1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 //! The job of the categorization module is to analyze an expression to
14 //! determine what kind of memory is used in evaluating it (for example,
15 //! where dereferences occur and what kind of pointer is dereferenced;
16 //! whether the memory is mutable; etc)
18 //! Categorization effectively transforms all of our expressions into
19 //! expressions of the following forms (the actual enum has many more
20 //! possibilities, naturally, but they are all variants of these base
23 //! E = rvalue // some computed rvalue
24 //! | x // address of a local variable or argument
25 //! | *E // deref of a ptr
26 //! | E.comp // access to an interior component
28 //! Imagine a routine ToAddr(Expr) that evaluates an expression and returns an
29 //! address where the result is to be found. If Expr is an lvalue, then this
30 //! is the address of the lvalue. If Expr is an rvalue, this is the address of
31 //! some temporary spot in memory where the result is stored.
33 //! Now, cat_expr() classifies the expression Expr and the address A=ToAddr(Expr)
36 //! - cat: what kind of expression was this? This is a subset of the
37 //! full expression forms which only includes those that we care about
38 //! for the purpose of the analysis.
39 //! - mutbl: mutability of the address A
40 //! - ty: the type of data found at the address A
42 //! The resulting categorization tree differs somewhat from the expressions
43 //! themselves. For example, auto-derefs are explicit. Also, an index a[b] is
44 //! decomposed into two operations: a dereference to reach the array data and
45 //! then an index to jump forward to the relevant item.
47 //! ## By-reference upvars
49 //! One part of the translation which may be non-obvious is that we translate
50 //! closure upvars into the dereference of a borrowed pointer; this more closely
51 //! resembles the runtime translation. So, for example, if we had:
55 //! let inc = || x += y;
57 //! Then when we categorize `x` (*within* the closure) we would yield a
58 //! result of `*x'`, effectively, where `x'` is a `Categorization::Upvar` reference
59 //! tied to `x`. The type of `x'` will be a borrowed pointer.
61 #![allow(non_camel_case_types)]
63 pub use self::PointerKind::*;
64 pub use self::InteriorKind::*;
65 pub use self::FieldName::*;
66 pub use self::MutabilityCategory::*;
67 pub use self::AliasableReason::*;
68 pub use self::Note::*;
70 use self::Aliasability::*;
73 use hir::def_id::{DefId, DefIndex};
74 use hir::map as hir_map;
76 use hir::def::{Def, CtorKind};
78 use ty::{self, Ty, TyCtxt};
79 use ty::fold::TypeFoldable;
81 use hir::{MutImmutable, MutMutable, PatKind};
82 use hir::pat_util::EnumerateAndAdjustIterator;
89 use util::nodemap::ItemLocalMap;
91 #[derive(Clone, PartialEq)]
92 pub enum Categorization<'tcx> {
93 Rvalue(ty::Region<'tcx>), // temporary val, argument is its scope
95 Upvar(Upvar), // upvar referenced by closure env
96 Local(ast::NodeId), // local variable
97 Deref(cmt<'tcx>, PointerKind<'tcx>), // deref of a ptr
98 Interior(cmt<'tcx>, InteriorKind), // something interior: field, tuple, etc
99 Downcast(cmt<'tcx>, DefId), // selects a particular enum variant (*1)
101 // (*1) downcast is only required if the enum has more than one variant
104 // Represents any kind of upvar
105 #[derive(Clone, Copy, PartialEq)]
108 pub kind: ty::ClosureKind
111 // different kinds of pointers:
112 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
113 pub enum PointerKind<'tcx> {
118 BorrowedPtr(ty::BorrowKind, ty::Region<'tcx>),
121 UnsafePtr(hir::Mutability),
123 /// Implicit deref of the `&T` that results from an overloaded index `[]`.
124 Implicit(ty::BorrowKind, ty::Region<'tcx>),
127 // We use the term "interior" to mean "something reachable from the
128 // base without a pointer dereference", e.g. a field
129 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
130 pub enum InteriorKind {
131 InteriorField(FieldName),
132 InteriorElement(InteriorOffsetKind),
135 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
137 NamedField(ast::Name),
138 PositionalField(usize)
141 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
142 pub enum InteriorOffsetKind {
143 Index, // e.g. `array_expr[index_expr]`
144 Pattern, // e.g. `fn foo([_, a, _, _]: [A; 4]) { ... }`
147 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
148 pub enum MutabilityCategory {
149 McImmutable, // Immutable.
150 McDeclared, // Directly declared as mutable.
151 McInherited, // Inherited from the fact that owner is mutable.
154 // A note about the provenance of a `cmt`. This is used for
155 // special-case handling of upvars such as mutability inference.
156 // Upvar categorization can generate a variable number of nested
157 // derefs. The note allows detecting them without deep pattern
158 // matching on the categorization.
159 #[derive(Clone, Copy, PartialEq, Debug)]
161 NoteClosureEnv(ty::UpvarId), // Deref through closure env
162 NoteUpvarRef(ty::UpvarId), // Deref through by-ref upvar
163 NoteNone // Nothing special
166 // `cmt`: "Category, Mutability, and Type".
168 // a complete categorization of a value indicating where it originated
169 // and how it is located, as well as the mutability of the memory in
170 // which the value is stored.
