1562 lines
59 KiB
Rust
1562 lines
59 KiB
Rust
// Copyright 2012-2014 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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//! # Categorization
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//!
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//! The job of the categorization module is to analyze an expression to
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//! determine what kind of memory is used in evaluating it (for example,
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//! where dereferences occur and what kind of pointer is dereferenced;
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//! whether the memory is mutable; etc)
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//!
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//! Categorization effectively transforms all of our expressions into
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//! expressions of the following forms (the actual enum has many more
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//! possibilities, naturally, but they are all variants of these base
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//! forms):
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//!
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//! E = rvalue // some computed rvalue
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//! | x // address of a local variable or argument
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//! | *E // deref of a ptr
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//! | E.comp // access to an interior component
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//!
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//! Imagine a routine ToAddr(Expr) that evaluates an expression and returns an
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//! address where the result is to be found. If Expr is a place, then this
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//! is the address of the place. If Expr is an rvalue, this is the address of
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//! some temporary spot in memory where the result is stored.
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//!
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//! Now, cat_expr() classifies the expression Expr and the address A=ToAddr(Expr)
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//! as follows:
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//!
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//! - cat: what kind of expression was this? This is a subset of the
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//! full expression forms which only includes those that we care about
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//! for the purpose of the analysis.
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//! - mutbl: mutability of the address A
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//! - ty: the type of data found at the address A
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//!
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//! The resulting categorization tree differs somewhat from the expressions
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//! themselves. For example, auto-derefs are explicit. Also, an index a[b] is
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//! decomposed into two operations: a dereference to reach the array data and
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//! then an index to jump forward to the relevant item.
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//!
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//! ## By-reference upvars
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//!
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//! One part of the codegen which may be non-obvious is that we translate
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//! closure upvars into the dereference of a borrowed pointer; this more closely
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//! resembles the runtime codegen. So, for example, if we had:
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//!
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//! let mut x = 3;
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//! let y = 5;
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//! let inc = || x += y;
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//!
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//! Then when we categorize `x` (*within* the closure) we would yield a
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//! result of `*x'`, effectively, where `x'` is a `Categorization::Upvar` reference
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//! tied to `x`. The type of `x'` will be a borrowed pointer.
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#![allow(non_camel_case_types)]
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pub use self::PointerKind::*;
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pub use self::InteriorKind::*;
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pub use self::MutabilityCategory::*;
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pub use self::AliasableReason::*;
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pub use self::Note::*;
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use self::Aliasability::*;
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use middle::region;
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use hir::def_id::{DefId, LocalDefId};
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use hir::map as hir_map;
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use infer::InferCtxt;
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use hir::def::{Def, CtorKind};
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use ty::adjustment;
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use ty::{self, Ty, TyCtxt};
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use ty::fold::TypeFoldable;
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use hir::{MutImmutable, MutMutable, PatKind};
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use hir::pat_util::EnumerateAndAdjustIterator;
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use hir;
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use syntax::ast::{self, Name};
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use syntax_pos::Span;
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use std::fmt;
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use std::hash::{Hash, Hasher};
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use rustc_data_structures::sync::Lrc;
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use std::rc::Rc;
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use util::nodemap::ItemLocalSet;
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#[derive(Clone, Debug, PartialEq)]
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pub enum Categorization<'tcx> {
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Rvalue(ty::Region<'tcx>), // temporary val, argument is its scope
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StaticItem,
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Upvar(Upvar), // upvar referenced by closure env
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Local(ast::NodeId), // local variable
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Deref(cmt<'tcx>, PointerKind<'tcx>), // deref of a ptr
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Interior(cmt<'tcx>, InteriorKind), // something interior: field, tuple, etc
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Downcast(cmt<'tcx>, DefId), // selects a particular enum variant (*1)
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// (*1) downcast is only required if the enum has more than one variant
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}
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// Represents any kind of upvar
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#[derive(Clone, Copy, PartialEq)]
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pub struct Upvar {
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pub id: ty::UpvarId,
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pub kind: ty::ClosureKind
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}
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// different kinds of pointers:
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#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
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pub enum PointerKind<'tcx> {
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/// `Box<T>`
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Unique,
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/// `&T`
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BorrowedPtr(ty::BorrowKind, ty::Region<'tcx>),
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/// `*T`
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UnsafePtr(hir::Mutability),
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/// Implicit deref of the `&T` that results from an overloaded index `[]`.
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Implicit(ty::BorrowKind, ty::Region<'tcx>),
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}
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// We use the term "interior" to mean "something reachable from the
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// base without a pointer dereference", e.g. a field
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#[derive(Clone, Copy, PartialEq, Eq, Hash)]
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pub enum InteriorKind {
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InteriorField(FieldIndex),
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InteriorElement(InteriorOffsetKind),
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}
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// Contains index of a field that is actually used for loan path comparisons and
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// string representation of the field that should be used only for diagnostics.
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#[derive(Clone, Copy, Eq)]
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pub struct FieldIndex(pub usize, pub Name);
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impl PartialEq for FieldIndex {
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fn eq(&self, rhs: &Self) -> bool {
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self.0 == rhs.0
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}
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}
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impl Hash for FieldIndex {
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fn hash<H: Hasher>(&self, h: &mut H) {
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self.0.hash(h)
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}
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}
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#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
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pub enum InteriorOffsetKind {
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Index, // e.g. `array_expr[index_expr]`
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Pattern, // e.g. `fn foo([_, a, _, _]: [A; 4]) { ... }`
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}
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#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
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pub enum MutabilityCategory {
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McImmutable, // Immutable.
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McDeclared, // Directly declared as mutable.
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McInherited, // Inherited from the fact that owner is mutable.
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}
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// A note about the provenance of a `cmt`. This is used for
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// special-case handling of upvars such as mutability inference.
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// Upvar categorization can generate a variable number of nested
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// derefs. The note allows detecting them without deep pattern
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// matching on the categorization.
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#[derive(Clone, Copy, PartialEq, Debug)]
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pub enum Note {
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NoteClosureEnv(ty::UpvarId), // Deref through closure env
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NoteUpvarRef(ty::UpvarId), // Deref through by-ref upvar
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NoteNone // Nothing special
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}
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// `cmt`: "Category, Mutability, and Type".
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//
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// a complete categorization of a value indicating where it originated
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// and how it is located, as well as the mutability of the memory in
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// which the value is stored.
