rust/src/librustc/middle/mem_categorization.rs

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// 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, 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;
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use util::ppaux::{ty_to_str, region_to_str, Repr};
use util::common::indenter;
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use syntax::ast::{m_imm, m_const, m_mutbl};
use syntax::ast;
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use syntax::codemap::span;
use syntax::print::pprust;
#[deriving(Eq)]
pub enum categorization {
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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
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cat_arg(ast::node_id), // formal argument
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cat_deref(cmt, uint, ptr_kind), // deref of a ptr
cat_interior(cmt, interior_kind), // something interior
cat_discr(cmt, ast::node_id), // match discriminant (see preserve())
cat_self(ast::node_id), // explicit `self`
}
#[deriving(Eq)]
struct CopiedUpvar {
upvar_id: ast::node_id,
onceness: ast::Onceness,
}
// different kinds of pointers:
#[deriving(Eq)]
pub enum ptr_kind {
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uniq_ptr(ast::mutability),
gc_ptr(ast::mutability),
region_ptr(ast::mutability, ty::Region),
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unsafe_ptr
}
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// We use the term "interior" to mean "something reachable from the
// base without a pointer dereference", e.g. a field
#[deriving(Eq)]
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pub enum interior_kind {
interior_tuple, // elt in a tuple
interior_anon_field, // anonymous field (in e.g.
// struct Foo(int, int);
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interior_variant(ast::def_id), // internals to a variant of given enum
interior_field(ast::ident, // name of field
ast::mutability), // declared mutability of field
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interior_index(ty::t, // type of vec/str/etc being deref'd
ast::mutability) // mutability of vec content
}
#[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_;
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// We pun on *T to mean both actual deref of a ptr as well
// as accessing of components:
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pub enum deref_kind {deref_ptr(ptr_kind), deref_interior(interior_kind)}
// 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<deref_kind> {
match ty::get(t).sty {
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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, _}) => {
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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(did, _) => {
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Some(deref_interior(interior_variant(did)))
}
ty::ty_struct(_, _) => {
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Some(deref_interior(interior_anon_field))
}
ty::ty_evec(mt, ty::vstore_fixed(_)) => {
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Some(deref_interior(interior_index(t, mt.mutbl)))
}
ty::ty_estr(ty::vstore_fixed(_)) => {
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Some(deref_interior(interior_index(t, m_imm)))
}
_ => None
}
}
pub fn deref_kind(tcx: ty::ctxt, t: ty::t) -> deref_kind {
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match opt_deref_kind(t) {
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Some(k) => k,
None => {
tcx.sess.bug(
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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 {
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fn id(&self) -> ast::node_id;
fn span(&self) -> span;
}
impl ast_node for @ast::expr {
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fn id(&self) -> ast::node_id { self.id }
fn span(&self) -> span { self.span }
}
impl ast_node for @ast::pat {
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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
}
}
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fn to_user_str(&self) -> &'static str {
match *self {
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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)
}
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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(
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&@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(
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&@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 {
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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);
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match expr.node {
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ast::expr_unary(ast::deref, e_base) => {
if self.method_map.contains_key(&expr.id) {
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return self.cat_rvalue(expr, expr_ty);
}
let base_cmt = self.cat_expr(e_base);
self.cat_deref(expr, base_cmt, 0)
}
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ast::expr_field(base, f_name, _) => {
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// 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), expr.id)
}
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ast::expr_index(base, _) => {
if self.method_map.contains_key(&expr.id) {
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return self.cat_rvalue(expr, expr_ty);
}
let base_cmt = self.cat_expr(base);
self.cat_index(expr, base_cmt)
}
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ast::expr_path(_) => {
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),
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ast::expr_addr_of(*) | ast::expr_call(*) | ast::expr_swap(*) |
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(*) |
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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(*) |
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ast::expr_repeat(*) | ast::expr_inline_asm(*) => {
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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 {
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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,
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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_ {
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id: id,
span: span,
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cat: cat_arg(vid),
mutbl: m,
ty:expr_ty
}
}
ast::def_self(self_id, is_implicit) => {
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let cat = if is_implicit {
cat_implicit_self
} else {
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cat_self(self_id)
};
@cmt_ {
id:id,
span:span,
cat:cat,
mutbl: McImmutable,
ty:expr_ty
}
}
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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)));
}
}
}
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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<N:ast_node>(&self, elt: N, expr_ty: ty::t) -> cmt {
@cmt_ {
id:elt.id(),
span:elt.span(),
cat:cat_rvalue,
mutbl:McImmutable,
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,
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interior_m: ast::mutability) -> MutabilityCategory
{
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match interior_m {
m_imm => base_m.inherit(),
m_const => McReadOnly,
m_mutbl => McDeclared
}
}
/// The `field_id` parameter is the ID of the enclosing expression or
/// pattern. It is used to determine which variant of an enum is in use.
