1577 lines
58 KiB
Rust
1577 lines
58 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 an lvalue, then this
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//! is the address of the lvalue. 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 translation 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 translation. 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 `cat_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::FieldName::*;
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pub use self::ElementKind::*;
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pub use self::MutabilityCategory::*;
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pub use self::InteriorSafety::*;
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pub use self::AliasableReason::*;
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pub use self::Note::*;
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pub use self::deref_kind::*;
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pub use self::categorization::*;
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use middle::def;
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use middle::region;
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use middle::ty::{mod, Ty};
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use util::nodemap::{DefIdMap, NodeMap};
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use util::ppaux::{ty_to_string, Repr};
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use syntax::ast::{MutImmutable, MutMutable};
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use syntax::ast;
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use syntax::ast_map;
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use syntax::codemap::Span;
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use syntax::print::pprust;
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use syntax::parse::token;
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use std::cell::RefCell;
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use std::rc::Rc;
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#[deriving(Clone, PartialEq, Show)]
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pub enum categorization<'tcx> {
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cat_rvalue(ty::Region), // temporary val, argument is its scope
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cat_static_item,
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cat_upvar(Upvar), // upvar referenced by closure env
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cat_local(ast::NodeId), // local variable
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cat_deref(cmt<'tcx>, uint, PointerKind), // deref of a ptr
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cat_interior(cmt<'tcx>, InteriorKind), // something interior: field, tuple, etc
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cat_downcast(cmt<'tcx>, ast::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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#[deriving(Clone, PartialEq, Show)]
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pub struct Upvar {
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pub id: ty::UpvarId,
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// Unboxed closure kinds are used even for old-style closures for simplicity
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pub kind: ty::UnboxedClosureKind,
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// Is this from an unboxed closure? Used only for diagnostics.
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pub is_unboxed: bool
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}
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impl Copy for Upvar {}
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// different kinds of pointers:
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#[deriving(Clone, PartialEq, Eq, Hash, Show)]
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pub enum PointerKind {
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OwnedPtr,
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BorrowedPtr(ty::BorrowKind, ty::Region),
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Implicit(ty::BorrowKind, ty::Region), // Implicit deref of a borrowed ptr.
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UnsafePtr(ast::Mutability)
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}
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impl Copy for PointerKind {}
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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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#[deriving(Clone, PartialEq, Eq, Hash, Show)]
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pub enum InteriorKind {
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InteriorField(FieldName),
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InteriorElement(ElementKind),
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}
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impl Copy for InteriorKind {}
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#[deriving(Clone, PartialEq, Eq, Hash, Show)]
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pub enum FieldName {
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NamedField(ast::Name),
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PositionalField(uint)
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}
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impl Copy for FieldName {}
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#[deriving(Clone, PartialEq, Eq, Hash, Show)]
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pub enum ElementKind {
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VecElement,
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OtherElement,
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}
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impl Copy for ElementKind {}
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#[deriving(Clone, PartialEq, Eq, Hash, Show)]
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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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impl Copy for MutabilityCategory {}
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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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#[deriving(Clone, PartialEq, Show)]
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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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impl Copy for Note {}
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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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#[deriving(Clone, PartialEq, Show)]
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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 lvalue
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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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// We pun on *T to mean both actual deref of a ptr as well
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// as accessing of components:
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pub enum deref_kind {
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deref_ptr(PointerKind),
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deref_interior(InteriorKind),
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}
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impl Copy for deref_kind {}
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// Categorizes a derefable type. Note that we include vectors and strings as
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// derefable (we model an index as the combination of a deref and then a
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// pointer adjustment).
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pub fn opt_deref_kind(t: Ty) -> Option<deref_kind> {
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match t.sty {
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ty::ty_uniq(_) |
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ty::ty_closure(box ty::ClosureTy {store: ty::UniqTraitStore, ..}) => {
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Some(deref_ptr(OwnedPtr))
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}
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ty::ty_rptr(r, mt) => {
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let kind = ty::BorrowKind::from_mutbl(mt.mutbl);
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Some(deref_ptr(BorrowedPtr(kind, r)))
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}
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ty::ty_closure(box ty::ClosureTy {
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store: ty::RegionTraitStore(r, _),
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..
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}) => {
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Some(deref_ptr(BorrowedPtr(ty::ImmBorrow, r)))
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}
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ty::ty_ptr(ref mt) => {
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Some(deref_ptr(UnsafePtr(mt.mutbl)))
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}
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ty::ty_enum(..) |
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ty::ty_struct(..) => { // newtype
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Some(deref_interior(InteriorField(PositionalField(0))))
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}
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ty::ty_vec(_, _) | ty::ty_str => {
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Some(deref_interior(InteriorElement(element_kind(t))))
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}
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_ => None
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}
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}
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pub fn deref_kind<'tcx>(tcx: &ty::ctxt<'tcx>, t: Ty<'tcx>) -> deref_kind {
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debug!("deref_kind {}", ty_to_string(tcx, t));
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match opt_deref_kind(t) {
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Some(k) => k,
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None => {
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tcx.sess.bug(
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format!("deref_kind() invoked on non-derefable type {}",
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ty_to_string(tcx, t)).as_slice());
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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 ast::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 ast::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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pub struct MemCategorizationContext<'t,TYPER:'t> {
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typer: &'t TYPER
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}
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impl<'t,TYPER:'t> Copy for MemCategorizationContext<'t,TYPER> {}
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pub type McResult<T> = Result<T, ()>;
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/// The `Typer` trait provides the interface for the mem-categorization
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/// module to the results of the type check. It can be used to query
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/// the type assigned to an expression node, to inquire after adjustments,
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/// and so on.
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///
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/// This interface is needed because mem-categorization is used from
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/// two places: `regionck` and `borrowck`. `regionck` executes before
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/// type inference is complete, and hence derives types and so on from
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/// intermediate tables. This also implies that type errors can occur,
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/// and hence `node_ty()` and friends return a `Result` type -- any
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/// error will propagate back up through the mem-categorization
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/// routines.
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///
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/// In the borrow checker, in contrast, type checking is complete and we
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/// know that no errors have occurred, so we simply consult the tcx and we
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/// can be sure that only `Ok` results will occur.
