1 // Copyright 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.
11 //! A different sort of visitor for walking fn bodies. Unlike the
12 //! normal visitor, which just walks the entire body in one shot, the
13 //! `ExprUseVisitor` determines how expressions are being used.
15 pub use self::LoanCause::*;
16 pub use self::ConsumeMode::*;
17 pub use self::MoveReason::*;
18 pub use self::MatchMode::*;
19 use self::TrackMatchMode::*;
20 use self::OverloadedCallType::*;
23 use hir::def_id::DefId;
25 use middle::mem_categorization as mc;
27 use ty::{self, TyCtxt, adjustment};
29 use hir::{self, PatKind};
30 use rustc_data_structures::sync::Lrc;
35 use util::nodemap::ItemLocalSet;
37 ///////////////////////////////////////////////////////////////////////////
40 /// This trait defines the callbacks you can expect to receive when
41 /// employing the ExprUseVisitor.
42 pub trait Delegate<'tcx> {
43 // The value found at `cmt` is either copied or moved, depending
46 consume_id: ast::NodeId,
51 // The value found at `cmt` has been determined to match the
52 // pattern binding `matched_pat`, and its subparts are being
53 // copied or moved depending on `mode`. Note that `matched_pat`
54 // is called on all variant/structs in the pattern (i.e., the
55 // interior nodes of the pattern's tree structure) while
56 // consume_pat is called on the binding identifiers in the pattern
57 // (which are leaves of the pattern's tree structure).
59 // Note that variants/structs and identifiers are disjoint; thus
60 // `matched_pat` and `consume_pat` are never both called on the
61 // same input pattern structure (though of `consume_pat` can be
62 // called on a subpart of an input passed to `matched_pat).
63 fn matched_pat(&mut self,
64 matched_pat: &hir::Pat,
68 // The value found at `cmt` is either copied or moved via the
69 // pattern binding `consume_pat`, depending on mode.
70 fn consume_pat(&mut self,
71 consume_pat: &hir::Pat,
75 // The value found at `borrow` is being borrowed at the point
76 // `borrow_id` for the region `loan_region` with kind `bk`.
78 borrow_id: ast::NodeId,
81 loan_region: ty::Region<'tcx>,
83 loan_cause: LoanCause);
85 // The local variable `id` is declared but not initialized.
86 fn decl_without_init(&mut self,
90 // The path at `cmt` is being assigned to.
92 assignment_id: ast::NodeId,
93 assignment_span: Span,
94 assignee_cmt: &mc::cmt_<'tcx>,
98 #[derive(Copy, Clone, PartialEq, Debug)]
100 ClosureCapture(Span),
111 #[derive(Copy, Clone, PartialEq, Debug)]
112 pub enum ConsumeMode {
113 Copy, // reference to x where x has a type that copies
114 Move(MoveReason), // reference to x where x has a type that moves
117 #[derive(Copy, Clone, PartialEq, Debug)]
118 pub enum MoveReason {
124 #[derive(Copy, Clone, PartialEq, Debug)]
132 #[derive(Copy, Clone, PartialEq, Debug)]
133 enum TrackMatchMode {
139 impl TrackMatchMode {
140 // Builds up the whole match mode for a pattern from its constituent
141 // parts. The lattice looks like this:
157 // * `(_, some_int)` pattern is Copying, since
158 // NonBinding + Copying => Copying
160 // * `(some_int, some_box)` pattern is Moving, since
161 // Copying + Moving => Moving
163 // * `(ref x, some_box)` pattern is Conflicting, since
164 // Borrowing + Moving => Conflicting
166 // Note that the `Unknown` and `Conflicting` states are
167 // represented separately from the other more interesting
168 // `Definite` states, which simplifies logic here somewhat.
169 fn lub(&mut self, mode: MatchMode) {
170 *self = match (*self, mode) {
171 // Note that clause order below is very significant.
172 (Unknown, new) => Definite(new),
173 (Definite(old), new) if old == new => Definite(old),
175 (Definite(old), NonBindingMatch) => Definite(old),
176 (Definite(NonBindingMatch), new) => Definite(new),
178 (Definite(old), CopyingMatch) => Definite(old),
179 (Definite(CopyingMatch), new) => Definite(new),
181 (Definite(_), _) => Conflicting,
182 (Conflicting, _) => *self,
186 fn match_mode(&self) -> MatchMode {
188 Unknown => NonBindingMatch,
189 Definite(mode) => mode,
191 // Conservatively return MovingMatch to let the
192 // compiler continue to make progress.
