| //! # 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>, |
| param_env: ty::ParamEnv<'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>, |
| param_env: ty::ParamEnv<'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, |
| param_env, |
| } |
| } |
| } |
| |
| 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>, |
| param_env: ty::ParamEnv<'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), |
| param_env, |
| } |
| } |
| |
| 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.try_eval_usize(self.tcx, self.param_env) == 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.pat)?; // see (*2) |
| let f_index = self.tcx.field_index(fp.hir_id, self.tables); |
| let cmt_field = Rc::new(self.cat_field(pat, cmt.clone(), f_index, |
| fp.ident, field_ty)); |
| self.cat_pattern_(cmt_field, &fp.pat, op)?; |
| } |
| } |
| |
| PatKind::Or(ref pats) => { |
| for pat in pats { |
| self.cat_pattern_(cmt.clone(), &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) |
| } |
| } |
