| // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! A different sort of visitor for walking fn bodies. Unlike the |
| //! normal visitor, which just walks the entire body in one shot, the |
| //! `ExprUseVisitor` determines how expressions are being used. |
| |
| pub use self::LoanCause::*; |
| pub use self::ConsumeMode::*; |
| pub use self::MoveReason::*; |
| pub use self::MatchMode::*; |
| use self::TrackMatchMode::*; |
| use self::OverloadedCallType::*; |
| |
| use hir::pat_util; |
| use hir::def::Def; |
| use hir::def_id::{DefId}; |
| use infer::InferCtxt; |
| use middle::mem_categorization as mc; |
| use ty::{self, TyCtxt, adjustment}; |
| |
| use hir::{self, PatKind}; |
| |
| use syntax::ast; |
| use syntax::ptr::P; |
| use syntax_pos::Span; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // The Delegate trait |
| |
| /// This trait defines the callbacks you can expect to receive when |
| /// employing the ExprUseVisitor. |
| pub trait Delegate<'tcx> { |
| // The value found at `cmt` is either copied or moved, depending |
| // on mode. |
| fn consume(&mut self, |
| consume_id: ast::NodeId, |
| consume_span: Span, |
| cmt: mc::cmt<'tcx>, |
| mode: ConsumeMode); |
| |
| // The value found at `cmt` has been determined to match the |
| // pattern binding `matched_pat`, and its subparts are being |
| // copied or moved depending on `mode`. Note that `matched_pat` |
| // is called on all variant/structs in the pattern (i.e., the |
| // interior nodes of the pattern's tree structure) while |
| // consume_pat is called on the binding identifiers in the pattern |
| // (which are leaves of the pattern's tree structure). |
| // |
| // Note that variants/structs and identifiers are disjoint; thus |
| // `matched_pat` and `consume_pat` are never both called on the |
| // same input pattern structure (though of `consume_pat` can be |
| // called on a subpart of an input passed to `matched_pat). |
| fn matched_pat(&mut self, |
| matched_pat: &hir::Pat, |
| cmt: mc::cmt<'tcx>, |
| mode: MatchMode); |
| |
| // The value found at `cmt` is either copied or moved via the |
| // pattern binding `consume_pat`, depending on mode. |
| fn consume_pat(&mut self, |
| consume_pat: &hir::Pat, |
| cmt: mc::cmt<'tcx>, |
| mode: ConsumeMode); |
| |
| // The value found at `borrow` is being borrowed at the point |
| // `borrow_id` for the region `loan_region` with kind `bk`. |
| fn borrow(&mut self, |
| borrow_id: ast::NodeId, |
| borrow_span: Span, |
| cmt: mc::cmt<'tcx>, |
| loan_region: ty::Region, |
| bk: ty::BorrowKind, |
| loan_cause: LoanCause); |
| |
| // The local variable `id` is declared but not initialized. |
| fn decl_without_init(&mut self, |
| id: ast::NodeId, |
| span: Span); |
| |
| // The path at `cmt` is being assigned to. |
| fn mutate(&mut self, |
| assignment_id: ast::NodeId, |
| assignment_span: Span, |
| assignee_cmt: mc::cmt<'tcx>, |
| mode: MutateMode); |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum LoanCause { |
| ClosureCapture(Span), |
| AddrOf, |
| AutoRef, |
| AutoUnsafe, |
| RefBinding, |
| OverloadedOperator, |
| ClosureInvocation, |
| ForLoop, |
| MatchDiscriminant |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum ConsumeMode { |
| Copy, // reference to x where x has a type that copies |
| Move(MoveReason), // reference to x where x has a type that moves |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum MoveReason { |
| DirectRefMove, |
| PatBindingMove, |
| CaptureMove, |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum MatchMode { |
| NonBindingMatch, |
| BorrowingMatch, |
| CopyingMatch, |
| MovingMatch, |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| enum TrackMatchMode { |
| Unknown, |
| Definite(MatchMode), |
| Conflicting, |
| } |
| |
| impl TrackMatchMode { |
| // Builds up the whole match mode for a pattern from its constituent |
