3 //! The job of the categorization module is to analyze an expression to
4 //! determine what kind of memory is used in evaluating it (for example,
5 //! where dereferences occur and what kind of pointer is dereferenced;
6 //! whether the memory is mutable, etc.).
8 //! Categorization effectively transforms all of our expressions into
9 //! expressions of the following forms (the actual enum has many more
10 //! possibilities, naturally, but they are all variants of these base
12 //! ```ignore (not-rust)
13 //! E = rvalue // some computed rvalue
14 //! | x // address of a local variable or argument
15 //! | *E // deref of a ptr
16 //! | E.comp // access to an interior component
18 //! Imagine a routine ToAddr(Expr) that evaluates an expression and returns an
19 //! address where the result is to be found. If Expr is a place, then this
20 //! is the address of the place. If `Expr` is an rvalue, this is the address of
21 //! some temporary spot in memory where the result is stored.
23 //! Now, `cat_expr()` classifies the expression `Expr` and the address `A = ToAddr(Expr)`
26 //! - `cat`: what kind of expression was this? This is a subset of the
27 //! full expression forms which only includes those that we care about
28 //! for the purpose of the analysis.
29 //! - `mutbl`: mutability of the address `A`.
30 //! - `ty`: the type of data found at the address `A`.
32 //! The resulting categorization tree differs somewhat from the expressions
33 //! themselves. For example, auto-derefs are explicit. Also, an index `a[b]` is
34 //! decomposed into two operations: a dereference to reach the array data and
35 //! then an index to jump forward to the relevant item.
37 //! ## By-reference upvars
39 //! One part of the codegen which may be non-obvious is that we translate
40 //! closure upvars into the dereference of a borrowed pointer; this more closely
41 //! resembles the runtime codegen. So, for example, if we had:
45 //! let inc = || x += y;
47 //! Then when we categorize `x` (*within* the closure) we would yield a
48 //! result of `*x'`, effectively, where `x'` is a `Categorization::Upvar` reference
49 //! tied to `x`. The type of `x'` will be a borrowed pointer.
51 use rustc_middle::hir::place::*;
52 use rustc_middle::ty::adjustment;
53 use rustc_middle::ty::fold::TypeFoldable;
54 use rustc_middle::ty::visit::TypeVisitable;
55 use rustc_middle::ty::{self, Ty, TyCtxt};
57 use rustc_data_structures::fx::FxIndexMap;
59 use rustc_hir::def::{CtorOf, DefKind, Res};
60 use rustc_hir::def_id::LocalDefId;
61 use rustc_hir::pat_util::EnumerateAndAdjustIterator;
62 use rustc_hir::PatKind;
63 use rustc_index::vec::Idx;
64 use rustc_infer::infer::InferCtxt;
66 use rustc_target::abi::VariantIdx;
67 use rustc_trait_selection::infer::InferCtxtExt;
69 pub(crate) trait HirNode {
70 fn hir_id(&self) -> hir::HirId;
71 fn span(&self) -> Span;
74 impl HirNode for hir::Expr<'_> {
75 fn hir_id(&self) -> hir::HirId {
78 fn span(&self) -> Span {
83 impl HirNode for hir::Pat<'_> {
84 fn hir_id(&self) -> hir::HirId {
87 fn span(&self) -> Span {
93 pub(crate) struct MemCategorizationContext<'a, 'tcx> {
94 pub(crate) typeck_results: &'a ty::TypeckResults<'tcx>,
95 infcx: &'a InferCtxt<'tcx>,
96 param_env: ty::ParamEnv<'tcx>,
97 body_owner: LocalDefId,
98 upvars: Option<&'tcx FxIndexMap<hir::HirId, hir::Upvar>>,
101 pub(crate) type McResult<T> = Result<T, ()>;
103 impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
104 /// Creates a `MemCategorizationContext`.