172 // *WARNING* The field `cmt.type` is NOT necessarily the same as the
173 // result of `node_id_to_type(cmt.id)`. This is because the `id` is
174 // always the `id` of the node producing the type; in an expression
175 // like `*x`, the type of this deref node is the deref'd type (`T`),
176 // but in a pattern like `@x`, the `@x` pattern is again a
177 // dereference, but its type is the type *before* the dereference
178 // (`@T`). So use `cmt.ty` to find the type of the value in a consistent
179 // fashion. For more details, see the method `cat_pattern`
180 #[derive(Clone, PartialEq)]
181 pub struct cmt_<'tcx> {
182 pub id: ast::NodeId, // id of expr/pat producing this value
183 pub span: Span, // span of same expr/pat
184 pub cat: Categorization<'tcx>, // categorization of expr
185 pub mutbl: MutabilityCategory, // mutability of expr as lvalue
186 pub ty: Ty<'tcx>, // type of the expr (*see WARNING above*)
187 pub note: Note, // Note about the provenance of this cmt
190 pub type cmt<'tcx> = Rc<cmt_<'tcx>>;
192 pub enum ImmutabilityBlame<'tcx> {
193 ImmLocal(ast::NodeId),
194 ClosureEnv(DefIndex),
195 LocalDeref(ast::NodeId),
196 AdtFieldDeref(&'tcx ty::AdtDef, &'tcx ty::FieldDef)
199 impl<'tcx> cmt_<'tcx> {
200 fn resolve_field(&self, field_name: FieldName) -> Option<(&'tcx ty::AdtDef, &'tcx ty::FieldDef)>
202 let adt_def = match self.ty.sty {
203 ty::TyAdt(def, _) => def,
204 ty::TyTuple(..) => return None,
205 // closures get `Categorization::Upvar` rather than `Categorization::Interior`
206 _ => bug!("interior cmt {:?} is not an ADT", self)
208 let variant_def = match self.cat {
209 Categorization::Downcast(_, variant_did) => {
210 adt_def.variant_with_id(variant_did)
213 assert!(adt_def.is_univariant());
217 let field_def = match field_name {
218 NamedField(name) => variant_def.field_named(name),
219 PositionalField(idx) => &variant_def.fields[idx]
221 Some((adt_def, field_def))
224 pub fn immutability_blame(&self) -> Option<ImmutabilityBlame<'tcx>> {
226 Categorization::Deref(ref base_cmt, BorrowedPtr(ty::ImmBorrow, _)) |
227 Categorization::Deref(ref base_cmt, Implicit(ty::ImmBorrow, _)) => {
228 // try to figure out where the immutable reference came from
230 Categorization::Local(node_id) =>
231 Some(ImmutabilityBlame::LocalDeref(node_id)),
232 Categorization::Interior(ref base_cmt, InteriorField(field_name)) => {
233 base_cmt.resolve_field(field_name).map(|(adt_def, field_def)| {
234 ImmutabilityBlame::AdtFieldDeref(adt_def, field_def)
237 Categorization::Upvar(Upvar { id, .. }) => {
238 if let NoteClosureEnv(..) = self.note {
239 Some(ImmutabilityBlame::ClosureEnv(id.closure_expr_id))
247 Categorization::Local(node_id) => {
248 Some(ImmutabilityBlame::ImmLocal(node_id))
250 Categorization::Rvalue(..) |
251 Categorization::Upvar(..) |
252 Categorization::Deref(_, UnsafePtr(..)) => {
253 // This should not be reachable up to inference limitations.
256 Categorization::Interior(ref base_cmt, _) |
257 Categorization::Downcast(ref base_cmt, _) |
258 Categorization::Deref(ref base_cmt, _) => {
259 base_cmt.immutability_blame()
261 Categorization::StaticItem => {
262 // Do we want to do something here?
270 fn id(&self) -> ast::NodeId;
271 fn span(&self) -> Span;
274 impl ast_node for hir::Expr {
275 fn id(&self) -> ast::NodeId { self.id }
276 fn span(&self) -> Span { self.span }
279 impl ast_node for hir::Pat {
280 fn id(&self) -> ast::NodeId { self.id }
281 fn span(&self) -> Span { self.span }
285 pub struct MemCategorizationContext<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
286 pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
287 pub region_scope_tree: &'a region::ScopeTree,
288 pub tables: &'a ty::TypeckTables<'tcx>,
289 rvalue_promotable_map: Option<Rc<ItemLocalMap<bool>>>,
290 infcx: Option<&'a InferCtxt<'a, 'gcx, 'tcx>>,
293 pub type McResult<T> = Result<T, ()>;
295 impl MutabilityCategory {
296 pub fn from_mutbl(m: hir::Mutability) -> MutabilityCategory {
298 MutImmutable => McImmutable,
299 MutMutable => McDeclared
301 debug!("MutabilityCategory::{}({:?}) => {:?}",
302 "from_mutbl", m, ret);
306 pub fn from_borrow_kind(borrow_kind: ty::BorrowKind) -> MutabilityCategory {
307 let ret = match borrow_kind {
308 ty::ImmBorrow => McImmutable,
309 ty::UniqueImmBorrow => McImmutable,
310 ty::MutBorrow => McDeclared,
312 debug!("MutabilityCategory::{}({:?}) => {:?}",
313 "from_borrow_kind", borrow_kind, ret);
317 fn from_pointer_kind(base_mutbl: MutabilityCategory,
318 ptr: PointerKind) -> MutabilityCategory {
319 let ret = match ptr {
323 BorrowedPtr(borrow_kind, _) | Implicit(borrow_kind, _) => {
324 MutabilityCategory::from_borrow_kind(borrow_kind)
327 MutabilityCategory::from_mutbl(m)
330 debug!("MutabilityCategory::{}({:?}, {:?}) => {:?}",
331 "from_pointer_kind", base_mutbl, ptr, ret);
335 fn from_local(tcx: TyCtxt, tables: &ty::TypeckTables, id: ast::NodeId) -> MutabilityCategory {
336 let ret = match tcx.hir.get(id) {
337 hir_map::NodeBinding(p) => match p.node {
338 PatKind::Binding(..) => {
339 let bm = *tables.pat_binding_modes()
341 .expect("missing binding mode");
342 if bm == ty::BindByValue(hir::MutMutable) {
348 _ => span_bug!(p.span, "expected identifier pattern")
350 _ => span_bug!(tcx.hir.span(id), "expected identifier pattern")
352 debug!("MutabilityCategory::{}(tcx, id={:?}) => {:?}",
353 "from_local", id, ret);
357 pub fn inherit(&self) -> MutabilityCategory {
358 let ret = match *self {
359 McImmutable => McImmutable,
360 McDeclared => McInherited,
361 McInherited => McInherited,
363 debug!("{:?}.inherit() => {:?}", self, ret);
367 pub fn is_mutable(&self) -> bool {
368 let ret = match *self {
369 McImmutable => false,
373 debug!("{:?}.is_mutable() => {:?}", self, ret);
377 pub fn is_immutable(&self) -> bool {
378 let ret = match *self {
380 McDeclared | McInherited => false
382 debug!("{:?}.is_immutable() => {:?}", self, ret);
386 pub fn to_user_str(&self) -> &'static str {
388 McDeclared | McInherited => "mutable",
389 McImmutable => "immutable",
394 impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx, 'tcx> {
395 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
396 region_scope_tree: &'a region::ScopeTree,
397 tables: &'a ty::TypeckTables<'tcx>,
398 rvalue_promotable_map: Option<Rc<ItemLocalMap<bool>>>)
399 -> MemCategorizationContext<'a, 'tcx, 'tcx> {
400 MemCategorizationContext {
404 rvalue_promotable_map,
410 impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
411 /// Creates a `MemCategorizationContext` during type inference.