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pub trait Typer<'tcx> {
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fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx>;
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fn node_ty(&self, id: ast::NodeId) -> McResult<Ty<'tcx>>;
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fn node_method_ty(&self, method_call: ty::MethodCall) -> Option<Ty<'tcx>>;
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fn adjustments<'a>(&'a self) -> &'a RefCell<NodeMap<ty::AutoAdjustment<'tcx>>>;
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fn is_method_call(&self, id: ast::NodeId) -> bool;
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fn temporary_scope(&self, rvalue_id: ast::NodeId) -> Option<region::CodeExtent>;
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fn upvar_borrow(&self, upvar_id: ty::UpvarId) -> ty::UpvarBorrow;
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fn capture_mode(&self, closure_expr_id: ast::NodeId)
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-> ast::CaptureClause;
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fn unboxed_closures<'a>(&'a self)
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-> &'a RefCell<DefIdMap<ty::UnboxedClosure<'tcx>>>;
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}
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impl MutabilityCategory {
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pub fn from_mutbl(m: ast::Mutability) -> MutabilityCategory {
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match m {
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MutImmutable => McImmutable,
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MutMutable => McDeclared
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}
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}
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pub fn from_borrow_kind(borrow_kind: ty::BorrowKind) -> MutabilityCategory {
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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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}
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pub fn from_pointer_kind(base_mutbl: MutabilityCategory,
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ptr: PointerKind) -> MutabilityCategory {
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match ptr {
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OwnedPtr => {
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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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}
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fn from_local(tcx: &ty::ctxt, id: ast::NodeId) -> MutabilityCategory {
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match tcx.map.get(id) {
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ast_map::NodeLocal(p) | ast_map::NodeArg(p) => match p.node {
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ast::PatIdent(bind_mode, _, _) => {
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if bind_mode == ast::BindByValue(ast::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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_ => tcx.sess.span_bug(p.span, "expected identifier pattern")
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},
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_ => tcx.sess.span_bug(tcx.map.span(id), "expected identifier pattern")
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}
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}
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pub fn inherit(&self) -> MutabilityCategory {
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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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}
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pub fn is_mutable(&self) -> bool {
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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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}
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pub fn is_immutable(&self) -> bool {
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match *self {
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McImmutable => true,
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McDeclared | McInherited => false
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}
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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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macro_rules! if_ok(
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($inp: expr) => (
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match $inp {
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Ok(v) => { v }
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Err(e) => { return Err(e); }
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}
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)
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)
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impl<'t,'tcx,TYPER:Typer<'tcx>> MemCategorizationContext<'t,TYPER> {
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pub fn new(typer: &'t TYPER) -> MemCategorizationContext<'t,TYPER> {
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MemCategorizationContext { typer: typer }
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}
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fn tcx(&self) -> &'t ty::ctxt<'tcx> {
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self.typer.tcx()
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}
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fn expr_ty(&self, expr: &ast::Expr) -> McResult<Ty<'tcx>> {
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self.typer.node_ty(expr.id)
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}
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fn expr_ty_adjusted(&self, expr: &ast::Expr) -> McResult<Ty<'tcx>> {
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let unadjusted_ty = if_ok!(self.expr_ty(expr));
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Ok(ty::adjust_ty(self.tcx(), expr.span, expr.id, unadjusted_ty,
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self.typer.adjustments().borrow().get(&expr.id),
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|method_call| self.typer.node_method_ty(method_call)))
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}
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fn node_ty(&self, id: ast::NodeId) -> McResult<Ty<'tcx>> {
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self.typer.node_ty(id)
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}
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fn pat_ty(&self, pat: &ast::Pat) -> McResult<Ty<'tcx>> {
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let tcx = self.typer.tcx();
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let base_ty = self.typer.node_ty(pat.id);
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// FIXME (Issue #18207): This code detects whether we are
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// looking at a `ref x`, and if so, figures out what the type
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// *being borrowed* is. But ideally we would put in a more
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// fundamental fix to this conflated use of the node id.
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let ret_ty = match pat.node {
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ast::PatIdent(ast::BindByRef(_), _, _) => {
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// a bind-by-ref means that the base_ty will be the type of the ident itself,
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// but what we want here is the type of the underlying value being borrowed.
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// So peel off one-level, turning the &T into T.
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base_ty.map(|t| {
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ty::deref(t, false).unwrap_or_else(|| {
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panic!("encountered BindByRef with non &-type");
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}).ty
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})
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}
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_ => base_ty,
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};
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debug!("pat_ty(pat={}) base_ty={} ret_ty={}",
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pat.repr(tcx), base_ty.repr(tcx), ret_ty.repr(tcx));
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ret_ty
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}
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pub fn cat_expr(&self, expr: &ast::Expr) -> McResult<cmt<'tcx>> {
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match self.typer.adjustments().borrow().get(&expr.id) {
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None => {
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// No adjustments.
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self.cat_expr_unadjusted(expr)
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}
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Some(adjustment) => {
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match *adjustment {
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ty::AdjustAddEnv(..) => {
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debug!("cat_expr(AdjustAddEnv): {}",
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expr.repr(self.tcx()));
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// Convert a bare fn to a closure by adding NULL env.
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// Result is an rvalue.
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let expr_ty = if_ok!(self.expr_ty_adjusted(expr));
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Ok(self.cat_rvalue_node(expr.id(), expr.span(), expr_ty))
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}
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ty::AdjustDerefRef(
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ty::AutoDerefRef {
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autoref: Some(_), ..}) => {
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debug!("cat_expr(AdjustDerefRef): {}",
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expr.repr(self.tcx()));
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// Equivalent to &*expr or something similar.
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// Result is an rvalue.
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let expr_ty = if_ok!(self.expr_ty_adjusted(expr));
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Ok(self.cat_rvalue_node(expr.id(), expr.span(), expr_ty))
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|
}
|
|
|
|
ty::AdjustDerefRef(
|
|
ty::AutoDerefRef {
|
|
autoref: None, autoderefs}) => {
|
|
// Equivalent to *expr or something similar.