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//
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// *WARNING* The field `cmt.type` is NOT necessarily the same as the
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// result of `node_id_to_type(cmt.id)`. This is because the `id` is
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// always the `id` of the node producing the type; in an expression
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// like `*x`, the type of this deref node is the deref'd type (`T`),
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// but in a pattern like `@x`, the `@x` pattern is again a
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// dereference, but its type is the type *before* the dereference
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// (`@T`). So use `cmt.ty` to find the type of the value in a consistent
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// fashion. For more details, see the method `cat_pattern`
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#[derive(Clone, Debug, PartialEq)]
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pub struct cmt_<'tcx> {
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pub id: ast::NodeId, // id of expr/pat producing this value
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pub span: Span, // span of same expr/pat
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pub cat: Categorization<'tcx>, // categorization of expr
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pub mutbl: MutabilityCategory, // mutability of expr as place
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pub ty: Ty<'tcx>, // type of the expr (*see WARNING above*)
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pub note: Note, // Note about the provenance of this cmt
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}
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pub type cmt<'tcx> = Rc<cmt_<'tcx>>;
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pub enum ImmutabilityBlame<'tcx> {
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ImmLocal(ast::NodeId),
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ClosureEnv(LocalDefId),
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LocalDeref(ast::NodeId),
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AdtFieldDeref(&'tcx ty::AdtDef, &'tcx ty::FieldDef)
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}
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impl<'tcx> cmt_<'tcx> {
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fn resolve_field(&self, field_index: usize) -> Option<(&'tcx ty::AdtDef, &'tcx ty::FieldDef)>
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{
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let adt_def = match self.ty.sty {
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ty::TyAdt(def, _) => def,
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ty::TyTuple(..) => return None,
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// closures get `Categorization::Upvar` rather than `Categorization::Interior`
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_ => bug!("interior cmt {:?} is not an ADT", self)
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};
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let variant_def = match self.cat {
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Categorization::Downcast(_, variant_did) => {
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adt_def.variant_with_id(variant_did)
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}
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_ => {
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assert_eq!(adt_def.variants.len(), 1);
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&adt_def.variants[0]
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}
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};
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Some((adt_def, &variant_def.fields[field_index]))
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}
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pub fn immutability_blame(&self) -> Option<ImmutabilityBlame<'tcx>> {
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match self.cat {
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Categorization::Deref(ref base_cmt, BorrowedPtr(ty::ImmBorrow, _)) |
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Categorization::Deref(ref base_cmt, Implicit(ty::ImmBorrow, _)) => {
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// try to figure out where the immutable reference came from
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match base_cmt.cat {
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Categorization::Local(node_id) =>
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Some(ImmutabilityBlame::LocalDeref(node_id)),
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Categorization::Interior(ref base_cmt, InteriorField(field_index)) => {
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base_cmt.resolve_field(field_index.0).map(|(adt_def, field_def)| {
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ImmutabilityBlame::AdtFieldDeref(adt_def, field_def)
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})
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}
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Categorization::Upvar(Upvar { id, .. }) => {
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if let NoteClosureEnv(..) = self.note {
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Some(ImmutabilityBlame::ClosureEnv(id.closure_expr_id))
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} else {
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None
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}
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}
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_ => None
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}
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}
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Categorization::Local(node_id) => {
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Some(ImmutabilityBlame::ImmLocal(node_id))
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}
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Categorization::Rvalue(..) |
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Categorization::Upvar(..) |
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Categorization::Deref(_, UnsafePtr(..)) => {
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// This should not be reachable up to inference limitations.
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None
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}
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Categorization::Interior(ref base_cmt, _) |
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Categorization::Downcast(ref base_cmt, _) |
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Categorization::Deref(ref base_cmt, _) => {
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base_cmt.immutability_blame()
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}
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Categorization::StaticItem => {
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// Do we want to do something here?
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None
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}
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}
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}
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}
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pub trait ast_node {
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fn id(&self) -> ast::NodeId;
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fn span(&self) -> Span;
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}
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impl ast_node for hir::Expr {
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fn id(&self) -> ast::NodeId { self.id }
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fn span(&self) -> Span { self.span }
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}
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impl ast_node for hir::Pat {
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fn id(&self) -> ast::NodeId { self.id }
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fn span(&self) -> Span { self.span }
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}
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#[derive(Clone)]
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pub struct MemCategorizationContext<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
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pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
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pub region_scope_tree: &'a region::ScopeTree,
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pub tables: &'a ty::TypeckTables<'tcx>,
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rvalue_promotable_map: Option<Lrc<ItemLocalSet>>,
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infcx: Option<&'a InferCtxt<'a, 'gcx, 'tcx>>,
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}
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pub type McResult<T> = Result<T, ()>;
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impl MutabilityCategory {
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pub fn from_mutbl(m: hir::Mutability) -> MutabilityCategory {
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let ret = match m {
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MutImmutable => McImmutable,
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MutMutable => McDeclared
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};
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debug!("MutabilityCategory::{}({:?}) => {:?}",
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"from_mutbl", m, ret);
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ret
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}
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pub fn from_borrow_kind(borrow_kind: ty::BorrowKind) -> MutabilityCategory {
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let ret = match borrow_kind {
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ty::ImmBorrow => McImmutable,
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ty::UniqueImmBorrow => McImmutable,
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ty::MutBorrow => McDeclared,
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};
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debug!("MutabilityCategory::{}({:?}) => {:?}",
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"from_borrow_kind", borrow_kind, ret);
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ret
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}
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fn from_pointer_kind(base_mutbl: MutabilityCategory,
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ptr: PointerKind) -> MutabilityCategory {
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let ret = match ptr {
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Unique => {
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base_mutbl.inherit()
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}
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BorrowedPtr(borrow_kind, _) | Implicit(borrow_kind, _) => {
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MutabilityCategory::from_borrow_kind(borrow_kind)
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}
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UnsafePtr(m) => {
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MutabilityCategory::from_mutbl(m)
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}
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};
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debug!("MutabilityCategory::{}({:?}, {:?}) => {:?}",
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"from_pointer_kind", base_mutbl, ptr, ret);
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ret
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}
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fn from_local(tcx: TyCtxt, tables: &ty::TypeckTables, id: ast::NodeId) -> MutabilityCategory {
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let ret = match tcx.hir.get(id) {
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hir_map::NodeBinding(p) => match p.node {
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PatKind::Binding(..) => {
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let bm = *tables.pat_binding_modes()
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.get(p.hir_id)
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.expect("missing binding mode");
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if bm == ty::BindByValue(hir::MutMutable) {
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McDeclared
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} else {
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McImmutable
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}
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}
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_ => span_bug!(p.span, "expected identifier pattern")
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},
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_ => span_bug!(tcx.hir.span(id), "expected identifier pattern")
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};
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debug!("MutabilityCategory::{}(tcx, id={:?}) => {:?}",
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"from_local", id, ret);
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ret
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}
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pub fn inherit(&self) -> MutabilityCategory {
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let ret = match *self {
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McImmutable => McImmutable,
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McDeclared => McInherited,
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McInherited => McInherited,
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};
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debug!("{:?}.inherit() => {:?}", self, ret);
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ret
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}
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pub fn is_mutable(&self) -> bool {
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let ret = match *self {
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McImmutable => false,
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McInherited => true,
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McDeclared => true,
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};
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debug!("{:?}.is_mutable() => {:?}", self, ret);
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ret
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}
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pub fn is_immutable(&self) -> bool {
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let ret = match *self {
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McImmutable => true,
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McDeclared | McInherited => false
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};
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debug!("{:?}.is_immutable() => {:?}", self, ret);
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ret
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}
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pub fn to_user_str(&self) -> &'static str {
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match *self {
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McDeclared | McInherited => "mutable",
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McImmutable => "immutable",
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}
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}
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}
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impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx, 'tcx> {
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pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
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region_scope_tree: &'a region::ScopeTree,
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tables: &'a ty::TypeckTables<'tcx>,
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rvalue_promotable_map: Option<Lrc<ItemLocalSet>>)
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-> MemCategorizationContext<'a, 'tcx, 'tcx> {
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MemCategorizationContext {
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tcx,
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region_scope_tree,
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tables,
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rvalue_promotable_map,
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infcx: None
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}
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}
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}
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impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
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/// Creates a `MemCategorizationContext` during type inference.
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/// This is used during upvar analysis and a few other places.
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/// Because the typeck tables are not yet complete, the results
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/// from the analysis must be used with caution:
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///
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/// - rvalue promotions are not known, so the lifetimes of
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/// temporaries may be overly conservative;
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/// - similarly, as the results of upvar analysis are not yet
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/// known, the results around upvar accesses may be incorrect.
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pub fn with_infer(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
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region_scope_tree: &'a region::ScopeTree,
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tables: &'a ty::TypeckTables<'tcx>)
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-> MemCategorizationContext<'a, 'gcx, 'tcx> {
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let tcx = infcx.tcx;
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// Subtle: we can't do rvalue promotion analysis until the
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// typeck phase is complete, which means that you can't trust
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// the rvalue lifetimes that result, but that's ok, since we
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// don't need to know those during type inference.