412 /// This is used during upvar analysis and a few other places.
413 /// Because the typeck tables are not yet complete, the results
414 /// from the analysis must be used with caution:
416 /// - rvalue promotions are not known, so the lifetimes of
417 /// temporaries may be overly conservative;
418 /// - similarly, as the results of upvar analysis are not yet
419 /// known, the results around upvar accesses may be incorrect.
420 pub fn with_infer(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
421 region_scope_tree: &'a region::ScopeTree,
422 tables: &'a ty::TypeckTables<'tcx>)
423 -> MemCategorizationContext<'a, 'gcx, 'tcx> {
426 // Subtle: we can't do rvalue promotion analysis until the
427 // typeck phase is complete, which means that you can't trust
428 // the rvalue lifetimes that result, but that's ok, since we
429 // don't need to know those during type inference.
430 let rvalue_promotable_map = None;
432 MemCategorizationContext {
436 rvalue_promotable_map,
441 pub fn type_moves_by_default(&self,
442 param_env: ty::ParamEnv<'tcx>,
446 self.infcx.map(|infcx| infcx.type_moves_by_default(param_env, ty, span))
448 self.tcx.lift_to_global(&(param_env, ty)).map(|(param_env, ty)| {
449 ty.moves_by_default(self.tcx.global_tcx(), param_env, span)
455 fn resolve_type_vars_if_possible<T>(&self, value: &T) -> T
456 where T: TypeFoldable<'tcx>
458 self.infcx.map(|infcx| infcx.resolve_type_vars_if_possible(value))
459 .unwrap_or_else(|| value.clone())
462 fn is_tainted_by_errors(&self) -> bool {
463 self.infcx.map_or(false, |infcx| infcx.is_tainted_by_errors())
466 fn resolve_type_vars_or_error(&self,
468 ty: Option<Ty<'tcx>>)
469 -> McResult<Ty<'tcx>> {
472 let ty = self.resolve_type_vars_if_possible(&ty);
473 if ty.references_error() || ty.is_ty_var() {
474 debug!("resolve_type_vars_or_error: error from {:?}", ty);
481 None if self.is_tainted_by_errors() => Err(()),
483 let id = self.tcx.hir.definitions().find_node_for_hir_id(id);
484 bug!("no type for node {}: {} in mem_categorization",
485 id, self.tcx.hir.node_to_string(id));
490 pub fn node_ty(&self,
492 -> McResult<Ty<'tcx>> {
493 self.resolve_type_vars_or_error(hir_id,
494 self.tables.node_id_to_type_opt(hir_id))
497 pub fn expr_ty(&self, expr: &hir::Expr) -> McResult<Ty<'tcx>> {
498 self.resolve_type_vars_or_error(expr.hir_id, self.tables.expr_ty_opt(expr))
501 pub fn expr_ty_adjusted(&self, expr: &hir::Expr) -> McResult<Ty<'tcx>> {
502 self.resolve_type_vars_or_error(expr.hir_id, self.tables.expr_ty_adjusted_opt(expr))
505 fn pat_ty(&self, pat: &hir::Pat) -> McResult<Ty<'tcx>> {
506 let base_ty = self.node_ty(pat.hir_id)?;
507 // This code detects whether we are looking at a `ref x`,
508 // and if so, figures out what the type *being borrowed* is.
509 let ret_ty = match pat.node {
510 PatKind::Binding(..) => {
511 let bm = *self.tables
514 .expect("missing binding mode");
516 if let ty::BindByReference(_) = bm {
517 // a bind-by-ref means that the base_ty will be the type of the ident itself,
518 // but what we want here is the type of the underlying value being borrowed.
519 // So peel off one-level, turning the &T into T.
520 match base_ty.builtin_deref(false, ty::NoPreference) {
523 debug!("By-ref binding of non-derefable type {:?}", base_ty);
533 debug!("pat_ty(pat={:?}) base_ty={:?} ret_ty={:?}",
534 pat, base_ty, ret_ty);
538 pub fn cat_expr(&self, expr: &hir::Expr) -> McResult<cmt<'tcx>> {
539 // This recursion helper avoids going through *too many*
540 // adjustments, since *only* non-overloaded deref recurses.
541 fn helper<'a, 'gcx, 'tcx>(mc: &MemCategorizationContext<'a, 'gcx, 'tcx>,
543 adjustments: &[adjustment::Adjustment<'tcx>])
544 -> McResult<cmt<'tcx>> {
545 match adjustments.split_last() {
546 None => mc.cat_expr_unadjusted(expr),
547 Some((adjustment, previous)) => {
548 mc.cat_expr_adjusted_with(expr, || helper(mc, expr, previous), adjustment)
553 helper(self, expr, self.tables.expr_adjustments(expr))
556 pub fn cat_expr_adjusted(&self, expr: &hir::Expr,
558 adjustment: &adjustment::Adjustment<'tcx>)
559 -> McResult<cmt<'tcx>> {
560 self.cat_expr_adjusted_with(expr, || Ok(previous), adjustment)
563 fn cat_expr_adjusted_with<F>(&self, expr: &hir::Expr,
565 adjustment: &adjustment::Adjustment<'tcx>)
566 -> McResult<cmt<'tcx>>
567 where F: FnOnce() -> McResult<cmt<'tcx>>
569 debug!("cat_expr_adjusted_with({:?}): {:?}", adjustment, expr);
570 let target = self.resolve_type_vars_if_possible(&adjustment.target);
571 match adjustment.kind {
572 adjustment::Adjust::Deref(overloaded) => {
573 // Equivalent to *expr or something similar.
574 let base = if let Some(deref) = overloaded {
575 let ref_ty = self.tcx.mk_ref(deref.region, ty::TypeAndMut {
579 self.cat_rvalue_node(expr.id, expr.span, ref_ty)
583 self.cat_deref(expr, base, false)
586 adjustment::Adjust::NeverToAny |
587 adjustment::Adjust::ReifyFnPointer |
588 adjustment::Adjust::UnsafeFnPointer |
589 adjustment::Adjust::ClosureFnPointer |
590 adjustment::Adjust::MutToConstPointer |
591 adjustment::Adjust::Borrow(_) |
592 adjustment::Adjust::Unsize => {
593 // Result is an rvalue.
