// Copyright 2012 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. /*! * # 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, arg, or upvar * | *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 an lvalue, then this * is the address of the lvalue. If Expr is an rvalue, this is the address of * some temporary spot in memory where the result is stored. * * Now, cat_expr() classies 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 derefence to reach the array data and * then an index to jump forward to the relevant item. */ use middle::ty; use middle::typeck; use util::ppaux::{ty_to_str, region_to_str, Repr}; use util::common::indenter; use syntax::ast::{m_imm, m_const, m_mutbl}; use syntax::ast; use syntax::codemap::span; use syntax::print::pprust; #[deriving(Eq)] pub enum categorization { cat_rvalue, // result of eval'ing some misc expr cat_static_item, cat_implicit_self, cat_copied_upvar(CopiedUpvar), // upvar copied into @fn or ~fn env cat_stack_upvar(cmt), // by ref upvar from &fn cat_local(ast::node_id), // local variable cat_arg(ast::node_id), // formal argument cat_deref(cmt, uint, ptr_kind), // deref of a ptr cat_interior(cmt, InteriorKind), // something interior: field, tuple, etc cat_downcast(cmt), // selects a particular enum variant (*) cat_discr(cmt, ast::node_id), // match discriminant (see preserve()) cat_self(ast::node_id), // explicit `self` // (*) downcast is only required if the enum has more than one variant } #[deriving(Eq)] struct CopiedUpvar { upvar_id: ast::node_id, onceness: ast::Onceness, } // different kinds of pointers: #[deriving(Eq)] pub enum ptr_kind { uniq_ptr(ast::mutability), gc_ptr(ast::mutability), region_ptr(ast::mutability, ty::Region), unsafe_ptr } // We use the term "interior" to mean "something reachable from the // base without a pointer dereference", e.g. a field #[deriving(Eq)] pub enum InteriorKind { InteriorField(FieldName), InteriorElement(ty::t), // ty::t is the type of the vec/str } #[deriving(Eq)] pub enum FieldName { NamedField(ast::ident), PositionalField(uint) } #[deriving(Eq)] pub enum MutabilityCategory { McImmutable, // Immutable. McReadOnly, // Read-only (`const`) McDeclared, // Directly declared as mutable. McInherited // Inherited from the fact that owner is mutable. } // `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_id_to_type(cmt.id)`. 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.type` to find the type of the value in a consistent // fashion. For more details, see the method `cat_pattern` #[deriving(Eq)] pub struct cmt_ { id: ast::node_id, // id of expr/pat producing this value span: span, // span of same expr/pat cat: categorization, // categorization of expr mutbl: MutabilityCategory, // mutability of expr as lvalue ty: ty::t // type of the expr (*see WARNING above*) } pub type cmt = @cmt_; // We pun on *T to mean both actual deref of a ptr as well // as accessing of components: pub enum deref_kind { deref_ptr(ptr_kind), deref_interior(InteriorKind), } // Categorizes a derefable type. Note that we include vectors and strings as // derefable (we model an index as the combination of a deref and then a // pointer adjustment). pub fn opt_deref_kind(t: ty::t) -> Option { match ty::get(t).sty { ty::ty_uniq(mt) => { Some(deref_ptr(uniq_ptr(mt.mutbl))) } ty::ty_evec(_, ty::vstore_uniq) | ty::ty_estr(ty::vstore_uniq) | ty::ty_closure(ty::ClosureTy {sigil: ast::OwnedSigil, _}) => { Some(deref_ptr(uniq_ptr(m_imm))) } ty::ty_rptr(r, mt) | ty::ty_evec(mt, ty::vstore_slice(r)) => { Some(deref_ptr(region_ptr(mt.mutbl, r))) } ty::ty_estr(ty::vstore_slice(r)) | ty::ty_closure(ty::ClosureTy {sigil: ast::BorrowedSigil, region: r, _}) => { Some(deref_ptr(region_ptr(ast::m_imm, r))) } ty::ty_box(mt) | ty::ty_evec(mt, ty::vstore_box) => { Some(deref_ptr(gc_ptr(mt.mutbl))) } ty::ty_estr(ty::vstore_box) | ty::ty_closure(ty::ClosureTy {sigil: ast::ManagedSigil, _}) => { Some(deref_ptr(gc_ptr(ast::m_imm))) } ty::ty_ptr(*) => { Some(deref_ptr(unsafe_ptr)) } ty::ty_enum(*) | ty::ty_struct(*) => { // newtype Some(deref_interior(InteriorField(PositionalField(0)))) } ty::ty_evec(_, ty::vstore_fixed(_)) | ty::ty_estr(ty::vstore_fixed(_)) => { Some(deref_interior(InteriorElement(t))) } _ => None } } pub fn deref_kind(tcx: ty::ctxt, t: ty::t) -> deref_kind { match opt_deref_kind(t) { Some(k) => k, None => { tcx.sess.bug( fmt!("deref_cat() invoked on non-derefable type %s", ty_to_str(tcx, t))); } } } pub fn cat_expr(tcx: ty::ctxt, method_map: typeck::method_map, expr: @ast::expr) -> cmt { let mcx = &mem_categorization_ctxt { tcx: tcx, method_map: method_map }; return mcx.cat_expr(expr); } pub fn cat_expr_unadjusted(tcx: ty::ctxt, method_map: typeck::method_map, expr: @ast::expr) -> cmt { let mcx = &mem_categorization_ctxt { tcx: tcx, method_map: method_map }; return mcx.cat_expr_unadjusted(expr); } pub fn cat_expr_autoderefd( tcx: ty::ctxt, method_map: typeck::method_map, expr: @ast::expr, autoderefs: uint) -> cmt { let mcx = &mem_categorization_ctxt { tcx: tcx, method_map: method_map }; return mcx.cat_expr_autoderefd(expr, autoderefs); } pub fn cat_def( tcx: ty::ctxt, method_map: typeck::method_map, expr_id: ast::node_id, expr_span: span, expr_ty: ty::t, def: ast::def) -> cmt { let mcx = &mem_categorization_ctxt { tcx: tcx, method_map: method_map }; return mcx.cat_def(expr_id, expr_span, expr_ty, def); } pub trait ast_node { fn id(&self) -> ast::node_id; fn span(&self) -> span; } impl ast_node for @ast::expr { fn id(&self) -> ast::node_id { self.id } fn span(&self) -> span { self.span } } impl ast_node for @ast::pat { fn id(&self) -> ast::node_id { self.id } fn span(&self) -> span { self.span } } pub struct mem_categorization_ctxt { tcx: ty::ctxt, method_map: typeck::method_map, } impl ToStr for MutabilityCategory { fn to_str(&self) -> ~str { fmt!("%?", *self) } } pub impl MutabilityCategory { fn from_mutbl(m: ast::mutability) -> MutabilityCategory { match m { m_imm => McImmutable, m_const => McReadOnly, m_mutbl => McDeclared } } fn inherit(&self) -> MutabilityCategory { match *self { McImmutable => McImmutable, McReadOnly => McReadOnly, McDeclared => McInherited, McInherited => McInherited } } fn is_mutable(&self) -> bool { match *self { McImmutable | McReadOnly => false, McDeclared | McInherited => true } } fn is_immutable(&self) -> bool { match *self { McImmutable => true, McReadOnly | McDeclared | McInherited => false } } fn to_user_str(&self) -> &'static str { match *self { McDeclared | McInherited => "mutable", McImmutable => "immutable", McReadOnly => "const" } } } pub impl mem_categorization_ctxt { fn expr_ty(&self, expr: @ast::expr) -> ty::t { ty::expr_ty(self.tcx, expr) } fn pat_ty(&self, pat: @ast::pat) -> ty::t { ty::node_id_to_type(self.tcx, pat.id) } fn cat_expr(&self, expr: @ast::expr) -> cmt { match self.tcx.adjustments.find(&expr.id) { None => { // No adjustments. self.cat_expr_unadjusted(expr) } Some(&@ty::AutoAddEnv(*)) => { // Convert a bare fn to a closure by adding NULL env. // Result