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let rvalue_promotable_map = None;
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MemCategorizationContext {
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tcx,
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region_scope_tree,
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tables,
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rvalue_promotable_map,
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infcx: Some(infcx),
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}
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}
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pub fn type_moves_by_default(&self,
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param_env: ty::ParamEnv<'tcx>,
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ty: Ty<'tcx>,
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span: Span)
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-> bool {
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self.infcx.map(|infcx| infcx.type_moves_by_default(param_env, ty, span))
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.or_else(|| {
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self.tcx.lift_to_global(&(param_env, ty)).map(|(param_env, ty)| {
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ty.moves_by_default(self.tcx.global_tcx(), param_env, span)
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})
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})
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.unwrap_or(true)
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}
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fn resolve_type_vars_if_possible<T>(&self, value: &T) -> T
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where T: TypeFoldable<'tcx>
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{
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self.infcx.map(|infcx| infcx.resolve_type_vars_if_possible(value))
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.unwrap_or_else(|| value.clone())
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}
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fn is_tainted_by_errors(&self) -> bool {
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self.infcx.map_or(false, |infcx| infcx.is_tainted_by_errors())
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}
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fn resolve_type_vars_or_error(&self,
|
|
id: hir::HirId,
|
|
ty: Option<Ty<'tcx>>)
|
|
-> McResult<Ty<'tcx>> {
|
|
match ty {
|
|
Some(ty) => {
|
|
let ty = self.resolve_type_vars_if_possible(&ty);
|
|
if ty.references_error() || ty.is_ty_var() {
|
|
debug!("resolve_type_vars_or_error: error from {:?}", ty);
|
|
Err(())
|
|
} else {
|
|
Ok(ty)
|
|
}
|
|
}
|
|
// FIXME
|
|
None if self.is_tainted_by_errors() => Err(()),
|
|
None => {
|
|
let id = self.tcx.hir.definitions().find_node_for_hir_id(id);
|
|
bug!("no type for node {}: {} in mem_categorization",
|
|
id, self.tcx.hir.node_to_string(id));
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn node_ty(&self,
|
|
hir_id: hir::HirId)
|
|
-> McResult<Ty<'tcx>> {
|
|
self.resolve_type_vars_or_error(hir_id,
|
|
self.tables.node_id_to_type_opt(hir_id))
|
|
}
|
|
|
|
pub fn expr_ty(&self, expr: &hir::Expr) -> McResult<Ty<'tcx>> {
|
|
self.resolve_type_vars_or_error(expr.hir_id, self.tables.expr_ty_opt(expr))
|
|
}
|
|
|
|
pub fn expr_ty_adjusted(&self, expr: &hir::Expr) -> McResult<Ty<'tcx>> {
|
|
self.resolve_type_vars_or_error(expr.hir_id, self.tables.expr_ty_adjusted_opt(expr))
|
|
}
|
|
|
|
/// Returns the type of value that this pattern matches against.
|
|
/// Some non-obvious cases:
|
|
///
|
|
/// - a `ref x` binding matches against a value of type `T` and gives
|
|
/// `x` the type `&T`; we return `T`.
|
|
/// - a pattern with implicit derefs (thanks to default binding
|
|
/// modes #42640) may look like `Some(x)` but in fact have
|
|
/// implicit deref patterns attached (e.g., it is really
|
|
/// `&Some(x)`). In that case, we return the "outermost" type
|
|
/// (e.g., `&Option<T>).
|
|
fn pat_ty(&self, pat: &hir::Pat) -> McResult<Ty<'tcx>> {
|
|
// Check for implicit `&` types wrapping the pattern; note
|
|
// that these are never attached to binding patterns, so
|
|
// actually this is somewhat "disjoint" from the code below
|
|
// that aims to account for `ref x`.
|
|
if let Some(vec) = self.tables.pat_adjustments().get(pat.hir_id) {
|
|
if let Some(first_ty) = vec.first() {
|
|
debug!("pat_ty(pat={:?}) found adjusted ty `{:?}`", pat, first_ty);
|
|
return Ok(first_ty);
|
|
}
|
|
}
|
|
|
|
self.pat_ty_unadjusted(pat)
|
|
}
|
|
|
|
|
|
/// Like `pat_ty`, but ignores implicit `&` patterns.
|
|
fn pat_ty_unadjusted(&self, pat: &hir::Pat) -> McResult<Ty<'tcx>> {
|
|
let base_ty = self.node_ty(pat.hir_id)?;
|
|
debug!("pat_ty(pat={:?}) base_ty={:?}", pat, base_ty);
|
|
|
|
// This code detects whether we are looking at a `ref x`,
|
|
// and if so, figures out what the type *being borrowed* is.
|
|
let ret_ty = match pat.node {
|
|
PatKind::Binding(..) => {
|
|
let bm = *self.tables
|
|
.pat_binding_modes()
|
|
.get(pat.hir_id)
|
|
.expect("missing binding mode");
|
|
|
|
if let ty::BindByReference(_) = bm {
|
|
// a bind-by-ref means that the base_ty will be the type of the ident itself,
|
|
// but what we want here is the type of the underlying value being borrowed.
|
|
// So peel off one-level, turning the &T into T.
|
|
match base_ty.builtin_deref(false) {
|
|
Some(t) => t.ty,
|
|
None => {
|
|
debug!("By-ref binding of non-derefable type {:?}", base_ty);
|
|
return Err(());
|
|
}
|
|
}
|
|
} else {
|
|
base_ty
|
|
}
|
|
}
|
|
_ => base_ty,
|
|
};
|
|
debug!("pat_ty(pat={:?}) ret_ty={:?}", pat, ret_ty);
|
|
|
|
Ok(ret_ty)
|
|
}
|
|
|
|
pub fn cat_expr(&self, expr: &hir::Expr) -> McResult<cmt_<'tcx>> {
|
|
// This recursion helper avoids going through *too many*
|
|
// adjustments, since *only* non-overloaded deref recurses.
|
|
fn helper<'a, 'gcx, 'tcx>(mc: &MemCategorizationContext<'a, 'gcx, 'tcx>,
|
|
expr: &hir::Expr,
|
|
adjustments: &[adjustment::Adjustment<'tcx>])
|
|
-> McResult<cmt_<'tcx>> {
|
|
match adjustments.split_last() {
|
|
None => mc.cat_expr_unadjusted(expr),
|
|
Some((adjustment, previous)) => {
|
|
mc.cat_expr_adjusted_with(expr, || helper(mc, expr, previous), adjustment)
|
|
}
|
|
}
|
|
}
|
|
|
|
helper(self, expr, self.tables.expr_adjustments(expr))
|
|
}
|
|
|
|
pub fn cat_expr_adjusted(&self, expr: &hir::Expr,
|
|
previous: cmt_<'tcx>,
|
|
adjustment: &adjustment::Adjustment<'tcx>)
|
|
-> McResult<cmt_<'tcx>> {
|
|
self.cat_expr_adjusted_with(expr, || Ok(previous), adjustment)
|
|
}
|
|
|
|
fn cat_expr_adjusted_with<F>(&self, expr: &hir::Expr,
|
|
previous: F,
|
|
adjustment: &adjustment::Adjustment<'tcx>)
|
|
-> McResult<cmt_<'tcx>>
|
|
where F: FnOnce() -> McResult<cmt_<'tcx>>
|
|
{
|
|
debug!("cat_expr_adjusted_with({:?}): {:?}", adjustment, expr);
|
|
let target = self.resolve_type_vars_if_possible(&adjustment.target);
|
|
match adjustment.kind {
|
|
adjustment::Adjust::Deref(overloaded) => {
|
|
// Equivalent to *expr or something similar.
|
|
let base = Rc::new(if let Some(deref) = overloaded {
|
|
let ref_ty = self.tcx.mk_ref(deref.region, ty::TypeAndMut {
|
|
ty: target,
|
|
mutbl: deref.mutbl,
|
|
});
|
|
self.cat_rvalue_node(expr.id, expr.span, ref_ty)
|
|
} else {
|
|
previous()?