|
|
self.cat_expr_autoderefd(expr, autoderefs)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn cat_expr_autoderefd(&self,
|
|
expr: &ast::Expr,
|
|
autoderefs: uint)
|
|
-> McResult<cmt<'tcx>> {
|
|
let mut cmt = if_ok!(self.cat_expr_unadjusted(expr));
|
|
debug!("cat_expr_autoderefd: autoderefs={}, cmt={}",
|
|
autoderefs,
|
|
cmt.repr(self.tcx()));
|
|
for deref in range(1u, autoderefs + 1) {
|
|
cmt = self.cat_deref(expr, cmt, deref, false);
|
|
}
|
|
return Ok(cmt);
|
|
}
|
|
|
|
pub fn cat_expr_unadjusted(&self, expr: &ast::Expr) -> McResult<cmt<'tcx>> {
|
|
debug!("cat_expr: id={} expr={}", expr.id, expr.repr(self.tcx()));
|
|
|
|
let expr_ty = if_ok!(self.expr_ty(expr));
|
|
match expr.node {
|
|
ast::ExprUnary(ast::UnDeref, ref e_base) => {
|
|
let base_cmt = if_ok!(self.cat_expr(&**e_base));
|
|
Ok(self.cat_deref(expr, base_cmt, 0, false))
|
|
}
|
|
|
|
ast::ExprField(ref base, f_name) => {
|
|
let base_cmt = if_ok!(self.cat_expr(&**base));
|
|
debug!("cat_expr(cat_field): id={} expr={} base={}",
|
|
expr.id,
|
|
expr.repr(self.tcx()),
|
|
base_cmt.repr(self.tcx()));
|
|
Ok(self.cat_field(expr, base_cmt, f_name.node.name, expr_ty))
|
|
}
|
|
|
|
ast::ExprTupField(ref base, idx) => {
|
|
let base_cmt = if_ok!(self.cat_expr(&**base));
|
|
Ok(self.cat_tup_field(expr, base_cmt, idx.node, expr_ty))
|
|
}
|
|
|
|
ast::ExprIndex(ref base, _) => {
|
|
let method_call = ty::MethodCall::expr(expr.id());
|
|
match self.typer.node_method_ty(method_call) {
|
|
Some(method_ty) => {
|
|
// If this is an index implemented by a method call, then it will
|
|
// include an implicit deref of the result.
|
|
let ret_ty = ty::ty_fn_ret(method_ty).unwrap();
|
|
Ok(self.cat_deref(expr,
|
|
self.cat_rvalue_node(expr.id(),
|
|
expr.span(),
|
|
ret_ty), 1, true))
|
|
}
|
|
None => {
|
|
let base_cmt = if_ok!(self.cat_expr(&**base));
|
|
Ok(self.cat_index(expr, base_cmt))
|
|
}
|
|
}
|
|
}
|
|
|
|
ast::ExprPath(_) => {
|
|
let def = (*self.tcx().def_map.borrow())[expr.id];
|
|
self.cat_def(expr.id, expr.span, expr_ty, def)
|
|
}
|
|
|
|
ast::ExprParen(ref e) => {
|
|
self.cat_expr(&**e)
|
|
}
|
|
|
|
ast::ExprAddrOf(..) | ast::ExprCall(..) |
|
|
ast::ExprAssign(..) | ast::ExprAssignOp(..) |
|
|
ast::ExprClosure(..) | ast::ExprRet(..) |
|
|
ast::ExprUnary(..) | ast::ExprSlice(..) |
|
|
ast::ExprMethodCall(..) | ast::ExprCast(..) |
|
|
ast::ExprVec(..) | ast::ExprTup(..) | ast::ExprIf(..) |
|
|
ast::ExprBinary(..) | ast::ExprWhile(..) |
|
|
ast::ExprBlock(..) | ast::ExprLoop(..) | ast::ExprMatch(..) |
|
|
ast::ExprLit(..) | ast::ExprBreak(..) | ast::ExprMac(..) |
|
|
ast::ExprAgain(..) | ast::ExprStruct(..) | ast::ExprRepeat(..) |
|
|
ast::ExprInlineAsm(..) | ast::ExprBox(..) |
|
|
ast::ExprForLoop(..) => {
|
|
Ok(self.cat_rvalue_node(expr.id(), expr.span(), expr_ty))
|
|
}
|
|
|
|
ast::ExprIfLet(..) => {
|
|
self.tcx().sess.span_bug(expr.span, "non-desugared ExprIfLet");
|
|
}
|
|
ast::ExprWhileLet(..) => {
|
|
self.tcx().sess.span_bug(expr.span, "non-desugared ExprWhileLet");
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn cat_def(&self,
|
|
id: ast::NodeId,
|
|
span: Span,
|
|
expr_ty: Ty<'tcx>,
|
|
def: def::Def)
|
|
-> McResult<cmt<'tcx>> {
|
|
debug!("cat_def: id={} expr={} def={}",
|
|
id, expr_ty.repr(self.tcx()), def);
|
|
|
|
match def {
|
|
def::DefStruct(..) | def::DefVariant(..) | def::DefFn(..) |
|
|
def::DefStaticMethod(..) | def::DefConst(..) => {
|
|
Ok(self.cat_rvalue_node(id, span, expr_ty))
|
|
}
|
|
def::DefMod(_) | def::DefForeignMod(_) | def::DefUse(_) |
|
|
def::DefTrait(_) | def::DefTy(..) | def::DefPrimTy(_) |
|
|
def::DefTyParam(..) | def::DefTyParamBinder(..) | def::DefRegion(_) |
|
|
def::DefLabel(_) | def::DefSelfTy(..) | def::DefMethod(..) |
|
|
def::DefAssociatedTy(..) => {
|
|
Ok(Rc::new(cmt_ {
|
|
id:id,
|
|
span:span,
|
|
cat:cat_static_item,
|
|
mutbl: McImmutable,
|
|
ty:expr_ty,
|
|
note: NoteNone
|
|
}))
|
|
}
|
|
|
|
def::DefStatic(_, mutbl) => {
|
|
Ok(Rc::new(cmt_ {
|
|
id:id,
|
|
span:span,
|
|
cat:cat_static_item,
|
|
mutbl: if mutbl { McDeclared } else { McImmutable},
|
|
ty:expr_ty,
|
|
note: NoteNone
|
|
}))
|
|
}
|
|
|
|
def::DefUpvar(var_id, fn_node_id, _) => {
|
|
let ty = if_ok!(self.node_ty(fn_node_id));
|
|
match ty.sty {
