730 lines
28 KiB
Rust
730 lines
28 KiB
Rust
// Copyright 2012-2014 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.
|
|
|
|
// Verifies that the types and values of const and static items
|
|
// are safe. The rules enforced by this module are:
|
|
//
|
|
// - For each *mutable* static item, it checks that its **type**:
|
|
// - doesn't have a destructor
|
|
// - doesn't own an owned pointer
|
|
//
|
|
// - For each *immutable* static item, it checks that its **value**:
|
|
// - doesn't own owned, managed pointers
|
|
// - doesn't contain a struct literal or a call to an enum variant / struct constructor where
|
|
// - the type of the struct/enum has a dtor
|
|
//
|
|
// Rules Enforced Elsewhere:
|
|
// - It's not possible to take the address of a static item with unsafe interior. This is enforced
|
|
// by borrowck::gather_loans
|
|
|
|
use middle::const_eval;
|
|
use middle::def;
|
|
use middle::expr_use_visitor as euv;
|
|
use middle::infer;
|
|
use middle::mem_categorization as mc;
|
|
use middle::traits;
|
|
use middle::ty::{self, Ty};
|
|
use util::nodemap::NodeMap;
|
|
use util::ppaux;
|
|
|
|
use syntax::ast;
|
|
use syntax::codemap::Span;
|
|
use syntax::print::pprust;
|
|
use syntax::visit::{self, Visitor};
|
|
|
|
use std::collections::hash_map::Entry;
|
|
|
|
// Const qualification, from partial to completely promotable.
|
|
bitflags! {
|
|
#[derive(RustcEncodable, RustcDecodable)]
|
|
flags ConstQualif: u8 {
|
|
// Const rvalue which can be placed behind a reference.
|
|
const PURE_CONST = 0b000000,
|
|
// Inner mutability (can not be placed behind a reference) or behind
|
|
// &mut in a non-global expression. Can be copied from static memory.
|
|
const MUTABLE_MEM = 0b000001,
|
|
// Constant value with a type that implements Drop. Can be copied
|
|
// from static memory, similar to MUTABLE_MEM.
|
|
const NEEDS_DROP = 0b000010,
|
|
// Even if the value can be placed in static memory, copying it from
|
|
// there is more expensive than in-place instantiation, and/or it may
|
|
// be too large. This applies to [T; N] and everything containing it.
|
|
// N.B.: references need to clear this flag to not end up on the stack.
|
|
const PREFER_IN_PLACE = 0b000100,
|
|
// May use more than 0 bytes of memory, doesn't impact the constness
|
|
// directly, but is not allowed to be borrowed mutably in a constant.
|
|
const NON_ZERO_SIZED = 0b001000,
|
|
// Actually borrowed, has to always be in static memory. Does not
|
|
// propagate, and requires the expression to behave like a 'static
|
|
// lvalue. The set of expressions with this flag is the minimum
|
|
// that have to be promoted.
|
|
const HAS_STATIC_BORROWS = 0b010000,
|
|
// Invalid const for miscellaneous reasons (e.g. not implemented).
|
|
const NOT_CONST = 0b100000,
|
|
|
|
// Borrowing the expression won't produce &'static T if any of these
|
|
// bits are set, though the value could be copied from static memory
|
|
// if `NOT_CONST` isn't set.
|
|
const NON_STATIC_BORROWS = MUTABLE_MEM.bits | NEEDS_DROP.bits | NOT_CONST.bits
|
|
}
|
|
}
|
|
|
|
#[derive(Copy, Eq, PartialEq)]
|
|
enum Mode {
|
|
Const,
|
|
Static,
|
|
StaticMut,
|
|
|
|
// An expression that occurs outside of any constant context
|
|
// (i.e. `const`, `static`, array lengths, etc.). The value
|
|
// can be variable at runtime, but will be promotable to
|
|
// static memory if we can prove it is actually constant.