|
|
});
|
|
self.cat_deref(expr, base, false)
|
|
}
|
|
|
|
adjustment::Adjust::NeverToAny |
|
|
adjustment::Adjust::ReifyFnPointer |
|
|
adjustment::Adjust::UnsafeFnPointer |
|
|
adjustment::Adjust::ClosureFnPointer |
|
|
adjustment::Adjust::MutToConstPointer |
|
|
adjustment::Adjust::Borrow(_) |
|
|
adjustment::Adjust::Unsize => {
|
|
// Result is an rvalue.
|
|
Ok(self.cat_rvalue_node(expr.id, expr.span, target))
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn cat_expr_unadjusted(&self, expr: &hir::Expr) -> McResult<cmt_<'tcx>> {
|
|
debug!("cat_expr: id={} expr={:?}", expr.id, expr);
|
|
|
|
let expr_ty = self.expr_ty(expr)?;
|
|
match expr.node {
|
|
hir::ExprUnary(hir::UnDeref, ref e_base) => {
|
|
if self.tables.is_method_call(expr) {
|
|
self.cat_overloaded_place(expr, e_base, false)
|
|
} else {
|
|
let base_cmt = Rc::new(self.cat_expr(&e_base)?);
|
|
self.cat_deref(expr, base_cmt, false)
|
|
}
|
|
}
|
|
|
|
hir::ExprField(ref base, f_name) => {
|
|
let base_cmt = Rc::new(self.cat_expr(&base)?);
|
|
debug!("cat_expr(cat_field): id={} expr={:?} base={:?}",
|
|
expr.id,
|
|
expr,
|
|
base_cmt);
|
|
let f_index = self.tcx.field_index(expr.id, self.tables);
|
|
Ok(self.cat_field(expr, base_cmt, f_index, f_name.node, expr_ty))
|
|
}
|
|
|
|
hir::ExprIndex(ref base, _) => {
|
|
if self.tables.is_method_call(expr) {
|
|
// If this is an index implemented by a method call, then it
|
|
// will include an implicit deref of the result.
|
|
// The call to index() returns a `&T` value, which
|
|
// is an rvalue. That is what we will be
|
|
// dereferencing.
|
|
self.cat_overloaded_place(expr, base, true)
|
|
} else {
|
|
let base_cmt = Rc::new(self.cat_expr(&base)?);
|
|
self.cat_index(expr, base_cmt, expr_ty, InteriorOffsetKind::Index)
|
|
}
|
|
}
|
|
|
|
hir::ExprPath(ref qpath) => {
|
|
let def = self.tables.qpath_def(qpath, expr.hir_id);
|
|
self.cat_def(expr.id, expr.span, expr_ty, def)
|
|
}
|
|
|
|
hir::ExprType(ref e, _) => {
|
|
self.cat_expr(&e)
|
|
}
|
|
|
|
hir::ExprAddrOf(..) | hir::ExprCall(..) |
|
|
hir::ExprAssign(..) | hir::ExprAssignOp(..) |
|
|
hir::ExprClosure(..) | hir::ExprRet(..) |
|
|
hir::ExprUnary(..) | hir::ExprYield(..) |
|
|
hir::ExprMethodCall(..) | hir::ExprCast(..) |
|
|
hir::ExprArray(..) | hir::ExprTup(..) | hir::ExprIf(..) |
|
|
hir::ExprBinary(..) | hir::ExprWhile(..) |
|
|
hir::ExprBlock(..) | hir::ExprLoop(..) | hir::ExprMatch(..) |
|
|
hir::ExprLit(..) | hir::ExprBreak(..) |
|
|
hir::ExprAgain(..) | hir::ExprStruct(..) | hir::ExprRepeat(..) |
|
|
hir::ExprInlineAsm(..) | hir::ExprBox(..) => {
|
|
Ok(self.cat_rvalue_node(expr.id(), expr.span(), expr_ty))
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn cat_def(&self,
|
|
id: ast::NodeId,
|
|
span: Span,
|
|
expr_ty: Ty<'tcx>,
|
|
def: Def)
|
|
-> McResult<cmt_<'tcx>> {
|
|
debug!("cat_def: id={} expr={:?} def={:?}",
|
|
id, expr_ty, def);
|
|
|
|
match def {
|
|
Def::StructCtor(..) | Def::VariantCtor(..) | Def::Const(..) |
|
|
Def::AssociatedConst(..) | Def::Fn(..) | Def::Method(..) => {
|
|
Ok(self.cat_rvalue_node(id, span, expr_ty))
|
|
}
|
|
|
|
Def::Static(def_id, mutbl) => {
|
|
// `#[thread_local]` statics may not outlive the current function.
|
|
for attr in &self.tcx.get_attrs(def_id)[..] {
|
|
if attr.check_name("thread_local") {
|
|
return Ok(self.cat_rvalue_node(id, span, expr_ty));
|
|
}
|
|
}
|
|
Ok(cmt_ {
|
|
id:id,
|
|
span:span,
|
|
cat:Categorization::StaticItem,
|
|
mutbl: if mutbl { McDeclared } else { McImmutable},
|
|
ty:expr_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
Def::Upvar(var_id, _, fn_node_id) => {
|
|
self.cat_upvar(id, span, var_id, fn_node_id)
|
|
}
|
|
|
|
Def::Local(vid) => {
|
|
Ok(cmt_ {
|
|
id,
|
|
span,
|
|
cat: Categorization::Local(vid),
|
|
mutbl: MutabilityCategory::from_local(self.tcx, self.tables, vid),
|
|
ty: expr_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
def => span_bug!(span, "unexpected definition in memory categorization: {:?}", def)
|
|
}
|
|
}
|
|
|
|
// Categorize an upvar, complete with invisible derefs of closure
|
|
// environment and upvar reference as appropriate.
|
|
fn cat_upvar(&self,
|
|
id: ast::NodeId,
|
|
span: Span,
|
|
var_id: ast::NodeId,
|
|
fn_node_id: ast::NodeId)
|
|
-> McResult<cmt_<'tcx>>
|
|
{
|
|
let fn_hir_id = self.tcx.hir.node_to_hir_id(fn_node_id);
|
|
|
|
// An upvar can have up to 3 components. We translate first to a
|
|
// `Categorization::Upvar`, which is itself a fiction -- it represents the reference to the
|
|
// field from the environment.
|
|
//
|
|
// `Categorization::Upvar`. Next, we add a deref through the implicit
|
|
// environment pointer with an anonymous free region 'env and
|
|
// appropriate borrow kind for closure kinds that take self by
|
|
// reference. Finally, if the upvar was captured
|
|
// by-reference, we add a deref through that reference. The
|
|
// region of this reference is an inference variable 'up that
|
|
// was previously generated and recorded in the upvar borrow
|
|
// map. The borrow kind bk is inferred by based on how the
|
|
// upvar is used.
|
|
//
|
|
// This results in the following table for concrete closure
|
|
// types:
|
|
//
|
|
// | move | ref
|
|
// ---------------+----------------------+-------------------------------
|
|
// Fn | copied -> &'env | upvar -> &'env -> &'up bk
|
|
// FnMut | copied -> &'env mut | upvar -> &'env mut -> &'up bk
|
|
// FnOnce | copied | upvar -> &'up bk
|
|
|
|
let kind = match self.node_ty(fn_hir_id)?.sty {
|
|
ty::TyGenerator(..) => ty::ClosureKind::FnOnce,
|
|
ty::TyClosure(closure_def_id, closure_substs) => {
|
|
match self.infcx {
|
|
// During upvar inference we may not know the
|
|
// closure kind, just use the LATTICE_BOTTOM value.