|
|
ty::ty_closure(ref closure_ty) => {
|
|
// Translate old closure type info into unboxed
|
|
// closure kind/capture mode
|
|
let (mode, kind) = match (closure_ty.store, closure_ty.onceness) {
|
|
// stack closure
|
|
(ty::RegionTraitStore(..), ast::Many) => {
|
|
(ast::CaptureByRef, ty::FnMutUnboxedClosureKind)
|
|
}
|
|
// proc or once closure
|
|
(_, ast::Once) => {
|
|
(ast::CaptureByValue, ty::FnOnceUnboxedClosureKind)
|
|
}
|
|
// There should be no such old closure type
|
|
(ty::UniqTraitStore, ast::Many) => {
|
|
self.tcx().sess.span_bug(span, "Impossible closure type");
|
|
}
|
|
};
|
|
self.cat_upvar(id, span, var_id, fn_node_id, kind, mode, false)
|
|
}
|
|
ty::ty_unboxed_closure(closure_id, _, _) => {
|
|
let unboxed_closures = self.typer.unboxed_closures().borrow();
|
|
let kind = (*unboxed_closures)[closure_id].kind;
|
|
let mode = self.typer.capture_mode(fn_node_id);
|
|
self.cat_upvar(id, span, var_id, fn_node_id, kind, mode, true)
|
|
}
|
|
_ => {
|
|
self.tcx().sess.span_bug(
|
|
span,
|
|
format!("Upvar of non-closure {} - {}",
|
|
fn_node_id,
|
|
ty.repr(self.tcx())).as_slice());
|
|
}
|
|
}
|
|
}
|
|
|
|
def::DefLocal(vid) => {
|
|
Ok(Rc::new(cmt_ {
|
|
id: id,
|
|
span: span,
|
|
cat: cat_local(vid),
|
|
mutbl: MutabilityCategory::from_local(self.tcx(), vid),
|
|
ty: expr_ty,
|
|
note: NoteNone
|
|
}))
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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,
|
|
kind: ty::UnboxedClosureKind,
|
|
mode: ast::CaptureClause,
|
|
is_unboxed: bool)
|
|
-> McResult<cmt<'tcx>> {
|
|
// An upvar can have up to 3 components. The base is a
|
|
// `cat_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
|
|
// old stack | N/A | upvar -> &'env mut -> &'up bk
|
|
// old proc/once | copied | N/A
|
|
let var_ty = if_ok!(self.node_ty(var_id));
|
|
|
|
let upvar_id = ty::UpvarId { var_id: var_id,
|
|
closure_expr_id: fn_node_id };
|
|
|
|
// Mutability of original variable itself
|
|
let var_mutbl = MutabilityCategory::from_local(self.tcx(), var_id);
|
|
|
|
// Construct information about env pointer dereference, if any
|
|
let mutbl = match kind {
|
|
ty::FnOnceUnboxedClosureKind => None, // None, env is by-value
|
|
ty::FnMutUnboxedClosureKind => match mode { // Depends on capture type
|
|
ast::CaptureByValue => Some(var_mutbl), // Mutable if the original var is
|
|
ast::CaptureByRef => Some(McDeclared) // Mutable regardless
|
|
},
|
|
ty::FnUnboxedClosureKind => Some(McImmutable) // Never mutable
|
|
};
|
|
let env_info = mutbl.map(|env_mutbl| {
|
|
// Look up the node ID of the closure body so we can construct
|
|
// a free region within it
|
|
let fn_body_id = {
|
|
let fn_expr = match self.tcx().map.find(fn_node_id) {
|
|
Some(ast_map::NodeExpr(e)) => e,
|
|
_ => unreachable!()
|
|
};
|
|
|
|
match fn_expr.node {
|
|
ast::ExprClosure(_, _, _, ref body) => body.id,
|
|
_ => unreachable!()
|
|
}
|
|
};
|
|
|
|
// Region of environment pointer
|
|
let env_region = ty::ReFree(ty::FreeRegion {
|
|
scope: region::CodeExtent::from_node_id(fn_body_id),
|
|
bound_region: ty::BrEnv
|
|
});
|
|
|
|
let env_ptr = BorrowedPtr(if env_mutbl.is_mutable() {
|
|
ty::MutBorrow
|
|
} else {
|
|
ty::ImmBorrow
|
|
}, env_region);
|
|
|
|
(env_mutbl, env_ptr)
|
|
});
|
|
|
|
// First, switch by capture mode
|
|
Ok(match mode {
|
|
ast::CaptureByValue => {
|
|
let mut base = cmt_ {
|
|
id: id,
|
|
span: span,
|
|
cat: cat_upvar(Upvar {
|
|
id: upvar_id,
|
|
kind: kind,
|
|
is_unboxed: is_unboxed
|
|
}),
|
|
mutbl: var_mutbl,
|
|
ty: var_ty,
|
|
note: NoteNone
|
|
};
|
|
|
|
match env_info {
|
|
Some((env_mutbl, env_ptr)) => {
|
|
// 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 `ty_err` in there
|
|
// instead of bothering to construct a proper
|
|
// one.
|
|
base.mutbl = McImmutable;
|
|
base.ty = ty::mk_err();
|
|
Rc::new(cmt_ {
|
|
id: id,
|
|
span: span,
|
|
cat: cat_deref(Rc::new(base), 0, env_ptr),
|
|
mutbl: env_mutbl,
|
|
ty: var_ty,
|
|
note: NoteClosureEnv(upvar_id)
|
|
})
|
|
}
|
|
None => Rc::new(base)
|
|
}
|
|
},
|
|
ast::CaptureByRef => {
|
|
// The type here is actually a ref (or ref of a ref),
|
|
// but we can again get away with not constructing one
|
|
// properly since it will never be used.