199 #[derive(Copy, Clone, PartialEq, Debug)]
200 pub enum MutateMode {
203 WriteAndRead, // x += y
206 #[derive(Copy, Clone)]
207 enum OverloadedCallType {
210 FnOnceOverloadedCall,
213 impl OverloadedCallType {
214 fn from_trait_id(tcx: TyCtxt, trait_id: DefId) -> OverloadedCallType {
215 for &(maybe_function_trait, overloaded_call_type) in &[
216 (tcx.lang_items().fn_once_trait(), FnOnceOverloadedCall),
217 (tcx.lang_items().fn_mut_trait(), FnMutOverloadedCall),
218 (tcx.lang_items().fn_trait(), FnOverloadedCall)
220 match maybe_function_trait {
221 Some(function_trait) if function_trait == trait_id => {
222 return overloaded_call_type
228 bug!("overloaded call didn't map to known function trait")
231 fn from_method_id(tcx: TyCtxt, method_id: DefId) -> OverloadedCallType {
232 let method = tcx.associated_item(method_id);
233 OverloadedCallType::from_trait_id(tcx, method.container.id())
237 ///////////////////////////////////////////////////////////////////////////
238 // The ExprUseVisitor type
240 // This is the code that actually walks the tree.
241 pub struct ExprUseVisitor<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
242 mc: mc::MemCategorizationContext<'a, 'gcx, 'tcx>,
243 delegate: &'a mut dyn Delegate<'tcx>,
244 param_env: ty::ParamEnv<'tcx>,
247 // If the MC results in an error, it's because the type check
248 // failed (or will fail, when the error is uncovered and reported
249 // during writeback). In this case, we just ignore this part of the
252 // Note that this macro appears similar to try!(), but, unlike try!(),
253 // it does not propagate the error.
254 macro_rules! return_if_err {
259 debug!("mc reported err");
266 impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx, 'tcx> {
267 /// Creates the ExprUseVisitor, configuring it with the various options provided:
269 /// - `delegate` -- who receives the callbacks
270 /// - `param_env` --- parameter environment for trait lookups (esp. pertaining to `Copy`)
271 /// - `region_scope_tree` --- region scope tree for the code being analyzed
272 /// - `tables` --- typeck results for the code being analyzed
273 /// - `rvalue_promotable_map` --- if you care about rvalue promotion, then provide
274 /// the map here (it can be computed with `tcx.rvalue_promotable_map(def_id)`).
275 /// `None` means that rvalues will be given more conservative lifetimes.
277 /// See also `with_infer`, which is used *during* typeck.
278 pub fn new(delegate: &'a mut (dyn Delegate<'tcx>+'a),
279 tcx: TyCtxt<'a, 'tcx, 'tcx>,
280 param_env: ty::ParamEnv<'tcx>,
281 region_scope_tree: &'a region::ScopeTree,
282 tables: &'a ty::TypeckTables<'tcx>,
283 rvalue_promotable_map: Option<Lrc<ItemLocalSet>>)
287 mc: mc::MemCategorizationContext::new(tcx,
290 rvalue_promotable_map),
297 impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
298 pub fn with_infer(delegate: &'a mut (dyn Delegate<'tcx>+'a),
299 infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
300 param_env: ty::ParamEnv<'tcx>,
301 region_scope_tree: &'a region::ScopeTree,
302 tables: &'a ty::TypeckTables<'tcx>)
306 mc: mc::MemCategorizationContext::with_infer(infcx, region_scope_tree, tables),
312 pub fn consume_body(&mut self, body: &hir::Body) {
313 debug!("consume_body(body={:?})", body);
315 for arg in &body.arguments {
316 let arg_ty = return_if_err!(self.mc.pat_ty_adjusted(&arg.pat));
317 debug!("consume_body: arg_ty = {:?}", arg_ty);
319 let fn_body_scope_r =
320 self.tcx().mk_region(ty::ReScope(region::Scope::Node(body.value.hir_id.local_id)));
321 let arg_cmt = Rc::new(self.mc.cat_rvalue(
324 fn_body_scope_r, // Args live only as long as the fn body.
