diff options
Diffstat (limited to 'compiler/rustc_typeck/src/mem_categorization.rs')
-rw-r--r-- | compiler/rustc_typeck/src/mem_categorization.rs | 786 |
1 files changed, 0 insertions, 786 deletions
diff --git a/compiler/rustc_typeck/src/mem_categorization.rs b/compiler/rustc_typeck/src/mem_categorization.rs deleted file mode 100644 index ced919f66..000000000 --- a/compiler/rustc_typeck/src/mem_categorization.rs +++ /dev/null @@ -1,786 +0,0 @@ -//! # Categorization -//! -//! The job of the categorization module is to analyze an expression to -//! determine what kind of memory is used in evaluating it (for example, -//! where dereferences occur and what kind of pointer is dereferenced; -//! whether the memory is mutable, etc.). -//! -//! Categorization effectively transforms all of our expressions into -//! expressions of the following forms (the actual enum has many more -//! possibilities, naturally, but they are all variants of these base -//! forms): -//! ```ignore (not-rust) -//! E = rvalue // some computed rvalue -//! | x // address of a local variable or argument -//! | *E // deref of a ptr -//! | E.comp // access to an interior component -//! ``` -//! Imagine a routine ToAddr(Expr) that evaluates an expression and returns an -//! address where the result is to be found. If Expr is a place, then this -//! is the address of the place. If `Expr` is an rvalue, this is the address of -//! some temporary spot in memory where the result is stored. -//! -//! Now, `cat_expr()` classifies the expression `Expr` and the address `A = ToAddr(Expr)` -//! as follows: -//! -//! - `cat`: what kind of expression was this? This is a subset of the -//! full expression forms which only includes those that we care about -//! for the purpose of the analysis. -//! - `mutbl`: mutability of the address `A`. -//! - `ty`: the type of data found at the address `A`. -//! -//! The resulting categorization tree differs somewhat from the expressions -//! themselves. For example, auto-derefs are explicit. Also, an index `a[b]` is -//! decomposed into two operations: a dereference to reach the array data and -//! then an index to jump forward to the relevant item. -//! -//! ## By-reference upvars -//! -//! One part of the codegen which may be non-obvious is that we translate -//! closure upvars into the dereference of a borrowed pointer; this more closely -//! resembles the runtime codegen. So, for example, if we had: -//! -//! let mut x = 3; -//! let y = 5; -//! let inc = || x += y; -//! -//! Then when we categorize `x` (*within* the closure) we would yield a -//! result of `*x'`, effectively, where `x'` is a `Categorization::Upvar` reference -//! tied to `x`. The type of `x'` will be a borrowed pointer. - -use rustc_middle::hir::place::*; -use rustc_middle::ty::adjustment; -use rustc_middle::ty::fold::TypeFoldable; -use rustc_middle::ty::visit::TypeVisitable; -use rustc_middle::ty::{self, Ty, TyCtxt}; - -use rustc_data_structures::fx::FxIndexMap; -use rustc_hir as hir; -use rustc_hir::def::{CtorOf, DefKind, Res}; -use rustc_hir::def_id::LocalDefId; -use rustc_hir::pat_util::EnumerateAndAdjustIterator; -use rustc_hir::PatKind; -use rustc_index::vec::Idx; -use rustc_infer::infer::InferCtxt; -use rustc_span::Span; -use rustc_target::abi::VariantIdx; -use rustc_trait_selection::infer::InferCtxtExt; - -pub(crate) trait HirNode { - fn hir_id(&self) -> hir::HirId; - fn span(&self) -> Span; -} - -impl HirNode for hir::Expr<'_> { - fn hir_id(&self) -> hir::HirId { - self.hir_id - } - fn span(&self) -> Span { - self.span - } -} - -impl HirNode for hir::Pat<'_> { - fn hir_id(&self) -> hir::HirId { - self.hir_id - } - fn span(&self) -> Span { - self.span - } -} - -#[derive(Clone)] -pub(crate) struct MemCategorizationContext<'a, 'tcx> { - pub(crate) typeck_results: &'a ty::TypeckResults<'tcx>, - infcx: &'a InferCtxt<'a, 'tcx>, - param_env: ty::ParamEnv<'tcx>, - body_owner: LocalDefId, - upvars: Option<&'tcx FxIndexMap<hir::HirId, hir::Upvar>>, -} - -pub(crate) type McResult<T> = Result<T, ()>; - -impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> { - /// Creates a `MemCategorizationContext`. - pub(crate) fn new( - infcx: &'a InferCtxt<'a, 'tcx>, - param_env: ty::ParamEnv<'tcx>, - body_owner: LocalDefId, - typeck_results: &'a ty::TypeckResults<'tcx>, - ) -> MemCategorizationContext<'a, 'tcx> { - MemCategorizationContext { - typeck_results, - infcx, - param_env, - body_owner, - upvars: infcx.tcx.upvars_mentioned(body_owner), - } - } - - pub(crate) fn tcx(&self) -> TyCtxt<'tcx> { - self.infcx.tcx - } - - pub(crate) fn type_is_copy_modulo_regions(&self, ty: Ty<'tcx>, span: Span) -> bool { - self.infcx.type_is_copy_modulo_regions(self.param_env, ty, span) - } - - fn resolve_vars_if_possible<T>(&self, value: T) -> T - where - T: TypeFoldable<'tcx>, - { - self.infcx.resolve_vars_if_possible(value) - } - - fn is_tainted_by_errors(&self) -> bool { - self.infcx.is_tainted_by_errors() - } - - fn resolve_type_vars_or_error( - &self, - id: hir::HirId, - ty: Option<Ty<'tcx>>, - ) -> McResult<Ty<'tcx>> { - match ty { - Some(ty) => { - let ty = self.resolve_vars_if_possible(ty); - if ty.references_error() || ty.is_ty_var() { - debug!("resolve_type_vars_or_error: error from {:?}", ty); - Err(()) - } else { - Ok(ty) - } - } - // FIXME - None if self.is_tainted_by_errors() => Err(()), - None => { - bug!( - "no type for node {}: {} in mem_categorization", - id, - self.tcx().hir().node_to_string(id) - ); - } - } - } - - pub(crate) fn node_ty(&self, hir_id: hir::HirId) -> McResult<Ty<'tcx>> { - self.resolve_type_vars_or_error(hir_id, self.typeck_results.node_type_opt(hir_id)) - } - - fn expr_ty(&self, expr: &hir::Expr<'_>) -> McResult<Ty<'tcx>> { - self.resolve_type_vars_or_error(expr.hir_id, self.typeck_results.expr_ty_opt(expr)) - } - - pub(crate) fn expr_ty_adjusted(&self, expr: &hir::Expr<'_>) -> McResult<Ty<'tcx>> { - self.resolve_type_vars_or_error(expr.hir_id, self.typeck_results.expr_ty_adjusted_opt(expr)) - } - - /// Returns the type of value that this pattern matches against. - /// Some non-obvious cases: - /// - /// - a `ref x` binding matches against a value of type `T` and gives - /// `x` the type `&T`; we return `T`. - /// - a pattern with implicit derefs (thanks to default binding - /// modes #42640) may look like `Some(x)` but in fact have - /// implicit deref patterns attached (e.g., it is really - /// `&Some(x)`). In that case, we return the "outermost" type - /// (e.g., `&Option<T>). - pub(crate) fn pat_ty_adjusted(&self, pat: &hir::Pat<'_>) -> McResult<Ty<'tcx>> { - // Check for implicit `&` types wrapping the pattern; note - // that these are never attached to binding patterns, so - // actually this is somewhat "disjoint" from the code below - // that aims to account for `ref x`. - if let Some(vec) = self.typeck_results.pat_adjustments().get(pat.hir_id) { - if let Some(first_ty) = vec.first() { - debug!("pat_ty(pat={:?}) found adjusted ty `{:?}`", pat, first_ty); - return Ok(*first_ty); - } - } - - self.pat_ty_unadjusted(pat) - } - - /// Like `pat_ty`, but ignores implicit `&` patterns. - fn pat_ty_unadjusted(&self, pat: &hir::Pat<'_>) -> McResult<Ty<'tcx>> { - let base_ty = self.node_ty(pat.hir_id)?; - debug!