106 infcx: &'a InferCtxt<'tcx>,
107 param_env: ty::ParamEnv<'tcx>,
108 body_owner: LocalDefId,
109 typeck_results: &'a ty::TypeckResults<'tcx>,
110 ) -> MemCategorizationContext<'a, 'tcx> {
111 MemCategorizationContext {
116 upvars: infcx.tcx.upvars_mentioned(body_owner),
120 pub(crate) fn tcx(&self) -> TyCtxt<'tcx> {
124 pub(crate) fn type_is_copy_modulo_regions(&self, ty: Ty<'tcx>, span: Span) -> bool {
125 self.infcx.type_is_copy_modulo_regions(self.param_env, ty, span)
128 fn resolve_vars_if_possible<T>(&self, value: T) -> T
130 T: TypeFoldable<'tcx>,
132 self.infcx.resolve_vars_if_possible(value)
135 fn is_tainted_by_errors(&self) -> bool {
136 self.infcx.is_tainted_by_errors().is_some()
139 fn resolve_type_vars_or_error(
142 ty: Option<Ty<'tcx>>,
143 ) -> McResult<Ty<'tcx>> {
146 let ty = self.resolve_vars_if_possible(ty);
147 if ty.references_error() || ty.is_ty_var() {
148 debug!("resolve_type_vars_or_error: error from {:?}", ty);
155 None if self.is_tainted_by_errors() => Err(()),
158 "no type for node {}: {} in mem_categorization",
160 self.tcx().hir().node_to_string(id)
166 pub(crate) fn node_ty(&self, hir_id: hir::HirId) -> McResult<Ty<'tcx>> {
167 self.resolve_type_vars_or_error(hir_id, self.typeck_results.node_type_opt(hir_id))
170 fn expr_ty(&self, expr: &hir::Expr<'_>) -> McResult<Ty<'tcx>> {
171 self.resolve_type_vars_or_error(expr.hir_id, self.typeck_results.expr_ty_opt(expr))
174 pub(crate) fn expr_ty_adjusted(&self, expr: &hir::Expr<'_>) -> McResult<Ty<'tcx>> {
175 self.resolve_type_vars_or_error(expr.hir_id, self.typeck_results.expr_ty_adjusted_opt(expr))
178 /// Returns the type of value that this pattern matches against.
179 /// Some non-obvious cases:
181 /// - a `ref x` binding matches against a value of type `T` and gives
182 /// `x` the type `&T`; we return `T`.
183 /// - a pattern with implicit derefs (thanks to default binding
184 /// modes #42640) may look like `Some(x)` but in fact have
185 /// implicit deref patterns attached (e.g., it is really
186 /// `&Some(x)`). In that case, we return the "outermost" type
187 /// (e.g., `&Option<T>`).
188 pub(crate) fn pat_ty_adjusted(&self, pat: &hir::Pat<'_>) -> McResult<Ty<'tcx>> {
189 // Check for implicit `&` types wrapping the pattern; note
190 // that these are never attached to binding patterns, so
191 // actually this is somewhat "disjoint" from the code below
192 // that aims to account for `ref x`.
193 if let Some(vec) = self.typeck_results.pat_adjustments().get(pat.hir_id) {
194 if let Some(first_ty) = vec.first() {
195 debug!("pat_ty(pat={:?}) found adjusted ty `{:?}`", pat, first_ty);
196 return Ok(*first_ty);
200 self.pat_ty_unadjusted(pat)
203 /// Like `pat_ty`, but ignores implicit `&` patterns.
204 fn pat_ty_unadjusted(&self, pat: &hir::Pat<'_>) -> McResult<Ty<'tcx>> {
205 let base_ty = self.node_ty(pat.hir_id)?;
206 debug!("pat_ty(pat={:?}) base_ty={:?}", pat, base_ty);
208 // This code detects whether we are looking at a `ref x`,
209 // and if so, figures out what the type *being borrowed* is.
210 let ret_ty = match pat.kind {
211 PatKind::Binding(..) => {
216 .expect("missing binding mode");
218 if let ty::BindByReference(_) = bm {
219 // a bind-by-ref means that the base_ty will be the type of the ident itself,
220 // but what we want here is the type of the underlying value being borrowed.
221 // So peel off one-level, turning the &T into T.
222 match base_ty.builtin_deref(false) {
225 debug!("By-ref binding of non-derefable type {:?}", base_ty);
235 debug!("pat_ty(pat={:?}) ret_ty={:?}", pat, ret_ty);
240 pub(crate) fn cat_expr(&self, expr: &hir::Expr<'_>) -> McResult<PlaceWithHirId<'tcx>> {
241 // This recursion helper avoids going through *too many*
242 // adjustments, since *only* non-overloaded deref recurses.