327 self.walk_irrefutable_pat(arg_cmt, &arg.pat);
330 self.consume_expr(&body.value);
333 fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
337 fn delegate_consume(&mut self,
338 consume_id: ast::NodeId,
340 cmt: &mc::cmt_<'tcx>) {
341 debug!("delegate_consume(consume_id={}, cmt={:?})",
344 let mode = copy_or_move(&self.mc, self.param_env, cmt, DirectRefMove);
345 self.delegate.consume(consume_id, consume_span, cmt, mode);
348 fn consume_exprs(&mut self, exprs: &[hir::Expr]) {
350 self.consume_expr(&expr);
354 pub fn consume_expr(&mut self, expr: &hir::Expr) {
355 debug!("consume_expr(expr={:?})", expr);
357 let cmt = return_if_err!(self.mc.cat_expr(expr));
358 self.delegate_consume(expr.id, expr.span, &cmt);
359 self.walk_expr(expr);
362 fn mutate_expr(&mut self,
363 assignment_expr: &hir::Expr,
366 let cmt = return_if_err!(self.mc.cat_expr(expr));
367 self.delegate.mutate(assignment_expr.id, assignment_expr.span, &cmt, mode);
368 self.walk_expr(expr);
371 fn borrow_expr(&mut self,
376 debug!("borrow_expr(expr={:?}, r={:?}, bk={:?})",
379 let cmt = return_if_err!(self.mc.cat_expr(expr));
380 self.delegate.borrow(expr.id, expr.span, &cmt, r, bk, cause);
385 fn select_from_expr(&mut self, expr: &hir::Expr) {
389 pub fn walk_expr(&mut self, expr: &hir::Expr) {
390 debug!("walk_expr(expr={:?})", expr);
392 self.walk_adjustment(expr);
395 hir::ExprPath(_) => { }
397 hir::ExprType(ref subexpr, _) => {
398 self.walk_expr(&subexpr)
401 hir::ExprUnary(hir::UnDeref, ref base) => { // *base
402 self.select_from_expr(&base);
405 hir::ExprField(ref base, _) => { // base.f
406 self.select_from_expr(&base);
409 hir::ExprIndex(ref lhs, ref rhs) => { // lhs[rhs]
410 self.select_from_expr(&lhs);
411 self.consume_expr(&rhs);
414 hir::ExprCall(ref callee, ref args) => { // callee(args)
415 self.walk_callee(expr, &callee);
416 self.consume_exprs(args);
419 hir::ExprMethodCall(.., ref args) => { // callee.m(args)
420 self.consume_exprs(args);
423 hir::ExprStruct(_, ref fields, ref opt_with) => {
424 self.walk_struct_expr(fields, opt_with);
427 hir::ExprTup(ref exprs) => {
428 self.consume_exprs(exprs);
431 hir::ExprIf(ref cond_expr, ref then_expr, ref opt_else_expr) => {
432 self.consume_expr(&cond_expr);
433 self.walk_expr(&then_expr);
434 if let Some(ref else_expr) = *opt_else_expr {
435 self.consume_expr(&else_expr);
439 hir::ExprMatch(ref discr, ref arms, _) => {
440 let discr_cmt = Rc::new(return_if_err!(self.mc.cat_expr(&discr)));
441 let r = self.tcx().types.re_empty;
442 self.borrow_expr(&discr, r, ty::ImmBorrow, MatchDiscriminant);
444 // treatment of the discriminant is handled while walking the arms.