594 Ok(self.cat_rvalue_node(expr.id, expr.span, target))
599 pub fn cat_expr_unadjusted(&self, expr: &hir::Expr) -> McResult<cmt<'tcx>> {
600 debug!("cat_expr: id={} expr={:?}", expr.id, expr);
602 let expr_ty = self.expr_ty(expr)?;
604 hir::ExprUnary(hir::UnDeref, ref e_base) => {
605 if self.tables.is_method_call(expr) {
606 self.cat_overloaded_lvalue(expr, e_base, false)
608 let base_cmt = self.cat_expr(&e_base)?;
609 self.cat_deref(expr, base_cmt, false)
613 hir::ExprField(ref base, f_name) => {
614 let base_cmt = self.cat_expr(&base)?;
615 debug!("cat_expr(cat_field): id={} expr={:?} base={:?}",
619 Ok(self.cat_field(expr, base_cmt, f_name.node, expr_ty))
622 hir::ExprTupField(ref base, idx) => {
623 let base_cmt = self.cat_expr(&base)?;
624 Ok(self.cat_tup_field(expr, base_cmt, idx.node, expr_ty))
627 hir::ExprIndex(ref base, _) => {
628 if self.tables.is_method_call(expr) {
629 // If this is an index implemented by a method call, then it
630 // will include an implicit deref of the result.
631 // The call to index() returns a `&T` value, which
632 // is an rvalue. That is what we will be
634 self.cat_overloaded_lvalue(expr, base, true)
636 let base_cmt = self.cat_expr(&base)?;
637 self.cat_index(expr, base_cmt, expr_ty, InteriorOffsetKind::Index)
641 hir::ExprPath(ref qpath) => {
642 let def = self.tables.qpath_def(qpath, expr.hir_id);
643 self.cat_def(expr.id, expr.span, expr_ty, def)
646 hir::ExprType(ref e, _) => {
650 hir::ExprAddrOf(..) | hir::ExprCall(..) |
651 hir::ExprAssign(..) | hir::ExprAssignOp(..) |
652 hir::ExprClosure(..) | hir::ExprRet(..) |
653 hir::ExprUnary(..) | hir::ExprYield(..) |
654 hir::ExprMethodCall(..) | hir::ExprCast(..) |
655 hir::ExprArray(..) | hir::ExprTup(..) | hir::ExprIf(..) |
656 hir::ExprBinary(..) | hir::ExprWhile(..) |
657 hir::ExprBlock(..) | hir::ExprLoop(..) | hir::ExprMatch(..) |
658 hir::ExprLit(..) | hir::ExprBreak(..) |
659 hir::ExprAgain(..) | hir::ExprStruct(..) | hir::ExprRepeat(..) |
660 hir::ExprInlineAsm(..) | hir::ExprBox(..) => {
661 Ok(self.cat_rvalue_node(expr.id(), expr.span(), expr_ty))
666 pub fn cat_def(&self,
671 -> McResult<cmt<'tcx>> {
672 debug!("cat_def: id={} expr={:?} def={:?}",
676 Def::StructCtor(..) | Def::VariantCtor(..) | Def::Const(..) |
677 Def::AssociatedConst(..) | Def::Fn(..) | Def::Method(..) => {
678 Ok(self.cat_rvalue_node(id, span, expr_ty))
681 Def::Static(def_id, mutbl) => {
682 // `#[thread_local]` statics may not outlive the current function.
683 for attr in &self.tcx.get_attrs(def_id)[..] {
684 if attr.check_name("thread_local") {
685 return Ok(self.cat_rvalue_node(id, span, expr_ty));
691 cat:Categorization::StaticItem,
692 mutbl: if mutbl { McDeclared } else { McImmutable},
698 Def::Upvar(var_id, _, fn_node_id) => {
699 self.cat_upvar(id, span, var_id, fn_node_id)
706 cat: Categorization::Local(vid),
707 mutbl: MutabilityCategory::from_local(self.tcx, self.tables, vid),
713 def => span_bug!(span, "unexpected definition in memory categorization: {:?}", def)
717 // Categorize an upvar, complete with invisible derefs of closure
718 // environment and upvar reference as appropriate.
723 fn_node_id: ast::NodeId)
724 -> McResult<cmt<'tcx>>
726 let fn_hir_id = self.tcx.hir.node_to_hir_id(fn_node_id);
728 // An upvar can have up to 3 components. We translate first to a
729 // `Categorization::Upvar`, which is itself a fiction -- it represents the reference to the
730 // field from the environment.
732 // `Categorization::Upvar`. Next, we add a deref through the implicit
733 // environment pointer with an anonymous free region 'env and
734 // appropriate borrow kind for closure kinds that take self by
735 // reference. Finally, if the upvar was captured
736 // by-reference, we add a deref through that reference. The
737 // region of this reference is an inference variable 'up that
738 // was previously generated and recorded in the upvar borrow
739 // map. The borrow kind bk is inferred by based on how the
742 // This results in the following table for concrete closure
746 // ---------------+----------------------+-------------------------------
747 // Fn | copied -> &'env | upvar -> &'env -> &'up bk
748 // FnMut | copied -> &'env mut | upvar -> &'env mut -> &'up bk
749 // FnOnce | copied | upvar -> &'up bk
751 let kind = match self.node_ty(fn_hir_id)?.sty {
752 ty::TyGenerator(..) => ty::ClosureKind::FnOnce,
754 match self.tables.closure_kinds().get(fn_hir_id) {
755 Some(&(kind, _)) => kind,
756 None => span_bug!(span, "missing closure kind"),
761 let closure_expr_def_index = self.tcx.hir.local_def_id(fn_node_id).index;
762 let var_hir_id = self.tcx.hir.node_to_hir_id(var_id);
763 let upvar_id = ty::UpvarId {
765 closure_expr_id: closure_expr_def_index
768 let var_ty = self.node_ty(var_hir_id)?;
770 // Mutability of original variable itself
771 let var_mutbl = MutabilityCategory::from_local(self.tcx, self.tables, var_id);
773 // Construct the upvar. This represents access to the field
774 // from the environment (perhaps we should eventually desugar
775 // this field further, but it will do for now).