244 mc: &MemCategorizationContext<'a, 'tcx>,
245 expr: &hir::Expr<'_>,
246 adjustments: &[adjustment::Adjustment<'tcx>],
247 ) -> McResult<PlaceWithHirId<'tcx>> {
248 match adjustments.split_last() {
249 None => mc.cat_expr_unadjusted(expr),
250 Some((adjustment, previous)) => {
251 mc.cat_expr_adjusted_with(expr, || helper(mc, expr, previous), adjustment)
256 helper(self, expr, self.typeck_results.expr_adjustments(expr))
259 pub(crate) fn cat_expr_adjusted(
261 expr: &hir::Expr<'_>,
262 previous: PlaceWithHirId<'tcx>,
263 adjustment: &adjustment::Adjustment<'tcx>,
264 ) -> McResult<PlaceWithHirId<'tcx>> {
265 self.cat_expr_adjusted_with(expr, || Ok(previous), adjustment)
268 #[instrument(level = "debug", skip(self, previous))]
269 fn cat_expr_adjusted_with<F>(
271 expr: &hir::Expr<'_>,
273 adjustment: &adjustment::Adjustment<'tcx>,
274 ) -> McResult<PlaceWithHirId<'tcx>>
276 F: FnOnce() -> McResult<PlaceWithHirId<'tcx>>,
278 let target = self.resolve_vars_if_possible(adjustment.target);
279 match adjustment.kind {
280 adjustment::Adjust::Deref(overloaded) => {
281 // Equivalent to *expr or something similar.
282 let base = if let Some(deref) = overloaded {
285 .mk_ref(deref.region, ty::TypeAndMut { ty: target, mutbl: deref.mutbl });
286 self.cat_rvalue(expr.hir_id, expr.span, ref_ty)
290 self.cat_deref(expr, base)
293 adjustment::Adjust::NeverToAny
294 | adjustment::Adjust::Pointer(_)
295 | adjustment::Adjust::Borrow(_)
296 | adjustment::Adjust::DynStar => {
297 // Result is an rvalue.
298 Ok(self.cat_rvalue(expr.hir_id, expr.span, target))
303 #[instrument(level = "debug", skip(self))]
304 pub(crate) fn cat_expr_unadjusted(
306 expr: &hir::Expr<'_>,
307 ) -> McResult<PlaceWithHirId<'tcx>> {
308 debug!("cat_expr: id={} expr={:?}", expr.hir_id, expr);
310 let expr_ty = self.expr_ty(expr)?;
312 hir::ExprKind::Unary(hir::UnOp::Deref, ref e_base) => {
313 if self.typeck_results.is_method_call(expr) {
314 self.cat_overloaded_place(expr, e_base)
316 let base = self.cat_expr(e_base)?;
317 self.cat_deref(expr, base)
321 hir::ExprKind::Field(ref base, _) => {
322 let base = self.cat_expr(base)?;
323 debug!("cat_expr(cat_field): id={} expr={:?} base={:?}", expr.hir_id, expr, base);
330 .expect("Field index not found");
332 Ok(self.cat_projection(
336 ProjectionKind::Field(field_idx as u32, VariantIdx::new(0)),
340 hir::ExprKind::Index(ref base, _) => {
341 if self.typeck_results.is_method_call(expr) {
342 // If this is an index implemented by a method call, then it
343 // will include an implicit deref of the result.
344 // The call to index() returns a `&T` value, which
345 // is an rvalue. That is what we will be
347 self.cat_overloaded_place(expr, base)
349 let base = self.cat_expr(base)?;
350 Ok(self.cat_projection(expr, base, expr_ty, ProjectionKind::Index))
354 hir::ExprKind::Path(ref qpath) => {
355 let res = self.typeck_results.qpath_res(qpath, expr.hir_id);
356 self.cat_res(expr.hir_id, expr.span, expr_ty, res)
359 hir::ExprKind::Type(ref e, _) => self.cat_expr(e),
361 hir::ExprKind::AddrOf(..)
362 | hir::ExprKind::Call(..)
363 | hir::ExprKind::Assign(..)
364 | hir::ExprKind::AssignOp(..)
365 | hir::ExprKind::Closure { .. }
366 | hir::ExprKind::Ret(..)
367 | hir::ExprKind::Unary(..)
368 | hir::ExprKind::Yield(..)
369 | hir::ExprKind::MethodCall(..)
370 | hir::ExprKind::Cast(..)
371 | hir::ExprKind::DropTemps(..)
372 | hir::ExprKind::Array(..)
373 | hir::ExprKind::If(..)
374 | hir::ExprKind::Tup(..)
375 | hir::ExprKind::Binary(..)
376 | hir::ExprKind::Block(..)
377 | hir::ExprKind::Let(..)
378 | hir::ExprKind::Loop(..)
379 | hir::ExprKind::Match(..)
380 | hir::ExprKind::Lit(..)