446 let mode = self.arm_move_mode(discr_cmt.clone(), arm);
447 let mode = mode.match_mode();
448 self.walk_arm(discr_cmt.clone(), arm, mode);
452 hir::ExprArray(ref exprs) => {
453 self.consume_exprs(exprs);
456 hir::ExprAddrOf(m, ref base) => { // &base
457 // make sure that the thing we are pointing out stays valid
458 // for the lifetime `scope_r` of the resulting ptr:
459 let expr_ty = return_if_err!(self.mc.expr_ty(expr));
460 if let ty::TyRef(r, _, _) = expr_ty.sty {
461 let bk = ty::BorrowKind::from_mutbl(m);
462 self.borrow_expr(&base, r, bk, AddrOf);
466 hir::ExprInlineAsm(ref ia, ref outputs, ref inputs) => {
467 for (o, output) in ia.outputs.iter().zip(outputs) {
469 self.consume_expr(output);
471 self.mutate_expr(expr, output,
473 MutateMode::WriteAndRead
475 MutateMode::JustWrite
479 self.consume_exprs(inputs);
482 hir::ExprContinue(..) |
483 hir::ExprLit(..) => {}
485 hir::ExprLoop(ref blk, _, _) => {
486 self.walk_block(&blk);
489 hir::ExprWhile(ref cond_expr, ref blk, _) => {
490 self.consume_expr(&cond_expr);
491 self.walk_block(&blk);
494 hir::ExprUnary(_, ref lhs) => {
495 self.consume_expr(&lhs);
498 hir::ExprBinary(_, ref lhs, ref rhs) => {
499 self.consume_expr(&lhs);
500 self.consume_expr(&rhs);
503 hir::ExprBlock(ref blk, _) => {
504 self.walk_block(&blk);
507 hir::ExprBreak(_, ref opt_expr) | hir::ExprRet(ref opt_expr) => {
508 if let Some(ref expr) = *opt_expr {
509 self.consume_expr(&expr);
513 hir::ExprAssign(ref lhs, ref rhs) => {
514 self.mutate_expr(expr, &lhs, MutateMode::JustWrite);
515 self.consume_expr(&rhs);
518 hir::ExprCast(ref base, _) => {
519 self.consume_expr(&base);
522 hir::ExprAssignOp(_, ref lhs, ref rhs) => {
523 if self.mc.tables.is_method_call(expr) {
524 self.consume_expr(lhs);
526 self.mutate_expr(expr, &lhs, MutateMode::WriteAndRead);
528 self.consume_expr(&rhs);
531 hir::ExprRepeat(ref base, _) => {
532 self.consume_expr(&base);
535 hir::ExprClosure(.., fn_decl_span, _) => {
536 self.walk_captures(expr, fn_decl_span)
539 hir::ExprBox(ref base) => {
540 self.consume_expr(&base);
543 hir::ExprYield(ref value) => {
544 self.consume_expr(&value);
549 fn walk_callee(&mut self, call: &hir::Expr, callee: &hir::Expr) {
550 let callee_ty = return_if_err!(self.mc.expr_ty_adjusted(callee));
551 debug!("walk_callee: callee={:?} callee_ty={:?}",
553 match callee_ty.sty {
554 ty::TyFnDef(..) | ty::TyFnPtr(_) => {
555 self.consume_expr(callee);
559 if let Some(def) = self.mc.tables.type_dependent_defs().get(call.hir_id) {
560 let def_id = def.def_id();
561 let call_scope = region::Scope::Node(call.hir_id.local_id);
562 match OverloadedCallType::from_method_id(self.tcx(), def_id) {
563 FnMutOverloadedCall => {
564 let call_scope_r = self.tcx().mk_region(ty::ReScope(call_scope));
565 self.borrow_expr(callee,
570 FnOverloadedCall => {
571 let call_scope_r = self.tcx().mk_region(ty::ReScope(call_scope));
572 self.borrow_expr(callee,
577 FnOnceOverloadedCall => self.consume_expr(callee),
580 self.tcx().sess.delay_span_bug(call.span,
581 "no type-dependent def for overloaded call");
587 fn walk_stmt(&mut self, stmt: &hir::Stmt) {
589 hir::StmtKind::Decl(ref decl, _) => {
591 hir::DeclLocal(ref local) => {
592 self.walk_local(&local);
595 hir::DeclItem(_) => {
596 // we don't visit nested items in this visitor,
597 // only the fn body we were given.
602 hir::StmtKind::Expr(ref expr, _) |
603 hir::StmtKind::Semi(ref expr, _) => {
604 self.consume_expr(&expr);
609 fn walk_local(&mut self, local: &hir::Local) {
612 local.pat.each_binding(|_, hir_id, span, _| {
613 let node_id = self.mc.tcx.hir.hir_to_node_id(hir_id);
614 self.delegate.decl_without_init(node_id, span);
619 // Variable declarations with
620 // initializers are considered
621 // "assigns", which is handled by
623 self.walk_expr(&expr);
624 let init_cmt = Rc::new(return_if_err!(self.mc.cat_expr(&expr)));
625 self.walk_irrefutable_pat(init_cmt, &local.pat);
630 /// Indicates that the value of `blk` will be consumed, meaning either copied or moved
631 /// depending on its type.