|
|
Var,
|
|
}
|
|
|
|
struct CheckCrateVisitor<'a, 'tcx: 'a> {
|
|
tcx: &'a ty::ctxt<'tcx>,
|
|
mode: Mode,
|
|
qualif: ConstQualif,
|
|
rvalue_borrows: NodeMap<ast::Mutability>
|
|
}
|
|
|
|
impl<'a, 'tcx> CheckCrateVisitor<'a, 'tcx> {
|
|
fn with_mode<F, R>(&mut self, mode: Mode, f: F) -> R where
|
|
F: FnOnce(&mut CheckCrateVisitor<'a, 'tcx>) -> R,
|
|
{
|
|
let (old_mode, old_qualif) = (self.mode, self.qualif);
|
|
self.mode = mode;
|
|
self.qualif = PURE_CONST;
|
|
let r = f(self);
|
|
self.mode = old_mode;
|
|
self.qualif = old_qualif;
|
|
r
|
|
}
|
|
|
|
fn with_euv<'b, F, R>(&'b mut self, item_id: Option<ast::NodeId>, f: F) -> R where
|
|
F: for<'t> FnOnce(&mut euv::ExprUseVisitor<'b, 't, 'tcx,
|
|
ty::ParameterEnvironment<'a, 'tcx>>) -> R,
|
|
{
|
|
let param_env = match item_id {
|
|
Some(item_id) => ty::ParameterEnvironment::for_item(self.tcx, item_id),
|
|
None => ty::empty_parameter_environment(self.tcx)
|
|
};
|
|
f(&mut euv::ExprUseVisitor::new(self, ¶m_env))
|
|
}
|
|
|
|
fn global_expr(&mut self, mode: Mode, expr: &ast::Expr) -> ConstQualif {
|
|
assert!(mode != Mode::Var);
|
|
match self.tcx.const_qualif_map.borrow_mut().entry(expr.id) {
|
|
Entry::Occupied(entry) => return *entry.get(),
|
|
Entry::Vacant(entry) => {
|
|
// Prevent infinite recursion on re-entry.
|
|
entry.insert(PURE_CONST);
|
|
}
|
|
}
|
|
self.with_mode(mode, |this| {
|
|
this.with_euv(None, |euv| euv.consume_expr(expr));
|
|
this.visit_expr(expr);
|
|
this.qualif
|
|
})
|
|
}
|
|
|
|
fn add_qualif(&mut self, qualif: ConstQualif) {
|
|
self.qualif = self.qualif | qualif;
|
|
}
|
|
|
|
fn record_borrow(&mut self, id: ast::NodeId, mutbl: ast::Mutability) {
|
|
match self.rvalue_borrows.entry(id) {
|
|
Entry::Occupied(mut entry) => {
|
|
// Merge the two borrows, taking the most demanding
|
|
// one, mutability-wise.
|
|
if mutbl == ast::MutMutable {
|
|
entry.insert(mutbl);
|
|
}
|
|
}
|
|
Entry::Vacant(entry) => {
|
|
entry.insert(mutbl);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn msg(&self) -> &'static str {
|
|
match self.mode {
|
|
Mode::Const => "constant",
|
|
Mode::StaticMut | Mode::Static => "static",
|
|
Mode::Var => unreachable!(),
|
|
}
|
|
}
|
|
|
|
fn check_static_mut_type(&self, e: &ast::Expr) {
|
|
let node_ty = ty::node_id_to_type(self.tcx, e.id);
|
|
let tcontents = ty::type_contents(self.tcx, node_ty);
|
|
|
|
let suffix = if tcontents.has_dtor() {
|
|
"destructors"
|
|
} else if tcontents.owns_owned() {
|
|
"owned pointers"
|
|
} else {
|
|
return
|
|
};
|
|
|
|
self.tcx.sess.span_err(e.span, &format!("mutable statics are not allowed \
|
|
to have {}", suffix)[]);
|
|
}
|
|
|
|
fn check_static_type(&self, e: &ast::Expr) {
|
|
let ty = ty::node_id_to_type(self.tcx, e.id);
|
|
let infcx = infer::new_infer_ctxt(self.tcx);
|
|
let mut fulfill_cx = traits::FulfillmentContext::new();
|
|
let cause = traits::ObligationCause::new(e.span, e.id, traits::SharedStatic);
|
|
fulfill_cx.register_builtin_bound(&infcx, ty, ty::BoundSync, cause);
|
|
let env = ty::empty_parameter_environment(self.tcx);
|
|
match fulfill_cx.select_all_or_error(&infcx, &env) {
|
|
Ok(()) => { },
|
|
Err(ref errors) => {
|
|