| // parts. The lattice looks like this: |
| // |
| // Conflicting |
| // / \ |
| // / \ |
| // Borrowing Moving |
| // \ / |
| // \ / |
| // Copying |
| // | |
| // NonBinding |
| // | |
| // Unknown |
| // |
| // examples: |
| // |
| // * `(_, some_int)` pattern is Copying, since |
| // NonBinding + Copying => Copying |
| // |
| // * `(some_int, some_box)` pattern is Moving, since |
| // Copying + Moving => Moving |
| // |
| // * `(ref x, some_box)` pattern is Conflicting, since |
| // Borrowing + Moving => Conflicting |
| // |
| // Note that the `Unknown` and `Conflicting` states are |
| // represented separately from the other more interesting |
| // `Definite` states, which simplifies logic here somewhat. |
| fn lub(&mut self, mode: MatchMode) { |
| *self = match (*self, mode) { |
| // Note that clause order below is very significant. |
| (Unknown, new) => Definite(new), |
| (Definite(old), new) if old == new => Definite(old), |
| |
| (Definite(old), NonBindingMatch) => Definite(old), |
| (Definite(NonBindingMatch), new) => Definite(new), |
| |
| (Definite(old), CopyingMatch) => Definite(old), |
| (Definite(CopyingMatch), new) => Definite(new), |
| |
| (Definite(_), _) => Conflicting, |
| (Conflicting, _) => *self, |
| }; |
| } |
| |
| fn match_mode(&self) -> MatchMode { |
| match *self { |
| Unknown => NonBindingMatch, |
| Definite(mode) => mode, |
| Conflicting => { |
| // Conservatively return MovingMatch to let the |
| // compiler continue to make progress. |
| MovingMatch |
| } |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum MutateMode { |
| Init, |
| JustWrite, // x = y |
| WriteAndRead, // x += y |
| } |
| |
| #[derive(Copy, Clone)] |
| enum OverloadedCallType { |
| FnOverloadedCall, |
| FnMutOverloadedCall, |
| FnOnceOverloadedCall, |
| } |
| |
| impl OverloadedCallType { |
| fn from_trait_id(tcx: TyCtxt, trait_id: DefId) -> OverloadedCallType { |
| for &(maybe_function_trait, overloaded_call_type) in &[ |
| (tcx.lang_items.fn_once_trait(), FnOnceOverloadedCall), |
| (tcx.lang_items.fn_mut_trait(), FnMutOverloadedCall), |
| (tcx.lang_items.fn_trait(), FnOverloadedCall) |
| ] { |
| match maybe_function_trait { |
| Some(function_trait) if function_trait == trait_id => { |
| return overloaded_call_type |
| } |
| _ => continue, |
| } |
| } |
| |
| bug!("overloaded call didn't map to known function trait") |
| } |
| |
| fn from_method_id(tcx: TyCtxt, method_id: DefId) -> OverloadedCallType { |
| let method = tcx.impl_or_trait_item(method_id); |
| OverloadedCallType::from_trait_id(tcx, method.container().id()) |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // The ExprUseVisitor type |
| // |
| // This is the code that actually walks the tree. Like |
| // mem_categorization, it requires a TYPER, which is a type that |
| // supplies types from the tree. After type checking is complete, you |
| // can just use the tcx as the typer. |
| pub struct ExprUseVisitor<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
| mc: mc::MemCategorizationContext<'a, 'gcx, 'tcx>, |
| delegate: &'a mut Delegate<'tcx>, |
| } |
| |
| // If the TYPER results in an error, it's because the type check |
| // failed (or will fail, when the error is uncovered and reported |
| // during writeback). In this case, we just ignore this part of the |
| // code. |
| // |
| // Note that this macro appears similar to try!(), but, unlike try!(), |
| // it does not propagate the error. |
| macro_rules! return_if_err { |
| ($inp: expr) => ( |
| match $inp { |
| Ok(v) => v, |
| Err(()) => { |
| debug!("mc reported err"); |
| return |
| } |
| } |
| ) |
| } |
| |
| /// Whether the elements of an overloaded operation are passed by value or by reference |
| enum PassArgs { |
| ByValue, |
| ByRef, |
| } |
| |
| impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> { |