|
|
Some(infcx) =>
|
|
infcx.closure_kind(closure_def_id, closure_substs)
|
|
.unwrap_or(ty::ClosureKind::LATTICE_BOTTOM),
|
|
|
|
None =>
|
|
self.tcx.global_tcx()
|
|
.lift(&closure_substs)
|
|
.expect("no inference cx, but inference variables in closure ty")
|
|
.closure_kind(closure_def_id, self.tcx.global_tcx()),
|
|
}
|
|
}
|
|
ref t => span_bug!(span, "unexpected type for fn in mem_categorization: {:?}", t),
|
|
};
|
|
|
|
let closure_expr_def_id = self.tcx.hir.local_def_id(fn_node_id);
|
|
let var_hir_id = self.tcx.hir.node_to_hir_id(var_id);
|
|
let upvar_id = ty::UpvarId {
|
|
var_id: var_hir_id,
|
|
closure_expr_id: closure_expr_def_id.to_local(),
|
|
};
|
|
|
|
let var_ty = self.node_ty(var_hir_id)?;
|
|
|
|
// Mutability of original variable itself
|
|
let var_mutbl = MutabilityCategory::from_local(self.tcx, self.tables, var_id);
|
|
|
|
// Construct the upvar. This represents access to the field
|
|
// from the environment (perhaps we should eventually desugar
|
|
// this field further, but it will do for now).
|
|
let cmt_result = cmt_ {
|
|
id,
|
|
span,
|
|
cat: Categorization::Upvar(Upvar {id: upvar_id, kind: kind}),
|
|
mutbl: var_mutbl,
|
|
ty: var_ty,
|
|
note: NoteNone
|
|
};
|
|
|
|
// If this is a `FnMut` or `Fn` closure, then the above is
|
|
// conceptually a `&mut` or `&` reference, so we have to add a
|
|
// deref.
|
|
let cmt_result = match kind {
|
|
ty::ClosureKind::FnOnce => {
|
|
cmt_result
|
|
}
|
|
ty::ClosureKind::FnMut => {
|
|
self.env_deref(id, span, upvar_id, var_mutbl, ty::MutBorrow, cmt_result)
|
|
}
|
|
ty::ClosureKind::Fn => {
|
|
self.env_deref(id, span, upvar_id, var_mutbl, ty::ImmBorrow, cmt_result)
|
|
}
|
|
};
|
|
|
|
// If this is a by-ref capture, then the upvar we loaded is
|
|
// actually a reference, so we have to add an implicit deref
|
|
// for that.
|
|
let upvar_capture = self.tables.upvar_capture(upvar_id);
|
|
let cmt_result = match upvar_capture {
|
|
ty::UpvarCapture::ByValue => {
|
|
cmt_result
|
|
}
|
|
ty::UpvarCapture::ByRef(upvar_borrow) => {
|
|
let ptr = BorrowedPtr(upvar_borrow.kind, upvar_borrow.region);
|
|
cmt_ {
|
|
id,
|
|
span,
|
|
cat: Categorization::Deref(Rc::new(cmt_result), ptr),
|
|
mutbl: MutabilityCategory::from_borrow_kind(upvar_borrow.kind),
|
|
ty: var_ty,
|
|
note: NoteUpvarRef(upvar_id)
|
|
}
|
|
}
|
|
};
|
|
|
|
let ret = cmt_result;
|
|
debug!("cat_upvar ret={:?}", ret);
|
|
Ok(ret)
|
|
}
|
|
|
|
fn env_deref(&self,
|
|
id: ast::NodeId,
|
|
span: Span,
|
|
upvar_id: ty::UpvarId,
|
|
upvar_mutbl: MutabilityCategory,
|
|
env_borrow_kind: ty::BorrowKind,
|
|
cmt_result: cmt_<'tcx>)
|
|
-> cmt_<'tcx>
|
|
{
|
|
// Region of environment pointer
|
|
let env_region = self.tcx.mk_region(ty::ReFree(ty::FreeRegion {
|
|
// The environment of a closure is guaranteed to
|
|
// outlive any bindings introduced in the body of the
|
|
// closure itself.
|
|
scope: upvar_id.closure_expr_id.to_def_id(),
|
|
bound_region: ty::BrEnv
|
|
}));
|
|
|
|
let env_ptr = BorrowedPtr(env_borrow_kind, env_region);
|
|
|
|
let var_ty = cmt_result.ty;
|
|
|
|
// We need to add the env deref. This means
|
|
// that the above is actually immutable and
|
|
// has a ref type. However, nothing should
|
|
// actually look at the type, so we can get
|
|
// away with stuffing a `TyError` in there
|
|
// instead of bothering to construct a proper
|
|
// one.
|
|
let cmt_result = cmt_ {
|
|
mutbl: McImmutable,
|
|
ty: self.tcx.types.err,
|
|
..cmt_result
|
|
};
|
|
|
|
let mut deref_mutbl = MutabilityCategory::from_borrow_kind(env_borrow_kind);
|
|
|
|
// Issue #18335. If variable is declared as immutable, override the
|
|
// mutability from the environment and substitute an `&T` anyway.
|
|
match upvar_mutbl {
|
|
McImmutable => { deref_mutbl = McImmutable; }
|
|
McDeclared | McInherited => { }
|
|
}
|
|
|
|
let ret = cmt_ {
|
|
id,
|
|
span,
|
|
cat: Categorization::Deref(Rc::new(cmt_result), env_ptr),
|
|
mutbl: deref_mutbl,
|
|
ty: var_ty,
|
|
note: NoteClosureEnv(upvar_id)
|
|
};
|
|
|
|
debug!("env_deref ret {:?}", ret);
|
|
|
|
ret
|
|
}
|
|
|
|
/// Returns the lifetime of a temporary created by expr with id `id`.
|
|
/// This could be `'static` if `id` is part of a constant expression.
|
|
pub fn temporary_scope(&self, id: hir::ItemLocalId) -> ty::Region<'tcx> {
|
|
let scope = self.region_scope_tree.temporary_scope(id);
|
|
self.tcx.mk_region(match scope {
|
|
Some(scope) => ty::ReScope(scope),
|
|
None => ty::ReStatic
|
|
})
|
|
}
|
|
|
|
pub fn cat_rvalue_node(&self,
|
|
id: ast::NodeId,
|
|
span: Span,
|
|
expr_ty: Ty<'tcx>)
|
|
-> cmt_<'tcx> {
|
|
let hir_id = self.tcx.hir.node_to_hir_id(id);
|
|
let promotable = self.rvalue_promotable_map.as_ref().map(|m| m.contains(&hir_id.local_id))
|
|
.unwrap_or(false);
|
|
|
|
// Always promote `[T; 0]` (even when e.g. borrowed mutably).
|
|
let promotable = match expr_ty.sty {
|
|
ty::TyArray(_, len) if len.assert_usize(self.tcx) == Some(0) => true,
|
|
_ => promotable,
|
|
};
|
|
|
|
// Compute maximum lifetime of this rvalue. This is 'static if
|
|
// we can promote to a constant, otherwise equal to enclosing temp
|
|
// lifetime.
|
|
let re = if promotable {
|
|
self.tcx.types.re_static
|
|
} else {
|
|
self.temporary_scope(hir_id.local_id)
|
|
};
|
|
let ret = self.cat_rvalue(id, span, re, expr_ty);
|
|
debug!("cat_rvalue_node ret {:?}", ret);
|
|
ret
|
|
}
|
|
|
|
pub fn cat_rvalue(&self,
|
|
cmt_id: ast::NodeId,
|
|
span: Span,
|
|
temp_scope: ty::Region<'tcx>,
|
|
expr_ty: Ty<'tcx>) -> cmt_<'tcx> {
|
|
let ret = cmt_ {
|
|
id:cmt_id,
|
|
span:span,
|
|
cat:Categorization::Rvalue(temp_scope),
|
|
mutbl:McDeclared,
|
|
ty:expr_ty,
|
|
note: NoteNone
|
|
};
|
|
debug!("cat_rvalue ret {:?}", ret);
|
|
ret
|
|
}
|
|
|
|
pub fn cat_field<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
f_index: usize,
|
|
f_name: Name,
|
|
f_ty: Ty<'tcx>)
|
|
-> cmt_<'tcx> {
|
|
let ret = cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
mutbl: base_cmt.mutbl.inherit(),
|
|
cat: Categorization::Interior(base_cmt, InteriorField(FieldIndex(f_index, f_name))),
|
|
ty: f_ty,
|
|
note: NoteNone
|
|
};
|
|
debug!("cat_field ret {:?}", ret);
|
|
ret
|
|
}
|
|
|
|
fn cat_overloaded_place(&self,
|
|
expr: &hir::Expr,
|
|
base: &hir::Expr,
|
|
implicit: bool)
|
|
-> McResult<cmt_<'tcx>> {
|
|
debug!("cat_overloaded_place: implicit={}", implicit);
|
|
|
|
// Reconstruct the output assuming it's a reference with the
|
|
// same region and mutability as the receiver. This holds for
|
|
// `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`.