traits::report_fulfillment_errors(&infcx, errors);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx, 'v> Visitor<'v> for CheckCrateVisitor<'a, 'tcx> {
|
|
fn visit_item(&mut self, i: &ast::Item) {
|
|
debug!("visit_item(item={})", pprust::item_to_string(i));
|
|
match i.node {
|
|
ast::ItemStatic(_, ast::MutImmutable, ref expr) => {
|
|
self.check_static_type(&**expr);
|
|
self.global_expr(Mode::Static, &**expr);
|
|
}
|
|
ast::ItemStatic(_, ast::MutMutable, ref expr) => {
|
|
self.check_static_mut_type(&**expr);
|
|
self.global_expr(Mode::StaticMut, &**expr);
|
|
}
|
|
ast::ItemConst(_, ref expr) => {
|
|
self.global_expr(Mode::Const, &**expr);
|
|
}
|
|
ast::ItemEnum(ref enum_definition, _) => {
|
|
for var in &enum_definition.variants {
|
|
if let Some(ref ex) = var.node.disr_expr {
|
|
self.global_expr(Mode::Const, &**ex);
|
|
}
|
|
}
|
|
}
|
|
_ => {
|
|
self.with_mode(Mode::Var, |v| visit::walk_item(v, i));
|
|
}
|
|
}
|
|
}
|
|
|
|
fn visit_fn(&mut self,
|
|
fk: visit::FnKind<'v>,
|
|
fd: &'v ast::FnDecl,
|
|
b: &'v ast::Block,
|
|
s: Span,
|
|
fn_id: ast::NodeId) {
|
|
assert!(self.mode == Mode::Var);
|
|
self.with_euv(Some(fn_id), |euv| euv.walk_fn(fd, b));
|
|
visit::walk_fn(self, fk, fd, b, s);
|
|
}
|
|
|
|
fn visit_pat(&mut self, p: &ast::Pat) {
|
|
match p.node {
|
|
ast::PatLit(ref lit) => {
|
|
self.global_expr(Mode::Const, &**lit);
|
|
}
|
|
ast::PatRange(ref start, ref end) => {
|
|
self.global_expr(Mode::Const, &**start);
|
|
self.global_expr(Mode::Const, &**end);
|
|
}
|
|
_ => visit::walk_pat(self, p)
|
|
}
|
|
}
|
|
|
|
fn visit_expr(&mut self, ex: &ast::Expr) {
|
|
let mut outer = self.qualif;
|
|
self.qualif = PURE_CONST;
|
|
|
|
let node_ty = ty::node_id_to_type(self.tcx, ex.id);
|
|
check_expr(self, ex, node_ty);
|
|
|
|
// Special-case some expressions to avoid certain flags bubbling up.
|
|
match ex.node {
|
|
ast::ExprCall(ref callee, ref args) => {
|
|
for arg in args.iter() {
|
|
self.visit_expr(&**arg)
|
|
}
|
|
|
|
let inner = self.qualif;
|
|
self.visit_expr(&**callee);
|
|
// The callee's size doesn't count in the call.
|
|
let added = self.qualif - inner;
|
|
self.qualif = inner | (added - NON_ZERO_SIZED);
|
|
}
|
|
ast::ExprRepeat(ref element, _) => {
|
|
self.visit_expr(&**element);
|
|
// The count is checked elsewhere (typeck).
|
|
let count = match node_ty.sty {
|
|
ty::ty_vec(_, Some(n)) => n,
|
|
_ => unreachable!()
|
|
};
|
|
// [element; 0] is always zero-sized.
|
|
if count == 0 {
|
|
self.qualif = self.qualif - (NON_ZERO_SIZED | PREFER_IN_PLACE);
|
|
}
|
|
}
|
|
ast::ExprMatch(ref discr, ref arms, _) => {
|
|
// Compute the most demanding borrow from all the arms'
|
|
// patterns and set that on the discriminator.
|
|
let mut borrow = None;
|
|
for pat in arms.iter().flat_map(|arm| arm.pats.iter()) {
|
|
let pat_borrow = self.rvalue_borrows.remove(&pat.id);
|
|
match (borrow, pat_borrow) {
|
|
(None, _) | (_, Some(ast::MutMutable)) => {
|
|
borrow = pat_borrow;
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
if let Some(mutbl) = borrow {
|
|
self.record_borrow(discr.id, mutbl);
|
|
}
|
|
visit::walk_expr(self, ex);
|
|
}
|
|
// Division by zero and overflow checking.