| pub fn new(delegate: &'a mut (Delegate<'tcx>+'a), |
| infcx: &'a InferCtxt<'a, 'gcx, 'tcx>) -> Self |
| { |
| ExprUseVisitor { |
| mc: mc::MemCategorizationContext::new(infcx), |
| delegate: delegate |
| } |
| } |
| |
| pub fn walk_fn(&mut self, |
| decl: &hir::FnDecl, |
| body: &hir::Block) { |
| self.walk_arg_patterns(decl, body); |
| self.walk_block(body); |
| } |
| |
| fn walk_arg_patterns(&mut self, |
| decl: &hir::FnDecl, |
| body: &hir::Block) { |
| for arg in &decl.inputs { |
| let arg_ty = return_if_err!(self.mc.infcx.node_ty(arg.pat.id)); |
| |
| let fn_body_scope = self.tcx().region_maps.node_extent(body.id); |
| let arg_cmt = self.mc.cat_rvalue( |
| arg.id, |
| arg.pat.span, |
| ty::ReScope(fn_body_scope), // Args live only as long as the fn body. |
| arg_ty); |
| |
| self.walk_irrefutable_pat(arg_cmt, &arg.pat); |
| } |
| } |
| |
| fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> { |
| self.mc.infcx.tcx |
| } |
| |
| fn delegate_consume(&mut self, |
| consume_id: ast::NodeId, |
| consume_span: Span, |
| cmt: mc::cmt<'tcx>) { |
| debug!("delegate_consume(consume_id={}, cmt={:?})", |
| consume_id, cmt); |
| |
| let mode = copy_or_move(self.mc.infcx, &cmt, DirectRefMove); |
| self.delegate.consume(consume_id, consume_span, cmt, mode); |
| } |
| |
| fn consume_exprs(&mut self, exprs: &[P<hir::Expr>]) { |
| for expr in exprs { |
| self.consume_expr(&expr); |
| } |
| } |
| |
| pub fn consume_expr(&mut self, expr: &hir::Expr) { |
| debug!("consume_expr(expr={:?})", expr); |
| |
| let cmt = return_if_err!(self.mc.cat_expr(expr)); |
| self.delegate_consume(expr.id, expr.span, cmt); |
| self.walk_expr(expr); |
| } |
| |
| fn mutate_expr(&mut self, |
| assignment_expr: &hir::Expr, |
| expr: &hir::Expr, |
| mode: MutateMode) { |
| let cmt = return_if_err!(self.mc.cat_expr(expr)); |
| self.delegate.mutate(assignment_expr.id, assignment_expr.span, cmt, mode); |
| self.walk_expr(expr); |
| } |
| |
| fn borrow_expr(&mut self, |
| expr: &hir::Expr, |
| r: ty::Region, |
| bk: ty::BorrowKind, |
| cause: LoanCause) { |
| debug!("borrow_expr(expr={:?}, r={:?}, bk={:?})", |
| expr, r, bk); |
| |
| let cmt = return_if_err!(self.mc.cat_expr(expr)); |
| self.delegate.borrow(expr.id, expr.span, cmt, r, bk, cause); |
| |
| self.walk_expr(expr) |
| } |
| |
| fn select_from_expr(&mut self, expr: &hir::Expr) { |
| self.walk_expr(expr) |
| } |
| |
| pub fn walk_expr(&mut self, expr: &hir::Expr) { |
| debug!("walk_expr(expr={:?})", expr); |
| |
| self.walk_adjustment(expr); |
| |
| match expr.node { |
| hir::ExprPath(..) => { } |
| |
| hir::ExprType(ref subexpr, _) => { |
| self.walk_expr(&subexpr) |
| } |
| |
| hir::ExprUnary(hir::UnDeref, ref base) => { // *base |
| if !self.walk_overloaded_operator(expr, &base, Vec::new(), PassArgs::ByRef) { |
| self.select_from_expr(&base); |
| } |
| } |
| |
| hir::ExprField(ref base, _) => { // base.f |
| self.select_from_expr(&base); |
| } |
| |
| hir::ExprTupField(ref base, _) => { // base.<n> |
| self.select_from_expr(&base); |
| } |
| |
| hir::ExprIndex(ref lhs, ref rhs) => { // lhs[rhs] |
| if !self.walk_overloaded_operator(expr, |
| &lhs, |
| vec![&rhs], |
| PassArgs::ByValue) { |
| self.select_from_expr(&lhs); |
| self.consume_expr(&rhs); |
| } |
| } |
| |
| hir::ExprCall(ref callee, ref args) => { // callee(args) |
| self.walk_callee(expr, &callee); |
| self.consume_exprs(args); |
| } |
| |
| hir::ExprMethodCall(_, _, ref args) => { // callee.m(args) |
| self.consume_exprs(args); |
| } |
| |
| hir::ExprStruct(_, ref fields, ref opt_with) => { |
| self.walk_struct_expr(expr, fields, opt_with); |
| } |
| |
| hir::ExprTup(ref exprs) => { |
| self.consume_exprs(exprs); |
| } |
| |
| hir::ExprIf(ref cond_expr, ref then_blk, ref opt_else_expr) => { |
| self.consume_expr(&cond_expr); |
| self.walk_block(&then_blk); |
