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//! # Categorization
//!
//! The job of the categorization module is to analyze an expression to
//! determine what kind of memory is used in evaluating it (for example,
//! where dereferences occur and what kind of pointer is dereferenced;
//! whether the memory is mutable, etc.).
//!
//! Categorization effectively transforms all of our expressions into
//! expressions of the following forms (the actual enum has many more
//! possibilities, naturally, but they are all variants of these base
//! forms):
//!
//! E = rvalue // some computed rvalue
//! | x // address of a local variable or argument
//! | *E // deref of a ptr
//! | E.comp // access to an interior component
//!
//! Imagine a routine ToAddr(Expr) that evaluates an expression and returns an
//! address where the result is to be found. If Expr is a place, then this
//! is the address of the place. If `Expr` is an rvalue, this is the address of
//! some temporary spot in memory where the result is stored.
//!
//! Now, `cat_expr()` classifies the expression `Expr` and the address `A = ToAddr(Expr)`
//! as follows:
//!
//! - `cat`: what kind of expression was this? This is a subset of the
//! full expression forms which only includes those that we care about
//! for the purpose of the analysis.
//! - `mutbl`: mutability of the address `A`.
//! - `ty`: the type of data found at the address `A`.
//!
//! The resulting categorization tree differs somewhat from the expressions
//! themselves. For example, auto-derefs are explicit. Also, an index a[b] is
//! decomposed into two operations: a dereference to reach the array data and
//! then an index to jump forward to the relevant item.
//!
//! ## By-reference upvars
//!
//! One part of the codegen which may be non-obvious is that we translate
//! closure upvars into the dereference of a borrowed pointer; this more closely
//! resembles the runtime codegen. So, for example, if we had:
//!
//! let mut x = 3;
//! let y = 5;
//! let inc = || x += y;
//!
//! Then when we categorize `x` (*within* the closure) we would yield a
//! result of `*x'`, effectively, where `x'` is a `Categorization::Upvar` reference
//! tied to `x`. The type of `x'` will be a borrowed pointer.
#![allow(non_camel_case_types)]
pub use self::PointerKind::*;
pub use self::InteriorKind::*;
pub use self::MutabilityCategory::*;
pub use self::AliasableReason::*;
pub use self::Note::*;
use self::Aliasability::*;
use crate::middle::region;
use crate::hir::def_id::{DefId, LocalDefId};
use crate::hir::Node;
use crate::infer::InferCtxt;
use crate::hir::def::{CtorOf, Res, DefKind, CtorKind};
use crate::ty::adjustment;
use crate::ty::{self, DefIdTree, Ty, TyCtxt};
use crate::ty::fold::TypeFoldable;
use crate::hir::{MutImmutable, MutMutable, PatKind};
use crate::hir::pat_util::EnumerateAndAdjustIterator;
use crate::hir;
use syntax::ast::{self, Name};
use syntax::symbol::sym;
use syntax_pos::Span;
use std::borrow::Cow;
use std::fmt;
use std::hash::{Hash, Hasher};
use rustc_data_structures::fx::FxIndexMap;
use std::rc::Rc;
use crate::util::nodemap::ItemLocalSet;
#[derive(Clone, Debug, PartialEq)]
pub enum Categorization<'tcx> {
Rvalue(ty::Region<'tcx>), // temporary val, argument is its scope
ThreadLocal(ty::Region<'tcx>), // value that cannot move, but still restricted in scope
StaticItem,
Upvar(Upvar), // upvar referenced by closure env
Local(hir::HirId), // local variable
Deref(cmt<'tcx>, PointerKind<'tcx>), // deref of a ptr
Interior(cmt<'tcx>, InteriorKind), // something interior: field, tuple, etc
Downcast(cmt<'tcx>, DefId), // selects a particular enum variant (*1)
// (*1) downcast is only required if the enum has more than one variant
}
// Represents any kind of upvar
#[derive(Clone, Copy, PartialEq)]
pub struct Upvar {
pub id: ty::UpvarId,
pub kind: ty::ClosureKind
}
// different kinds of pointers:
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub enum PointerKind<'tcx> {
/// `Box<T>`
Unique,
/// `&T`
BorrowedPtr(ty::BorrowKind, ty::Region<'tcx>),
/// `*T`
UnsafePtr(hir::Mutability),
}
// We use the term "interior" to mean "something reachable from the
// base without a pointer dereference", e.g., a field
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub enum InteriorKind {
InteriorField(FieldIndex),
InteriorElement(InteriorOffsetKind),
}
// Contains index of a field that is actually used for loan path comparisons and
// string representation of the field that should be used only for diagnostics.