is an rvalue. let expr_ty = ty::expr_ty_adjusted(self.tcx, expr); self.cat_rvalue(expr, expr_ty) } Some( &@ty::AutoDerefRef( ty::AutoDerefRef { autoref: Some(_), _})) => { // Equivalent to &*expr or something similar. // Result is an rvalue. let expr_ty = ty::expr_ty_adjusted(self.tcx, expr); self.cat_rvalue(expr, expr_ty) } Some( &@ty::AutoDerefRef( ty::AutoDerefRef { autoref: None, autoderefs: autoderefs})) => { // Equivalent to *expr or something similar. self.cat_expr_autoderefd(expr, autoderefs) } } } fn cat_expr_autoderefd(&self, expr: @ast::expr, autoderefs: uint) -> cmt { let mut cmt = self.cat_expr_unadjusted(expr); for uint::range(1, autoderefs+1) |deref| { cmt = self.cat_deref(expr, cmt, deref); } return cmt; } fn cat_expr_unadjusted(&self, expr: @ast::expr) -> cmt { debug!("cat_expr: id=%d expr=%s", expr.id, pprust::expr_to_str(expr, self.tcx.sess.intr())); let expr_ty = self.expr_ty(expr); match expr.node { ast::expr_unary(ast::deref, e_base) => { if self.method_map.contains_key(&expr.id) { return self.cat_rvalue(expr, expr_ty); } let base_cmt = self.cat_expr(e_base); self.cat_deref(expr, base_cmt, 0) } ast::expr_field(base, f_name, _) => { // Method calls are now a special syntactic form, // so `a.b` should always be a field. assert!(!self.method_map.contains_key(&expr.id)); let base_cmt = self.cat_expr(base); self.cat_field(expr, base_cmt, f_name, self.expr_ty(expr)) } ast::expr_index(base, _) => { if self.method_map.contains_key(&expr.id) { return self.cat_rvalue(expr, expr_ty); } let base_cmt = self.cat_expr(base); self.cat_index(expr, base_cmt, 0) } ast::expr_path(_) | ast::expr_self => { let def = self.tcx.def_map.get_copy(&expr.id); self.cat_def(expr.id, expr.span, expr_ty, def) } ast::expr_paren(e) => self.cat_expr_unadjusted(e), ast::expr_addr_of(*) | ast::expr_call(*) | ast::expr_assign(*) | ast::expr_assign_op(*) | ast::expr_fn_block(*) | ast::expr_ret(*) | ast::expr_loop_body(*) | ast::expr_do_body(*) | ast::expr_unary(*) | ast::expr_method_call(*) | ast::expr_copy(*) | ast::expr_cast(*) | ast::expr_vstore(*) | ast::expr_vec(*) | ast::expr_tup(*) | ast::expr_if(*) | ast::expr_log(*) | ast::expr_binary(*) | ast::expr_while(*) | ast::expr_block(*) | ast::expr_loop(*) | ast::expr_match(*) | ast::expr_lit(*) | ast::expr_break(*) | ast::expr_mac(*) | ast::expr_again(*) | ast::expr_struct(*) | ast::expr_repeat(*) | ast::expr_inline_asm(*) => { return self.cat_rvalue(expr, expr_ty); } } } fn cat_def(&self, id: ast::node_id, span: span, expr_ty: ty::t, def: ast::def) -> cmt { match def { ast::def_fn(*) | ast::def_static_method(*) | ast::def_mod(_) | ast::def_foreign_mod(_) | ast::def_const(_) | ast::def_use(_) | ast::def_variant(*) | ast::def_trait(_) | ast::def_ty(_) | ast::def_prim_ty(_) | ast::def_ty_param(*) | ast::def_struct(*) | ast::def_typaram_binder(*) | ast::def_region(_) | ast::def_label(_) | ast::def_self_ty(*) => { @cmt_ { id:id, span:span, cat:cat_static_item, mutbl: McImmutable, ty:expr_ty } } ast::def_arg(vid, mutbl) => { // Idea: make this could be rewritten to model by-ref // stuff as `&const` and `&mut`? // m: mutability of the argument let m = if mutbl {McDeclared} else {McImmutable}; @cmt_ { id: id, span: span, cat: cat_arg(vid), mutbl: m, ty:expr_ty } } ast::def_self(self_id, is_implicit) => { let cat = if is_implicit { cat_implicit_self } else { cat_self(self_id) }; @cmt_ { id:id, span:span, cat:cat, mutbl: McImmutable, ty:expr_ty } } ast::def_upvar(upvar_id, inner, fn_node_id, _) => { let