("pat_ty(pat={:?}) base_ty={:?}", pat, base_ty); - - // This code detects whether we are looking at a `ref x`, - // and if so, figures out what the type *being borrowed* is. - let ret_ty = match pat.kind { - PatKind::Binding(..) => { - let bm = *self - .typeck_results - .pat_binding_modes() - .get(pat.hir_id) - .expect("missing binding mode"); - - if let ty::BindByReference(_) = bm { - // a bind-by-ref means that the base_ty will be the type of the ident itself, - // but what we want here is the type of the underlying value being borrowed. - // So peel off one-level, turning the &T into T. - match base_ty.builtin_deref(false) { - Some(t) => t.ty, - None => { - debug!("By-ref binding of non-derefable type {:?}", base_ty); - return Err(()); - } - } - } else { - base_ty - } - } - _ => base_ty, - }; - debug!("pat_ty(pat={:?}) ret_ty={:?}", pat, ret_ty); - - Ok(ret_ty) - } - - pub(crate) fn cat_expr(&self, expr: &hir::Expr<'_>) -> McResult<PlaceWithHirId<'tcx>> { - // This recursion helper avoids going through *too many* - // adjustments, since *only* non-overloaded deref recurses. - fn helper<'a, 'tcx>( - mc: &MemCategorizationContext<'a, 'tcx>, - expr: &hir::Expr<'_>, - adjustments: &[adjustment::Adjustment<'tcx>], - ) -> McResult<PlaceWithHirId<'tcx>> { - match adjustments.split_last() { - None => mc.cat_expr_unadjusted(expr), - Some((adjustment, previous)) => { - mc.cat_expr_adjusted_with(expr, || helper(mc, expr, previous), adjustment) - } - } - } - - helper(self, expr, self.typeck_results.expr_adjustments(expr)) - } - - pub(crate) fn cat_expr_adjusted( - &self, - expr: &hir::Expr<'_>, - previous: PlaceWithHirId<'tcx>, - adjustment: &adjustment::Adjustment<'tcx>, - ) -> McResult<PlaceWithHirId<'tcx>> { - self.cat_expr_adjusted_with(expr, || Ok(previous), adjustment) - } - - fn cat_expr_adjusted_with<F>( - &self, - expr: &hir::Expr<'_>, - previous: F, - adjustment: &adjustment::Adjustment<'tcx>, - ) -> McResult<PlaceWithHirId<'tcx>> - where - F: FnOnce() -> McResult<PlaceWithHirId<'tcx>>, - { - debug!("cat_expr_adjusted_with({:?}): {:?}", adjustment, expr); - let target = self.resolve_vars_if_possible(adjustment.target); - match adjustment.kind { - adjustment::Adjust::Deref(overloaded) => { - // Equivalent to *expr or something similar. - let base = if let Some(deref) = overloaded { - let ref_ty = self - .tcx() - .mk_ref(deref.region, ty::TypeAndMut { ty: target, mutbl: deref.mutbl }); - self.cat_rvalue(expr.hir_id, expr.span, ref_ty) - } else { - previous()? - }; - self.cat_deref(expr, base) - } - - adjustment::Adjust::NeverToAny - | adjustment::Adjust::Pointer(_) - | adjustment::Adjust::Borrow(_) => { - // Result is an rvalue. - Ok(self.cat_rvalue(expr.hir_id, expr.span, target)) - } - } - } - - pub(crate) fn cat_expr_unadjusted( - &self, - expr: &hir::Expr<'_>, - ) -> McResult<PlaceWithHirId<'tcx>> { - debug!("cat_expr: id={} expr={:?}", expr.hir_id, expr); - - let expr_ty = self.expr_ty(expr)?; - match expr.kind { - hir::ExprKind::Unary(hir::UnOp::Deref, ref e_base) => { - if self.typeck_results.is_method_call(expr) { - self.cat_overloaded_place(expr, e_base) - } else { - let base = self.cat_expr(e_base)?; - self.cat_deref(expr, base) - } - } - - hir::ExprKind::Field(ref base, _) => { - let base = self.cat_expr(base)?; - debug!("cat_expr(cat_field): id={} expr={:?} base={:?