|
|
let place_ty = self.expr_ty(expr)?;
|
|
let base_ty = self.expr_ty_adjusted(base)?;
|
|
|
|
let (region, mutbl) = match base_ty.sty {
|
|
ty::TyRef(region, _, mutbl) => (region, mutbl),
|
|
_ => {
|
|
span_bug!(expr.span, "cat_overloaded_place: base is not a reference")
|
|
}
|
|
};
|
|
let ref_ty = self.tcx.mk_ref(region, ty::TypeAndMut {
|
|
ty: place_ty,
|
|
mutbl,
|
|
});
|
|
|
|
let base_cmt = Rc::new(self.cat_rvalue_node(expr.id, expr.span, ref_ty));
|
|
self.cat_deref(expr, base_cmt, implicit)
|
|
}
|
|
|
|
pub fn cat_deref<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
implicit: bool)
|
|
-> McResult<cmt_<'tcx>> {
|
|
debug!("cat_deref: base_cmt={:?}", base_cmt);
|
|
|
|
let base_cmt_ty = base_cmt.ty;
|
|
let deref_ty = match base_cmt_ty.builtin_deref(true) {
|
|
Some(mt) => mt.ty,
|
|
None => {
|
|
debug!("Explicit deref of non-derefable type: {:?}",
|
|
base_cmt_ty);
|
|
return Err(());
|
|
}
|
|
};
|
|
|
|
let ptr = match base_cmt.ty.sty {
|
|
ty::TyAdt(def, ..) if def.is_box() => Unique,
|
|
ty::TyRawPtr(ref mt) => UnsafePtr(mt.mutbl),
|
|
ty::TyRef(r, _, mutbl) => {
|
|
let bk = ty::BorrowKind::from_mutbl(mutbl);
|
|
if implicit { Implicit(bk, r) } else { BorrowedPtr(bk, r) }
|
|
}
|
|
ref ty => bug!("unexpected type in cat_deref: {:?}", ty)
|
|
};
|
|
let ret = cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
// For unique ptrs, we inherit mutability from the owning reference.
|
|
mutbl: MutabilityCategory::from_pointer_kind(base_cmt.mutbl, ptr),
|
|
cat: Categorization::Deref(base_cmt, ptr),
|
|
ty: deref_ty,
|
|
note: NoteNone
|
|
};
|
|
debug!("cat_deref ret {:?}", ret);
|
|
Ok(ret)
|
|
}
|
|
|
|
fn cat_index<N:ast_node>(&self,
|
|
elt: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
element_ty: Ty<'tcx>,
|
|
context: InteriorOffsetKind)
|
|
-> McResult<cmt_<'tcx>> {
|
|
//! Creates a cmt for an indexing operation (`[]`).
|
|
//!
|
|
//! One subtle aspect of indexing that may not be
|
|
//! immediately obvious: for anything other than a fixed-length
|
|
//! vector, an operation like `x[y]` actually consists of two
|
|
//! disjoint (from the point of view of borrowck) operations.
|
|
//! The first is a deref of `x` to create a pointer `p` that points
|
|
//! at the first element in the array. The second operation is
|
|
//! an index which adds `y*sizeof(T)` to `p` to obtain the
|
|
//! pointer to `x[y]`. `cat_index` will produce a resulting
|
|
//! cmt containing both this deref and the indexing,
|
|
//! presuming that `base_cmt` is not of fixed-length type.
|
|
//!
|
|
//! # Parameters
|
|
//! - `elt`: the AST node being indexed
|
|
//! - `base_cmt`: the cmt of `elt`
|
|
|
|
let interior_elem = InteriorElement(context);
|
|
let ret = self.cat_imm_interior(elt, base_cmt, element_ty, interior_elem);
|
|
debug!("cat_index ret {:?}", ret);
|
|
return Ok(ret);
|
|
}
|
|
|
|
pub fn cat_imm_interior<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
interior_ty: Ty<'tcx>,
|
|
interior: InteriorKind)
|
|
-> cmt_<'tcx> {
|
|
let ret = cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
mutbl: base_cmt.mutbl.inherit(),
|
|
cat: Categorization::Interior(base_cmt, interior),
|
|
ty: interior_ty,
|
|
note: NoteNone
|
|
};
|
|
debug!("cat_imm_interior ret={:?}", ret);
|
|
ret
|
|
}
|
|
|
|
pub fn cat_downcast_if_needed<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
variant_did: DefId)
|
|
-> cmt<'tcx> {
|
|
// univariant enums do not need downcasts
|
|
let base_did = self.tcx.parent_def_id(variant_did).unwrap();
|
|
if self.tcx.adt_def(base_did).variants.len() != 1 {
|
|
let base_ty = base_cmt.ty;
|
|
let ret = Rc::new(cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
mutbl: base_cmt.mutbl.inherit(),
|
|
cat: Categorization::Downcast(base_cmt, variant_did),
|
|
ty: base_ty,
|
|
note: NoteNone
|
|
});
|
|
debug!("cat_downcast ret={:?}", ret);
|
|
ret
|
|
} else {
|
|
debug!("cat_downcast univariant={:?}", base_cmt);
|
|
base_cmt
|
|
}
|
|
}
|
|
|
|
pub fn cat_pattern<F>(&self, cmt: cmt<'tcx>, pat: &hir::Pat, mut op: F) -> McResult<()>
|
|
where F: FnMut(cmt<'tcx>, &hir::Pat),
|
|
{
|
|
self.cat_pattern_(cmt, pat, &mut op)
|
|
}
|
|
|
|
// FIXME(#19596) This is a workaround, but there should be a better way to do this
|
|
fn cat_pattern_<F>(&self, mut cmt: cmt<'tcx>, pat: &hir::Pat, op: &mut F) -> McResult<()>
|
|
where F : FnMut(cmt<'tcx>, &hir::Pat)
|
|
{
|
|
// Here, `cmt` is the categorization for the value being
|
|
// matched and pat is the pattern it is being matched against.
|
|
//
|
|
// In general, the way that this works is that we walk down
|
|
// the pattern, constructing a cmt that represents the path
|
|
// that will be taken to reach the value being matched.
|
|
//
|
|
// When we encounter named bindings, we take the cmt that has
|
|
// been built up and pass it off to guarantee_valid() so that
|
|
// we can be sure that the binding will remain valid for the
|
|
// duration of the arm.
|
|
//
|
|
// (*2) There is subtlety concerning the correspondence between
|
|
// pattern ids and types as compared to *expression* ids and
|
|
// types. This is explained briefly. on the definition of the
|
|
// type `cmt`, so go off and read what it says there, then
|
|
// come back and I'll dive into a bit more detail here. :) OK,
|
|
// back?
|
|
//
|
|
// In general, the id of the cmt should be the node that
|
|
// "produces" the value---patterns aren't executable code
|
|
// exactly, but I consider them to "execute" when they match a
|
|
// value, and I consider them to produce the value that was
|
|
// matched. So if you have something like:
|
|
//
|
|
// let x = @@3;
|
|
// match x {
|
|
// @@y { ... }
|
|
// }
|
|
//
|
|
// In this case, the cmt and the relevant ids would be:
|
|
//
|
|
// CMT Id Type of Id Type of cmt
|
|
//
|
|
// local(x)->@->@
|
|
// ^~~~~~~^ `x` from discr @@int @@int
|
|
// ^~~~~~~~~~^ `@@y` pattern node @@int @int
|
|
// ^~~~~~~~~~~~~^ `@y` pattern node @int int
|
|
//
|
|
// You can see that the types of the id and the cmt are in
|
|
// sync in the first line, because that id is actually the id
|
|
// of an expression. But once we get to pattern ids, the types
|
|
// step out of sync again. So you'll see below that we always
|
|
// get the type of the *subpattern* and use that.