776 let cmt_result = cmt_ {
779 cat: Categorization::Upvar(Upvar {id: upvar_id, kind: kind}),
785 // If this is a `FnMut` or `Fn` closure, then the above is
786 // conceptually a `&mut` or `&` reference, so we have to add a
788 let cmt_result = match kind {
789 ty::ClosureKind::FnOnce => {
792 ty::ClosureKind::FnMut => {
793 self.env_deref(id, span, upvar_id, var_mutbl, ty::MutBorrow, cmt_result)
795 ty::ClosureKind::Fn => {
796 self.env_deref(id, span, upvar_id, var_mutbl, ty::ImmBorrow, cmt_result)
800 // If this is a by-ref capture, then the upvar we loaded is
801 // actually a reference, so we have to add an implicit deref
803 let upvar_capture = self.tables.upvar_capture(upvar_id);
804 let cmt_result = match upvar_capture {
805 ty::UpvarCapture::ByValue => {
808 ty::UpvarCapture::ByRef(upvar_borrow) => {
809 let ptr = BorrowedPtr(upvar_borrow.kind, upvar_borrow.region);
813 cat: Categorization::Deref(Rc::new(cmt_result), ptr),
814 mutbl: MutabilityCategory::from_borrow_kind(upvar_borrow.kind),
816 note: NoteUpvarRef(upvar_id)
821 let ret = Rc::new(cmt_result);
822 debug!("cat_upvar ret={:?}", ret);
829 upvar_id: ty::UpvarId,
830 upvar_mutbl: MutabilityCategory,
831 env_borrow_kind: ty::BorrowKind,
832 cmt_result: cmt_<'tcx>)
835 // Region of environment pointer
836 let env_region = self.tcx.mk_region(ty::ReFree(ty::FreeRegion {
837 // The environment of a closure is guaranteed to
838 // outlive any bindings introduced in the body of the
840 scope: DefId::local(upvar_id.closure_expr_id),
841 bound_region: ty::BrEnv
844 let env_ptr = BorrowedPtr(env_borrow_kind, env_region);
846 let var_ty = cmt_result.ty;
848 // We need to add the env deref. This means
849 // that the above is actually immutable and
850 // has a ref type. However, nothing should
851 // actually look at the type, so we can get
852 // away with stuffing a `TyError` in there
853 // instead of bothering to construct a proper
855 let cmt_result = cmt_ {
857 ty: self.tcx.types.err,
861 let mut deref_mutbl = MutabilityCategory::from_borrow_kind(env_borrow_kind);
863 // Issue #18335. If variable is declared as immutable, override the
864 // mutability from the environment and substitute an `&T` anyway.
866 McImmutable => { deref_mutbl = McImmutable; }
867 McDeclared | McInherited => { }
873 cat: Categorization::Deref(Rc::new(cmt_result), env_ptr),
876 note: NoteClosureEnv(upvar_id)
879 debug!("env_deref ret {:?}", ret);
884 /// Returns the lifetime of a temporary created by expr with id `id`.
885 /// This could be `'static` if `id` is part of a constant expression.
886 pub fn temporary_scope(&self, id: hir::ItemLocalId) -> ty::Region<'tcx> {
887 let scope = self.region_scope_tree.temporary_scope(id);
888 self.tcx.mk_region(match scope {
889 Some(scope) => ty::ReScope(scope),
894 pub fn cat_rvalue_node(&self,
899 let hir_id = self.tcx.hir.node_to_hir_id(id);
900 let promotable = self.rvalue_promotable_map.as_ref().map(|m| m[&hir_id.local_id])
903 // Always promote `[T; 0]` (even when e.g. borrowed mutably).
904 let promotable = match expr_ty.sty {
905 ty::TyArray(_, len) if
906 len.val.to_const_int().and_then(|i| i.to_u64()) == Some(0) => true,
910 // Compute maximum lifetime of this rvalue. This is 'static if
911 // we can promote to a constant, otherwise equal to enclosing temp
913 let re = if promotable {
914 self.tcx.types.re_static
916 self.temporary_scope(hir_id.local_id)
918 let ret = self.cat_rvalue(id, span, re, expr_ty);
919 debug!("cat_rvalue_node ret {:?}", ret);
923 pub fn cat_rvalue(&self,
926 temp_scope: ty::Region<'tcx>,
927 expr_ty: Ty<'tcx>) -> cmt<'tcx> {
928 let ret = Rc::new(cmt_ {
931 cat:Categorization::Rvalue(temp_scope),
936 debug!("cat_rvalue ret {:?}", ret);
940 pub fn cat_field<N:ast_node>(&self,
946 let ret = Rc::new(cmt_ {
949 mutbl: base_cmt.mutbl.inherit(),
950 cat: Categorization::Interior(base_cmt, InteriorField(NamedField(f_name))),
954 debug!("cat_field ret {:?}", ret);
958 pub fn cat_tup_field<N:ast_node>(&self,
964 let ret = Rc::new(cmt_ {
967 mutbl: base_cmt.mutbl.inherit(),
968 cat: Categorization::Interior(base_cmt, InteriorField(PositionalField(f_idx))),
972 debug!("cat_tup_field ret {:?}", ret);
976 fn cat_overloaded_lvalue(&self,
980 -> McResult<cmt<'tcx>> {
981 debug!("cat_overloaded_lvalue: implicit={}", implicit);
983 // Reconstruct the output assuming it's a reference with the
984 // same region and mutability as the receiver. This holds for
985 // `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`.
986 let lvalue_ty = self.expr_ty(expr)?;
987 let base_ty = self.expr_ty_adjusted(base)?;
989 let (region, mutbl) = match base_ty.sty {
990 ty::TyRef(region, mt) => (region, mt.mutbl),
992 span_bug!(expr.span, "cat_overloaded_lvalue: base is not a reference")
995 let ref_ty = self.tcx.mk_ref(region, ty::TypeAndMut {
1000 let base_cmt = self.cat_rvalue_node(expr.id, expr.span, ref_ty);
1001 self.cat_deref(expr, base_cmt, implicit)
1004 pub fn cat_deref<N:ast_node>(&self,
1006 base_cmt: cmt<'tcx>,
1008 -> McResult<cmt<'tcx>> {
1009 debug!("cat_deref: base_cmt={:?}", base_cmt);
1011 let base_cmt_ty = base_cmt.ty;
1012 let deref_ty = match base_cmt_ty.builtin_deref(true, ty::NoPreference) {
1015 debug!("Explicit deref of non-derefable type: {:?}",
1021 let ptr = match base_cmt.ty.sty {
1022 ty::TyAdt(def, ..) if def.is_box() => Unique,
1023 ty::TyRawPtr(ref mt) => UnsafePtr(mt.mutbl),
1024 ty::TyRef(r, mt) => {
1025 let bk = ty::BorrowKind::from_mutbl(mt.mutbl);
1026 if implicit { Implicit(bk, r) } else { BorrowedPtr(bk, r) }
1028 ref ty => bug!("unexpected type in cat_deref: {:?}", ty)
1030 let ret = Rc::new(cmt_ {
1033 // For unique ptrs, we inherit mutability from the owning reference.