#[derive(Clone, Copy, Eq)]
pub struct FieldIndex(pub usize, pub Name);
impl PartialEq for FieldIndex {
fn eq(&self, rhs: &Self) -> bool {
self.0 == rhs.0
}
}
impl Hash for FieldIndex {
fn hash<H: Hasher>(&self, h: &mut H) {
self.0.hash(h)
}
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
pub enum InteriorOffsetKind {
Index, // e.g., `array_expr[index_expr]`
Pattern, // e.g., `fn foo([_, a, _, _]: [A; 4]) { ... }`
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
pub enum MutabilityCategory {
McImmutable, // Immutable.
McDeclared, // Directly declared as mutable.
McInherited, // Inherited from the fact that owner is mutable.
}
// A note about the provenance of a `cmt`. This is used for
// special-case handling of upvars such as mutability inference.
// Upvar categorization can generate a variable number of nested
// derefs. The note allows detecting them without deep pattern
// matching on the categorization.
#[derive(Clone, Copy, PartialEq, Debug)]
pub enum Note {
NoteClosureEnv(ty::UpvarId), // Deref through closure env
NoteUpvarRef(ty::UpvarId), // Deref through by-ref upvar
NoteIndex, // Deref as part of desugaring `x[]` into its two components
NoteNone // Nothing special
}
// `cmt`: "Category, Mutability, and Type".
//
// a complete categorization of a value indicating where it originated
// and how it is located, as well as the mutability of the memory in
// which the value is stored.
//
// *WARNING* The field `cmt.type` is NOT necessarily the same as the
// result of `node_type(cmt.id)`.
//
// (FIXME: rewrite the following comment given that `@x` managed
// pointers have been obsolete for quite some time.)
//
// This is because the `id` is always the `id` of the node producing the
// type; in an expression like `*x`, the type of this deref node is the
// deref'd type (`T`), but in a pattern like `@x`, the `@x` pattern is
// again a dereference, but its type is the type *before* the
// dereference (`@T`). So use `cmt.ty` to find the type of the value in
// a consistent fashion. For more details, see the method `cat_pattern`
#[derive(Clone, Debug, PartialEq)]
pub struct cmt_<'tcx> {
pub hir_id: hir::HirId, // HIR id of expr/pat producing this value
pub span: Span, // span of same expr/pat
pub cat: Categorization<'tcx>, // categorization of expr
pub mutbl: MutabilityCategory, // mutability of expr as place
pub ty: Ty<'tcx>, // type of the expr (*see WARNING above*)
pub note: Note, // Note about the provenance of this cmt
}
pub type cmt<'tcx> = Rc<cmt_<'tcx>>;
pub trait HirNode {
fn hir_id(&self) -> hir::HirId;
fn span(&self) -> Span;
}
impl HirNode for hir::Expr {
fn hir_id(&self) -> hir::HirId { self.hir_id }
fn span(&self) -> Span { self.span }
}
impl HirNode for hir::Pat {
fn hir_id(&self) -> hir::HirId { self.hir_id }
fn span(&self) -> Span { self.span }
}
#[derive(Clone)]
pub struct MemCategorizationContext<'a, 'tcx> {
pub tcx: TyCtxt<'tcx>,
pub body_owner: DefId,
pub upvars: Option<&'tcx FxIndexMap<hir::HirId, hir::Upvar>>,