|
|
let mut base = cmt_ {
|
|
id: id,
|
|
span: span,
|
|
cat: cat_upvar(Upvar {
|
|
id: upvar_id,
|
|
kind: kind,
|
|
is_unboxed: is_unboxed
|
|
}),
|
|
mutbl: McImmutable,
|
|
ty: ty::mk_err(),
|
|
note: NoteNone
|
|
};
|
|
|
|
match env_info {
|
|
Some((env_mutbl, env_ptr)) => {
|
|
base = cmt_ {
|
|
id: id,
|
|
span: span,
|
|
cat: cat_deref(Rc::new(base), 0, env_ptr),
|
|
mutbl: env_mutbl,
|
|
ty: ty::mk_err(),
|
|
note: NoteClosureEnv(upvar_id)
|
|
};
|
|
}
|
|
None => {}
|
|
}
|
|
|
|
// Look up upvar borrow so we can get its region
|
|
let upvar_borrow = self.typer.upvar_borrow(upvar_id);
|
|
let ptr = BorrowedPtr(upvar_borrow.kind, upvar_borrow.region);
|
|
|
|
Rc::new(cmt_ {
|
|
id: id,
|
|
span: span,
|
|
cat: cat_deref(Rc::new(base), 0, ptr),
|
|
mutbl: MutabilityCategory::from_borrow_kind(upvar_borrow.kind),
|
|
ty: var_ty,
|
|
note: NoteUpvarRef(upvar_id)
|
|
})
|
|
}
|
|
})
|
|
}
|
|
|
|
pub fn cat_rvalue_node(&self,
|
|
id: ast::NodeId,
|
|
span: Span,
|
|
expr_ty: Ty<'tcx>)
|
|
-> cmt<'tcx> {
|
|
match self.typer.temporary_scope(id) {
|
|
Some(scope) => {
|
|
match expr_ty.sty {
|
|
ty::ty_vec(_, Some(0)) => self.cat_rvalue(id, span, ty::ReStatic, expr_ty),
|
|
_ => self.cat_rvalue(id, span, ty::ReScope(scope), expr_ty)
|
|
}
|
|
}
|
|
None => {
|
|
self.cat_rvalue(id, span, ty::ReStatic, expr_ty)
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn cat_rvalue(&self,
|
|
cmt_id: ast::NodeId,
|
|
span: Span,
|
|
temp_scope: ty::Region,
|
|
expr_ty: Ty<'tcx>) -> cmt<'tcx> {
|
|
Rc::new(cmt_ {
|
|
id:cmt_id,
|
|
span:span,
|
|
cat:cat_rvalue(temp_scope),
|
|
mutbl:McDeclared,
|
|
ty:expr_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
pub fn cat_field<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
f_name: ast::Name,
|
|
f_ty: Ty<'tcx>)
|
|
-> cmt<'tcx> {
|
|
Rc::new(cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
mutbl: base_cmt.mutbl.inherit(),
|
|
cat: cat_interior(base_cmt, InteriorField(NamedField(f_name))),
|
|
ty: f_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
pub fn cat_tup_field<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
f_idx: uint,
|
|
f_ty: Ty<'tcx>)
|
|
-> cmt<'tcx> {
|
|
Rc::new(cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
mutbl: base_cmt.mutbl.inherit(),
|
|
cat: cat_interior(base_cmt, InteriorField(PositionalField(f_idx))),
|
|
ty: f_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
fn cat_deref<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
deref_cnt: uint,
|
|
implicit: bool)
|
|
-> cmt<'tcx> {
|
|
let adjustment = match self.typer.adjustments().borrow().get(&node.id()) {
|
|
Some(adj) if ty::adjust_is_object(adj) => ty::AutoObject,
|
|
_ if deref_cnt != 0 => ty::AutoDeref(deref_cnt),
|
|
_ => ty::NoAdjustment
|
|
};
|
|
|
|
let method_call = ty::MethodCall {
|
|
expr_id: node.id(),
|
|
adjustment: adjustment
|
|
};
|
|
let method_ty = self.typer.node_method_ty(method_call);
|
|
|
|
debug!("cat_deref: method_call={} method_ty={}",
|
|
method_call, method_ty.map(|ty| ty.repr(self.tcx())));
|
|
|
|
let base_cmt = match method_ty {
|
|
Some(method_ty) => {
|
|
let ref_ty = ty::ty_fn_ret(method_ty).unwrap();
|
|
self.cat_rvalue_node(node.id(), node.span(), ref_ty)
|
|
}
|
|
None => base_cmt
|
|
};
|
|
match ty::deref(base_cmt.ty, true) {
|
|
Some(mt) => self.cat_deref_common(node, base_cmt, deref_cnt, mt.ty, implicit),
|
|
None => {
|
|
self.tcx().sess.span_bug(
|
|
node.span(),
|
|
format!("Explicit deref of non-derefable type: {}",
|
|
base_cmt.ty.repr(self.tcx())).as_slice());
|
|
}
|
|
}
|
|
}
|
|
|
|
fn cat_deref_common<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
deref_cnt: uint,
|
|
deref_ty: Ty<'tcx>,
|
|
implicit: bool)
|
|
-> cmt<'tcx> {
|
|
let (m, cat) = match deref_kind(self.tcx(), base_cmt.ty) {
|
|
deref_ptr(ptr) => {
|
|
let ptr = if implicit {
|
|
match ptr {
|
|
BorrowedPtr(bk, r) => Implicit(bk, r),
|
|
_ => self.tcx().sess.span_bug(node.span(),
|
|
"Implicit deref of non-borrowed pointer")
|
|
}
|
|
} else {
|
|
ptr
|
|
};
|
|
// for unique ptrs, we inherit mutability from the
|
|
// owning reference.
|
|
(MutabilityCategory::from_pointer_kind(base_cmt.mutbl, ptr),
|
|
cat_deref(base_cmt, deref_cnt, ptr))
|
|
}
|
|
deref_interior(interior) => {
|
|
(base_cmt.mutbl.inherit(), cat_interior(base_cmt, interior))
|
|
}
|
|
};
|
|
Rc::new(cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
cat: cat,
|
|
mutbl: m,
|
|
ty: deref_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
pub fn cat_index<N:ast_node>(&self,
|
|
elt: &N,
|
|
mut base_cmt: cmt<'tcx>)
|
|
-> 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 method_call = ty::MethodCall::expr(elt.id());
|
|
let method_ty = self.typer.node_method_ty(method_call);
|
|
|
|
let element_ty = match method_ty {
|
|
Some(method_ty) => {
|
|
let ref_ty = ty::ty_fn_ret(method_ty).unwrap();
|
|
base_cmt = self.cat_rvalue_node(elt.id(), elt.span(), ref_ty);
|
|
ty::ty_fn_args(method_ty)[0]
|
|
}
|
|
None => {
|
|
match ty::array_element_ty(base_cmt.ty) {
|
|
Some(ty) => ty,
|
|
None => {
|
|
self.tcx().sess.span_bug(
|
|
elt.span(),
|
|
format!("Explicit index of non-index type `{}`",
|
|
base_cmt.ty.repr(self.tcx())).as_slice());
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
let m = base_cmt.mutbl.inherit();
|
|
return interior(elt, base_cmt.clone(), base_cmt.ty, m, element_ty);
|
|
|
|
fn interior<'tcx, N: ast_node>(elt: &N,
|
|
of_cmt: cmt<'tcx>,
|
|
vec_ty: Ty<'tcx>,
|
|
mutbl: MutabilityCategory,
|
|
element_ty: Ty<'tcx>) -> cmt<'tcx>
|
|
{
|
|
Rc::new(cmt_ {
|
|
id:elt.id(),
|
|
span:elt.span(),
|
|
cat:cat_interior(of_cmt, InteriorElement(element_kind(vec_ty))),
|
|
mutbl:mutbl,
|
|
ty:element_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
}
|
|
|
|
// Takes either a vec or a reference to a vec and returns the cmt for the
|
|
// underlying vec.