|
|
ast::ExprBinary(op, _, _) => {
|
|
visit::walk_expr(self, ex);
|
|
let div_or_rem = op.node == ast::BiDiv || op.node == ast::BiRem;
|
|
match node_ty.sty {
|
|
ty::ty_uint(_) | ty::ty_int(_) if div_or_rem => {
|
|
if !self.qualif.intersects(NOT_CONST) {
|
|
match const_eval::eval_const_expr_partial(self.tcx, ex, None) {
|
|
Ok(_) => {}
|
|
Err(msg) => {
|
|
span_err!(self.tcx.sess, ex.span, E0020,
|
|
"{} in a constant expression", msg)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
_ => visit::walk_expr(self, ex)
|
|
}
|
|
|
|
// Handle borrows on (or inside the autorefs of) this expression.
|
|
match self.rvalue_borrows.remove(&ex.id) {
|
|
Some(ast::MutImmutable) => {
|
|
// Constants cannot be borrowed if they contain interior mutability as
|
|
// it means that our "silent insertion of statics" could change
|
|
// initializer values (very bad).
|
|
// If the type doesn't have interior mutability, then `MUTABLE_MEM` has
|
|
// propagated from another error, so erroring again would be just noise.
|
|
let tc = ty::type_contents(self.tcx, node_ty);
|
|
if self.qualif.intersects(MUTABLE_MEM) && tc.interior_unsafe() {
|
|
outer = outer | NOT_CONST;
|
|
if self.mode != Mode::Var {
|
|
self.tcx.sess.span_err(ex.span,
|
|
"cannot borrow a constant which contains \
|
|
interior mutability, create a static instead");
|
|
}
|
|
}
|
|
// If the reference has to be 'static, avoid in-place initialization
|
|
// as that will end up pointing to the stack instead.
|
|
if !self.qualif.intersects(NON_STATIC_BORROWS) {
|
|
self.qualif = self.qualif - PREFER_IN_PLACE;
|
|
self.add_qualif(HAS_STATIC_BORROWS);
|
|
}
|
|
}
|
|
Some(ast::MutMutable) => {
|
|
// `&mut expr` means expr could be mutated, unless it's zero-sized.
|
|
if self.qualif.intersects(NON_ZERO_SIZED) {
|
|
if self.mode == Mode::Var {
|
|
outer = outer | NOT_CONST;
|
|
self.add_qualif(MUTABLE_MEM);
|
|
} else {
|
|
span_err!(self.tcx.sess, ex.span, E0017,
|
|
"references in {}s may only refer \
|
|
to immutable values", self.msg())
|
|
}
|
|
}
|
|
if !self.qualif.intersects(NON_STATIC_BORROWS) {
|
|
self.add_qualif(HAS_STATIC_BORROWS);
|
|
}
|
|
}
|
|
None => {}
|
|
}
|
|
self.tcx.const_qualif_map.borrow_mut().insert(ex.id, self.qualif);
|
|
// Don't propagate certain flags.
|
|
self.qualif = outer | (self.qualif - HAS_STATIC_BORROWS);
|
|
}
|
|
}
|
|
|
|
/// This function is used to enforce the constraints on
|
|
/// const/static items. It walks through the *value*
|
|
/// of the item walking down the expression and evaluating
|
|
/// every nested expression. If the expression is not part
|
|
/// of a const/static item, it is qualified for promotion
|
|
/// instead of producing errors.
|
|
fn check_expr<'a, 'tcx>(v: &mut CheckCrateVisitor<'a, 'tcx>,
|
|
e: &ast::Expr, node_ty: Ty<'tcx>) {
|
|
match node_ty.sty {
|
|
ty::ty_struct(did, _) |
|
|
ty::ty_enum(did, _) if ty::has_dtor(v.tcx, did) => {
|
|
v.add_qualif(NEEDS_DROP);
|
|
if v.mode != Mode::Var {
|
|
v.tcx.sess.span_err(e.span,
|
|
&format!("{}s are not allowed to have destructors",
|
|
v.msg())[]);
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
let method_call = ty::MethodCall::expr(e.id);
|
|
match e.node {
|
|
ast::ExprUnary(..) |
|
|
ast::ExprBinary(..) |
|
|
ast::ExprIndex(..) if v.tcx.method_map.borrow().contains_key(&method_call) => {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
span_err!(v.tcx.sess, e.span, E0011,
|
|
"user-defined operators are not allowed in {}s", v.msg());
|
|
}
|
|
}
|
|
ast::ExprBox(..) |
|
|
ast::ExprUnary(ast::UnUniq, _) => {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
span_err!(v.tcx.sess, e.span, E0010,
|
|
"allocations are not allowed in {}s", v.msg());
|
|
}
|
|
}
|
|
ast::ExprUnary(ast::UnDeref, ref ptr) => {
|
|
match ty::node_id_to_type(v.tcx, ptr.id).sty {
|
|
ty::ty_ptr(_) => {
|
|
// This shouldn't be allowed in constants at all.