pub region_scope_tree: &'a region::ScopeTree,
pub tables: &'a ty::TypeckTables<'tcx>,
rvalue_promotable_map: Option<&'tcx ItemLocalSet>,
infcx: Option<&'a InferCtxt<'a, 'tcx>>,
}
pub type McResult<T> = Result<T, ()>;
impl MutabilityCategory {
pub fn from_mutbl(m: hir::Mutability) -> MutabilityCategory {
let ret = match m {
MutImmutable => McImmutable,
MutMutable => McDeclared
};
debug!("MutabilityCategory::{}({:?}) => {:?}",
"from_mutbl", m, ret);
ret
}
pub fn from_borrow_kind(borrow_kind: ty::BorrowKind) -> MutabilityCategory {
let ret = match borrow_kind {
ty::ImmBorrow => McImmutable,
ty::UniqueImmBorrow => McImmutable,
ty::MutBorrow => McDeclared,
};
debug!("MutabilityCategory::{}({:?}) => {:?}",
"from_borrow_kind", borrow_kind, ret);
ret
}
fn from_pointer_kind(base_mutbl: MutabilityCategory,
ptr: PointerKind<'_>) -> MutabilityCategory {
let ret = match ptr {
Unique => {
base_mutbl.inherit()
}
BorrowedPtr(borrow_kind, _) => {
MutabilityCategory::from_borrow_kind(borrow_kind)
}
UnsafePtr(m) => {
MutabilityCategory::from_mutbl(m)
}
};
debug!("MutabilityCategory::{}({:?}, {:?}) => {:?}",
"from_pointer_kind", base_mutbl, ptr, ret);
ret
}
fn from_local(
tcx: TyCtxt<'_>,
tables: &ty::TypeckTables<'_>,
id: hir::HirId,
) -> MutabilityCategory {
let ret = match tcx.hir().get(id) {
Node::Binding(p) => match p.node {
PatKind::Binding(..) => {
let bm = *tables.pat_binding_modes()
.get(p.hir_id)
.expect("missing binding mode");
if bm == ty::BindByValue(hir::MutMutable) {
McDeclared
} else {
McImmutable
}
}
_ => span_bug!(p.span, "expected identifier pattern")
},
_ => span_bug!(tcx.hir().span(id), "expected identifier pattern")
};
debug!("MutabilityCategory::{}(tcx, id={:?}) => {:?}",
"from_local", id, ret);
ret
}
pub fn inherit(&self) -> MutabilityCategory {
let ret = match *self {
McImmutable => McImmutable,
McDeclared => McInherited,
McInherited => McInherited,
};
debug!("{:?}.inherit() => {:?}", self, ret);
ret
}
pub fn is_mutable(&self) -> bool {
let ret = match *self {
McImmutable => false,
McInherited => true,
McDeclared => true,
};
debug!("{:?}.is_mutable() => {:?}", self, ret);
ret
}
pub fn is_immutable(&self) -> bool {
let ret = match *self {
McImmutable => true,
McDeclared | McInherited => false
};
debug!("{:?}.is_immutable() => {:?}", self, ret);
ret
}
pub fn to_user_str(&self) -> &'static str {
match *self {
McDeclared | McInherited => "mutable",
McImmutable => "immutable",
}
}
}
impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
pub fn new(
tcx: TyCtxt<'tcx>,
body_owner: DefId,
region_scope_tree: &'a region::ScopeTree,
tables: &'a ty::TypeckTables<'tcx>,
rvalue_promotable_map: Option<&'tcx ItemLocalSet>,
) -> MemCategorizationContext<'a, 'tcx> {
MemCategorizationContext {
tcx,
body_owner,
upvars: tcx.upvars(body_owner),
region_scope_tree,
tables,
rvalue_promotable_map,
infcx: None
}
}
}
impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
/// Creates a `MemCategorizationContext` during type inference.
/// This is used during upvar analysis and a few other places.