}", expr.hir_id, expr, base); - - let field_idx = self - .typeck_results - .field_indices() - .get(expr.hir_id) - .cloned() - .expect("Field index not found"); - - Ok(self.cat_projection( - expr, - base, - expr_ty, - ProjectionKind::Field(field_idx as u32, VariantIdx::new(0)), - )) - } - - hir::ExprKind::Index(ref base, _) => { - if self.typeck_results.is_method_call(expr) { - // If this is an index implemented by a method call, then it - // will include an implicit deref of the result. - // The call to index() returns a `&T` value, which - // is an rvalue. That is what we will be - // dereferencing. - self.cat_overloaded_place(expr, base) - } else { - let base = self.cat_expr(base)?; - Ok(self.cat_projection(expr, base, expr_ty, ProjectionKind::Index)) - } - } - - hir::ExprKind::Path(ref qpath) => { - let res = self.typeck_results.qpath_res(qpath, expr.hir_id); - self.cat_res(expr.hir_id, expr.span, expr_ty, res) - } - - hir::ExprKind::Type(ref e, _) => self.cat_expr(e), - - hir::ExprKind::AddrOf(..) - | hir::ExprKind::Call(..) - | hir::ExprKind::Assign(..) - | hir::ExprKind::AssignOp(..) - | hir::ExprKind::Closure { .. } - | hir::ExprKind::Ret(..) - | hir::ExprKind::Unary(..) - | hir::ExprKind::Yield(..) - | hir::ExprKind::MethodCall(..) - | hir::ExprKind::Cast(..) - | hir::ExprKind::DropTemps(..) - | hir::ExprKind::Array(..) - | hir::ExprKind::If(..) - | hir::ExprKind::Tup(..) - | hir::ExprKind::Binary(..) - | hir::ExprKind::Block(..) - | hir::ExprKind::Let(..) - | hir::ExprKind::Loop(..) - | hir::ExprKind::Match(..) - | hir::ExprKind::Lit(..) - | hir::ExprKind::ConstBlock(..) - | hir::ExprKind::Break(..) - | hir::ExprKind::Continue(..) - | hir::ExprKind::Struct(..) - | hir::ExprKind::Repeat(..) - | hir::ExprKind::InlineAsm(..) - | hir::ExprKind::Box(..) - | hir::ExprKind::Err => Ok(self.cat_rvalue(expr.hir_id, expr.span, expr_ty)), - } - } - - pub(crate) fn cat_res( - &self, - hir_id: hir::HirId, - span: Span, - expr_ty: Ty<'tcx>, - res: Res, - ) -> McResult<PlaceWithHirId<'tcx>> { - debug!("cat_res: id={:?} expr={:?} def={:?}", hir_id, expr_ty, res); - - match res { - Res::Def( - DefKind::Ctor(..) - | DefKind::Const - | DefKind::ConstParam - | DefKind::AssocConst - | DefKind::Fn - | DefKind::AssocFn, - _, - ) - | Res::SelfCtor(..) => Ok(self.cat_rvalue(hir_id, span, expr_ty)), - - Res::Def(DefKind::Static(_), _) => { - Ok(PlaceWithHirId::new(hir_id, expr_ty, PlaceBase::StaticItem, Vec::new())) - } - - Res::Local(var_id) => { - if self.upvars.map_or(false, |upvars| upvars.contains_key(&var_id)) { - self.cat_upvar(hir_id, var_id) - } else { - Ok(PlaceWithHirId::new(hir_id, expr_ty, PlaceBase::Local(var_id), Vec::new())) - } - } - - def => span_bug!(span, "unexpected definition in memory categorization: {:?}", def), - } - } - - /// Categorize an upvar. - /// - /// Note: the actual upvar access contains invisible derefs of closure - /// environment and upvar reference as appropriate. Only regionck cares - /// about these dereferences, so we let it compute them as needed. - fn cat_upvar(&self, hir_id: hir::HirId, var_id: hir::HirId) -> McResult<PlaceWithHirId<'tcx>> { - let closure_expr_def_id = self.body_owner; - - let upvar_id = ty::UpvarId { - var_path: ty::UpvarPath { hir_id: var_id }, - closure_expr_id: closure_expr_def_id, - }; - let var_ty = self.node_ty(var_id)?; - - let ret = PlaceWithHirId::new(hir_id, var_ty, PlaceBase::Upvar(upvar_id), Vec::new()); - - debug!("cat_upvar ret={:?}", ret); - Ok(ret) - } - - pub(crate) fn cat_rvalue( - &self, - hir_id: hir::HirId, - span: Span, - expr_ty: Ty<'tcx>, - ) -> PlaceWithHirId<'tcx> { - debug!("cat_rvalue hir_id={:?