1034 mutbl: MutabilityCategory::from_pointer_kind(base_cmt.mutbl, ptr),
1035 cat: Categorization::Deref(base_cmt, ptr),
1039 debug!("cat_deref ret {:?}", ret);
1043 fn cat_index<N:ast_node>(&self,
1045 base_cmt: cmt<'tcx>,
1046 element_ty: Ty<'tcx>,
1047 context: InteriorOffsetKind)
1048 -> McResult<cmt<'tcx>> {
1049 //! Creates a cmt for an indexing operation (`[]`).
1051 //! One subtle aspect of indexing that may not be
1052 //! immediately obvious: for anything other than a fixed-length
1053 //! vector, an operation like `x[y]` actually consists of two
1054 //! disjoint (from the point of view of borrowck) operations.
1055 //! The first is a deref of `x` to create a pointer `p` that points
1056 //! at the first element in the array. The second operation is
1057 //! an index which adds `y*sizeof(T)` to `p` to obtain the
1058 //! pointer to `x[y]`. `cat_index` will produce a resulting
1059 //! cmt containing both this deref and the indexing,
1060 //! presuming that `base_cmt` is not of fixed-length type.
1063 //! - `elt`: the AST node being indexed
1064 //! - `base_cmt`: the cmt of `elt`
1066 let interior_elem = InteriorElement(context);
1068 self.cat_imm_interior(elt, base_cmt, element_ty, interior_elem);
1069 debug!("cat_index ret {:?}", ret);
1073 pub fn cat_imm_interior<N:ast_node>(&self,
1075 base_cmt: cmt<'tcx>,
1076 interior_ty: Ty<'tcx>,
1077 interior: InteriorKind)
1079 let ret = Rc::new(cmt_ {
1082 mutbl: base_cmt.mutbl.inherit(),
1083 cat: Categorization::Interior(base_cmt, interior),
1087 debug!("cat_imm_interior ret={:?}", ret);
1091 pub fn cat_downcast_if_needed<N:ast_node>(&self,
1093 base_cmt: cmt<'tcx>,
1096 // univariant enums do not need downcasts
1097 let base_did = self.tcx.parent_def_id(variant_did).unwrap();
1098 if !self.tcx.adt_def(base_did).is_univariant() {
1099 let base_ty = base_cmt.ty;
1100 let ret = Rc::new(cmt_ {
1103 mutbl: base_cmt.mutbl.inherit(),
1104 cat: Categorization::Downcast(base_cmt, variant_did),
1108 debug!("cat_downcast ret={:?}", ret);
1111 debug!("cat_downcast univariant={:?}", base_cmt);
1116 pub fn cat_pattern<F>(&self, cmt: cmt<'tcx>, pat: &hir::Pat, mut op: F) -> McResult<()>
1117 where F: FnMut(cmt<'tcx>, &hir::Pat),
1119 self.cat_pattern_(cmt, pat, &mut op)
1122 // FIXME(#19596) This is a workaround, but there should be a better way to do this
1123 fn cat_pattern_<F>(&self, mut cmt: cmt<'tcx>, pat: &hir::Pat, op: &mut F) -> McResult<()>
1124 where F : FnMut(cmt<'tcx>, &hir::Pat)
1126 // Here, `cmt` is the categorization for the value being
1127 // matched and pat is the pattern it is being matched against.
1129 // In general, the way that this works is that we walk down
1130 // the pattern, constructing a cmt that represents the path
1131 // that will be taken to reach the value being matched.
1133 // When we encounter named bindings, we take the cmt that has
1134 // been built up and pass it off to guarantee_valid() so that
1135 // we can be sure that the binding will remain valid for the
1136 // duration of the arm.
1138 // (*2) There is subtlety concerning the correspondence between
1139 // pattern ids and types as compared to *expression* ids and
1140 // types. This is explained briefly. on the definition of the
1141 // type `cmt`, so go off and read what it says there, then
1142 // come back and I'll dive into a bit more detail here. :) OK,
1145 // In general, the id of the cmt should be the node that
1146 // "produces" the value---patterns aren't executable code
1147 // exactly, but I consider them to "execute" when they match a
1148 // value, and I consider them to produce the value that was
1149 // matched. So if you have something like:
1156 // In this case, the cmt and the relevant ids would be:
1158 // CMT Id Type of Id Type of cmt
1161 // ^~~~~~~^ `x` from discr @@int @@int
1162 // ^~~~~~~~~~^ `@@y` pattern node @@int @int
1163 // ^~~~~~~~~~~~~^ `@y` pattern node @int int
1165 // You can see that the types of the id and the cmt are in
1166 // sync in the first line, because that id is actually the id
1167 // of an expression. But once we get to pattern ids, the types
1168 // step out of sync again. So you'll see below that we always
1169 // get the type of the *subpattern* and use that.
1171 debug!("cat_pattern: {:?} cmt={:?}", pat, cmt);
1173 // If (pattern) adjustments are active for this pattern, adjust the `cmt` correspondingly.
1174 // `cmt`s are constructed differently from patterns. For example, in
1178 // &&Some(x, ) => { ... },
1183 // the pattern `&&Some(x,)` is represented as `Ref { Ref { TupleStruct }}`. To build the
1184 // corresponding `cmt` we start with a `cmt` for `foo`, and then, by traversing the
1185 // pattern, try to answer the question: given the address of `foo`, how is `x` reached?
1187 // `&&Some(x,)` `cmt_foo`
1188 // `&Some(x,)` `deref { cmt_foo}`
1189 // `Some(x,)` `deref { deref { cmt_foo }}`
1190 // (x,)` `field0 { deref { deref { cmt_foo }}}` <- resulting cmt
1192 // The above example has no adjustments. If the code were instead the (after adjustments,
1193 // equivalent) version
1197 // Some(x, ) => { ... },
1202 // Then we see that to get the same result, we must start with `deref { deref { cmt_foo }}`
1203 // instead of `cmt_foo` since the pattern is now `Some(x,)` and not `&&Some(x,)`, even
1204 // though its assigned type is that of `&&Some(x,)`.