fn cat_field<N:ast_node>(&self,
node: N,
base_cmt: cmt,
f_name: ast::ident,
f_ty: ty::t,
field_id: ast::node_id) -> cmt {
let f_mutbl = m_imm;
let m = self.inherited_mutability(base_cmt.mutbl, f_mutbl);
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let f_interior = interior_field(f_name, f_mutbl);
@cmt_ {
id: node.id(),
span: node.span(),
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cat: cat_interior(base_cmt, f_interior),
mutbl: m,
ty: f_ty
}
}
fn cat_deref_fn<N:ast_node>(&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<N:ast_node>(&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<N:ast_node>(&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.
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let m = match ptr {
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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
}
}
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deref_interior(interior) => {
let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl);
@cmt_ {
id:node.id(),
span:node.span(),
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cat:cat_interior(base_cmt, interior),
mutbl:m,
ty:mt.ty
}
}
}
}
fn cat_index<N:ast_node>(&self,
elt: N,
base_cmt: cmt) -> cmt {
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let mt = match ty::index(base_cmt.ty) {
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Some(mt) => mt,
None => {
self.tcx.sess.span_bug(
elt.span(),
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fmt!("Explicit index of non-index type `%s`",
ty_to_str(self.tcx, base_cmt.ty)));
}
};
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return match deref_kind(self.tcx, base_cmt.ty) {
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deref_ptr(ptr) => {
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// for unique ptrs, we inherit mutability from the
// owning reference.
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let m = match ptr {
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uniq_ptr(*) => {
self.inherited_mutability(base_cmt.mutbl, mt.mutbl)
}
gc_ptr(_) | region_ptr(_, _) | unsafe_ptr => {
MutabilityCategory::from_mutbl(mt.mutbl)
}
};
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// the deref is explicit in the resulting cmt
let deref_cmt = @cmt_ {
id:elt.id(),
span:elt.span(),
cat:cat_deref(base_cmt, 0u, ptr),
mutbl:m,
ty:mt.ty
};
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interior(elt, deref_cmt, base_cmt.ty, m, mt)
}
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deref_interior(_) => {
// fixed-length vectors have no deref
let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl);
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interior(elt, base_cmt, base_cmt.ty, m, mt)
}
};
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fn interior<N: ast_node>(elt: N, of_cmt: cmt,
vect: ty::t, mutbl: MutabilityCategory,
mt: ty::mt) -> cmt
{
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let interior = interior_index(vect, mt.mutbl);
@cmt_ {
id:elt.id(),
span:elt.span(),
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cat:cat_interior(of_cmt, interior),
mutbl:mutbl,
ty:mt.ty
}
}
}
fn cat_imm_interior<N:ast_node>(&self,
node: N,
base_cmt: cmt,
interior_ty: ty::t,
interior: interior_kind) -> cmt {
@cmt_ {
id: node.id(),
span: node.span(),
cat: cat_interior(base_cmt, interior),
mutbl: base_cmt.mutbl.inherit(),
ty: interior_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.