}, expr_ty={:?}, span={:?}", hir_id, expr_ty, span); - let ret = PlaceWithHirId::new(hir_id, expr_ty, PlaceBase::Rvalue, Vec::new()); - debug!("cat_rvalue ret={:?}", ret); - ret - } - - pub(crate) fn cat_projection<N: HirNode>( - &self, - node: &N, - base_place: PlaceWithHirId<'tcx>, - ty: Ty<'tcx>, - kind: ProjectionKind, - ) -> PlaceWithHirId<'tcx> { - let mut projections = base_place.place.projections; - projections.push(Projection { kind, ty }); - let ret = PlaceWithHirId::new( - node.hir_id(), - base_place.place.base_ty, - base_place.place.base, - projections, - ); - debug!("cat_field ret {:?}", ret); - ret - } - - fn cat_overloaded_place( - &self, - expr: &hir::Expr<'_>, - base: &hir::Expr<'_>, - ) -> McResult<PlaceWithHirId<'tcx>> { - debug!("cat_overloaded_place(expr={:?}, base={:?})", expr, base); - - // Reconstruct the output assuming it's a reference with the - // same region and mutability as the receiver. This holds for - // `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`. - let place_ty = self.expr_ty(expr)?; - let base_ty = self.expr_ty_adjusted(base)?; - - let ty::Ref(region, _, mutbl) = *base_ty.kind() else { - span_bug!(expr.span, "cat_overloaded_place: base is not a reference"); - }; - let ref_ty = self.tcx().mk_ref(region, ty::TypeAndMut { ty: place_ty, mutbl }); - - let base = self.cat_rvalue(expr.hir_id, expr.span, ref_ty); - self.cat_deref(expr, base) - } - - fn cat_deref( - &self, - node: &impl HirNode, - base_place: PlaceWithHirId<'tcx>, - ) -> McResult<PlaceWithHirId<'tcx>> { - debug!("cat_deref: base_place={:?}", base_place); - - let base_curr_ty = base_place.place.ty(); - let deref_ty = match base_curr_ty.builtin_deref(true) { - Some(mt) => mt.ty, - None => { - debug!("explicit deref of non-derefable type: {:?}", base_curr_ty); - return Err(()); - } - }; - let mut projections = base_place.place.projections; - projections.push(Projection { kind: ProjectionKind::Deref, ty: deref_ty }); - - let ret = PlaceWithHirId::new( - node.hir_id(), - base_place.place.base_ty, - base_place.place.base, - projections, - ); - debug!("cat_deref ret {:?}", ret); - Ok(ret) - } - - pub(crate) fn cat_pattern<F>( - &self, - place: PlaceWithHirId<'tcx>, - pat: &hir::Pat<'_>, - mut op: F, - ) -> McResult<()> - where - F: FnMut(&PlaceWithHirId<'tcx>, &hir::Pat<'_>), - { - self.cat_pattern_(place, pat, &mut op) - } - - /// Returns the variant index for an ADT used within a Struct or TupleStruct pattern - /// Here `pat_hir_id` is the HirId of the pattern itself. - fn variant_index_for_adt( - &self, - qpath: &hir::QPath<'_>, - pat_hir_id: hir::HirId, - span: Span, - ) -> McResult<VariantIdx> { - let res = self.typeck_results.qpath_res(qpath, pat_hir_id); - let ty = self.typeck_results.node_type(pat_hir_id); - let ty::Adt(adt_def, _) = ty.kind() else { - self.tcx() - .sess - .delay_span_bug(span, "struct or tuple struct pattern not applied to an ADT"); - return Err(()); - }; - - match res { - Res::Def(DefKind::Variant, variant_id) => Ok(adt_def.variant_index_with_id(variant_id)), - Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_id) => { - Ok(adt_def.variant_index_with_ctor_id(variant_ctor_id)) - } - Res::Def(DefKind::Ctor(CtorOf::Struct, ..), _) - | Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _) - | Res::SelfCtor(..) - | Res::SelfTy { .. } => { - // Structs and Unions have only have one variant. - Ok(VariantIdx::new(0)) - } - _ => bug!("expected ADT path, found={:?