|
|
v.add_qualif(NOT_CONST);
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
ast::ExprCast(ref from, _) => {
|
|
let toty = ty::expr_ty(v.tcx, e);
|
|
let fromty = ty::expr_ty(v.tcx, &**from);
|
|
let is_legal_cast =
|
|
ty::type_is_numeric(toty) ||
|
|
ty::type_is_unsafe_ptr(toty) ||
|
|
(ty::type_is_bare_fn(toty) && ty::type_is_bare_fn_item(fromty));
|
|
if !is_legal_cast {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
span_err!(v.tcx.sess, e.span, E0012,
|
|
"can not cast to `{}` in {}s",
|
|
ppaux::ty_to_string(v.tcx, toty), v.msg());
|
|
}
|
|
}
|
|
if ty::type_is_unsafe_ptr(fromty) && ty::type_is_numeric(toty) {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
span_err!(v.tcx.sess, e.span, E0018,
|
|
"can not cast a pointer to an integer in {}s", v.msg());
|
|
}
|
|
}
|
|
}
|
|
ast::ExprPath(_) | ast::ExprQPath(_) => {
|
|
let def = v.tcx.def_map.borrow().get(&e.id).cloned();
|
|
match def {
|
|
Some(def::DefVariant(_, _, _)) => {
|
|
// Count the discriminator or function pointer.
|
|
v.add_qualif(NON_ZERO_SIZED);
|
|
}
|
|
Some(def::DefStruct(_)) => {
|
|
if let ty::ty_bare_fn(..) = node_ty.sty {
|
|
// Count the function pointer.
|
|
v.add_qualif(NON_ZERO_SIZED);
|
|
}
|
|
}
|
|
Some(def::DefFn(..)) |
|
|
Some(def::DefStaticMethod(..)) | Some(def::DefMethod(..)) => {
|
|
// Count the function pointer.
|
|
v.add_qualif(NON_ZERO_SIZED);
|
|
}
|
|
Some(def::DefStatic(..)) => {
|
|
match v.mode {
|
|
Mode::Static | Mode::StaticMut => {}
|
|
Mode::Const => {
|
|
span_err!(v.tcx.sess, e.span, E0013,
|
|
"constants cannot refer to other statics, \
|
|
insert an intermediate constant instead");
|
|
}
|
|
Mode::Var => v.add_qualif(NOT_CONST)
|
|
}
|
|
}
|
|
Some(def::DefConst(did)) => {
|
|
if let Some(expr) = const_eval::lookup_const_by_id(v.tcx, did) {
|
|
let inner = v.global_expr(Mode::Const, expr);
|
|
v.add_qualif(inner);
|
|
} else {
|
|
v.tcx.sess.span_bug(e.span, "DefConst doesn't point \
|
|
to an ItemConst");
|
|
}
|
|
}
|
|
def => {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
debug!("(checking const) found bad def: {:?}", def);
|
|
span_err!(v.tcx.sess, e.span, E0014,
|
|
"paths in {}s may only refer to constants \
|
|
or functions", v.msg());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
ast::ExprCall(ref callee, _) => {
|
|
let mut callee = &**callee;
|
|
loop {
|
|
callee = match callee.node {
|
|
ast::ExprParen(ref inner) => &**inner,
|
|
ast::ExprBlock(ref block) => match block.expr {
|
|
Some(ref tail) => &**tail,
|
|
None => break
|
|
},
|
|
_ => break
|
|
};
|
|
}
|
|
let def = v.tcx.def_map.borrow().get(&callee.id).cloned();
|
|
match def {
|
|
Some(def::DefStruct(..)) => {}
|
|
Some(def::DefVariant(..)) => {
|
|
// Count the discriminator.