1205 for _ in 0..self.tables
1210 cmt = self.cat_deref(pat, cmt, true /* implicit */)?;
1212 let cmt = cmt; // lose mutability
1214 // Invoke the callback, but only now, after the `cmt` has adjusted.
1216 // To see that this makes sense, consider `match &Some(3) { Some(x) => { ... }}`. In that
1217 // case, the initial `cmt` will be that for `&Some(3)` and the pattern is `Some(x)`. We
1218 // don't want to call `op` with these incompatible values. As written, what happens instead
1219 // is that `op` is called with the adjusted cmt (that for `*&Some(3)`) and the pattern
1220 // `Some(x)` (which matches). Recursing once more, `*&Some(3)` and the pattern `Some(x)`
1221 // result in the cmt `Downcast<Some>(*&Some(3)).0` associated to `x` and invoke `op` with
1222 // that (where the `ref` on `x` is implied).
1223 op(cmt.clone(), pat);
1226 PatKind::TupleStruct(ref qpath, ref subpats, ddpos) => {
1227 let def = self.tables.qpath_def(qpath, pat.hir_id);
1228 let (cmt, expected_len) = match def {
1230 debug!("access to unresolvable pattern {:?}", pat);
1233 Def::VariantCtor(def_id, CtorKind::Fn) => {
1234 let enum_def = self.tcx.parent_def_id(def_id).unwrap();
1235 (self.cat_downcast_if_needed(pat, cmt, def_id),
1236 self.tcx.adt_def(enum_def).variant_with_id(def_id).fields.len())
1238 Def::StructCtor(_, CtorKind::Fn) => {
1239 match self.pat_ty(&pat)?.sty {
1240 ty::TyAdt(adt_def, _) => {
1241 (cmt, adt_def.struct_variant().fields.len())
1244 span_bug!(pat.span, "tuple struct pattern unexpected type {:?}", ty);
1249 span_bug!(pat.span, "tuple struct pattern didn't resolve \
1250 to variant or struct {:?}", def);
1254 for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
1255 let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
1256 let subcmt = self.cat_imm_interior(pat, cmt.clone(), subpat_ty,
1257 InteriorField(PositionalField(i)));
1258 self.cat_pattern_(subcmt, &subpat, op)?;
1262 PatKind::Struct(ref qpath, ref field_pats, _) => {
1263 // {f1: p1, ..., fN: pN}
1264 let def = self.tables.qpath_def(qpath, pat.hir_id);
1265 let cmt = match def {
1267 debug!("access to unresolvable pattern {:?}", pat);
1270 Def::Variant(variant_did) |
1271 Def::VariantCtor(variant_did, ..) => {
1272 self.cat_downcast_if_needed(pat, cmt, variant_did)
1277 for fp in field_pats {
1278 let field_ty = self.pat_ty(&fp.node.pat)?; // see (*2)
1279 let cmt_field = self.cat_field(pat, cmt.clone(), fp.node.name, field_ty);
1280 self.cat_pattern_(cmt_field, &fp.node.pat, op)?;
1284 PatKind::Binding(.., Some(ref subpat)) => {
1285 self.cat_pattern_(cmt, &subpat, op)?;
1288 PatKind::Tuple(ref subpats, ddpos) => {
1290 let expected_len = match self.pat_ty(&pat)?.sty {
1291 ty::TyTuple(ref tys, _) => tys.len(),
1292 ref ty => span_bug!(pat.span, "tuple pattern unexpected type {:?}", ty),
1294 for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
1295 let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
1296 let subcmt = self.cat_imm_interior(pat, cmt.clone(), subpat_ty,
1297 InteriorField(PositionalField(i)));
1298 self.cat_pattern_(subcmt, &subpat, op)?;
1302 PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => {
1303 // box p1, &p1, &mut p1. we can ignore the mutability of
1304 // PatKind::Ref since that information is already contained
1306 let subcmt = self.cat_deref(pat, cmt, false)?;
1307 self.cat_pattern_(subcmt, &subpat, op)?;
1310 PatKind::Slice(ref before, ref slice, ref after) => {
1311 let element_ty = match cmt.ty.builtin_index() {
1314 debug!("Explicit index of non-indexable type {:?}", cmt);
1318 let context = InteriorOffsetKind::Pattern;
1319 let elt_cmt = self.cat_index(pat, cmt, element_ty, context)?;
1320 for before_pat in before {
1321 self.cat_pattern_(elt_cmt.clone(), &before_pat, op)?;
1323 if let Some(ref slice_pat) = *slice {
1324 self.cat_pattern_(elt_cmt.clone(), &slice_pat, op)?;
1326 for after_pat in after {
1327 self.cat_pattern_(elt_cmt.clone(), &after_pat, op)?;
1331 PatKind::Path(_) | PatKind::Binding(.., None) |
1332 PatKind::Lit(..) | PatKind::Range(..) | PatKind::Wild => {
1341 #[derive(Clone, Debug)]
1342 pub enum Aliasability {
1343 FreelyAliasable(AliasableReason),
1345 ImmutableUnique(Box<Aliasability>),
1348 #[derive(Copy, Clone, Debug)]
1349 pub enum AliasableReason {
1355 impl<'tcx> cmt_<'tcx> {
1356 pub fn guarantor(&self) -> cmt<'tcx> {
1357 //! Returns `self` after stripping away any derefs or
1358 //! interior content. The return value is basically the `cmt` which
1359 //! determines how long the value in `self` remains live.
1362 Categorization::Rvalue(..) |
1363 Categorization::StaticItem |
1364 Categorization::Local(..) |
1365 Categorization::Deref(_, UnsafePtr(..)) |
1366 Categorization::Deref(_, BorrowedPtr(..)) |
1367 Categorization::Deref(_, Implicit(..)) |
1368 Categorization::Upvar(..) => {
1369 Rc::new((*self).clone())
1371 Categorization::Downcast(ref b, _) |
1372 Categorization::Interior(ref b, _) |
1373 Categorization::Deref(ref b, Unique) => {
1379 /// Returns `FreelyAliasable(_)` if this lvalue represents a freely aliasable pointer type.
1380 pub fn freely_aliasable(&self) -> Aliasability {
1381 // Maybe non-obvious: copied upvars can only be considered
1382 // non-aliasable in once closures, since any other kind can be
1383 // aliased and eventually recused.