ty = ty::node_id_to_type(self.tcx, fn_node_id); match ty::get(ty).sty { ty::ty_closure(ref closure_ty) => { let sigil = closure_ty.sigil; match sigil { ast::BorrowedSigil => { let upvar_cmt = self.cat_def(id, span, expr_ty, *inner); @cmt_ { id:id, span:span, cat:cat_stack_upvar(upvar_cmt), mutbl:upvar_cmt.mutbl.inherit(), ty:upvar_cmt.ty } } ast::OwnedSigil | ast::ManagedSigil => { // FIXME #2152 allow mutation of moved upvars @cmt_ { id:id, span:span, cat:cat_copied_upvar(CopiedUpvar { upvar_id: upvar_id, onceness: closure_ty.onceness}), mutbl:McImmutable, ty:expr_ty } } } } _ => { self.tcx.sess.span_bug( span, fmt!("Upvar of non-closure %? - %s", fn_node_id, ty.repr(self.tcx))); } } } ast::def_local(vid, mutbl) => { let m = if mutbl {McDeclared} else {McImmutable}; @cmt_ { id:id, span:span, cat:cat_local(vid), mutbl:m, ty:expr_ty } } ast::def_binding(vid, _) => { // by-value/by-ref bindings are local variables @cmt_ { id:id, span:span, cat:cat_local(vid), mutbl:McImmutable, ty:expr_ty } } } } fn cat_rvalue(&self, elt: N, expr_ty: ty::t) -> cmt { @cmt_ { id:elt.id(), span:elt.span(), cat:cat_rvalue, mutbl:McDeclared, ty:expr_ty } } /// inherited mutability: used in cases where the mutability of a /// component is inherited from the base it is a part of. For /// example, a record field is mutable if it is declared mutable /// or if the container is mutable. fn inherited_mutability(&self, base_m: MutabilityCategory, interior_m: ast::mutability) -> MutabilityCategory { match interior_m { m_imm => base_m.inherit(), m_const => McReadOnly, m_mutbl => McDeclared } } fn cat_field(&self, node: N, base_cmt: cmt, f_name: ast::ident, f_ty: ty::t) -> cmt { @cmt_ { id: node.id(), span: node.span(), cat: cat_interior(base_cmt, InteriorField(NamedField(f_name))), mutbl: base_cmt.mutbl.inherit(), ty: f_ty } } fn cat_deref_fn(&self, node: N, base_cmt: cmt, deref_cnt: uint) -> cmt { // Bit of a hack: the "dereference" of a function pointer like // `@fn()` is a mere logical concept. We interpret it as // dereferencing the environment pointer; of course, we don't // know what type lies at the other end, so we just call it // `()` (the empty tuple). let mt = ty::mt {ty: ty::mk_tup(self.tcx, ~[]), mutbl: m_imm}; return self.cat_deref_common(node, base_cmt, deref_cnt, mt); } fn cat_deref(&self, node: N, base_cmt: cmt, deref_cnt: uint) -> cmt { let mt = match ty::deref(self.tcx, base_cmt.ty, true) { Some(mt) => mt, None => { self.tcx.sess.span_bug( node.span(), fmt!("Explicit deref of non-derefable type: %s", ty_to_str(self.tcx, base_cmt.ty))); } }; return self.cat_deref_common(node, base_cmt, deref_cnt, mt); } fn cat_deref_common(&self, node: N, base_cmt: cmt, deref_cnt: uint, mt: ty::mt) -> cmt { match deref_kind(self.tcx, base_cmt.ty) { deref_ptr(ptr) => { // for unique ptrs, we inherit mutability from the // owning reference. let m = match ptr { uniq_ptr(*) => { self.inherited_mutability(base_cmt.mutbl, mt.mutbl) } gc_ptr(*) | region_ptr(_, _) | unsafe_ptr => { MutabilityCategory::from_mutbl(mt.mutbl) } }; @cmt_ { id:node.id(), span:node.span(), cat:cat_deref(base_cmt, deref_cnt, ptr), mutbl:m, ty:mt.ty } } deref_interior(interior) => { let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl); @cmt_ { id:node.id(), span:node.span(), cat:cat_interior(base_cmt, interior), mutbl:m, ty:mt.ty } } } } fn cat_index(&self, elt: N, base_cmt: cmt, derefs: uint) -> cmt { //! Creates a cmt for an indexing operation (`[]`); this //! indexing operation may occurs as part of an //! AutoBorrowVec, which when converting a `~[]` to an `&[]` //! effectively takes the address of the 0th element. //! //! 