|
|
|
|
debug!("cat_pattern: {:?} cmt={:?}", pat, cmt);
|
|
|
|
// If (pattern) adjustments are active for this pattern, adjust the `cmt` correspondingly.
|
|
// `cmt`s are constructed differently from patterns. For example, in
|
|
//
|
|
// ```
|
|
// match foo {
|
|
// &&Some(x, ) => { ... },
|
|
// _ => { ... },
|
|
// }
|
|
// ```
|
|
//
|
|
// the pattern `&&Some(x,)` is represented as `Ref { Ref { TupleStruct }}`. To build the
|
|
// corresponding `cmt` we start with a `cmt` for `foo`, and then, by traversing the
|
|
// pattern, try to answer the question: given the address of `foo`, how is `x` reached?
|
|
//
|
|
// `&&Some(x,)` `cmt_foo`
|
|
// `&Some(x,)` `deref { cmt_foo}`
|
|
// `Some(x,)` `deref { deref { cmt_foo }}`
|
|
// (x,)` `field0 { deref { deref { cmt_foo }}}` <- resulting cmt
|
|
//
|
|
// The above example has no adjustments. If the code were instead the (after adjustments,
|
|
// equivalent) version
|
|
//
|
|
// ```
|
|
// match foo {
|
|
// Some(x, ) => { ... },
|
|
// _ => { ... },
|
|
// }
|
|
// ```
|
|
//
|
|
// Then we see that to get the same result, we must start with `deref { deref { cmt_foo }}`
|
|
// instead of `cmt_foo` since the pattern is now `Some(x,)` and not `&&Some(x,)`, even
|
|
// though its assigned type is that of `&&Some(x,)`.
|
|
for _ in 0..self.tables
|
|
.pat_adjustments()
|
|
.get(pat.hir_id)
|
|
.map(|v| v.len())
|
|
.unwrap_or(0) {
|
|
cmt = Rc::new(self.cat_deref(pat, cmt, true /* implicit */)?);
|
|
}
|
|
let cmt = cmt; // lose mutability
|
|
|
|
// Invoke the callback, but only now, after the `cmt` has adjusted.
|
|
//
|
|
// To see that this makes sense, consider `match &Some(3) { Some(x) => { ... }}`. In that
|
|
// case, the initial `cmt` will be that for `&Some(3)` and the pattern is `Some(x)`. We
|
|
// don't want to call `op` with these incompatible values. As written, what happens instead
|
|
// is that `op` is called with the adjusted cmt (that for `*&Some(3)`) and the pattern
|
|
// `Some(x)` (which matches). Recursing once more, `*&Some(3)` and the pattern `Some(x)`
|
|
// result in the cmt `Downcast<Some>(*&Some(3)).0` associated to `x` and invoke `op` with
|
|
// that (where the `ref` on `x` is implied).
|
|
op(cmt.clone(), pat);
|
|
|
|
match pat.node {
|
|
PatKind::TupleStruct(ref qpath, ref subpats, ddpos) => {
|
|
let def = self.tables.qpath_def(qpath, pat.hir_id);
|
|
let (cmt, expected_len) = match def {
|
|
Def::Err => {
|
|
debug!("access to unresolvable pattern {:?}", pat);
|
|
return Err(())
|
|
}
|
|
Def::VariantCtor(def_id, CtorKind::Fn) => {
|
|
let enum_def = self.tcx.parent_def_id(def_id).unwrap();
|
|
(self.cat_downcast_if_needed(pat, cmt, def_id),
|
|
self.tcx.adt_def(enum_def).variant_with_id(def_id).fields.len())
|
|
}
|
|
Def::StructCtor(_, CtorKind::Fn) => {
|
|
match self.pat_ty_unadjusted(&pat)?.sty {
|
|
ty::TyAdt(adt_def, _) => {
|
|
(cmt, adt_def.non_enum_variant().fields.len())
|
|
}
|
|
ref ty => {
|
|
span_bug!(pat.span, "tuple struct pattern unexpected type {:?}", ty);
|
|
}
|
|
}
|
|
}
|
|
def => {
|
|
span_bug!(pat.span, "tuple struct pattern didn't resolve \
|
|
to variant or struct {:?}", def);
|
|
}
|
|
};
|
|
|
|
for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
|
|
let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
|
|
let interior = InteriorField(FieldIndex(i, Name::intern(&i.to_string())));
|
|
let subcmt = Rc::new(self.cat_imm_interior(pat, cmt.clone(), subpat_ty, interior));
|
|
self.cat_pattern_(subcmt, &subpat, op)?;
|
|
}
|
|
}
|
|
|
|
PatKind::Struct(ref qpath, ref field_pats, _) => {
|
|
// {f1: p1, ..., fN: pN}
|
|
let def = self.tables.qpath_def(qpath, pat.hir_id);
|
|
let cmt = match def {
|
|
Def::Err => {
|
|
debug!("access to unresolvable pattern {:?}", pat);
|
|
return Err(())
|
|
},
|
|
Def::Variant(variant_did) |
|
|
Def::VariantCtor(variant_did, ..) => {
|
|
self.cat_downcast_if_needed(pat, cmt, variant_did)
|
|
},
|
|
_ => cmt
|
|
};
|
|
|
|
for fp in field_pats {
|
|
let field_ty = self.pat_ty(&fp.node.pat)?; // see (*2)
|
|
let f_index = self.tcx.field_index(fp.node.id, self.tables);
|
|
let cmt_field =
|
|
Rc::new(self.cat_field(pat, cmt.clone(), f_index, fp.node.name, field_ty));
|
|
self.cat_pattern_(cmt_field, &fp.node.pat, op)?;
|
|
}
|
|
}
|
|
|
|
PatKind::Binding(.., Some(ref subpat)) => {
|
|
self.cat_pattern_(cmt, &subpat, op)?;
|
|
}
|
|
|
|
PatKind::Tuple(ref subpats, ddpos) => {
|
|
// (p1, ..., pN)
|
|
let expected_len = match self.pat_ty_unadjusted(&pat)?.sty {
|
|
ty::TyTuple(ref tys) => tys.len(),
|
|
ref ty => span_bug!(pat.span, "tuple pattern unexpected type {:?}", ty),
|
|
};
|
|
for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
|
|
let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
|
|
let interior = InteriorField(FieldIndex(i, Name::intern(&i.to_string())));
|
|
let subcmt = Rc::new(self.cat_imm_interior(pat, cmt.clone(), subpat_ty, interior));
|
|
self.cat_pattern_(subcmt, &subpat, op)?;
|
|
}
|
|
}
|
|
|
|
PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => {
|
|
// box p1, &p1, &mut p1. we can ignore the mutability of
|
|
// PatKind::Ref since that information is already contained
|
|
// in the type.