381 | hir::ExprKind::ConstBlock(..)
382 | hir::ExprKind::Break(..)
383 | hir::ExprKind::Continue(..)
384 | hir::ExprKind::Struct(..)
385 | hir::ExprKind::Repeat(..)
386 | hir::ExprKind::InlineAsm(..)
387 | hir::ExprKind::Box(..)
388 | hir::ExprKind::Err => Ok(self.cat_rvalue(expr.hir_id, expr.span, expr_ty)),
392 #[instrument(level = "debug", skip(self, span))]
393 pub(crate) fn cat_res(
399 ) -> McResult<PlaceWithHirId<'tcx>> {
404 | DefKind::ConstParam
405 | DefKind::AssocConst
410 | Res::SelfCtor(..) => Ok(self.cat_rvalue(hir_id, span, expr_ty)),
412 Res::Def(DefKind::Static(_), _) => {
413 Ok(PlaceWithHirId::new(hir_id, expr_ty, PlaceBase::StaticItem, Vec::new()))
416 Res::Local(var_id) => {
417 if self.upvars.map_or(false, |upvars| upvars.contains_key(&var_id)) {
418 self.cat_upvar(hir_id, var_id)
420 Ok(PlaceWithHirId::new(hir_id, expr_ty, PlaceBase::Local(var_id), Vec::new()))
424 def => span_bug!(span, "unexpected definition in memory categorization: {:?}", def),
428 /// Categorize an upvar.
430 /// Note: the actual upvar access contains invisible derefs of closure
431 /// environment and upvar reference as appropriate. Only regionck cares
432 /// about these dereferences, so we let it compute them as needed.
433 fn cat_upvar(&self, hir_id: hir::HirId, var_id: hir::HirId) -> McResult<PlaceWithHirId<'tcx>> {
434 let closure_expr_def_id = self.body_owner;
436 let upvar_id = ty::UpvarId {
437 var_path: ty::UpvarPath { hir_id: var_id },
438 closure_expr_id: closure_expr_def_id,
440 let var_ty = self.node_ty(var_id)?;
442 let ret = PlaceWithHirId::new(hir_id, var_ty, PlaceBase::Upvar(upvar_id), Vec::new());
444 debug!("cat_upvar ret={:?}", ret);
448 pub(crate) fn cat_rvalue(
453 ) -> PlaceWithHirId<'tcx> {
454 debug!("cat_rvalue hir_id={:?}, expr_ty={:?}, span={:?}", hir_id, expr_ty, span);
455 let ret = PlaceWithHirId::new(hir_id, expr_ty, PlaceBase::Rvalue, Vec::new());
456 debug!("cat_rvalue ret={:?}", ret);
460 pub(crate) fn cat_projection<N: HirNode>(
463 base_place: PlaceWithHirId<'tcx>,
465 kind: ProjectionKind,
466 ) -> PlaceWithHirId<'tcx> {
467 let mut projections = base_place.place.projections;
468 projections.push(Projection { kind, ty });
469 let ret = PlaceWithHirId::new(
471 base_place.place.base_ty,
472 base_place.place.base,
475 debug!("cat_field ret {:?}", ret);
479 #[instrument(level = "debug", skip(self))]
480 fn cat_overloaded_place(
482 expr: &hir::Expr<'_>,
483 base: &hir::Expr<'_>,
484 ) -> McResult<PlaceWithHirId<'tcx>> {
485 // Reconstruct the output assuming it's a reference with the
486 // same region and mutability as the receiver. This holds for
487 // `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`.
488 let place_ty = self.expr_ty(expr)?;
489 let base_ty = self.expr_ty_adjusted(base)?;
491 let ty::Ref(region, _, mutbl) = *base_ty.kind() else {
492 span_bug!(expr.span, "cat_overloaded_place: base is not a reference");
494 let ref_ty = self.tcx().mk_ref(region, ty::TypeAndMut { ty: place_ty, mutbl });
496 let base = self.cat_rvalue(expr.hir_id, expr.span, ref_ty);
497 self.cat_deref(expr, base)
500 #[instrument(level = "debug", skip(self, node))]
504 base_place: PlaceWithHirId<'tcx>,
505 ) -> McResult<PlaceWithHirId<'tcx>> {
506 let base_curr_ty = base_place.place.ty();
507 let deref_ty = match base_curr_ty.builtin_deref(true) {
510 debug!("explicit deref of non-derefable type: {:?}", base_curr_ty);
514 let mut projections = base_place.place.projections;
515 projections.push(Projection { kind: ProjectionKind::Deref, ty: deref_ty });
517 let ret = PlaceWithHirId::new(
519 base_place.place.base_ty,
520 base_place.place.base,
523 debug!("cat_deref ret {:?}", ret);
527 pub(crate) fn cat_pattern<F>(
529 place: PlaceWithHirId<'tcx>,
534 F: FnMut(&PlaceWithHirId<'tcx>, &hir::Pat<'_>),
536 self.cat_pattern_(place, pat, &mut op)
539 /// Returns the variant index for an ADT used within a Struct or TupleStruct pattern
540 /// Here `pat_hir_id` is the HirId of the pattern itself.