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. //! //! In the event that a deref is needed, the "deref count" //! is taken from the parameter `derefs`. See the comment //! on the def'n of `root_map_key` in borrowck/mod.rs //! for more details about deref counts; the summary is //! that `derefs` should be 0 for an explicit indexing //! operation and N+1 for an indexing that is part of //! an auto-adjustment, where N is the number of autoderefs //! in that adjustment. //! //! # Parameters //! - `elt`: the AST node being indexed //! - `base_cmt`: the cmt of `elt` //! - `derefs`: the deref number to be used for //! the implicit index deref, if any (see above) let mt = match ty::index(base_cmt.ty) { Some(mt) => mt, None => { self.tcx.sess.span_bug( elt.span(), fmt!("Explicit index of non-index type `%s`", ty_to_str(self.tcx, base_cmt.ty))); } }; return match deref_kind(self.tcx, base_cmt.ty) { deref_ptr(ptr) => { // for unique ptrs, we inherit mutability from the // owning reference. let m = match ptr { uniq_ptr(*) => { self.inherited_mutability(base_cmt.mutbl, mt.mutbl) } gc_ptr(_) | region_ptr(_, _) | unsafe_ptr => { MutabilityCategory::from_mutbl(mt.mutbl) } }; // the deref is explicit in the resulting cmt let deref_cmt = @cmt_ { id:elt.id(), span:elt.span(), cat:cat_deref(base_cmt, derefs, ptr), mutbl:m, ty:mt.ty }; interior(elt, deref_cmt, base_cmt.ty, m, mt) } deref_interior(_) => { // fixed-length vectors have no deref let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl); interior(elt, base_cmt, base_cmt.ty, m, mt) } }; fn interior(elt: N, of_cmt: cmt, vec_ty: ty::t, mutbl: MutabilityCategory, mt: ty::mt) -> cmt { @cmt_ { id:elt.id(), span:elt.span(), cat:cat_interior(of_cmt, InteriorElement(vec_ty)), mutbl:mutbl, ty:mt.ty } } } fn cat_imm_interior(&self, node: N, base_cmt: cmt, interior_ty: ty::t, interior: InteriorKind) -> cmt { @cmt_ { id: node.id(), span: node.span(), cat: cat_interior(base_cmt, interior), mutbl: base_cmt.mutbl.inherit(), ty: interior_ty } } fn cat_downcast(&self, node: N, base_cmt: cmt, downcast_ty: ty::t) -> cmt { @cmt_ { id: node.id(), span: node.span(), cat: cat_downcast(base_cmt), mutbl: base_cmt.mutbl.inherit(), ty: downcast_ty } } fn cat_pattern(&self, cmt: cmt, pat: @ast::pat, op: &fn(cmt, @ast::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. // // (*) 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. So if you have something like: // // let x = @@3; // match x { // @@y { ... } // } // // In this case, the cmt and the relevant ids would be: // // CMT Id Type of Id Type of cmt // // local(x)->@->@ // ^~~~~~~^ `x` from discr @@int @@int // ^~~~~~~~~~^ `@@y` pattern node @@int @int // ^~~~~~~~~~~~~^ `@y` pattern node @int int // // You can see that the types of the id and the cmt are in // sync in the first line, because that id is actually the id // of an expression. But once we get to pattern ids, the types // step out of sync again. So you'll see below that we always // get the type of the *subpattern* and use that. let tcx = self.tcx; debug!