1128 lines
40 KiB
Rust
1128 lines
40 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A different sort of visitor for walking fn bodies. Unlike the
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//! normal visitor, which just walks the entire body in one shot, the
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//! `ExprUseVisitor` determines how expressions are being used.
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pub use self::LoanCause::*;
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pub use self::ConsumeMode::*;
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pub use self::MoveReason::*;
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pub use self::MatchMode::*;
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use self::TrackMatchMode::*;
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use self::OverloadedCallType::*;
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use hir::pat_util;
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use hir::def::Def;
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use hir::def_id::{DefId};
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use infer::InferCtxt;
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use middle::mem_categorization as mc;
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use ty::{self, TyCtxt, adjustment};
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use hir::{self, PatKind};
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use syntax::ast;
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use syntax::ptr::P;
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use syntax::codemap::Span;
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///////////////////////////////////////////////////////////////////////////
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// The Delegate trait
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/// This trait defines the callbacks you can expect to receive when
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/// employing the ExprUseVisitor.
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pub trait Delegate<'tcx> {
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// The value found at `cmt` is either copied or moved, depending
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// on mode.
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fn consume(&mut self,
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consume_id: ast::NodeId,
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consume_span: Span,
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cmt: mc::cmt<'tcx>,
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mode: ConsumeMode);
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// The value found at `cmt` has been determined to match the
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// pattern binding `matched_pat`, and its subparts are being
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// copied or moved depending on `mode`. Note that `matched_pat`
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// is called on all variant/structs in the pattern (i.e., the
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// interior nodes of the pattern's tree structure) while
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// consume_pat is called on the binding identifiers in the pattern
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// (which are leaves of the pattern's tree structure).
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//
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// Note that variants/structs and identifiers are disjoint; thus
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// `matched_pat` and `consume_pat` are never both called on the
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// same input pattern structure (though of `consume_pat` can be
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// called on a subpart of an input passed to `matched_pat).
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fn matched_pat(&mut self,
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matched_pat: &hir::Pat,
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cmt: mc::cmt<'tcx>,
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mode: MatchMode);
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// The value found at `cmt` is either copied or moved via the
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// pattern binding `consume_pat`, depending on mode.
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fn consume_pat(&mut self,
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consume_pat: &hir::Pat,
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cmt: mc::cmt<'tcx>,
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mode: ConsumeMode);
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// The value found at `borrow` is being borrowed at the point
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// `borrow_id` for the region `loan_region` with kind `bk`.
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fn borrow(&mut self,
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borrow_id: ast::NodeId,
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borrow_span: Span,
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cmt: mc::cmt<'tcx>,
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loan_region: ty::Region,
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bk: ty::BorrowKind,
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loan_cause: LoanCause);
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// The local variable `id` is declared but not initialized.
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fn decl_without_init(&mut self,
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id: ast::NodeId,
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span: Span);
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// The path at `cmt` is being assigned to.
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fn mutate(&mut self,
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assignment_id: ast::NodeId,
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assignment_span: Span,
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assignee_cmt: mc::cmt<'tcx>,
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mode: MutateMode);
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}
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#[derive(Copy, Clone, PartialEq, Debug)]
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pub enum LoanCause {
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ClosureCapture(Span),
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AddrOf,
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AutoRef,
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AutoUnsafe,
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RefBinding,
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OverloadedOperator,
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ClosureInvocation,
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ForLoop,
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MatchDiscriminant
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}
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#[derive(Copy, Clone, PartialEq, Debug)]
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pub enum ConsumeMode {
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Copy, // reference to x where x has a type that copies
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Move(MoveReason), // reference to x where x has a type that moves
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}
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#[derive(Copy, Clone, PartialEq, Debug)]
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pub enum MoveReason {
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DirectRefMove,
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PatBindingMove,
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CaptureMove,
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}
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#[derive(Copy, Clone, PartialEq, Debug)]
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pub enum MatchMode {
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NonBindingMatch,
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BorrowingMatch,
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CopyingMatch,
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MovingMatch,
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}
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#[derive(Copy, Clone, PartialEq, Debug)]
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enum TrackMatchMode {
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Unknown,
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Definite(MatchMode),
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Conflicting,
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}
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impl TrackMatchMode {
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// Builds up the whole match mode for a pattern from its constituent
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// parts. The lattice looks like this:
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//
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// Conflicting
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// / \
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// / \
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// Borrowing Moving
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// \ /
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// \ /
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// Copying
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// |
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// NonBinding
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// |
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// Unknown
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//
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// examples:
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//
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// * `(_, some_int)` pattern is Copying, since
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// NonBinding + Copying => Copying
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//
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// * `(some_int, some_box)` pattern is Moving, since
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// Copying + Moving => Moving
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//
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// * `(ref x, some_box)` pattern is Conflicting, since
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// Borrowing + Moving => Conflicting
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//
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// Note that the `Unknown` and `Conflicting` states are
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// represented separately from the other more interesting
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// `Definite` states, which simplifies logic here somewhat.