|
|
let subcmt = Rc::new(self.cat_deref(pat, cmt, false)?);
|
|
self.cat_pattern_(subcmt, &subpat, op)?;
|
|
}
|
|
|
|
PatKind::Slice(ref before, ref slice, ref after) => {
|
|
let element_ty = match cmt.ty.builtin_index() {
|
|
Some(ty) => ty,
|
|
None => {
|
|
debug!("Explicit index of non-indexable type {:?}", cmt);
|
|
return Err(());
|
|
}
|
|
};
|
|
let context = InteriorOffsetKind::Pattern;
|
|
let elt_cmt = Rc::new(self.cat_index(pat, cmt, element_ty, context)?);
|
|
for before_pat in before {
|
|
self.cat_pattern_(elt_cmt.clone(), &before_pat, op)?;
|
|
}
|
|
if let Some(ref slice_pat) = *slice {
|
|
self.cat_pattern_(elt_cmt.clone(), &slice_pat, op)?;
|
|
}
|
|
for after_pat in after {
|
|
self.cat_pattern_(elt_cmt.clone(), &after_pat, op)?;
|
|
}
|
|
}
|
|
|
|
PatKind::Path(_) | PatKind::Binding(.., None) |
|
|
PatKind::Lit(..) | PatKind::Range(..) | PatKind::Wild => {
|
|
// always ok
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
#[derive(Clone, Debug)]
|
|
pub enum Aliasability {
|
|
FreelyAliasable(AliasableReason),
|
|
NonAliasable,
|
|
ImmutableUnique(Box<Aliasability>),
|
|
}
|
|
|
|
#[derive(Copy, Clone, Debug)]
|
|
pub enum AliasableReason {
|
|
AliasableBorrowed,
|
|
AliasableStatic,
|
|
AliasableStaticMut,
|
|
}
|
|
|
|
impl<'tcx> cmt_<'tcx> {
|
|
pub fn guarantor(&self) -> cmt_<'tcx> {
|
|
//! Returns `self` after stripping away any derefs or
|
|
//! interior content. The return value is basically the `cmt` which
|
|
//! determines how long the value in `self` remains live.
|
|
|
|
match self.cat {
|
|
Categorization::Rvalue(..) |
|
|
Categorization::StaticItem |
|
|
Categorization::Local(..) |
|
|
Categorization::Deref(_, UnsafePtr(..)) |
|
|
Categorization::Deref(_, BorrowedPtr(..)) |
|
|
Categorization::Deref(_, Implicit(..)) |
|
|
Categorization::Upvar(..) => {
|
|
(*self).clone()
|
|
}
|
|
Categorization::Downcast(ref b, _) |
|
|
Categorization::Interior(ref b, _) |
|
|
Categorization::Deref(ref b, Unique) => {
|
|
b.guarantor()
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns `FreelyAliasable(_)` if this place represents a freely aliasable pointer type.
|
|
pub fn freely_aliasable(&self) -> Aliasability {
|
|
// Maybe non-obvious: copied upvars can only be considered
|
|
// non-aliasable in once closures, since any other kind can be
|
|
// aliased and eventually recused.
|
|
|
|
match self.cat {
|
|
Categorization::Deref(ref b, BorrowedPtr(ty::MutBorrow, _)) |
|
|
Categorization::Deref(ref b, Implicit(ty::MutBorrow, _)) |
|
|
Categorization::Deref(ref b, BorrowedPtr(ty::UniqueImmBorrow, _)) |
|
|
Categorization::Deref(ref b, Implicit(ty::UniqueImmBorrow, _)) |
|
|
Categorization::Deref(ref b, Unique) |
|
|
Categorization::Downcast(ref b, _) |
|
|
Categorization::Interior(ref b, _) => {
|
|
// Aliasability depends on base cmt
|
|
b.freely_aliasable()
|
|
}
|
|
|
|
Categorization::Rvalue(..) |
|
|
Categorization::Local(..) |
|
|
Categorization::Upvar(..) |
|
|
Categorization::Deref(_, UnsafePtr(..)) => { // yes, it's aliasable, but...
|
|
NonAliasable
|
|
}
|
|
|
|
Categorization::StaticItem => {
|
|
if self.mutbl.is_mutable() {
|
|
FreelyAliasable(AliasableStaticMut)
|
|
} else {
|
|
FreelyAliasable(AliasableStatic)
|
|
}
|
|
}
|
|
|
|
Categorization::Deref(_, BorrowedPtr(ty::ImmBorrow, _)) |
|
|
Categorization::Deref(_, Implicit(ty::ImmBorrow, _)) => {
|
|
FreelyAliasable(AliasableBorrowed)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Digs down through one or two layers of deref and grabs the
|
|
// Categorization of the cmt for the upvar if a note indicates there is
|
|
// one.
|
|
pub fn upvar_cat(&self) -> Option<&Categorization<'tcx>> {
|
|
match self.note {
|
|
NoteClosureEnv(..) | NoteUpvarRef(..) => {
|
|
Some(match self.cat {
|
|
Categorization::Deref(ref inner, _) => {
|
|
match inner.cat {
|
|
Categorization::Deref(ref inner, _) => &inner.cat,
|
|
Categorization::Upvar(..) => &inner.cat,
|
|
_ => bug!()
|
|
}
|
|
}
|
|
_ => bug!()
|
|
})
|
|
}
|
|
NoteNone => None
|
|
}
|
|
}
|
|
|
|
pub fn descriptive_string(&self, tcx: TyCtxt) -> String {
|
|
match self.cat {
|
|
Categorization::StaticItem => {
|
|
"static item".to_string()
|
|
}
|
|
Categorization::Rvalue(..) => {
|
|
"non-place".to_string()
|
|
}
|
|
Categorization::Local(vid) => {
|
|
if tcx.hir.is_argument(vid) {
|
|
"argument".to_string()
|
|
} else {
|
|
"local variable".to_string()
|
|
}
|
|
}
|
|
Categorization::Deref(_, pk) => {
|
|
match self.upvar_cat() {
|
|
Some(&Categorization::Upvar(ref var)) => {
|
|
var.to_string()
|
|
}
|
|
Some(_) => bug!(),
|
|
None => {
|
|
match pk {
|
|
Implicit(..) => {
|
|
format!("indexed content")
|
|
}
|
|
Unique => {
|
|
format!("`Box` content")
|
|
}
|
|
UnsafePtr(..) => {
|
|
format!("dereference of raw pointer")
|
|
}
|
|
BorrowedPtr(..) => {
|
|
format!("borrowed content")
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
Categorization::Interior(_, InteriorField(..)) => {
|
|
"field".to_string()
|
|
}
|
|
Categorization::Interior(_, InteriorElement(InteriorOffsetKind::Index)) => {
|
|
"indexed content".to_string()
|
|
}
|
|
Categorization::Interior(_, InteriorElement(InteriorOffsetKind::Pattern)) => {
|
|
"pattern-bound indexed content".to_string()
|
|
}
|
|
Categorization::Upvar(ref var) => {
|
|
var.to_string()
|
|
}
|
|
Categorization::Downcast(ref cmt, _) => {
|
|
cmt.descriptive_string(tcx)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn ptr_sigil(ptr: PointerKind) -> &'static str {
|
|
match ptr {
|
|
Unique => "Box",
|
|
BorrowedPtr(ty::ImmBorrow, _) |
|
|
Implicit(ty::ImmBorrow, _) => "&",
|
|
BorrowedPtr(ty::MutBorrow, _) |
|
|
Implicit(ty::MutBorrow, _) => "&mut",
|
|
BorrowedPtr(ty::UniqueImmBorrow, _) |
|
|
Implicit(ty::UniqueImmBorrow, _) => "&unique",
|
|
UnsafePtr(_) => "*",
|
|
}
|
|
}
|
|
|
|
impl fmt::Debug for InteriorKind {
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
match *self {
|
|
InteriorField(FieldIndex(_, info)) => write!(f, "{}", info),
|
|
InteriorElement(..) => write!(f, "[]"),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl fmt::Debug for Upvar {
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
write!(f, "{:?}/{:?}", self.id, self.kind)
|
|
}
|
|
}
|
|
|
|
impl fmt::Display for Upvar {
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
let kind = match self.kind {
|
|
ty::ClosureKind::Fn => "Fn",
|
|
ty::ClosureKind::FnMut => "FnMut",
|
|
ty::ClosureKind::FnOnce => "FnOnce",
|
|
};
|
|
write!(f, "captured outer variable in an `{}` closure", kind)
|
|
}
|
|
}
|