632 fn walk_block(&mut self, blk: &hir::Block) {
633 debug!("walk_block(blk.id={})", blk.id);
635 for stmt in &blk.stmts {
636 self.walk_stmt(stmt);
639 if let Some(ref tail_expr) = blk.expr {
640 self.consume_expr(&tail_expr);
644 fn walk_struct_expr(&mut self,
645 fields: &[hir::Field],
646 opt_with: &Option<P<hir::Expr>>) {
647 // Consume the expressions supplying values for each field.
648 for field in fields {
649 self.consume_expr(&field.expr);
652 let with_expr = match *opt_with {
657 let with_cmt = Rc::new(return_if_err!(self.mc.cat_expr(&with_expr)));
659 // Select just those fields of the `with`
660 // expression that will actually be used
661 match with_cmt.ty.sty {
662 ty::TyAdt(adt, substs) if adt.is_struct() => {
663 // Consume those fields of the with expression that are needed.
664 for (f_index, with_field) in adt.non_enum_variant().fields.iter().enumerate() {
665 let is_mentioned = fields.iter().any(|f| {
666 self.tcx().field_index(f.id, self.mc.tables) == f_index
669 let cmt_field = self.mc.cat_field(
674 with_field.ty(self.tcx(), substs)
676 self.delegate_consume(with_expr.id, with_expr.span, &cmt_field);
681 // the base expression should always evaluate to a
682 // struct; however, when EUV is run during typeck, it
683 // may not. This will generate an error earlier in typeck,
684 // so we can just ignore it.
685 if !self.tcx().sess.has_errors() {
688 "with expression doesn't evaluate to a struct");
693 // walk the with expression so that complex expressions
694 // are properly handled.
695 self.walk_expr(with_expr);
698 // Invoke the appropriate delegate calls for anything that gets
699 // consumed or borrowed as part of the automatic adjustment
701 fn walk_adjustment(&mut self, expr: &hir::Expr) {
702 let adjustments = self.mc.tables.expr_adjustments(expr);
703 let mut cmt = return_if_err!(self.mc.cat_expr_unadjusted(expr));
704 for adjustment in adjustments {
705 debug!("walk_adjustment expr={:?} adj={:?}", expr, adjustment);
706 match adjustment.kind {
707 adjustment::Adjust::NeverToAny |
708 adjustment::Adjust::ReifyFnPointer |
709 adjustment::Adjust::UnsafeFnPointer |
710 adjustment::Adjust::ClosureFnPointer |
711 adjustment::Adjust::MutToConstPointer |
712 adjustment::Adjust::Unsize => {
713 // Creating a closure/fn-pointer or unsizing consumes
714 // the input and stores it into the resulting rvalue.
715 self.delegate_consume(expr.id, expr.span, &cmt);
718 adjustment::Adjust::Deref(None) => {}
720 // Autoderefs for overloaded Deref calls in fact reference
721 // their receiver. That is, if we have `(*x)` where `x`
722 // is of type `Rc<T>`, then this in fact is equivalent to
723 // `x.deref()`. Since `deref()` is declared with `&self`,
724 // this is an autoref of `x`.
725 adjustment::Adjust::Deref(Some(ref deref)) => {
726 let bk = ty::BorrowKind::from_mutbl(deref.mutbl);
727 self.delegate.borrow(expr.id, expr.span, &cmt, deref.region, bk, AutoRef);
730 adjustment::Adjust::Borrow(ref autoref) => {
731 self.walk_autoref(expr, &cmt, autoref);
734 cmt = return_if_err!(self.mc.cat_expr_adjusted(expr, cmt, &adjustment));
738 /// Walks the autoref `autoref` applied to the autoderef'd
739 /// `expr`. `cmt_base` is the mem-categorized form of `expr`
740 /// after all relevant autoderefs have occurred.