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fn lub(&mut self, mode: MatchMode) {
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*self = match (*self, mode) {
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// Note that clause order below is very significant.
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(Unknown, new) => Definite(new),
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(Definite(old), new) if old == new => Definite(old),
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(Definite(old), NonBindingMatch) => Definite(old),
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(Definite(NonBindingMatch), new) => Definite(new),
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(Definite(old), CopyingMatch) => Definite(old),
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(Definite(CopyingMatch), new) => Definite(new),
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(Definite(_), _) => Conflicting,
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(Conflicting, _) => *self,
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};
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}
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fn match_mode(&self) -> MatchMode {
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match *self {
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Unknown => NonBindingMatch,
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Definite(mode) => mode,
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Conflicting => {
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// Conservatively return MovingMatch to let the
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// compiler continue to make progress.
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MovingMatch
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}
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}
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}
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}
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#[derive(Copy, Clone, PartialEq, Debug)]
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pub enum MutateMode {
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Init,
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JustWrite, // x = y
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WriteAndRead, // x += y
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}
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#[derive(Copy, Clone)]
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enum OverloadedCallType {
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FnOverloadedCall,
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FnMutOverloadedCall,
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FnOnceOverloadedCall,
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}
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impl OverloadedCallType {
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fn from_trait_id(tcx: TyCtxt, trait_id: DefId) -> OverloadedCallType {
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for &(maybe_function_trait, overloaded_call_type) in &[
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(tcx.lang_items.fn_once_trait(), FnOnceOverloadedCall),
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(tcx.lang_items.fn_mut_trait(), FnMutOverloadedCall),
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(tcx.lang_items.fn_trait(), FnOverloadedCall)
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] {
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match maybe_function_trait {
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Some(function_trait) if function_trait == trait_id => {
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return overloaded_call_type
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}
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_ => continue,
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}
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}
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bug!("overloaded call didn't map to known function trait")
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}
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fn from_method_id(tcx: TyCtxt, method_id: DefId) -> OverloadedCallType {
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let method = tcx.impl_or_trait_item(method_id);
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OverloadedCallType::from_trait_id(tcx, method.container().id())
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}
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}
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///////////////////////////////////////////////////////////////////////////
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// The ExprUseVisitor type
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//
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// This is the code that actually walks the tree. Like
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// mem_categorization, it requires a TYPER, which is a type that
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// supplies types from the tree. After type checking is complete, you
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// can just use the tcx as the typer.
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pub struct ExprUseVisitor<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
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mc: mc::MemCategorizationContext<'a, 'gcx, 'tcx>,
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delegate: &'a mut Delegate<'tcx>,
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}
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// If the TYPER results in an error, it's because the type check
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// failed (or will fail, when the error is uncovered and reported
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// during writeback). In this case, we just ignore this part of the
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// code.
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//
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// Note that this macro appears similar to try!(), but, unlike try!(),
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// it does not propagate the error.
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macro_rules! return_if_err {
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($inp: expr) => (
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match $inp {
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Ok(v) => v,
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Err(()) => {
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debug!("mc reported err");
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return
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}
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}
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)
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}
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/// Whether the elements of an overloaded operation are passed by value or by reference
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enum PassArgs {
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ByValue,
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ByRef,
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}
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impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
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pub fn new(delegate: &'a mut (Delegate<'tcx>+'a),
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infcx: &'a InferCtxt<'a, 'gcx, 'tcx>) -> Self
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{
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ExprUseVisitor {
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mc: mc::MemCategorizationContext::new(infcx),
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delegate: delegate
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}
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}
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pub fn walk_fn(&mut self,
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decl: &hir::FnDecl,
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body: &hir::Block) {
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self.walk_arg_patterns(decl, body);
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self.walk_block(body);
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}
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fn walk_arg_patterns(&mut self,
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decl: &hir::FnDecl,
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body: &hir::Block) {
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for arg in &decl.inputs {
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let arg_ty = return_if_err!(self.mc.infcx.node_ty(arg.pat.id));
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let fn_body_scope = self.tcx().region_maps.node_extent(body.id);
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let arg_cmt = self.mc.cat_rvalue(
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arg.id,
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arg.pat.span,
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ty::ReScope(fn_body_scope), // Args live only as long as the fn body.