1386 Categorization::Deref(ref b, BorrowedPtr(ty::MutBorrow, _)) |
1387 Categorization::Deref(ref b, Implicit(ty::MutBorrow, _)) |
1388 Categorization::Deref(ref b, BorrowedPtr(ty::UniqueImmBorrow, _)) |
1389 Categorization::Deref(ref b, Implicit(ty::UniqueImmBorrow, _)) |
1390 Categorization::Deref(ref b, Unique) |
1391 Categorization::Downcast(ref b, _) |
1392 Categorization::Interior(ref b, _) => {
1393 // Aliasability depends on base cmt
1394 b.freely_aliasable()
1397 Categorization::Rvalue(..) |
1398 Categorization::Local(..) |
1399 Categorization::Upvar(..) |
1400 Categorization::Deref(_, UnsafePtr(..)) => { // yes, it's aliasable, but...
1404 Categorization::StaticItem => {
1405 if self.mutbl.is_mutable() {
1406 FreelyAliasable(AliasableStaticMut)
1408 FreelyAliasable(AliasableStatic)
1412 Categorization::Deref(_, BorrowedPtr(ty::ImmBorrow, _)) |
1413 Categorization::Deref(_, Implicit(ty::ImmBorrow, _)) => {
1414 FreelyAliasable(AliasableBorrowed)
1419 // Digs down through one or two layers of deref and grabs the cmt
1420 // for the upvar if a note indicates there is one.
1421 pub fn upvar(&self) -> Option<cmt<'tcx>> {
1423 NoteClosureEnv(..) | NoteUpvarRef(..) => {
1424 Some(match self.cat {
1425 Categorization::Deref(ref inner, _) => {
1427 Categorization::Deref(ref inner, _) => inner.clone(),
1428 Categorization::Upvar(..) => inner.clone(),
1440 pub fn descriptive_string(&self, tcx: TyCtxt) -> String {
1442 Categorization::StaticItem => {
1443 "static item".to_string()
1445 Categorization::Rvalue(..) => {
1446 "non-lvalue".to_string()
1448 Categorization::Local(vid) => {
1449 if tcx.hir.is_argument(vid) {
1450 "argument".to_string()
1452 "local variable".to_string()
1455 Categorization::Deref(_, pk) => {
1456 let upvar = self.upvar();
1457 match upvar.as_ref().map(|i| &i.cat) {
1458 Some(&Categorization::Upvar(ref var)) => {
1465 format!("indexed content")
1468 format!("`Box` content")
1471 format!("dereference of raw pointer")
1473 BorrowedPtr(..) => {
1474 format!("borrowed content")
1480 Categorization::Interior(_, InteriorField(NamedField(_))) => {
1483 Categorization::Interior(_, InteriorField(PositionalField(_))) => {
1484 "anonymous field".to_string()
1486 Categorization::Interior(_, InteriorElement(InteriorOffsetKind::Index)) => {
1487 "indexed content".to_string()
1489 Categorization::Interior(_, InteriorElement(InteriorOffsetKind::Pattern)) => {
1490 "pattern-bound indexed content".to_string()
1492 Categorization::Upvar(ref var) => {
1495 Categorization::Downcast(ref cmt, _) => {
1496 cmt.descriptive_string(tcx)
1502 impl<'tcx> fmt::Debug for cmt_<'tcx> {
1503 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1504 write!(f, "{{{:?} id:{} m:{:?} ty:{:?}}}",
1512 impl<'tcx> fmt::Debug for Categorization<'tcx> {
1513 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1515 Categorization::StaticItem => write!(f, "static"),
1516 Categorization::Rvalue(r) => { write!(f, "rvalue({:?})", r) }
1517 Categorization::Local(id) => {
1518 let name = ty::tls::with(|tcx| tcx.hir.name(id));
1519 write!(f, "local({})", name)
1521 Categorization::Upvar(upvar) => {
1522 write!(f, "upvar({:?})", upvar)
1524 Categorization::Deref(ref cmt, ptr) => {
1525 write!(f, "{:?}-{:?}->", cmt.cat, ptr)
1527 Categorization::Interior(ref cmt, interior) => {
1528 write!(f, "{:?}.{:?}", cmt.cat, interior)
1530 Categorization::Downcast(ref cmt, _) => {
1531 write!(f, "{:?}->(enum)", cmt.cat)
1537 pub fn ptr_sigil(ptr: PointerKind) -> &'static str {
1540 BorrowedPtr(ty::ImmBorrow, _) |
1541 Implicit(ty::ImmBorrow, _) => "&",
1542 BorrowedPtr(ty::MutBorrow, _) |
1543 Implicit(ty::MutBorrow, _) => "&mut",
1544 BorrowedPtr(ty::UniqueImmBorrow, _) |
1545 Implicit(ty::UniqueImmBorrow, _) => "&unique",
1546 UnsafePtr(_) => "*",
1550 impl<'tcx> fmt::Debug for PointerKind<'tcx> {
1551 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1553 Unique => write!(f, "Box"),
1554 BorrowedPtr(ty::ImmBorrow, ref r) |
1555 Implicit(ty::ImmBorrow, ref r) => {
1556 write!(f, "&{:?}", r)
1558 BorrowedPtr(ty::MutBorrow, ref r) |
1559 Implicit(ty::MutBorrow, ref r) => {
1560 write!(f, "&{:?} mut", r)
1562 BorrowedPtr(ty::UniqueImmBorrow, ref r) |
1563 Implicit(ty::UniqueImmBorrow, ref r) => {
1564 write!(f, "&{:?} uniq", r)
1566 UnsafePtr(_) => write!(f, "*")
1571 impl fmt::Debug for InteriorKind {
1572 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1574 InteriorField(NamedField(fld)) => write!(f, "{}", fld),
1575 InteriorField(PositionalField(i)) => write!(f, "#{}", i),
1576 InteriorElement(..) => write!(f, "[]"),
1581 impl fmt::Debug for Upvar {
1582 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1583 write!(f, "{:?}/{:?}", self.id, self.kind)
1587 impl fmt::Display for Upvar {
1588 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1589 let kind = match self.kind {
1590 ty::ClosureKind::Fn => "Fn",
1591 ty::ClosureKind::FnMut => "FnMut",
1592 ty::ClosureKind::FnOnce => "FnOnce",
1594 write!(f, "captured outer variable in an `{}` closure", kind)