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let tcx = self.tcx;
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debug!("cat_pattern: id=%d pat=%s cmt=%s",
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pat.id, pprust::pat_to_str(pat, tcx.sess.intr()),
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cmt.repr(tcx));
let _i = indenter();
op(cmt, pat);
match pat.node {
ast::pat_wild => {
// _
}
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ast::pat_enum(_, None) => {
// variant(*)
}
ast::pat_enum(_, Some(ref subpats)) => {
match self.tcx.def_map.find(&pat.id) {
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Some(&ast::def_variant(enum_did, _)) => {
// variant(x, y, z)
for subpats.each |&subpat| {
let subpat_ty = self.pat_ty(subpat); // see (*)
let subcmt =
self.cat_imm_interior(pat, cmt, subpat_ty,
interior_variant(enum_did));
self.cat_pattern(subcmt, subpat, op);
}
}
Some(&ast::def_fn(*)) |
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Some(&ast::def_struct(*)) => {
for subpats.each |&subpat| {
let subpat_ty = self.pat_ty(subpat); // see (*)
let cmt_field =
self.cat_imm_interior(pat, cmt, subpat_ty,
interior_anon_field);
self.cat_pattern(cmt_field, subpat, op);
}
}
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Some(&ast::def_const(*)) => {
for subpats.each |&subpat| {
self.cat_pattern(cmt, subpat, op);
}
}
_ => {
self.tcx.sess.span_bug(
pat.span,
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"enum pattern didn't resolve to enum or struct");
}
}
}
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ast::pat_ident(_, _, Some(subpat)) => {
self.cat_pattern(cmt, subpat, op);
}
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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, pat.id);
self.cat_pattern(cmt_field, fp.pat, op);
}
}
ast::pat_tup(ref subpats) => {
// (p1, ..., pN)
for subpats.each |&subpat| {
let subpat_ty = self.pat_ty(subpat); // see (*)
let subcmt = self.cat_imm_interior(pat, cmt, subpat_ty,
interior_tuple);
self.cat_pattern(subcmt, subpat, op);
}
}
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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) => {
for before.each |&before_pat| {
let elt_cmt = self.cat_index(pat, cmt);
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| {
let elt_cmt = self.cat_index(pat, cmt);
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 {
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cat_static_item => ~"static item",
cat_implicit_self => ~"self reference",
cat_copied_upvar(_) => {
~"captured outer variable in a heap closure"
}
cat_rvalue => ~"non-lvalue",
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cat_local(_) => ~"local variable",
cat_self(_) => ~"self value",
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cat_arg(*) => ~"argument",
cat_deref(_, _, pk) => fmt!("dereference of %s pointer",
ptr_sigil(pk)),
cat_interior(_, interior_field(*)) => ~"field",
cat_interior(_, interior_tuple) => ~"tuple content",
cat_interior(_, interior_anon_field) => ~"anonymous field",
cat_interior(_, interior_variant(_)) => ~"enum content",
cat_interior(_, interior_index(t, _)) => {
match ty::get(t).sty {
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ty::ty_evec(*) => ~"vec content",
ty::ty_estr(*) => ~"str content",
_ => ~"indexed content"
}
}
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cat_stack_upvar(_) => {
~"captured outer variable"
}
cat_discr(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<ast::mutability> {
// 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);
}
}
}
_ => {}
}
}
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_ => { }
}
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return None;
}
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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
}
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cat_stack_upvar(b) |
cat_discr(b, _) |
cat_interior(b, _) |
cat_deref(b, _, uniq_ptr(*)) => {
b.guarantor()
}
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}
}
fn is_freely_aliasable(&self) -> bool {
self.freely_aliasable().is_some()
}
fn freely_aliasable(&self) -> Option<AliasableReason> {
//! 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(*) |
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cat_arg(_) |
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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(*) |
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cat_implicit_self(*) => {
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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_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 |
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cat_copied_upvar(*) |
cat_local(*) |
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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))
}
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cat_stack_upvar(cmt) |
cat_discr(cmt, _) => cmt.cat.repr(tcx)
}
}
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}
pub fn ptr_sigil(ptr: ptr_kind) -> ~str {
match ptr {
uniq_ptr(_) => ~"~",
gc_ptr(_) => ~"@",
region_ptr(_, _) => ~"&",
unsafe_ptr => ~"*"
}
}
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impl Repr for interior_kind {
fn repr(&self, tcx: ty::ctxt) -> ~str {
match *self {
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interior_field(fld, _) => copy *tcx.sess.str_of(fld),
interior_index(*) => ~"[]",
interior_tuple => ~"()",
interior_anon_field => ~"<anonymous field>",
interior_variant(_) => ~"<enum>"
}
}
}