/// Because the typeck tables are not yet complete, the results
/// from the analysis must be used with caution:
///
/// - rvalue promotions are not known, so the lifetimes of
/// temporaries may be overly conservative;
/// - similarly, as the results of upvar analysis are not yet
/// known, the results around upvar accesses may be incorrect.
pub fn with_infer(
infcx: &'a InferCtxt<'a, 'tcx>,
body_owner: DefId,
region_scope_tree: &'a region::ScopeTree,
tables: &'a ty::TypeckTables<'tcx>,
) -> MemCategorizationContext<'a, 'tcx> {
let tcx = infcx.tcx;
// Subtle: we can't do rvalue promotion analysis until the
// typeck phase is complete, which means that you can't trust
// the rvalue lifetimes that result, but that's ok, since we
// don't need to know those during type inference.
let rvalue_promotable_map = None;
MemCategorizationContext {
tcx,
body_owner,
upvars: tcx.upvars(body_owner),
region_scope_tree,
tables,
rvalue_promotable_map,
infcx: Some(infcx),
}
}
pub fn type_is_copy_modulo_regions(
&self,
param_env: ty::ParamEnv<'tcx>,
ty: Ty<'tcx>,
span: Span,
) -> bool {
self.infcx.map(|infcx| infcx.type_is_copy_modulo_regions(param_env, ty, span))
.or_else(|| {
if (param_env, ty).has_local_value() {
None
} else {
Some(ty.is_copy_modulo_regions(self.tcx, param_env, span))
}
})
.unwrap_or(true)
}
fn resolve_vars_if_possible<T>(&self, value: &T) -> T
where T: TypeFoldable<'tcx>
{
self.infcx.map(|infcx| infcx.resolve_vars_if_possible(value))
.unwrap_or_else(|| value.clone())
}
fn is_tainted_by_errors(&self) -> bool {
self.infcx.map_or(false, |infcx| infcx.is_tainted_by_errors())
}
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_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 => {
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_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>).
pub fn pat_ty_adjusted(&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, 'tcx>(
mc: &MemCategorizationContext<'a, '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_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.hir_id, expr.span, ref_ty)
} else {
previous()?
});
self.cat_deref(expr, base, NoteNone)
}
adjustment::Adjust::NeverToAny |
adjustment::Adjust::Pointer(_) |
adjustment::Adjust::Borrow(_) => {
// Result is an rvalue.
Ok(self.cat_rvalue_node(expr.hir_id, expr.span, target))
}
}
}
pub fn cat_expr_unadjusted(&self, expr: &hir::Expr) -> McResult<cmt_<'tcx>> {
debug!("cat_expr: id={} expr={:?}", expr.hir_id, expr);
let expr_ty = self.expr_ty(expr)?;
match expr.node {
hir::ExprKind::Unary(hir::UnDeref, ref e_base) => {
if self.tables.is_method_call(expr) {
self.cat_overloaded_place(expr, e_base, NoteNone)
} else {
let base_cmt = Rc::new(self.cat_expr(&e_base)?);
self.cat_deref(expr, base_cmt, NoteNone)
}
}
hir::ExprKind::Field(ref base, f_ident) => {
let base_cmt = Rc::new(self.cat_expr(&base)?);
debug!("cat_expr(cat_field): id={} expr={:?} base={:?}",
expr.hir_id,
expr,
base_cmt);
let f_index = self.tcx.field_index(expr.hir_id, self.tables);
Ok(self.cat_field(expr, base_cmt, f_index, f_ident, expr_ty))
}
hir::ExprKind::Index(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, NoteIndex)
} else {
let base_cmt = Rc::new(self.cat_expr(&base)?);
self.cat_index(expr, base_cmt, expr_ty, InteriorOffsetKind::Index)
}
}
hir::ExprKind::Path(ref qpath) => {
let res = self.tables.qpath_res(qpath, expr.hir_id);
self.cat_res(expr.hir_id, expr.span, expr_ty, res)
}
hir::ExprKind::Type(ref e, _) => {
self.cat_expr(&e)
}
hir::ExprKind::AddrOf(..) | hir::ExprKind::Call(..) |
hir::ExprKind::Assign(..) | hir::ExprKind::AssignOp(..) |
hir::ExprKind::Closure(..) | hir::ExprKind::Ret(..) |