741 fn walk_autoref(&mut self,
743 cmt_base: &mc::cmt_<'tcx>,
744 autoref: &adjustment::AutoBorrow<'tcx>) {
745 debug!("walk_autoref(expr.id={} cmt_base={:?} autoref={:?})",
751 adjustment::AutoBorrow::Ref(r, m) => {
752 self.delegate.borrow(expr.id,
756 ty::BorrowKind::from_mutbl(m.into()),
760 adjustment::AutoBorrow::RawPtr(m) => {
761 debug!("walk_autoref: expr.id={} cmt_base={:?}",
765 // Converting from a &T to *T (or &mut T to *mut T) is
766 // treated as borrowing it for the enclosing temporary
768 let r = self.tcx().mk_region(ty::ReScope(
769 region::Scope::Node(expr.hir_id.local_id)));
771 self.delegate.borrow(expr.id,
775 ty::BorrowKind::from_mutbl(m),
781 fn arm_move_mode(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &hir::Arm) -> TrackMatchMode {
782 let mut mode = Unknown;
783 for pat in &arm.pats {
784 self.determine_pat_move_mode(discr_cmt.clone(), &pat, &mut mode);
789 fn walk_arm(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &hir::Arm, mode: MatchMode) {
790 for pat in &arm.pats {
791 self.walk_pat(discr_cmt.clone(), &pat, mode);
794 if let Some(ref guard) = arm.guard {
795 self.consume_expr(&guard);
798 self.consume_expr(&arm.body);
801 /// Walks a pat that occurs in isolation (i.e. top-level of fn
802 /// arg or let binding. *Not* a match arm or nested pat.)
803 fn walk_irrefutable_pat(&mut self, cmt_discr: mc::cmt<'tcx>, pat: &hir::Pat) {
804 let mut mode = Unknown;
805 self.determine_pat_move_mode(cmt_discr.clone(), pat, &mut mode);
806 let mode = mode.match_mode();
807 self.walk_pat(cmt_discr, pat, mode);
810 /// Identifies any bindings within `pat` and accumulates within
811 /// `mode` whether the overall pattern/match structure is a move,
813 fn determine_pat_move_mode(&mut self,
814 cmt_discr: mc::cmt<'tcx>,
816 mode: &mut TrackMatchMode) {
817 debug!("determine_pat_move_mode cmt_discr={:?} pat={:?}", cmt_discr,
819 return_if_err!(self.mc.cat_pattern(cmt_discr, pat, |cmt_pat, pat| {
820 if let PatKind::Binding(..) = pat.node {
821 let bm = *self.mc.tables.pat_binding_modes().get(pat.hir_id)
822 .expect("missing binding mode");
824 ty::BindByReference(..) =>
825 mode.lub(BorrowingMatch),
826 ty::BindByValue(..) => {
827 match copy_or_move(&self.mc, self.param_env, &cmt_pat, PatBindingMove) {
828 Copy => mode.lub(CopyingMatch),
829 Move(..) => mode.lub(MovingMatch),
837 /// The core driver for walking a pattern; `match_mode` must be
838 /// established up front, e.g. via `determine_pat_move_mode` (see
839 /// also `walk_irrefutable_pat` for patterns that stand alone).
840 fn walk_pat(&mut self, cmt_discr: mc::cmt<'tcx>, pat: &hir::Pat, match_mode: MatchMode) {
841 debug!("walk_pat(cmt_discr={:?}, pat={:?})", cmt_discr, pat);
843 let tcx = self.tcx();
844 let ExprUseVisitor { ref mc, ref mut delegate, param_env } = *self;
845 return_if_err!(mc.cat_pattern(cmt_discr.clone(), pat, |cmt_pat, pat| {
846 if let PatKind::Binding(_, canonical_id, ..) = pat.node {
848 "walk_pat: binding cmt_pat={:?} pat={:?} match_mode={:?}",
853 if let Some(&bm) = mc.tables.pat_binding_modes().get(pat.hir_id) {
854 debug!("walk_pat: pat.hir_id={:?} bm={:?}", pat.hir_id, bm);
856 // pat_ty: the type of the binding being produced.
857 let pat_ty = return_if_err!(mc.node_ty(pat.hir_id));
858 debug!("walk_pat: pat_ty={:?}", pat_ty);
860 // Each match binding is effectively an assignment to the
861 // binding being produced.