}", res), - } - } - - /// Returns the total number of fields in an ADT variant used within a pattern. - /// Here `pat_hir_id` is the HirId of the pattern itself. - fn total_fields_in_adt_variant( - &self, - pat_hir_id: hir::HirId, - variant_index: VariantIdx, - span: Span, - ) -> McResult<usize> { - let ty = self.typeck_results.node_type(pat_hir_id); - match ty.kind() { - ty::Adt(adt_def, _) => Ok(adt_def.variant(variant_index).fields.len()), - _ => { - self.tcx() - .sess - .delay_span_bug(span, "struct or tuple struct pattern not applied to an ADT"); - Err(()) - } - } - } - - /// Returns the total number of fields in a tuple used within a Tuple pattern. - /// Here `pat_hir_id` is the HirId of the pattern itself. - fn total_fields_in_tuple(&self, pat_hir_id: hir::HirId, span: Span) -> McResult<usize> { - let ty = self.typeck_results.node_type(pat_hir_id); - match ty.kind() { - ty::Tuple(substs) => Ok(substs.len()), - _ => { - self.tcx().sess.delay_span_bug(span, "tuple pattern not applied to a tuple"); - Err(()) - } - } - } - - // FIXME(#19596) This is a workaround, but there should be a better way to do this - fn cat_pattern_<F>( - &self, - mut place_with_id: PlaceWithHirId<'tcx>, - pat: &hir::Pat<'_>, - op: &mut F, - ) -> McResult<()> - where - F: FnMut(&PlaceWithHirId<'tcx>, &hir::Pat<'_>), - { - // Here, `place` is the `PlaceWithHirId` being matched and pat is the pattern it - // is being matched against. - // - // In general, the way that this works is that we walk down the pattern, - // constructing a `PlaceWithHirId` that represents the path that will be taken - // to reach the value being matched. - - debug!("cat_pattern(pat={:?}, place_with_id={:?})", pat, place_with_id); - - // If (pattern) adjustments are active for this pattern, adjust the `PlaceWithHirId` correspondingly. - // `PlaceWithHirId`s are constructed differently from patterns. For example, in - // - // ``` - // match foo { - // &&Some(x, ) => { ... }, - // _ => { ... }, - // } - // ``` - // - // the pattern `&&Some(x,)` is represented as `Ref { Ref { TupleStruct }}`. To build the - // corresponding `PlaceWithHirId` we start with the `PlaceWithHirId` for `foo`, and then, by traversing the - // pattern, try to answer the question: given the address of `foo`, how is `x` reached? - // - // `&&Some(x,)` `place_foo` - // `&Some(x,)` `deref { place_foo}` - // `Some(x,)` `deref { deref { place_foo }}` - // (x,)` `field0 { deref { deref { place_foo }}}` <- resulting place - // - // The above example has no adjustments. If the code were instead the (after adjustments, - // equivalent) version - // - // ``` - // match foo { - // Some(x, ) => { ... }, - // _ => { ... }, - // } - // ``` - // - // Then we see that to get the same result, we must start with - // `deref { deref { place_foo }}` instead of `place_foo` since the pattern is now `Some(x,)` - // and not `&&Some(x,)`, even though its assigned type is that of `&&Some(x,)`. - for _ in 0..self.typeck_results.pat_adjustments().get(pat.hir_id).map_or(0, |v| v.len()) { - debug!("cat_pattern: applying adjustment to place_with_id={:?}", place_with_id); - place_with_id = self.cat_deref(pat, place_with_id)?; - } - let place_with_id = place_with_id; // lose mutability - debug!("cat_pattern: applied adjustment derefs to get place_with_id={:?