("cat_pattern: id=%d pat=%s cmt=%s", pat.id, pprust::pat_to_str(pat, tcx.sess.intr()), cmt.repr(tcx)); let _i = indenter(); op(cmt, pat); match pat.node { ast::pat_wild => { // _ } ast::pat_enum(_, None) => { // variant(*) } ast::pat_enum(_, Some(ref subpats)) => { match self.tcx.def_map.find(&pat.id) { Some(&ast::def_variant(enum_did, _)) => { // variant(x, y, z) let downcast_cmt = { if ty::enum_is_univariant(tcx, enum_did) { cmt // univariant, no downcast needed } else { self.cat_downcast(pat, cmt, cmt.ty) } }; for subpats.eachi |i, &subpat| { let subpat_ty = self.pat_ty(subpat); // see (*) let subcmt = self.cat_imm_interior( pat, downcast_cmt, subpat_ty, InteriorField(PositionalField(i))); self.cat_pattern(subcmt, subpat, op); } } Some(&ast::def_fn(*)) | Some(&ast::def_struct(*)) => { for subpats.eachi |i, &subpat| { let subpat_ty = self.pat_ty(subpat); // see (*) let cmt_field = self.cat_imm_interior( pat, cmt, subpat_ty, InteriorField(PositionalField(i))); self.cat_pattern(cmt_field, subpat, op); } } Some(&ast::def_const(*)) => { for subpats.each |&subpat| { self.cat_pattern(cmt, subpat, op); } } _ => { self.tcx.sess.span_bug( pat.span, "enum pattern didn't resolve to enum or struct"); } } } ast::pat_ident(_, _, Some(subpat)) => { self.cat_pattern(cmt, subpat, op); } ast::pat_ident(_, _, None) => { // nullary variant or identifier: ignore } ast::pat_struct(_, ref field_pats, _) => { // {f1: p1, ..., fN: pN} for field_pats.each |fp| { let field_ty = self.pat_ty(fp.pat); // see (*) let cmt_field = self.cat_field(pat, cmt, fp.ident, field_ty); self.cat_pattern(cmt_field, fp.pat, op); } } ast::pat_tup(ref subpats) => { // (p1, ..., pN) for subpats.eachi |i, &subpat| { let subpat_ty = self.pat_ty(subpat); // see (*) let subcmt = self.cat_imm_interior( pat, cmt, subpat_ty, InteriorField(PositionalField(i))); self.cat_pattern(subcmt, subpat, op); } } ast::pat_box(subpat) | ast::pat_uniq(subpat) | ast::pat_region(subpat) => { // @p1, ~p1 let subcmt = self.cat_deref(pat, cmt, 0); self.cat_pattern(subcmt, subpat, op); } ast::pat_vec(ref before, slice, ref after) => { let elt_cmt = self.cat_index(pat, cmt, 0); for before.each |&before_pat| { self.cat_pattern(elt_cmt, before_pat, op); } for slice.each |&slice_pat| { let slice_ty = self.pat_ty(slice_pat); let slice_cmt = self.cat_rvalue(pat, slice_ty); self.cat_pattern(slice_cmt, slice_pat, op); } for after.each |&after_pat| { self.cat_pattern(elt_cmt, after_pat, op); } } ast::pat_lit(_) | ast::pat_range(_, _) => { /*always ok*/ } } } fn mut_to_str(&self, mutbl: ast::mutability) -> ~str { match mutbl { m_mutbl => ~"mutable", m_const => ~"const", m_imm => ~"immutable" } } fn cmt_to_str(&self, cmt: cmt) -> ~str { match cmt.cat { cat_static_item => { ~"static item" } cat_implicit_self => { ~"self reference" } cat_copied_upvar(_) => { ~"captured outer variable in a heap closure" } cat_rvalue => { ~"non-lvalue" } cat_local(_) => { ~"local variable" } cat_self(_) => { ~"self value" } cat_arg(*) => { ~"argument" } cat_deref(_, _, pk) => { fmt!("dereference of %s pointer", ptr_sigil(pk)) } cat_interior(_, InteriorField(NamedField(_))) => { ~"field" } cat_interior(_, InteriorField(PositionalField(_))) => { ~"anonymous field" } cat_interior(_, InteriorElement(t)) => { match ty::get(t).sty { ty::ty_evec(*) => ~"vec content", ty::ty_estr(*) => ~"str content", _ => ~"indexed content" } } cat_stack_upvar(_) => { ~"captured outer variable" } cat_discr(cmt, _) => { self.cmt_to_str(cmt) } cat_downcast(cmt) => { self.cmt_to_str(cmt) } } } fn region_to_str(&self, r: ty::Region) -> ~str { region_to_str(self.tcx, r) } } /// The node_id here is the node of the expression that references the field. /// This function looks it up in the def map in case the type happens to be /// an enum to determine which variant is in