| if let Some(ref else_expr) = *opt_else_expr { |
| self.consume_expr(&else_expr); |
| } |
| } |
| |
| hir::ExprMatch(ref discr, ref arms, _) => { |
| let discr_cmt = return_if_err!(self.mc.cat_expr(&discr)); |
| self.borrow_expr(&discr, ty::ReEmpty, ty::ImmBorrow, MatchDiscriminant); |
| |
| // treatment of the discriminant is handled while walking the arms. |
| for arm in arms { |
| let mode = self.arm_move_mode(discr_cmt.clone(), arm); |
| let mode = mode.match_mode(); |
| self.walk_arm(discr_cmt.clone(), arm, mode); |
| } |
| } |
| |
| hir::ExprVec(ref exprs) => { |
| self.consume_exprs(exprs); |
| } |
| |
| hir::ExprAddrOf(m, ref base) => { // &base |
| // make sure that the thing we are pointing out stays valid |
| // for the lifetime `scope_r` of the resulting ptr: |
| let expr_ty = return_if_err!(self.mc.infcx.node_ty(expr.id)); |
| if let ty::TyRef(&r, _) = expr_ty.sty { |
| let bk = ty::BorrowKind::from_mutbl(m); |
| self.borrow_expr(&base, r, bk, AddrOf); |
| } |
| } |
| |
| hir::ExprInlineAsm(ref ia, ref outputs, ref inputs) => { |
| for (o, output) in ia.outputs.iter().zip(outputs) { |
| if o.is_indirect { |
| self.consume_expr(output); |
| } else { |
| self.mutate_expr(expr, output, |
| if o.is_rw { |
| MutateMode::WriteAndRead |
| } else { |
| MutateMode::JustWrite |
| }); |
| } |
| } |
| self.consume_exprs(inputs); |
| } |
| |
| hir::ExprBreak(..) | |
| hir::ExprAgain(..) | |
| hir::ExprLit(..) => {} |
| |
| hir::ExprLoop(ref blk, _) => { |
| self.walk_block(&blk); |
| } |
| |
| hir::ExprWhile(ref cond_expr, ref blk, _) => { |
| self.consume_expr(&cond_expr); |
| self.walk_block(&blk); |
| } |
| |
| hir::ExprUnary(op, ref lhs) => { |
| let pass_args = if op.is_by_value() { |
| PassArgs::ByValue |
| } else { |
| PassArgs::ByRef |
| }; |
| |
| if !self.walk_overloaded_operator(expr, &lhs, Vec::new(), pass_args) { |
| self.consume_expr(&lhs); |
| } |
| } |
| |
| hir::ExprBinary(op, ref lhs, ref rhs) => { |
| let pass_args = if op.node.is_by_value() { |
| PassArgs::ByValue |
| } else { |
| PassArgs::ByRef |
| }; |
| |
| if !self.walk_overloaded_operator(expr, &lhs, vec![&rhs], pass_args) { |
| self.consume_expr(&lhs); |
| self.consume_expr(&rhs); |
| } |
| } |
| |
| hir::ExprBlock(ref blk) => { |
| self.walk_block(&blk); |
| } |
| |
| hir::ExprRet(ref opt_expr) => { |
| if let Some(ref expr) = *opt_expr { |
| self.consume_expr(&expr); |
| } |
| } |
| |
| hir::ExprAssign(ref lhs, ref rhs) => { |
| self.mutate_expr(expr, &lhs, MutateMode::JustWrite); |
| self.consume_expr(&rhs); |
| } |
| |
| hir::ExprCast(ref base, _) => { |
| self.consume_expr(&base); |
| } |
| |
| hir::ExprAssignOp(op, ref lhs, ref rhs) => { |
| // NB All our assignment operations take the RHS by value |
| assert!(op.node.is_by_value()); |
| |
| if !self.walk_overloaded_operator(expr, lhs, vec![rhs], PassArgs::ByValue) { |
| self.mutate_expr(expr, &lhs, MutateMode::WriteAndRead); |
| self.consume_expr(&rhs); |
| } |
| } |
| |
| hir::ExprRepeat(ref base, ref count) => { |
| self.consume_expr(&base); |
| self.consume_expr(&count); |
| } |
| |
| hir::ExprClosure(_, _, _, fn_decl_span) => { |
| self.walk_captures(expr, fn_decl_span) |
| } |
| |
| hir::ExprBox(ref base) => { |
| self.consume_expr(&base); |
| } |
| } |
| } |
| |
| fn walk_callee(&mut self, call: &hir::Expr, callee: &hir::Expr) { |
| let callee_ty = return_if_err!(self.mc.infcx.expr_ty_adjusted(callee)); |
| debug!("walk_callee: callee={:?} callee_ty={:?}", |
| callee, callee_ty); |
| let call_scope = self.tcx().region_maps.node_extent(call.id); |
| match callee_ty.sty { |
| ty::TyFnDef(..) | ty::TyFnPtr(_) => { |
| self.consume_expr(callee); |
| } |
| ty::TyError => { } |
| _ => { |
| let overloaded_call_type = |
| match self.mc.infcx.node_method_id(ty::MethodCall::expr(call.id)) { |
| Some(method_id) => { |
| OverloadedCallType::from_method_id(self.tcx(), method_id) |