541 fn variant_index_for_adt(
543 qpath: &hir::QPath<'_>,
544 pat_hir_id: hir::HirId,
546 ) -> McResult<VariantIdx> {
547 let res = self.typeck_results.qpath_res(qpath, pat_hir_id);
548 let ty = self.typeck_results.node_type(pat_hir_id);
549 let ty::Adt(adt_def, _) = ty.kind() else {
552 .delay_span_bug(span, "struct or tuple struct pattern not applied to an ADT");
557 Res::Def(DefKind::Variant, variant_id) => Ok(adt_def.variant_index_with_id(variant_id)),
558 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_id) => {
559 Ok(adt_def.variant_index_with_ctor_id(variant_ctor_id))
561 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), _)
562 | Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _)
564 | Res::SelfTyParam { .. }
565 | Res::SelfTyAlias { .. } => {
566 // Structs and Unions have only have one variant.
567 Ok(VariantIdx::new(0))
569 _ => bug!("expected ADT path, found={:?}", res),
573 /// Returns the total number of fields in an ADT variant used within a pattern.
574 /// Here `pat_hir_id` is the HirId of the pattern itself.
575 fn total_fields_in_adt_variant(
577 pat_hir_id: hir::HirId,
578 variant_index: VariantIdx,
580 ) -> McResult<usize> {
581 let ty = self.typeck_results.node_type(pat_hir_id);
583 ty::Adt(adt_def, _) => Ok(adt_def.variant(variant_index).fields.len()),
587 .delay_span_bug(span, "struct or tuple struct pattern not applied to an ADT");
593 /// Returns the total number of fields in a tuple used within a Tuple pattern.
594 /// Here `pat_hir_id` is the HirId of the pattern itself.
595 fn total_fields_in_tuple(&self, pat_hir_id: hir::HirId, span: Span) -> McResult<usize> {
596 let ty = self.typeck_results.node_type(pat_hir_id);
598 ty::Tuple(substs) => Ok(substs.len()),
600 self.tcx().sess.delay_span_bug(span, "tuple pattern not applied to a tuple");
606 // FIXME(#19596) This is a workaround, but there should be a better way to do this
609 mut place_with_id: PlaceWithHirId<'tcx>,
614 F: FnMut(&PlaceWithHirId<'tcx>, &hir::Pat<'_>),
616 // Here, `place` is the `PlaceWithHirId` being matched and pat is the pattern it
617 // is being matched against.
619 // In general, the way that this works is that we walk down the pattern,
620 // constructing a `PlaceWithHirId` that represents the path that will be taken
621 // to reach the value being matched.
623 debug!("cat_pattern(pat={:?}, place_with_id={:?})", pat, place_with_id);
625 // If (pattern) adjustments are active for this pattern, adjust the `PlaceWithHirId` correspondingly.
626 // `PlaceWithHirId`s are constructed differently from patterns. For example, in
630 // &&Some(x, ) => { ... },
635 // the pattern `&&Some(x,)` is represented as `Ref { Ref { TupleStruct }}`. To build the
636 // corresponding `PlaceWithHirId` we start with the `PlaceWithHirId` for `foo`, and then, by traversing the
637 // pattern, try to answer the question: given the address of `foo`, how is `x` reached?
639 // `&&Some(x,)` `place_foo`
640 // `&Some(x,)` `deref { place_foo}`
641 // `Some(x,)` `deref { deref { place_foo }}`
642 // (x,)` `field0 { deref { deref { place_foo }}}` <- resulting place
644 // The above example has no adjustments. If the code were instead the (after adjustments,
645 // equivalent) version
649 // Some(x, ) => { ... },
654 // Then we see that to get the same result, we must start with
655 // `deref { deref { place_foo }}` instead of `place_foo` since the pattern is now `Some(x,)`
656 // and not `&&Some(x,)`, even though its assigned type is that of `&&Some(x,)`.