|
|
fn deref_vec<N:ast_node>(&self,
|
|
elt: &N,
|
|
base_cmt: cmt<'tcx>)
|
|
-> cmt<'tcx> {
|
|
match deref_kind(self.tcx(), base_cmt.ty) {
|
|
deref_ptr(ptr) => {
|
|
// for unique ptrs, we inherit mutability from the
|
|
// owning reference.
|
|
let m = MutabilityCategory::from_pointer_kind(base_cmt.mutbl, ptr);
|
|
|
|
// the deref is explicit in the resulting cmt
|
|
Rc::new(cmt_ {
|
|
id:elt.id(),
|
|
span:elt.span(),
|
|
cat:cat_deref(base_cmt.clone(), 0, ptr),
|
|
mutbl:m,
|
|
ty: match ty::deref(base_cmt.ty, false) {
|
|
Some(mt) => mt.ty,
|
|
None => self.tcx().sess.bug("Found non-derefable type")
|
|
},
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
deref_interior(_) => {
|
|
base_cmt
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Given a pattern P like: `[_, ..Q, _]`, where `vec_cmt` is the cmt for `P`, `slice_pat` is
|
|
/// the pattern `Q`, returns:
|
|
///
|
|
/// * a cmt for `Q`
|
|
/// * the mutability and region of the slice `Q`
|
|
///
|
|
/// These last two bits of info happen to be things that borrowck needs.
|
|
pub fn cat_slice_pattern(&self,
|
|
vec_cmt: cmt<'tcx>,
|
|
slice_pat: &ast::Pat)
|
|
-> McResult<(cmt<'tcx>, ast::Mutability, ty::Region)> {
|
|
let slice_ty = if_ok!(self.node_ty(slice_pat.id));
|
|
let (slice_mutbl, slice_r) = vec_slice_info(self.tcx(),
|
|
slice_pat,
|
|
slice_ty);
|
|
let cmt_slice = self.cat_index(slice_pat, self.deref_vec(slice_pat, vec_cmt));
|
|
return Ok((cmt_slice, slice_mutbl, slice_r));
|
|
|
|
/// In a pattern like [a, b, ..c], normally `c` has slice type, but if you have [a, b,
|
|
/// ..ref c], then the type of `ref c` will be `&&[]`, so to extract the slice details we
|
|
/// have to recurse through rptrs.
|
|
fn vec_slice_info(tcx: &ty::ctxt,
|
|
pat: &ast::Pat,
|
|
slice_ty: Ty)
|
|
-> (ast::Mutability, ty::Region) {
|
|
match slice_ty.sty {
|
|
ty::ty_rptr(r, ref mt) => match mt.ty.sty {
|
|
ty::ty_vec(_, None) => (mt.mutbl, r),
|
|
_ => vec_slice_info(tcx, pat, mt.ty),
|
|
},
|
|
|
|
_ => {
|
|
tcx.sess.span_bug(pat.span,
|
|
"type of slice pattern is not a slice");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn cat_imm_interior<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
interior_ty: Ty<'tcx>,
|
|
interior: InteriorKind)
|
|
-> cmt<'tcx> {
|
|
Rc::new(cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
mutbl: base_cmt.mutbl.inherit(),
|
|
cat: cat_interior(base_cmt, interior),
|
|
ty: interior_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
pub fn cat_downcast<N:ast_node>(&self,
|
|
node: &N,
|
|
base_cmt: cmt<'tcx>,
|
|
downcast_ty: Ty<'tcx>,
|
|
variant_did: ast::DefId)
|
|
-> cmt<'tcx> {
|
|
Rc::new(cmt_ {
|
|
id: node.id(),
|
|
span: node.span(),
|
|
mutbl: base_cmt.mutbl.inherit(),
|
|
cat: cat_downcast(base_cmt, variant_did),
|
|
ty: downcast_ty,
|
|
note: NoteNone
|
|
})
|
|
}
|
|
|
|
// FIXME(#19596) unbox `op`
|
|
pub fn cat_pattern(&self,
|
|
cmt: cmt<'tcx>,
|
|
pat: &ast::Pat,
|
|
op: |&MemCategorizationContext<'t, TYPER>, cmt<'tcx>, &ast::Pat|)
|
|
-> McResult<()> {
|
|
// 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: id={} pat={} cmt={}",
|
|
pat.id, pprust::pat_to_string(pat),
|
|
cmt.repr(self.tcx()));
|
|
|
|
op(self, cmt.clone(), pat);
|
|
|
|
let def_map = self.tcx().def_map.borrow();
|
|
let opt_def = def_map.get(&pat.id);
|
|
|
|
// Note: This goes up here (rather than within the PatEnum arm
|
|
// alone) because struct patterns can refer to struct types or
|
|
// to struct variants within enums.
|
|
let cmt = match opt_def {
|
|
Some(&def::DefVariant(enum_did, variant_did, _))
|
|
// univariant enums do not need downcasts
|
|
if !ty::enum_is_univariant(self.tcx(), enum_did) => {
|
|
self.cat_downcast(pat, cmt.clone(), cmt.ty, variant_did)
|
|
}
|
|
_ => cmt
|
|
};
|
|
|
|
match pat.node {
|
|
ast::PatWild(_) => {
|
|
// _
|
|
}
|
|
|
|
ast::PatEnum(_, None) => {
|
|
// variant(..)