| } |
| None => { |
| span_bug!( |
| callee.span, |
| "unexpected callee type {}", |
| callee_ty) |
| } |
| }; |
| match overloaded_call_type { |
| FnMutOverloadedCall => { |
| self.borrow_expr(callee, |
| ty::ReScope(call_scope), |
| ty::MutBorrow, |
| ClosureInvocation); |
| } |
| FnOverloadedCall => { |
| self.borrow_expr(callee, |
| ty::ReScope(call_scope), |
| ty::ImmBorrow, |
| ClosureInvocation); |
| } |
| FnOnceOverloadedCall => self.consume_expr(callee), |
| } |
| } |
| } |
| } |
| |
| fn walk_stmt(&mut self, stmt: &hir::Stmt) { |
| match stmt.node { |
| hir::StmtDecl(ref decl, _) => { |
| match decl.node { |
| hir::DeclLocal(ref local) => { |
| self.walk_local(&local); |
| } |
| |
| hir::DeclItem(_) => { |
| // we don't visit nested items in this visitor, |
| // only the fn body we were given. |
| } |
| } |
| } |
| |
| hir::StmtExpr(ref expr, _) | |
| hir::StmtSemi(ref expr, _) => { |
| self.consume_expr(&expr); |
| } |
| } |
| } |
| |
| fn walk_local(&mut self, local: &hir::Local) { |
| match local.init { |
| None => { |
| let delegate = &mut self.delegate; |
| pat_util::pat_bindings(&local.pat, |_, id, span, _| { |
| delegate.decl_without_init(id, span); |
| }) |
| } |
| |
| Some(ref expr) => { |
| // Variable declarations with |
| // initializers are considered |
| // "assigns", which is handled by |
| // `walk_pat`: |
| self.walk_expr(&expr); |
| let init_cmt = return_if_err!(self.mc.cat_expr(&expr)); |
| self.walk_irrefutable_pat(init_cmt, &local.pat); |
| } |
| } |
| } |
| |
| /// Indicates that the value of `blk` will be consumed, meaning either copied or moved |
| /// depending on its type. |
| fn walk_block(&mut self, blk: &hir::Block) { |
| debug!("walk_block(blk.id={})", blk.id); |
| |
| for stmt in &blk.stmts { |
| self.walk_stmt(stmt); |
| } |
| |
| if let Some(ref tail_expr) = blk.expr { |
| self.consume_expr(&tail_expr); |
| } |
| } |
| |
| fn walk_struct_expr(&mut self, |
| _expr: &hir::Expr, |
| fields: &[hir::Field], |
| opt_with: &Option<P<hir::Expr>>) { |
| // Consume the expressions supplying values for each field. |
| for field in fields { |
| self.consume_expr(&field.expr); |
| } |
| |
| let with_expr = match *opt_with { |
| Some(ref w) => &**w, |
| None => { return; } |
| }; |
| |
| let with_cmt = return_if_err!(self.mc.cat_expr(&with_expr)); |
| |
| // Select just those fields of the `with` |
| // expression that will actually be used |
| if let ty::TyStruct(def, substs) = with_cmt.ty.sty { |
| // Consume those fields of the with expression that are needed. |
| for with_field in &def.struct_variant().fields { |
| if !contains_field_named(with_field, fields) { |
| let cmt_field = self.mc.cat_field( |
| &*with_expr, |
| with_cmt.clone(), |
| with_field.name, |
| with_field.ty(self.tcx(), substs) |
| ); |
| self.delegate_consume(with_expr.id, with_expr.span, cmt_field); |
| } |
| } |
| } else { |
| // the base expression should always evaluate to a |
| // struct; however, when EUV is run during typeck, it |
| // may not. This will generate an error earlier in typeck, |
| // so we can just ignore it. |
| if !self.tcx().sess.has_errors() { |
| span_bug!( |
| with_expr.span, |
| "with expression doesn't evaluate to a struct"); |
| } |
| }; |
| |
| // walk the with expression so that complex expressions |
| // are properly handled. |
| self.walk_expr(with_expr); |
| |
| fn contains_field_named(field: ty::FieldDef, |
| fields: &[hir::Field]) |
| -> bool |
| { |
| fields.iter().any( |
| |f| f.name.node == field.name) |
| } |
| } |
| |
| // Invoke the appropriate delegate calls for anything that gets |
| // consumed or borrowed as part of the automatic adjustment |
| // process. |
| fn walk_adjustment(&mut self, expr: &hir::Expr) { |
| let infcx = self.mc.infcx; |
| //NOTE(@jroesch): mixed RefCell borrow causes crash |