862 let def = Def::Local(canonical_id);
863 if let Ok(ref binding_cmt) = mc.cat_def(pat.hir_id, pat.span, pat_ty, def) {
864 delegate.mutate(pat.id, pat.span, binding_cmt, MutateMode::Init);
867 // It is also a borrow or copy/move of the value being matched.
869 ty::BindByReference(m) => {
870 if let ty::TyRef(r, _, _) = pat_ty.sty {
871 let bk = ty::BorrowKind::from_mutbl(m);
872 delegate.borrow(pat.id, pat.span, &cmt_pat, r, bk, RefBinding);
875 ty::BindByValue(..) => {
876 let mode = copy_or_move(mc, param_env, &cmt_pat, PatBindingMove);
877 debug!("walk_pat binding consuming pat");
878 delegate.consume_pat(pat, &cmt_pat, mode);
882 tcx.sess.delay_span_bug(pat.span, "missing binding mode");
887 // Do a second pass over the pattern, calling `matched_pat` on
888 // the interior nodes (enum variants and structs), as opposed
889 // to the above loop's visit of than the bindings that form
890 // the leaves of the pattern tree structure.
891 return_if_err!(mc.cat_pattern(cmt_discr, pat, |cmt_pat, pat| {
892 let qpath = match pat.node {
893 PatKind::Path(ref qpath) |
894 PatKind::TupleStruct(ref qpath, ..) |
895 PatKind::Struct(ref qpath, ..) => qpath,
898 let def = mc.tables.qpath_def(qpath, pat.hir_id);
900 Def::Variant(variant_did) |
901 Def::VariantCtor(variant_did, ..) => {
902 let downcast_cmt = mc.cat_downcast_if_needed(pat, cmt_pat, variant_did);
904 debug!("variant downcast_cmt={:?} pat={:?}", downcast_cmt, pat);
905 delegate.matched_pat(pat, &downcast_cmt, match_mode);
907 Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) |
908 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => {
909 debug!("struct cmt_pat={:?} pat={:?}", cmt_pat, pat);
910 delegate.matched_pat(pat, &cmt_pat, match_mode);
917 fn walk_captures(&mut self, closure_expr: &hir::Expr, fn_decl_span: Span) {
918 debug!("walk_captures({:?})", closure_expr);
920 self.tcx().with_freevars(closure_expr.id, |freevars| {
921 for freevar in freevars {
922 let var_hir_id = self.tcx().hir.node_to_hir_id(freevar.var_id());
923 let closure_def_id = self.tcx().hir.local_def_id(closure_expr.id);
924 let upvar_id = ty::UpvarId {
926 closure_expr_id: closure_def_id.to_local(),
928 let upvar_capture = self.mc.tables.upvar_capture(upvar_id);
929 let cmt_var = return_if_err!(self.cat_captured_var(closure_expr.hir_id,
932 match upvar_capture {
933 ty::UpvarCapture::ByValue => {
934 let mode = copy_or_move(&self.mc,
938 self.delegate.consume(closure_expr.id, freevar.span, &cmt_var, mode);
940 ty::UpvarCapture::ByRef(upvar_borrow) => {
941 self.delegate.borrow(closure_expr.id,
946 ClosureCapture(freevar.span));
953 fn cat_captured_var(&mut self,
954 closure_hir_id: hir::HirId,
956 upvar: &hir::Freevar)
957 -> mc::McResult<mc::cmt_<'tcx>> {
958 // Create the cmt for the variable being borrowed, from the
959 // caller's perspective
960 let var_hir_id = self.tcx().hir.node_to_hir_id(upvar.var_id());
961 let var_ty = self.mc.node_ty(var_hir_id)?;
962 self.mc.cat_def(closure_hir_id, closure_span, var_ty, upvar.def)
966 fn copy_or_move<'a, 'gcx, 'tcx>(mc: &mc::MemCategorizationContext<'a, 'gcx, 'tcx>,
967 param_env: ty::ParamEnv<'tcx>,
968 cmt: &mc::cmt_<'tcx>,
969 move_reason: MoveReason)
972 if mc.type_moves_by_default(param_env, cmt.ty, cmt.span) {