657 for _ in 0..self.typeck_results.pat_adjustments().get(pat.hir_id).map_or(0, |v| v.len()) {
658 debug!("cat_pattern: applying adjustment to place_with_id={:?}", place_with_id);
659 place_with_id = self.cat_deref(pat, place_with_id)?;
661 let place_with_id = place_with_id; // lose mutability
662 debug!("cat_pattern: applied adjustment derefs to get place_with_id={:?}", place_with_id);
664 // Invoke the callback, but only now, after the `place_with_id` has adjusted.
666 // To see that this makes sense, consider `match &Some(3) { Some(x) => { ... }}`. In that
667 // case, the initial `place_with_id` will be that for `&Some(3)` and the pattern is `Some(x)`. We
668 // don't want to call `op` with these incompatible values. As written, what happens instead
669 // is that `op` is called with the adjusted place (that for `*&Some(3)`) and the pattern
670 // `Some(x)` (which matches). Recursing once more, `*&Some(3)` and the pattern `Some(x)`
671 // result in the place `Downcast<Some>(*&Some(3)).0` associated to `x` and invoke `op` with
672 // that (where the `ref` on `x` is implied).
673 op(&place_with_id, pat);
676 PatKind::Tuple(subpats, dots_pos) => {
678 let total_fields = self.total_fields_in_tuple(pat.hir_id, pat.span)?;
680 for (i, subpat) in subpats.iter().enumerate_and_adjust(total_fields, dots_pos) {
681 let subpat_ty = self.pat_ty_adjusted(subpat)?;
682 let projection_kind = ProjectionKind::Field(i as u32, VariantIdx::new(0));
684 self.cat_projection(pat, place_with_id.clone(), subpat_ty, projection_kind);
685 self.cat_pattern_(sub_place, subpat, op)?;
689 PatKind::TupleStruct(ref qpath, subpats, dots_pos) => {
691 let variant_index = self.variant_index_for_adt(qpath, pat.hir_id, pat.span)?;
693 self.total_fields_in_adt_variant(pat.hir_id, variant_index, pat.span)?;
695 for (i, subpat) in subpats.iter().enumerate_and_adjust(total_fields, dots_pos) {
696 let subpat_ty = self.pat_ty_adjusted(subpat)?;
697 let projection_kind = ProjectionKind::Field(i as u32, variant_index);
699 self.cat_projection(pat, place_with_id.clone(), subpat_ty, projection_kind);
700 self.cat_pattern_(sub_place, subpat, op)?;
704 PatKind::Struct(ref qpath, field_pats, _) => {
705 // S { f1: p1, ..., fN: pN }
707 let variant_index = self.variant_index_for_adt(qpath, pat.hir_id, pat.span)?;
709 for fp in field_pats {
710 let field_ty = self.pat_ty_adjusted(fp.pat)?;
711 let field_index = self
716 .expect("no index for a field");
718 let field_place = self.cat_projection(
720 place_with_id.clone(),
722 ProjectionKind::Field(field_index as u32, variant_index),
724 self.cat_pattern_(field_place, fp.pat, op)?;
728 PatKind::Or(pats) => {
730 self.cat_pattern_(place_with_id.clone(), pat, op)?;
734 PatKind::Binding(.., Some(ref subpat)) => {
735 self.cat_pattern_(place_with_id, subpat, op)?;
738 PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => {
739 // box p1, &p1, &mut p1. we can ignore the mutability of
740 // PatKind::Ref since that information is already contained
742 let subplace = self.cat_deref(pat, place_with_id)?;
743 self.cat_pattern_(subplace, subpat, op)?;
746 PatKind::Slice(before, ref slice, after) => {
747 let Some(element_ty) = place_with_id.place.ty().builtin_index() else {
748 debug!("explicit index of non-indexable type {:?}", place_with_id);
751 let elt_place = self.cat_projection(
753 place_with_id.clone(),
755 ProjectionKind::Index,
757 for before_pat in before {
758 self.cat_pattern_(elt_place.clone(), before_pat, op)?;
760 if let Some(ref slice_pat) = *slice {
761 let slice_pat_ty = self.pat_ty_adjusted(slice_pat)?;
762 let slice_place = self.cat_projection(
766 ProjectionKind::Subslice,
768 self.cat_pattern_(slice_place, slice_pat, op)?;
770 for after_pat in after {
771 self.cat_pattern_(elt_place.clone(), after_pat, op)?;
776 | PatKind::Binding(.., None)