}", place_with_id); - - // Invoke the callback, but only now, after the `place_with_id` has adjusted. - // - // To see that this makes sense, consider `match &Some(3) { Some(x) => { ... }}`. In that - // case, the initial `place_with_id` will be that for `&Some(3)` and the pattern is `Some(x)`. We - // don't want to call `op` with these incompatible values. As written, what happens instead - // is that `op` is called with the adjusted place (that for `*&Some(3)`) and the pattern - // `Some(x)` (which matches). Recursing once more, `*&Some(3)` and the pattern `Some(x)` - // result in the place `Downcast<Some>(*&Some(3)).0` associated to `x` and invoke `op` with - // that (where the `ref` on `x` is implied). - op(&place_with_id, pat); - - match pat.kind { - PatKind::Tuple(subpats, dots_pos) => { - // (p1, ..., pN) - let total_fields = self.total_fields_in_tuple(pat.hir_id, pat.span)?; - - for (i, subpat) in subpats.iter().enumerate_and_adjust(total_fields, dots_pos) { - let subpat_ty = self.pat_ty_adjusted(subpat)?; - let projection_kind = ProjectionKind::Field(i as u32, VariantIdx::new(0)); - let sub_place = - self.cat_projection(pat, place_with_id.clone(), subpat_ty, projection_kind); - self.cat_pattern_(sub_place, subpat, op)?; - } - } - - PatKind::TupleStruct(ref qpath, subpats, dots_pos) => { - // S(p1, ..., pN) - let variant_index = self.variant_index_for_adt(qpath, pat.hir_id, pat.span)?; - let total_fields = - self.total_fields_in_adt_variant(pat.hir_id, variant_index, pat.span)?; - - for (i, subpat) in subpats.iter().enumerate_and_adjust(total_fields, dots_pos) { - let subpat_ty = self.pat_ty_adjusted(subpat)?; - let projection_kind = ProjectionKind::Field(i as u32, variant_index); - let sub_place = - self.cat_projection(pat, place_with_id.clone(), subpat_ty, projection_kind); - self.cat_pattern_(sub_place, subpat, op)?; - } - } - - PatKind::Struct(ref qpath, field_pats, _) => { - // S { f1: p1, ..., fN: pN } - - let variant_index = self.variant_index_for_adt(qpath, pat.hir_id, pat.span)?; - - for fp in field_pats { - let field_ty = self.pat_ty_adjusted(fp.pat)?; - let field_index = self - .typeck_results - .field_indices() - .get(fp.hir_id) - .cloned() - .expect("no index for a field"); - - let field_place = self.cat_projection( - pat, - place_with_id.clone(), - field_ty, - ProjectionKind::Field(field_index as u32, variant_index), - ); - self.cat_pattern_(field_place, fp.pat, op)?; - } - } - - PatKind::Or(pats) => { - for pat in pats { - self.cat_pattern_(place_with_id.clone(), pat, op)?; - } - } - - PatKind::Binding(.., Some(ref subpat)) => { - self.cat_pattern_(place_with_id, subpat, op)?; - } - - PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => { - // box p1, &p1, &mut p1. we can ignore the mutability of - // PatKind::Ref since that information is already contained - // in the type. - let subplace = self.cat_deref(pat, place_with_id)?; - self.cat_pattern_(subplace, subpat, op)?; - } - - PatKind::Slice(before, ref slice, after) => { - let Some(element_ty) = place_with_id.place.ty().builtin_index() else { - debug!("explicit index of non-indexable type {:?}", place_with_id); - return Err(()); - }; - let elt_place = self.cat_projection( - pat, - place_with_id.clone(), - element_ty, - ProjectionKind::Index, - ); - for before_pat in before { - self.cat_pattern_(elt_place.clone(), before_pat, op)?; - } - if let Some(ref slice_pat) = *slice { - let slice_pat_ty = self.pat_ty_adjusted(slice_pat)?; - let slice_place = self.cat_projection( - pat, - place_with_id, - slice_pat_ty, - ProjectionKind::Subslice, - ); - self.cat_pattern_(slice_place, slice_pat, op)?; - } - for after_pat in after { - self.cat_pattern_(elt_place.clone(), after_pat, op)?; - } - } - - PatKind::Path(_) - | PatKind::Binding(.., None) - | PatKind::Lit(..) - | PatKind::Range(..) - | PatKind::Wild => { - // always ok - } - } - - Ok(()) - } -} |