| let adj = infcx.adjustments().get(&expr.id).map(|x| x.clone()); |
| if let Some(adjustment) = adj { |
| match adjustment { |
| adjustment::AdjustReifyFnPointer | |
| adjustment::AdjustUnsafeFnPointer | |
| adjustment::AdjustMutToConstPointer => { |
| // Creating a closure/fn-pointer or unsizing consumes |
| // the input and stores it into the resulting rvalue. |
| debug!("walk_adjustment: trivial adjustment"); |
| let cmt_unadjusted = |
| return_if_err!(self.mc.cat_expr_unadjusted(expr)); |
| self.delegate_consume(expr.id, expr.span, cmt_unadjusted); |
| } |
| adjustment::AdjustDerefRef(ref adj) => { |
| self.walk_autoderefref(expr, adj); |
| } |
| } |
| } |
| } |
| |
| /// Autoderefs for overloaded Deref calls in fact reference their receiver. That is, if we have |
| /// `(*x)` where `x` is of type `Rc<T>`, then this in fact is equivalent to `x.deref()`. Since |
| /// `deref()` is declared with `&self`, this is an autoref of `x`. |
| fn walk_autoderefs(&mut self, |
| expr: &hir::Expr, |
| autoderefs: usize) { |
| debug!("walk_autoderefs expr={:?} autoderefs={}", expr, autoderefs); |
| |
| for i in 0..autoderefs { |
| let deref_id = ty::MethodCall::autoderef(expr.id, i as u32); |
| if let Some(method_ty) = self.mc.infcx.node_method_ty(deref_id) { |
| let cmt = return_if_err!(self.mc.cat_expr_autoderefd(expr, i)); |
| |
| // the method call infrastructure should have |
| // replaced all late-bound regions with variables: |
| let self_ty = method_ty.fn_sig().input(0); |
| let self_ty = self.tcx().no_late_bound_regions(&self_ty).unwrap(); |
| |
| let (m, r) = match self_ty.sty { |
| ty::TyRef(r, ref m) => (m.mutbl, r), |
| _ => span_bug!(expr.span, |
| "bad overloaded deref type {:?}", |
| method_ty) |
| }; |
| let bk = ty::BorrowKind::from_mutbl(m); |
| self.delegate.borrow(expr.id, expr.span, cmt, |
| *r, bk, AutoRef); |
| } |
| } |
| } |
| |
| fn walk_autoderefref(&mut self, |
| expr: &hir::Expr, |
| adj: &adjustment::AutoDerefRef<'tcx>) { |
| debug!("walk_autoderefref expr={:?} adj={:?}", |
| expr, |
| adj); |
| |
| self.walk_autoderefs(expr, adj.autoderefs); |
| |
| let cmt_derefd = |
| return_if_err!(self.mc.cat_expr_autoderefd(expr, adj.autoderefs)); |
| |
| let cmt_refd = |
| self.walk_autoref(expr, cmt_derefd, adj.autoref); |
| |
| if adj.unsize.is_some() { |
| // Unsizing consumes the thin pointer and produces a fat one. |
| self.delegate_consume(expr.id, expr.span, cmt_refd); |
| } |
| } |
| |
| |
| /// Walks the autoref `opt_autoref` applied to the autoderef'd |
| /// `expr`. `cmt_derefd` is the mem-categorized form of `expr` |
| /// after all relevant autoderefs have occurred. Because AutoRefs |
| /// can be recursive, this function is recursive: it first walks |
| /// deeply all the way down the autoref chain, and then processes |
| /// the autorefs on the way out. At each point, it returns the |
| /// `cmt` for the rvalue that will be produced by introduced an |
| /// autoref. |
| fn walk_autoref(&mut self, |
| expr: &hir::Expr, |
| cmt_base: mc::cmt<'tcx>, |
| opt_autoref: Option<adjustment::AutoRef<'tcx>>) |
| -> mc::cmt<'tcx> |
| { |
| debug!("walk_autoref(expr.id={} cmt_derefd={:?} opt_autoref={:?})", |
| expr.id, |
| cmt_base, |
| opt_autoref); |
| |
| let cmt_base_ty = cmt_base.ty; |
| |
| let autoref = match opt_autoref { |
| Some(ref autoref) => autoref, |
| None => { |
| // No AutoRef. |
| return cmt_base; |
| } |
| }; |
| |
| match *autoref { |
| adjustment::AutoPtr(r, m) => { |
| self.delegate.borrow(expr.id, |
| expr.span, |
| cmt_base, |
| *r, |
| ty::BorrowKind::from_mutbl(m), |
| AutoRef); |
| } |
| |
| adjustment::AutoUnsafe(m) => { |
| debug!("walk_autoref: expr.id={} cmt_base={:?}", |
| expr.id, |
| cmt_base); |
| |
| // Converting from a &T to *T (or &mut T to *mut T) is |
| // treated as borrowing it for the enclosing temporary |
| // scope. |