hir::ExprKind::Unary(..) | hir::ExprKind::Yield(..) |
hir::ExprKind::MethodCall(..) | hir::ExprKind::Cast(..) | hir::ExprKind::DropTemps(..) |
hir::ExprKind::Array(..) | hir::ExprKind::Tup(..) |
hir::ExprKind::Binary(..) |
hir::ExprKind::Block(..) | hir::ExprKind::Loop(..) | hir::ExprKind::Match(..) |
hir::ExprKind::Lit(..) | hir::ExprKind::Break(..) |
hir::ExprKind::Continue(..) | hir::ExprKind::Struct(..) | hir::ExprKind::Repeat(..) |
hir::ExprKind::InlineAsm(..) | hir::ExprKind::Box(..) | hir::ExprKind::Err => {
Ok(self.cat_rvalue_node(expr.hir_id, expr.span, expr_ty))
}
}
}
pub fn cat_res(&self,
hir_id: hir::HirId,
span: Span,
expr_ty: Ty<'tcx>,
res: Res)
-> McResult<cmt_<'tcx>> {
debug!("cat_res: id={:?} expr={:?} def={:?}",
hir_id, expr_ty, res);
match res {
Res::Def(DefKind::Ctor(..), _)
| Res::Def(DefKind::Const, _)
| Res::Def(DefKind::ConstParam, _)
| Res::Def(DefKind::AssocConst, _)
| Res::Def(DefKind::Fn, _)
| Res::Def(DefKind::Method, _)
| Res::SelfCtor(..) => {
Ok(self.cat_rvalue_node(hir_id, span, expr_ty))
}
Res::Def(DefKind::Static, def_id) => {
// `#[thread_local]` statics may not outlive the current function, but
// they also cannot be moved out of.
let is_thread_local = self.tcx.get_attrs(def_id)[..]
.iter()
.any(|attr| attr.check_name(sym::thread_local));
let cat = if is_thread_local {
let re = self.temporary_scope(hir_id.local_id);
Categorization::ThreadLocal(re)
} else {
Categorization::StaticItem
};
Ok(cmt_ {
hir_id,
span,
cat,
mutbl: match self.tcx.static_mutability(def_id).unwrap() {
hir::MutImmutable => McImmutable,
hir::MutMutable => McDeclared,
},
ty:expr_ty,
note: NoteNone
})
}
Res::Local(var_id) => {
if self.upvars.map_or(false, |upvars| upvars.contains_key(&var_id)) {
self.cat_upvar(hir_id, span, var_id)
} else {
Ok(cmt_ {
hir_id,
span,
cat: Categorization::Local(var_id),
mutbl: MutabilityCategory::from_local(self.tcx, self.tables, var_id),
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,
hir_id: hir::HirId,
span: Span,
var_id: hir::HirId,
) -> McResult<cmt_<'tcx>> {
// 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 closure_expr_def_id = self.body_owner;
let fn_hir_id = self.tcx.hir().local_def_id_to_hir_id(
LocalDefId::from_def_id(closure_expr_def_id),
);
let ty = self.node_ty(fn_hir_id)?;
let kind = match ty.sty {
ty::Generator(..) => ty::ClosureKind::FnOnce,
ty::Closure(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 =>
closure_substs.closure_kind(closure_def_id, self.tcx.global_tcx()),
}
}
_ => span_bug!(span, "unexpected type for fn in mem_categorization: {:?}", ty),
};
let upvar_id = ty::UpvarId {
var_path: ty::UpvarPath { hir_id: var_id },
closure_expr_id: closure_expr_def_id.to_local(),
};
let var_ty = self.node_ty(var_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_ {
hir_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(hir_id, span, upvar_id, var_mutbl, ty::MutBorrow, cmt_result)
}
ty::ClosureKind::Fn => {
self.env_deref(hir_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_ {
hir_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,
hir_id: hir::HirId,
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 `Error` 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_ {
hir_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,
hir_id: hir::HirId,
span: Span,
expr_ty: Ty<'tcx>)
-> cmt_<'tcx> {
debug!("cat_rvalue_node(id={:?}, span={:?}, expr_ty={:?})",
hir_id, span, expr_ty);
let promotable = self.rvalue_promotable_map.as_ref().map(|m| m.contains(&hir_id.local_id))
.unwrap_or(false);
debug!("cat_rvalue_node: promotable = {:?}", promotable);
// Always promote `[T; 0]` (even when e.g., borrowed mutably).