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arg_ty);
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self.walk_irrefutable_pat(arg_cmt, &arg.pat);
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}
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}
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fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
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self.mc.infcx.tcx
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}
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fn delegate_consume(&mut self,
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consume_id: ast::NodeId,
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consume_span: Span,
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cmt: mc::cmt<'tcx>) {
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debug!("delegate_consume(consume_id={}, cmt={:?})",
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consume_id, cmt);
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let mode = copy_or_move(self.mc.infcx, &cmt, DirectRefMove);
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self.delegate.consume(consume_id, consume_span, cmt, mode);
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}
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fn consume_exprs(&mut self, exprs: &[P<hir::Expr>]) {
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for expr in exprs {
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self.consume_expr(&expr);
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}
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}
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pub fn consume_expr(&mut self, expr: &hir::Expr) {
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debug!("consume_expr(expr={:?})", expr);
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let cmt = return_if_err!(self.mc.cat_expr(expr));
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self.delegate_consume(expr.id, expr.span, cmt);
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self.walk_expr(expr);
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}
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fn mutate_expr(&mut self,
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assignment_expr: &hir::Expr,
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expr: &hir::Expr,
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mode: MutateMode) {
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let cmt = return_if_err!(self.mc.cat_expr(expr));
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self.delegate.mutate(assignment_expr.id, assignment_expr.span, cmt, mode);
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self.walk_expr(expr);
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}
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fn borrow_expr(&mut self,
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expr: &hir::Expr,
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r: ty::Region,
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bk: ty::BorrowKind,
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cause: LoanCause) {
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debug!("borrow_expr(expr={:?}, r={:?}, bk={:?})",
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expr, r, bk);
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let cmt = return_if_err!(self.mc.cat_expr(expr));
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self.delegate.borrow(expr.id, expr.span, cmt, r, bk, cause);
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self.walk_expr(expr)
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}
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fn select_from_expr(&mut self, expr: &hir::Expr) {
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self.walk_expr(expr)
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}
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pub fn walk_expr(&mut self, expr: &hir::Expr) {
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debug!("walk_expr(expr={:?})", expr);
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self.walk_adjustment(expr);
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match expr.node {
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hir::ExprPath(..) => { }
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hir::ExprType(ref subexpr, _) => {
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self.walk_expr(&subexpr)
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}
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hir::ExprUnary(hir::UnDeref, ref base) => { // *base
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if !self.walk_overloaded_operator(expr, &base, Vec::new(), PassArgs::ByRef) {
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self.select_from_expr(&base);
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}
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}
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hir::ExprField(ref base, _) => { // base.f
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self.select_from_expr(&base);
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}
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hir::ExprTupField(ref base, _) => { // base.<n>
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self.select_from_expr(&base);
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}
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hir::ExprIndex(ref lhs, ref rhs) => { // lhs[rhs]
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if !self.walk_overloaded_operator(expr,
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&lhs,
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vec![&rhs],
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PassArgs::ByValue) {
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self.select_from_expr(&lhs);
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self.consume_expr(&rhs);
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}
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}
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hir::ExprCall(ref callee, ref args) => { // callee(args)
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self.walk_callee(expr, &callee);
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self.consume_exprs(args);
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}
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hir::ExprMethodCall(_, _, ref args) => { // callee.m(args)
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self.consume_exprs(args);
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}
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hir::ExprStruct(_, ref fields, ref opt_with) => {
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self.walk_struct_expr(expr, fields, opt_with);
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}
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hir::ExprTup(ref exprs) => {
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self.consume_exprs(exprs);
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}
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hir::ExprIf(ref cond_expr, ref then_blk, ref opt_else_expr) => {
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self.consume_expr(&cond_expr);
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self.walk_block(&then_blk);
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if let Some(ref else_expr) = *opt_else_expr {
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self.consume_expr(&else_expr);
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}
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}
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hir::ExprMatch(ref discr, ref arms, _) => {
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let discr_cmt = return_if_err!(self.mc.cat_expr(&discr));
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self.borrow_expr(&discr, ty::ReEmpty, ty::ImmBorrow, MatchDiscriminant);
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// treatment of the discriminant is handled while walking the arms.