| let r = ty::ReScope(self.tcx().region_maps.node_extent(expr.id)); |
| |
| self.delegate.borrow(expr.id, |
| expr.span, |
| cmt_base, |
| r, |
| ty::BorrowKind::from_mutbl(m), |
| AutoUnsafe); |
| } |
| } |
| |
| // Construct the categorization for the result of the autoref. |
| // This is always an rvalue, since we are producing a new |
| // (temporary) indirection. |
| |
| let adj_ty = cmt_base_ty.adjust_for_autoref(self.tcx(), opt_autoref); |
| |
| self.mc.cat_rvalue_node(expr.id, expr.span, adj_ty) |
| } |
| |
| |
| // When this returns true, it means that the expression *is* a |
| // method-call (i.e. via the operator-overload). This true result |
| // also implies that walk_overloaded_operator already took care of |
| // recursively processing the input arguments, and thus the caller |
| // should not do so. |
| fn walk_overloaded_operator(&mut self, |
| expr: &hir::Expr, |
| receiver: &hir::Expr, |
| rhs: Vec<&hir::Expr>, |
| pass_args: PassArgs) |
| -> bool |
| { |
| if !self.mc.infcx.is_method_call(expr.id) { |
| return false; |
| } |
| |
| match pass_args { |
| PassArgs::ByValue => { |
| self.consume_expr(receiver); |
| for &arg in &rhs { |
| self.consume_expr(arg); |
| } |
| |
| return true; |
| }, |
| PassArgs::ByRef => {}, |
| } |
| |
| self.walk_expr(receiver); |
| |
| // Arguments (but not receivers) to overloaded operator |
| // methods are implicitly autoref'd which sadly does not use |
| // adjustments, so we must hardcode the borrow here. |
| |
| let r = ty::ReScope(self.tcx().region_maps.node_extent(expr.id)); |
| let bk = ty::ImmBorrow; |
| |
| for &arg in &rhs { |
| self.borrow_expr(arg, r, bk, OverloadedOperator); |
| } |
| return true; |
| } |
| |
| fn arm_move_mode(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &hir::Arm) -> TrackMatchMode { |
| let mut mode = Unknown; |
| for pat in &arm.pats { |
| self.determine_pat_move_mode(discr_cmt.clone(), &pat, &mut mode); |
| } |
| mode |
| } |
| |
| fn walk_arm(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &hir::Arm, mode: MatchMode) { |
| for pat in &arm.pats { |
| self.walk_pat(discr_cmt.clone(), &pat, mode); |
| } |
| |
| if let Some(ref guard) = arm.guard { |
| self.consume_expr(&guard); |
| } |
| |
| self.consume_expr(&arm.body); |
| } |
| |
| /// Walks a pat that occurs in isolation (i.e. top-level of fn |
| /// arg or let binding. *Not* a match arm or nested pat.) |
| fn walk_irrefutable_pat(&mut self, cmt_discr: mc::cmt<'tcx>, pat: &hir::Pat) { |
| let mut mode = Unknown; |
| self.determine_pat_move_mode(cmt_discr.clone(), pat, &mut mode); |
| let mode = mode.match_mode(); |
| self.walk_pat(cmt_discr, pat, mode); |
| } |
| |
| /// Identifies any bindings within `pat` and accumulates within |
| /// `mode` whether the overall pattern/match structure is a move, |
| /// copy, or borrow. |
| fn determine_pat_move_mode(&mut self, |
| cmt_discr: mc::cmt<'tcx>, |
| pat: &hir::Pat, |
| mode: &mut TrackMatchMode) { |
| debug!("determine_pat_move_mode cmt_discr={:?} pat={:?}", cmt_discr, |
| pat); |
| return_if_err!(self.mc.cat_pattern(cmt_discr, pat, |_mc, cmt_pat, pat| { |
| match pat.node { |
| PatKind::Binding(hir::BindByRef(..), _, _) => |
| mode.lub(BorrowingMatch), |
| PatKind::Binding(hir::BindByValue(..), _, _) => { |
| match copy_or_move(self.mc.infcx, &cmt_pat, PatBindingMove) { |
| Copy => mode.lub(CopyingMatch), |
| Move(..) => mode.lub(MovingMatch), |
| } |
| } |
| _ => {} |
| } |
| })); |
| } |
| |
| /// The core driver for walking a pattern; `match_mode` must be |
| /// established up front, e.g. via `determine_pat_move_mode` (see |
| /// also `walk_irrefutable_pat` for patterns that stand alone). |
| fn walk_pat(&mut self, cmt_discr: mc::cmt<'tcx>, pat: &hir::Pat, match_mode: MatchMode) { |
| debug!("walk_pat cmt_discr={:?} pat={:?}", cmt_discr, pat); |
| |
