:?}", expr),
563 _ => span_bug!(expr.span, "not a literal: {:?}", expr),
567 LitToConstInput { lit: &lit.node, ty: self.typeck_results.expr_ty(expr), neg };
568 match self.tcx.at(expr.span).lit_to_const(lit_input) {
569 Ok(val) => *self.const_to_pat(val, expr.hir_id, lit.span, false).kind,
570 Err(LitToConstError::Reported) => PatKind::Wild,
571 Err(LitToConstError::TypeError) => bug!("lower_lit: had type error"),
577 impl<'tcx> UserAnnotatedTyHelpers<'tcx> for PatCtxt<'_, 'tcx> {
578 fn tcx(&self) -> TyCtxt<'tcx> {
582 fn typeck_results(&self) -> &ty::TypeckResults<'tcx> {
587 crate trait PatternFoldable<'tcx>: Sized {
588 fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
589 self.super_fold_with(folder)
592 fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self;
595 crate trait PatternFolder<'tcx>: Sized {
596 fn fold_pattern(&mut self, pattern: &Pat<'tcx>) -> Pat<'tcx> {
597 pattern.super_fold_with(self)
600 fn fold_pattern_kind(&mut self, kind: &PatKind<'tcx>) -> PatKind<'tcx> {
601 kind.super_fold_with(self)
605 impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Box<T> {
606 fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
607 let content: T = (**self).fold_with(folder);
612 impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Vec<T> {
613 fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
614 self.iter().map(|t| t.fold_with(folder)).collect()
618 impl<'tcx, T: PatternFoldable<'tcx>> PatternFoldable<'tcx> for Option<T> {
619 fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
620 self.as_ref().map(|t| t.fold_with(folder))
624 macro_rules! CloneImpls {
625 (<$lt_tcx:tt> $($ty:ty),+) => {
627 impl<$lt_tcx> PatternFoldable<$lt_tcx> for $ty {
628 fn super_fold_with<F: PatternFolder<$lt_tcx>>(&self, _: &mut F) -> Self {
637 Span, Field, Mutability, Symbol, hir::HirId, usize, ty::Const<'tcx>,
638 Region<'tcx>, Ty<'tcx>, BindingMode, &'tcx AdtDef,
639 SubstsRef<'tcx>, &'tcx GenericArg<'tcx>, UserType<'tcx>,
640 UserTypeProjection, PatTyProj<'tcx>
643 impl<'tcx> PatternFoldable<'tcx> for FieldPat<'tcx> {
644 fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
645 FieldPat { field: self.field.fold_with(folder), pattern: self.pattern.fold_with(folder) }
649 impl<'tcx> PatternFoldable<'tcx> for Pat<'tcx> {
650 fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
651 folder.fold_pattern(self)
654 fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
656 ty: self.ty.fold_with(folder),
657 span: self.span.fold_with(folder),
658 kind: self.kind.fold_with(folder),
663 impl<'tcx> PatternFoldable<'tcx> for PatKind<'tcx> {
664 fn fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
665 folder.fold_pattern_kind(self)
668 fn super_fold_with<F: PatternFolder<'tcx>>(&self, folder: &mut F) -> Self {
670 PatKind::Wild => PatKind::Wild,
671 PatKind::AscribeUserType {
673 ascription: Ascription { variance, ref user_ty, user_ty_span },
674 } => PatKind::AscribeUserType {
675 subpattern: subpattern.fold_with(folder),
676 ascription: Ascription {
677 user_ty: user_ty.fold_with(folder),
682 PatKind::Binding { mutability, name, mode, var, ty, ref subpattern, is_primary } => {
684 mutability: mutability.fold_with(folder),
685 name: name.fold_with(folder),
686 mode: mode.fold_with(folder),
687 var: var.fold_with(folder),
688 ty: ty.fold_with(folder),
689 subpattern: subpattern.fold_with(folder),
693 PatKind::Variant { adt_def, substs, variant_index, ref subpatterns } => {
695 adt_def: adt_def.fold_with(folder),
696 substs: substs.fold_with(folder),
698 subpatterns: subpatterns.fold_with(folder),
701 PatKind::Leaf { ref subpatterns } => {
702 PatKind::Leaf { subpatterns: subpatterns.fold_with(folder) }
704 PatKind::Deref { ref subpattern } => {
705 PatKind::Deref { subpattern: subpattern.fold_with(folder) }
707 PatKind::Constant { value } => PatKind::Constant { value },
708 PatKind::Range(range) => PatKind::Range(range),
709 PatKind::Slice { ref prefix, ref slice, ref suffix } => PatKind::Slice {
710 prefix: prefix.fold_with(folder),
711 slice: slice.fold_with(folder),
712 suffix: suffix.fold_with(folder),
714 PatKind::Array { ref prefix, ref slice, ref suffix } => PatKind::Array {
715 prefix: prefix.fold_with(folder),
716 slice: slice.fold_with(folder),
717 suffix: suffix.fold_with(folder),
719 PatKind::Or { ref pats } => PatKind::Or { pats: pats.fold_with(folder) },
724 crate fn compare_const_vals<'tcx>(
726 a: &'tcx ty::Const<'tcx>,
727 b: &'tcx ty::Const<'tcx>,
728 param_env: ty::ParamEnv<'tcx>,
730 ) -> Option<Ordering> {
731 trace!("compare_const_vals: {:?}, {:?}", a, b);
733 let from_bool = |v: bool| v.then_some(Ordering::Equal);
735 let fallback = || from_bool(a == b);
737 // Use the fallback if any type differs
738 if a.ty != b.ty || a.ty != ty {
742 // Early return for equal constants (so e.g. references to ZSTs can be compared, even if they
743 // are just integer addresses).
745 return from_bool(true);
748 let a_bits = a.try_eval_bits(tcx, param_env, ty);
749 let b_bits = b.try_eval_bits(tcx, param_env, ty);
751 if let (Some(a), Some(b)) = (a_bits, b_bits) {
752 use rustc_apfloat::Float;
753 return match *ty.kind() {
754 ty::Float(ty::FloatTy::F32) => {
755 let l = rustc_apfloat::ieee::Single::from_bits(a);
756 let r = rustc_apfloat::ieee::Single::from_bits(b);
759 ty::Float(ty::FloatTy::F64) => {
760 let l = rustc_apfloat::ieee::Double::from_bits(a);
761 let r = rustc_apfloat::ieee::Double::from_bits(b);
765 use rustc_middle::ty::layout::IntegerExt;
766 let size = rustc_target::abi::Integer::from_int_ty(&tcx, ity).size();
767 let a = size.sign_extend(a);
768 let b = size.sign_extend(b);
769 Some((a as i128).cmp(&(b as i128)))
771 _ => Some(a.cmp(&b)),
775 if let ty::Str = ty.kind() {
777 ty::ConstKind::Value(a_val @ ConstValue::Slice { .. }),
778 ty::ConstKind::Value(b_val @ ConstValue::Slice { .. }),
781 let a_bytes = get_slice_bytes(&tcx, a_val);
782 let b_bytes = get_slice_bytes(&tcx, b_val);
783 return from_bool(a_bytes == b_bytes);