let promotable = match expr_ty.sty {
ty::Array(_, len) if len.assert_usize(self.tcx) == Some(0) => true,
_ => promotable,
};
debug!("cat_rvalue_node: promotable = {:?} (2)", 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.lifetimes.re_static
} else {
self.temporary_scope(hir_id.local_id)
};
let ret = self.cat_rvalue(hir_id, span, re, expr_ty);
debug!("cat_rvalue_node ret {:?}", ret);
ret
}
pub fn cat_rvalue(&self,
cmt_hir_id: hir::HirId,
span: Span,
temp_scope: ty::Region<'tcx>,
expr_ty: Ty<'tcx>) -> cmt_<'tcx> {
let ret = cmt_ {
hir_id: cmt_hir_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: HirNode>(&self,
node: &N,
base_cmt: cmt<'tcx>,
f_index: usize,
f_ident: ast::Ident,
f_ty: Ty<'tcx>)
-> cmt_<'tcx> {
let ret = cmt_ {
hir_id: node.hir_id(),
span: node.span(),
mutbl: base_cmt.mutbl.inherit(),
cat: Categorization::Interior(base_cmt,
InteriorField(FieldIndex(f_index, f_ident.name))),
ty: f_ty,
note: NoteNone
};
debug!("cat_field ret {:?}", ret);
ret
}
fn cat_overloaded_place(
&self,
expr: &hir::Expr,
base: &hir::Expr,
note: Note,
) -> McResult<cmt_<'tcx>> {
debug!("cat_overloaded_place(expr={:?}, base={:?}, note={:?})",
expr,
base,
note);
// 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::Ref(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.hir_id, expr.span, ref_ty));
self.cat_deref(expr, base_cmt, note)
}
pub fn cat_deref(
&self,
node: &impl HirNode,
base_cmt: cmt<'tcx>,
note: Note,
) -> 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::Adt(def, ..) if def.is_box() => Unique,
ty::RawPtr(ref mt) => UnsafePtr(mt.mutbl),
ty::Ref(r, _, mutbl) => {
let bk = ty::BorrowKind::from_mutbl(mutbl);
BorrowedPtr(bk, r)
}
_ => bug!("unexpected type in cat_deref: {:?}", base_cmt.ty)
};
let ret = cmt_ {
hir_id: node.hir_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: note,
};
debug!("cat_deref ret {:?}", ret);
Ok(ret)
}
fn cat_index<N: HirNode>(&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 HIR 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:HirNode>(&self,
node: &N,
base_cmt: cmt<'tcx>,
interior_ty: Ty<'tcx>,
interior: InteriorKind)
-> cmt_<'tcx> {
let ret = cmt_ {
hir_id: node.hir_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:HirNode>(&self,
node: &N,
base_cmt: cmt<'tcx>,
variant_did: DefId)
-> cmt<'tcx> {
// univariant enums do not need downcasts
let base_did = self.tcx.parent(variant_did).unwrap();
if self.tcx.adt_def(base_did).variants.len() != 1 {
let base_ty = base_cmt.ty;
let ret = Rc::new(cmt_ {
hir_id: node.hir_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:
//
// (FIXME: `@@3` is not legal code anymore!)