|
|
}
|
|
ast::PatEnum(_, Some(ref subpats)) => {
|
|
match opt_def {
|
|
Some(&def::DefVariant(..)) => {
|
|
// variant(x, y, z)
|
|
for (i, subpat) in subpats.iter().enumerate() {
|
|
let subpat_ty = if_ok!(self.pat_ty(&**subpat)); // see (*2)
|
|
|
|
let subcmt =
|
|
self.cat_imm_interior(
|
|
pat, cmt.clone(), subpat_ty,
|
|
InteriorField(PositionalField(i)));
|
|
|
|
if_ok!(self.cat_pattern(subcmt, &**subpat, |x,y,z| op(x,y,z)));
|
|
}
|
|
}
|
|
Some(&def::DefStruct(..)) => {
|
|
for (i, subpat) in subpats.iter().enumerate() {
|
|
let subpat_ty = if_ok!(self.pat_ty(&**subpat)); // see (*2)
|
|
let cmt_field =
|
|
self.cat_imm_interior(
|
|
pat, cmt.clone(), subpat_ty,
|
|
InteriorField(PositionalField(i)));
|
|
if_ok!(self.cat_pattern(cmt_field, &**subpat,
|
|
|x,y,z| op(x,y,z)));
|
|
}
|
|
}
|
|
Some(&def::DefConst(..)) => {
|
|
for subpat in subpats.iter() {
|
|
if_ok!(self.cat_pattern(cmt.clone(), &**subpat, |x,y,z| op(x,y,z)));
|
|
}
|
|
}
|
|
_ => {
|
|
self.tcx().sess.span_bug(
|
|
pat.span,
|
|
"enum pattern didn't resolve to enum or struct");
|
|
}
|
|
}
|
|
}
|
|
|
|
ast::PatIdent(_, _, Some(ref subpat)) => {
|
|
if_ok!(self.cat_pattern(cmt, &**subpat, op));
|
|
}
|
|
|
|
ast::PatIdent(_, _, None) => {
|
|
// nullary variant or identifier: ignore
|
|
}
|
|
|
|
ast::PatStruct(_, ref field_pats, _) => {
|
|
// {f1: p1, ..., fN: pN}
|
|
for fp in field_pats.iter() {
|
|
let field_ty = if_ok!(self.pat_ty(&*fp.node.pat)); // see (*2)
|
|
let cmt_field = self.cat_field(pat, cmt.clone(), fp.node.ident.name, field_ty);
|
|
if_ok!(self.cat_pattern(cmt_field, &*fp.node.pat, |x,y,z| op(x,y,z)));
|
|
}
|
|
}
|
|
|
|
ast::PatTup(ref subpats) => {
|
|
// (p1, ..., pN)
|
|
for (i, subpat) in subpats.iter().enumerate() {
|
|
let subpat_ty = if_ok!(self.pat_ty(&**subpat)); // see (*2)
|
|
let subcmt =
|
|
self.cat_imm_interior(
|
|
pat, cmt.clone(), subpat_ty,
|
|
InteriorField(PositionalField(i)));
|
|
if_ok!(self.cat_pattern(subcmt, &**subpat, |x,y,z| op(x,y,z)));
|
|
}
|
|
}
|
|
|
|
ast::PatBox(ref subpat) | ast::PatRegion(ref subpat) => {
|
|
// @p1, ~p1, ref p1
|
|
let subcmt = self.cat_deref(pat, cmt, 0, false);
|
|
if_ok!(self.cat_pattern(subcmt, &**subpat, op));
|
|
}
|
|
|
|
ast::PatVec(ref before, ref slice, ref after) => {
|
|
let elt_cmt = self.cat_index(pat, self.deref_vec(pat, cmt));
|
|
for before_pat in before.iter() {
|
|
if_ok!(self.cat_pattern(elt_cmt.clone(), &**before_pat,
|
|
|x,y,z| op(x,y,z)));
|
|
}
|
|
for slice_pat in slice.iter() {
|
|
let slice_ty = if_ok!(self.pat_ty(&**slice_pat));
|
|
let slice_cmt = self.cat_rvalue_node(pat.id(), pat.span(), slice_ty);
|
|
if_ok!(self.cat_pattern(slice_cmt, &**slice_pat, |x,y,z| op(x,y,z)));
|
|
}
|
|
for after_pat in after.iter() {
|
|
if_ok!(self.cat_pattern(elt_cmt.clone(), &**after_pat, |x,y,z| op(x,y,z)));
|
|
}
|
|
}
|
|
|
|
ast::PatLit(_) | ast::PatRange(_, _) => {
|
|
/*always ok*/
|
|
}
|
|
|
|
ast::PatMac(_) => {
|
|
self.tcx().sess.span_bug(pat.span, "unexpanded macro");
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
pub fn cmt_to_string(&self, cmt: &cmt_<'tcx>) -> String {
|
|
fn upvar_to_string(upvar: &Upvar, is_copy: bool) -> String {
|
|
if upvar.is_unboxed {
|
|
let kind = match upvar.kind {
|
|
ty::FnUnboxedClosureKind => "Fn",
|
|
ty::FnMutUnboxedClosureKind => "FnMut",
|
|
ty::FnOnceUnboxedClosureKind => "FnOnce"
|
|
};
|
|
format!("captured outer variable in an `{}` closure", kind)
|
|
} else {
|
|
(match (upvar.kind, is_copy) {
|
|
(ty::FnOnceUnboxedClosureKind, true) => "captured outer variable in a proc",
|
|
_ => "captured outer variable"
|
|
}).to_string()
|
|
}
|
|
}
|
|
|
|
match cmt.cat {
|
|
cat_static_item => {
|
|
"static item".to_string()
|
|
}
|
|
cat_rvalue(..) => {
|
|
"non-lvalue".to_string()
|
|
}
|
|
cat_local(vid) => {
|
|
match self.tcx().map.find(vid) {
|
|
Some(ast_map::NodeArg(_)) => {
|
|
"argument".to_string()
|
|
}
|
|
_ => "local variable".to_string()
|
|
}
|
|
}
|
|
cat_deref(_, _, pk) => {
|
|
let upvar = cmt.upvar();
|
|
match upvar.as_ref().map(|i| &i.cat) {
|
|
Some(&cat_upvar(ref var)) => {
|
|
upvar_to_string(var, false)
|
|
}
|
|
Some(_) => unreachable!(),
|
|
None => {
|
|
match pk {
|
|
Implicit(..) => {
|
|
"dereference (dereference is implicit, due to indexing)".to_string()
|
|
}
|
|
OwnedPtr => format!("dereference of `{}`", ptr_sigil(pk)),
|
|
_ => format!("dereference of `{}`-pointer", ptr_sigil(pk))
|
|
}
|
|
}
|
|
}
|
|
}
|
|
cat_interior(_, InteriorField(NamedField(_))) => {
|
|
"field".to_string()
|
|
}
|
|
cat_interior(_, InteriorField(PositionalField(_))) => {
|
|
"anonymous field".to_string()
|
|
}
|
|
cat_interior(_, InteriorElement(VecElement)) => {
|
|
"vec content".to_string()
|
|
}
|
|
cat_interior(_, InteriorElement(OtherElement)) => {
|
|
"indexed content".to_string()
|
|
}
|
|
cat_upvar(ref var) => {
|
|
upvar_to_string(var, true)
|
|
}
|
|
cat_downcast(ref cmt, _) => {
|
|
self.cmt_to_string(&**cmt)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub enum InteriorSafety {
|
|
InteriorUnsafe,
|
|
InteriorSafe
|
|
}
|
|
|
|
impl Copy for InteriorSafety {}
|
|
|
|
pub enum AliasableReason {
|
|
AliasableBorrowed,
|
|
AliasableClosure(ast::NodeId), // Aliasable due to capture Fn closure env
|
|
AliasableOther,
|
|
AliasableStatic(InteriorSafety),
|
|
AliasableStaticMut(InteriorSafety),
|
|
}
|
|
|
|
impl Copy for AliasableReason {}
|
|
|
|
impl<'tcx> cmt_<'tcx> {
|
|
pub fn guarantor(&self) -> cmt<'tcx> {
|
|
//! Returns `self` after stripping away any owned pointer derefs or
|
|
//! interior content. The return value is basically the `cmt` which
|
|
//! determines how long the value in `self` remains live.