| let tcx = &self.tcx(); |
| let mc = &self.mc; |
| let infcx = self.mc.infcx; |
| let delegate = &mut self.delegate; |
| return_if_err!(mc.cat_pattern(cmt_discr.clone(), pat, |mc, cmt_pat, pat| { |
| if let PatKind::Binding(bmode, _, _) = pat.node { |
| debug!("binding cmt_pat={:?} pat={:?} match_mode={:?}", cmt_pat, pat, match_mode); |
| |
| // pat_ty: the type of the binding being produced. |
| let pat_ty = return_if_err!(infcx.node_ty(pat.id)); |
| |
| // Each match binding is effectively an assignment to the |
| // binding being produced. |
| if let Ok(binding_cmt) = mc.cat_def(pat.id, pat.span, pat_ty, |
| tcx.expect_def(pat.id)) { |
| delegate.mutate(pat.id, pat.span, binding_cmt, MutateMode::Init); |
| } |
| |
| // It is also a borrow or copy/move of the value being matched. |
| match bmode { |
| hir::BindByRef(m) => { |
| if let ty::TyRef(&r, _) = pat_ty.sty { |
| let bk = ty::BorrowKind::from_mutbl(m); |
| delegate.borrow(pat.id, pat.span, cmt_pat, r, bk, RefBinding); |
| } |
| } |
| hir::BindByValue(..) => { |
| let mode = copy_or_move(infcx, &cmt_pat, PatBindingMove); |
| debug!("walk_pat binding consuming pat"); |
| delegate.consume_pat(pat, cmt_pat, mode); |
| } |
| } |
| } |
| })); |
| |
| // Do a second pass over the pattern, calling `matched_pat` on |
| // the interior nodes (enum variants and structs), as opposed |
| // to the above loop's visit of than the bindings that form |
| // the leaves of the pattern tree structure. |
| return_if_err!(mc.cat_pattern(cmt_discr, pat, |mc, cmt_pat, pat| { |
| match tcx.expect_def_or_none(pat.id) { |
| Some(Def::Variant(enum_did, variant_did)) => { |
| let downcast_cmt = if tcx.lookup_adt_def(enum_did).is_univariant() { |
| cmt_pat |
| } else { |
| let cmt_pat_ty = cmt_pat.ty; |
| mc.cat_downcast(pat, cmt_pat, cmt_pat_ty, variant_did) |
| }; |
| |
| debug!("variant downcast_cmt={:?} pat={:?}", downcast_cmt, pat); |
| delegate.matched_pat(pat, downcast_cmt, match_mode); |
| } |
| Some(Def::Struct(..)) | Some(Def::TyAlias(..)) | Some(Def::AssociatedTy(..)) => { |
| debug!("struct cmt_pat={:?} pat={:?}", cmt_pat, pat); |
| delegate.matched_pat(pat, cmt_pat, match_mode); |
| } |
| _ => {} |
| } |
| })); |
| } |
| |
| fn walk_captures(&mut self, closure_expr: &hir::Expr, fn_decl_span: Span) { |
| debug!("walk_captures({:?})", closure_expr); |
| |
| self.tcx().with_freevars(closure_expr.id, |freevars| { |
| for freevar in freevars { |
| let id_var = freevar.def.var_id(); |
| let upvar_id = ty::UpvarId { var_id: id_var, |
| closure_expr_id: closure_expr.id }; |
| let upvar_capture = self.mc.infcx.upvar_capture(upvar_id).unwrap(); |
| let cmt_var = return_if_err!(self.cat_captured_var(closure_expr.id, |
| fn_decl_span, |
| freevar.def)); |
| match upvar_capture { |
| ty::UpvarCapture::ByValue => { |
| let mode = copy_or_move(self.mc.infcx, &cmt_var, CaptureMove); |
| self.delegate.consume(closure_expr.id, freevar.span, cmt_var, mode); |
| } |
| ty::UpvarCapture::ByRef(upvar_borrow) => { |
| self.delegate.borrow(closure_expr.id, |
| fn_decl_span, |
| cmt_var, |
| upvar_borrow.region, |
| upvar_borrow.kind, |
| ClosureCapture(freevar.span)); |
| } |
| } |
| } |
| }); |
| } |
| |
| fn cat_captured_var(&mut self, |
| closure_id: ast::NodeId, |
| closure_span: Span, |
| upvar_def: Def) |
| -> mc::McResult<mc::cmt<'tcx>> { |
| // Create the cmt for the variable being borrowed, from the |
| // caller's perspective |
| let var_id = upvar_def.var_id(); |
| let var_ty = self.mc.infcx.node_ty(var_id)?; |
| self.mc.cat_def(closure_id, closure_span, var_ty, upvar_def) |
| } |
| } |
| |
| fn copy_or_move<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>, |
| cmt: &mc::cmt<'tcx>, |
| move_reason: MoveReason) |
| -> ConsumeMode |
| { |
| if infcx.type_moves_by_default(cmt.ty, cmt.span) { |
| Move(move_reason) |
| } else { |
| Copy |
| } |
| } |