//
// 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(pat={:?}, 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)
{
debug!("cat_pattern: applying adjustment to cmt={:?}", cmt);
cmt = Rc::new(self.cat_deref(pat, cmt, NoteNone)?);
}
let cmt = cmt; // lose mutability
debug!("cat_pattern: applied adjustment derefs to get cmt={:?}", cmt);
// 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 res = self.tables.qpath_res(qpath, pat.hir_id);
let (cmt, expected_len) = match res {
Res::Err => {
debug!("access to unresolvable pattern {:?}", pat);
return Err(())
}
Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), variant_ctor_did) => {
let variant_did = self.tcx.parent(variant_ctor_did).unwrap();
let enum_did = self.tcx.parent(variant_did).unwrap();
(self.cat_downcast_if_needed(pat, cmt, variant_did),
self.tcx.adt_def(enum_did)
.variant_with_ctor_id(variant_ctor_did).fields.len())
}
Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), _)
| Res::SelfCtor(..) => {
let ty = self.pat_ty_unadjusted(&pat)?;
match ty.sty {
ty::Adt(adt_def, _) => {
(cmt, adt_def.non_enum_variant().fields.len())
}
_ => {
span_bug!(pat.span,
"tuple struct pattern unexpected type {:?}", ty);
}
}
}
def => {
debug!(
"tuple struct pattern didn't resolve to variant or struct {:?} at {:?}",
def,
pat.span,
);
self.tcx.sess.delay_span_bug(pat.span, &format!(
"tuple struct pattern didn't resolve to variant or struct {:?}",
def,
));
return Err(());
}
};
for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
let subpat_ty = self.pat_ty_adjusted(&subpat)?; // see (*2)
let interior = InteriorField(FieldIndex(i, sym::integer(i)));
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 res = self.tables.qpath_res(qpath, pat.hir_id);
let cmt = match res {
Res::Err => {
debug!("access to unresolvable pattern {:?}", pat);
return Err(())
}
Res::Def(DefKind::Ctor(CtorOf::Variant, _), variant_ctor_did) => {
let variant_did = self.tcx.parent(variant_ctor_did).unwrap();
self.cat_downcast_if_needed(pat, cmt, variant_did)
}
Res::Def(DefKind::Variant, variant_did) => {
self.cat_downcast_if_needed(pat, cmt, variant_did)
}
_ => cmt,
};
for fp in field_pats {
let field_ty = self.pat_ty_adjusted(&fp.node.pat)?; // see (*2)
let f_index = self.tcx.field_index(fp.node.hir_id, self.tables);
let cmt_field = Rc::new(self.cat_field(pat, cmt.clone(), f_index,
fp.node.ident, 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 ty = self.pat_ty_unadjusted(&pat)?;
let expected_len = match ty.sty {
ty::Tuple(ref tys) => tys.len(),
_ => 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_adjusted(&subpat)?; // see (*2)
let interior = InteriorField(FieldIndex(i, sym::integer(i)));
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, NoteNone)?);
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::ThreadLocal(..) |
Categorization::Local(..) |
Categorization::Deref(_, UnsafePtr(..)) |
Categorization::Deref(_, BorrowedPtr(..)) |
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, BorrowedPtr(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::ThreadLocal(..) |
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, _)) => {
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!()
})
}
NoteIndex | NoteNone => None
}
}
pub fn descriptive_string(&self, tcx: TyCtxt<'_>) -> Cow<'static, str> {
match self.cat {
Categorization::StaticItem => {
"static item".into()
}
Categorization::ThreadLocal(..) => {
"thread-local static item".into()
}
Categorization::Rvalue(..) => {
"non-place".into()
}
Categorization::Local(vid) => {
if tcx.hir().is_argument(vid) {
"argument"
} else {
"local variable"
}.into()
}
Categorization::Deref(_, pk) => {
match self.upvar_cat() {
Some(&Categorization::Upvar(ref var)) => {
var.to_string().into()
}
Some(_) => bug!(),
None => {
match pk {
Unique => {
"`Box` content"
}
UnsafePtr(..) => {
"dereference of raw pointer"
}
BorrowedPtr(..) => {
match self.note {
NoteIndex => "indexed content",
_ => "borrowed content"
}
}
}.into()
}
}
}
Categorization::Interior(_, InteriorField(..)) => {
"field".into()
}
Categorization::Interior(_, InteriorElement(InteriorOffsetKind::Index)) => {
"indexed content".into()
}
Categorization::Interior(_, InteriorElement(InteriorOffsetKind::Pattern)) => {
"pattern-bound indexed content".into()
}
Categorization::Upvar(ref var) => {
var.to_string().into()
}
Categorization::Downcast(ref cmt, _) => {
cmt.descriptive_string(tcx).into()
}
}
}
}
pub fn ptr_sigil(ptr: PointerKind<'_>) -> &'static str {
match ptr {
Unique => "Box",
BorrowedPtr(ty::ImmBorrow, _) => "&",
BorrowedPtr(ty::MutBorrow, _) => "&mut",
BorrowedPtr(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)
}
}
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