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for arm in arms {
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let mode = self.arm_move_mode(discr_cmt.clone(), arm);
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let mode = mode.match_mode();
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self.walk_arm(discr_cmt.clone(), arm, mode);
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}
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}
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hir::ExprVec(ref exprs) => {
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self.consume_exprs(exprs);
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}
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hir::ExprAddrOf(m, ref base) => { // &base
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// make sure that the thing we are pointing out stays valid
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// for the lifetime `scope_r` of the resulting ptr:
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let expr_ty = return_if_err!(self.mc.infcx.node_ty(expr.id));
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if let ty::TyRef(&r, _) = expr_ty.sty {
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let bk = ty::BorrowKind::from_mutbl(m);
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self.borrow_expr(&base, r, bk, AddrOf);
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}
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}
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hir::ExprInlineAsm(ref ia, ref outputs, ref inputs) => {
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for (o, output) in ia.outputs.iter().zip(outputs) {
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if o.is_indirect {
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self.consume_expr(output);
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} else {
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self.mutate_expr(expr, output,
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if o.is_rw {
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MutateMode::WriteAndRead
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} else {
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MutateMode::JustWrite
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});
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}
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}
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self.consume_exprs(inputs);
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}
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hir::ExprBreak(..) |
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hir::ExprAgain(..) |
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hir::ExprLit(..) => {}
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hir::ExprLoop(ref blk, _) => {
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self.walk_block(&blk);
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}
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hir::ExprWhile(ref cond_expr, ref blk, _) => {
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self.consume_expr(&cond_expr);
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self.walk_block(&blk);
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}
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hir::ExprUnary(op, ref lhs) => {
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let pass_args = if op.is_by_value() {
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PassArgs::ByValue
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} else {
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PassArgs::ByRef
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};
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if !self.walk_overloaded_operator(expr, &lhs, Vec::new(), pass_args) {
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self.consume_expr(&lhs);
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}
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}
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hir::ExprBinary(op, ref lhs, ref rhs) => {
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let pass_args = if op.node.is_by_value() {
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PassArgs::ByValue
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} else {
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PassArgs::ByRef
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};
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if !self.walk_overloaded_operator(expr, &lhs, vec![&rhs], pass_args) {
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self.consume_expr(&lhs);
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self.consume_expr(&rhs);
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}
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}
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hir::ExprBlock(ref blk) => {
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self.walk_block(&blk);
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}
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hir::ExprRet(ref opt_expr) => {
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if let Some(ref expr) = *opt_expr {
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self.consume_expr(&expr);
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}
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}
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hir::ExprAssign(ref lhs, ref rhs) => {
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self.mutate_expr(expr, &lhs, MutateMode::JustWrite);
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self.consume_expr(&rhs);
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}
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hir::ExprCast(ref base, _) => {
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self.consume_expr(&base);
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}
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|
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);
|
|
match self.mc.infcx.node_method_ty(deref_id) {
|
|
None => {}
|
|
Some(method_ty) => {
|
|
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| {
|
|
match pat.node {
|
|
PatKind::Binding(bmode, _, _) => {
|
|
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 pat.node {
|
|
PatKind::Struct(..) | PatKind::TupleStruct(..) |
|
|
PatKind::Path(..) | PatKind::QPath(..) => {
|
|
match tcx.expect_def(pat.id) {
|
|
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);
|
|
}
|
|
|
|
Def::Struct(..) | Def::TyAlias(..) => {
|
|
// A struct (in either the value or type
|
|
// namespace; we encounter the former on
|
|
// e.g. patterns for unit structs).
|
|
|
|
debug!("struct cmt_pat={:?} pat={:?}",
|
|
cmt_pat,
|
|
pat);
|
|
|
|
delegate.matched_pat(pat, cmt_pat, match_mode);
|
|
}
|
|
|
|
Def::Const(..) | Def::AssociatedConst(..) => {
|
|
// This is a leaf (i.e. identifier binding
|
|
// or constant value to match); thus no
|
|
// `matched_pat` call.
|
|
}
|
|
|
|
def => {
|
|
// An enum type should never be in a pattern.
|
|
// Remaining cases are e.g. Def::Fn, to
|
|
// which identifiers within patterns
|
|
// should not resolve. However, we do
|
|
// encouter this when using the
|
|
// expr-use-visitor during typeck. So just
|
|
// ignore it, an error should have been
|
|
// reported.
|
|
|
|
if !tcx.sess.has_errors() {
|
|
span_bug!(pat.span,
|
|
"Pattern has unexpected def: {:?} and type {:?}",
|
|
def,
|
|
cmt_pat.ty);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
PatKind::Wild | PatKind::Tuple(..) | PatKind::Box(..) |
|
|
PatKind::Ref(..) | PatKind::Lit(..) | PatKind::Range(..) |
|
|
PatKind::Vec(..) | PatKind::Binding(..) => {
|
|
// Each of these cases does not
|
|
// correspond to an enum variant or struct, so we
|
|
// do not do any `matched_pat` calls for these
|
|
// cases either.
|
|
}
|
|
}
|
|
}));
|
|
}
|
|
|
|
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
|
|
}
|
|
}
|