|
|
|
|
match self.cat {
|
|
cat_rvalue(..) |
|
|
cat_static_item |
|
|
cat_local(..) |
|
|
cat_deref(_, _, UnsafePtr(..)) |
|
|
cat_deref(_, _, BorrowedPtr(..)) |
|
|
cat_deref(_, _, Implicit(..)) |
|
|
cat_upvar(..) => {
|
|
Rc::new((*self).clone())
|
|
}
|
|
cat_downcast(ref b, _) |
|
|
cat_interior(ref b, _) |
|
|
cat_deref(ref b, _, OwnedPtr) => {
|
|
b.guarantor()
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns `Some(_)` if this lvalue represents a freely aliasable pointer type.
|
|
pub fn freely_aliasable(&self, ctxt: &ty::ctxt<'tcx>)
|
|
-> Option<AliasableReason> {
|
|
// 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 {
|
|
cat_deref(ref b, _, BorrowedPtr(ty::MutBorrow, _)) |
|
|
cat_deref(ref b, _, Implicit(ty::MutBorrow, _)) |
|
|
cat_deref(ref b, _, BorrowedPtr(ty::UniqueImmBorrow, _)) |
|
|
cat_deref(ref b, _, Implicit(ty::UniqueImmBorrow, _)) |
|
|
cat_downcast(ref b, _) |
|
|
cat_deref(ref b, _, OwnedPtr) |
|
|
cat_interior(ref b, _) => {
|
|
// Aliasability depends on base cmt
|
|
b.freely_aliasable(ctxt)
|
|
}
|
|
|
|
cat_rvalue(..) |
|
|
cat_local(..) |
|
|
cat_upvar(..) |
|
|
cat_deref(_, _, UnsafePtr(..)) => { // yes, it's aliasable, but...
|
|
None
|
|
}
|
|
|
|
cat_static_item(..) => {
|
|
let int_safe = if ty::type_interior_is_unsafe(ctxt, self.ty) {
|
|
InteriorUnsafe
|
|
} else {
|
|
InteriorSafe
|
|
};
|
|
|
|
if self.mutbl.is_mutable() {
|
|
Some(AliasableStaticMut(int_safe))
|
|
} else {
|
|
Some(AliasableStatic(int_safe))
|
|
}
|
|
}
|
|
|
|
cat_deref(ref base, _, BorrowedPtr(ty::ImmBorrow, _)) |
|
|
cat_deref(ref base, _, Implicit(ty::ImmBorrow, _)) => {
|
|
match base.cat {
|
|
cat_upvar(Upvar{ id, .. }) => Some(AliasableClosure(id.closure_expr_id)),
|
|
_ => Some(AliasableBorrowed)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Digs down through one or two layers of deref and grabs the cmt
|
|
// for the upvar if a note indicates there is one.
|
|
pub fn upvar(&self) -> Option<cmt<'tcx>> {
|
|
match self.note {
|
|
NoteClosureEnv(..) | NoteUpvarRef(..) => {
|
|
Some(match self.cat {
|
|
cat_deref(ref inner, _, _) => {
|
|
match inner.cat {
|
|
cat_deref(ref inner, _, _) => inner.clone(),
|
|
cat_upvar(..) => inner.clone(),
|
|
_ => unreachable!()
|
|
}
|
|
}
|
|
_ => unreachable!()
|
|
})
|
|
}
|
|
NoteNone => None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Repr<'tcx> for cmt_<'tcx> {
|
|
fn repr(&self, tcx: &ty::ctxt<'tcx>) -> String {
|
|
format!("{{{} id:{} m:{} ty:{}}}",
|
|
self.cat.repr(tcx),
|
|
self.id,
|
|
self.mutbl,
|
|
self.ty.repr(tcx))
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Repr<'tcx> for categorization<'tcx> {
|
|
fn repr(&self, tcx: &ty::ctxt<'tcx>) -> String {
|
|
match *self {
|
|
cat_static_item |
|
|
cat_rvalue(..) |
|
|
cat_local(..) |
|
|
cat_upvar(..) => {
|
|
format!("{}", *self)
|
|
}
|
|
cat_deref(ref cmt, derefs, ptr) => {
|
|
format!("{}-{}{}->", cmt.cat.repr(tcx), ptr_sigil(ptr), derefs)
|
|
}
|
|
cat_interior(ref cmt, interior) => {
|
|
format!("{}.{}", cmt.cat.repr(tcx), interior.repr(tcx))
|
|
}
|
|
cat_downcast(ref cmt, _) => {
|
|
format!("{}->(enum)", cmt.cat.repr(tcx))
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn ptr_sigil(ptr: PointerKind) -> &'static str {
|
|
match ptr {
|
|
OwnedPtr => "Box",
|
|
BorrowedPtr(ty::ImmBorrow, _) |
|
|
Implicit(ty::ImmBorrow, _) => "&",
|
|
BorrowedPtr(ty::MutBorrow, _) |
|
|
Implicit(ty::MutBorrow, _) => "&mut",
|
|
BorrowedPtr(ty::UniqueImmBorrow, _) |
|
|
Implicit(ty::UniqueImmBorrow, _) => "&unique",
|
|
UnsafePtr(_) => "*"
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Repr<'tcx> for InteriorKind {
|
|
fn repr(&self, _tcx: &ty::ctxt) -> String {
|
|
match *self {
|
|
InteriorField(NamedField(fld)) => {
|
|
token::get_name(fld).get().to_string()
|
|
}
|
|
InteriorField(PositionalField(i)) => format!("#{}", i),
|
|
InteriorElement(_) => "[]".to_string(),
|
|
}
|
|
}
|
|
}
|
|
|
|
fn element_kind(t: Ty) -> ElementKind {
|
|
match t.sty {
|
|
ty::ty_rptr(_, ty::mt{ty, ..}) |
|
|
ty::ty_uniq(ty) => match ty.sty {
|
|
ty::ty_vec(_, None) => VecElement,
|
|
_ => OtherElement
|
|
},
|
|
ty::ty_vec(..) => VecElement,
|
|
_ => OtherElement
|
|
}
|
|
}
|