use. pub fn field_mutbl(tcx: ty::ctxt, base_ty: ty::t, f_name: ast::ident, node_id: ast::node_id) -> Option { // Need to refactor so that struct/enum fields can be treated uniformly. match ty::get(base_ty).sty { ty::ty_struct(did, _) => { for ty::lookup_struct_fields(tcx, did).each |fld| { if fld.ident == f_name { return Some(ast::m_imm); } } } ty::ty_enum(*) => { match tcx.def_map.get_copy(&node_id) { ast::def_variant(_, variant_id) => { for ty::lookup_struct_fields(tcx, variant_id).each |fld| { if fld.ident == f_name { return Some(ast::m_imm); } } } _ => {} } } _ => { } } return None; } pub enum AliasableReason { AliasableManaged(ast::mutability), AliasableBorrowed(ast::mutability), AliasableOther } pub impl cmt_ { fn guarantor(@self) -> cmt { //! Returns `self` after stripping away any owned pointer derefs or //! interior content. The return value is basically the `cmt` which //! determines how long the value in `self` remains live. match self.cat { cat_rvalue | cat_static_item | cat_implicit_self | cat_copied_upvar(*) | cat_local(*) | cat_self(*) | cat_arg(*) | cat_deref(_, _, unsafe_ptr(*)) | cat_deref(_, _, gc_ptr(*)) | cat_deref(_, _, region_ptr(*)) => { self } cat_downcast(b) | cat_stack_upvar(b) | cat_discr(b, _) | cat_interior(b, _) | cat_deref(b, _, uniq_ptr(*)) => { b.guarantor() } } } fn is_freely_aliasable(&self) -> bool { self.freely_aliasable().is_some() } fn freely_aliasable(&self) -> Option { //! True if this lvalue resides in an area that is //! freely aliasable, meaning that rustc cannot track //! the alias//es with precision. // Maybe non-obvious: copied upvars can only be considered // non-aliasable in once closures, since any other kind can be // aliased and eventually recused. match self.cat { cat_copied_upvar(CopiedUpvar {onceness: ast::Once, _}) | cat_rvalue(*) | cat_local(*) | cat_arg(_) | cat_self(*) | cat_deref(_, _, unsafe_ptr(*)) | // of course it is aliasable, but... cat_deref(_, _, region_ptr(m_mutbl, _)) => { None } cat_copied_upvar(CopiedUpvar {onceness: ast::Many, _}) | cat_static_item(*) | cat_implicit_self(*) => { Some(AliasableOther) } cat_deref(_, _, gc_ptr(m)) => { Some(AliasableManaged(m)) } cat_deref(_, _, region_ptr(m @ m_const, _)) | cat_deref(_, _, region_ptr(m @ m_imm, _)) => { Some(AliasableBorrowed(m)) } cat_downcast(b) | cat_stack_upvar(b) | cat_deref(b, _, uniq_ptr(*)) | cat_interior(b, _) | cat_discr(b, _) => { b.freely_aliasable() } } } } impl Repr for cmt { fn repr(&self, tcx: ty::ctxt) -> ~str { fmt!("{%s id:%d m:%? ty:%s}", self.cat.repr(tcx), self.id, self.mutbl, self.ty.repr(tcx)) } } impl Repr for categorization { fn repr(&self, tcx: ty::ctxt) -> ~str { match *self { cat_static_item | cat_implicit_self | cat_rvalue | cat_copied_upvar(*) | cat_local(*) | cat_self(*) | cat_arg(*) => fmt!("%?", *self), cat_deref(cmt, derefs, ptr) => { fmt!("%s->(%s, %u)", cmt.cat.repr(tcx), ptr_sigil(ptr), derefs) } cat_interior(cmt, interior) => { fmt!("%s.%s", cmt.cat.repr(tcx), interior.repr(tcx)) } cat_downcast(cmt) => { fmt!("%s->(enum)", cmt.cat.repr(tcx)) } cat_stack_upvar(cmt) | cat_discr(cmt, _) => cmt.cat.repr(tcx) } } } pub fn ptr_sigil(ptr: ptr_kind) -> ~str { match ptr { uniq_ptr(_) => ~"~", gc_ptr(_) => ~"@", region_ptr(_, _) => ~"&", unsafe_ptr => ~"*" } } impl Repr for InteriorKind { fn repr(&self, tcx: ty::ctxt) -> ~str { match *self { InteriorField(NamedField(fld)) => copy *tcx.sess.str_of(fld), InteriorField(PositionalField(i)) => fmt!("#%?", i), InteriorElement(_) => ~"[]", } } }