|
|
v.add_qualif(NON_ZERO_SIZED);
|
|
}
|
|
_ => {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
span_err!(v.tcx.sess, e.span, E0015,
|
|
"function calls in {}s are limited to \
|
|
struct and enum constructors", v.msg());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
ast::ExprBlock(ref block) => {
|
|
// Check all statements in the block
|
|
let mut block_span_err = |span| {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
span_err!(v.tcx.sess, span, E0016,
|
|
"blocks in {}s are limited to items and \
|
|
tail expressions", v.msg());
|
|
}
|
|
};
|
|
for stmt in &block.stmts {
|
|
match stmt.node {
|
|
ast::StmtDecl(ref decl, _) => {
|
|
match decl.node {
|
|
ast::DeclLocal(_) => block_span_err(decl.span),
|
|
|
|
// Item statements are allowed
|
|
ast::DeclItem(_) => {}
|
|
}
|
|
}
|
|
ast::StmtExpr(ref expr, _) => block_span_err(expr.span),
|
|
ast::StmtSemi(ref semi, _) => block_span_err(semi.span),
|
|
ast::StmtMac(..) => {
|
|
v.tcx.sess.span_bug(e.span, "unexpanded statement \
|
|
macro in const?!")
|
|
}
|
|
}
|
|
}
|
|
}
|
|
ast::ExprStruct(..) => {
|
|
let did = v.tcx.def_map.borrow().get(&e.id).map(|def| def.def_id());
|
|
if did == v.tcx.lang_items.unsafe_cell_type() {
|
|
v.add_qualif(MUTABLE_MEM);
|
|
}
|
|
}
|
|
|
|
ast::ExprLit(_) |
|
|
ast::ExprAddrOf(..) => {
|
|
v.add_qualif(NON_ZERO_SIZED);
|
|
}
|
|
|
|
ast::ExprRepeat(..) => {
|
|
v.add_qualif(PREFER_IN_PLACE);
|
|
}
|
|
|
|
ast::ExprClosure(..) => {
|
|
// Paths in constant constexts cannot refer to local variables,
|
|
// as there are none, and thus closures can't have upvars there.
|
|
if ty::with_freevars(v.tcx, e.id, |fv| !fv.is_empty()) {
|
|
assert!(v.mode == Mode::Var,
|
|
"global closures can't capture anything");
|
|
v.add_qualif(NOT_CONST);
|
|
}
|
|
}
|
|
|
|
ast::ExprUnary(..) |
|
|
ast::ExprBinary(..) |
|
|
ast::ExprIndex(..) |
|
|
ast::ExprField(..) |
|
|
ast::ExprTupField(..) |
|
|
ast::ExprVec(_) |
|
|
ast::ExprParen(..) |
|
|
ast::ExprTup(..) => {}
|
|
|
|
// Conditional control flow (possible to implement).
|
|
ast::ExprMatch(..) |
|
|
ast::ExprIf(..) |
|
|
ast::ExprIfLet(..) |
|
|
|
|
// Loops (not very meaningful in constants).
|
|
ast::ExprWhile(..) |
|
|
ast::ExprWhileLet(..) |
|
|
ast::ExprForLoop(..) |
|
|
ast::ExprLoop(..) |
|
|
|
|
// More control flow (also not very meaningful).
|
|
ast::ExprBreak(_) |
|
|
ast::ExprAgain(_) |
|
|
ast::ExprRet(_) |
|
|
|
|
// Miscellaneous expressions that could be implemented.
|
|
ast::ExprRange(..) |
|
|
|
|
// Various other expressions.
|
|
ast::ExprMethodCall(..) |
|
|
ast::ExprAssign(..) |
|
|
ast::ExprAssignOp(..) |
|
|
ast::ExprInlineAsm(_) |
|
|
ast::ExprMac(_) => {
|
|
v.add_qualif(NOT_CONST);
|
|
if v.mode != Mode::Var {
|
|
span_err!(v.tcx.sess, e.span, E0019,
|
|
"{} contains unimplemented expression type", v.msg());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn check_crate(tcx: &ty::ctxt) {
|
|
visit::walk_crate(&mut CheckCrateVisitor {
|
|
tcx: tcx,
|
|
mode: Mode::Var,
|
|
qualif: NOT_CONST,
|
|
rvalue_borrows: NodeMap()
|
|
}, tcx.map.krate());
|
|
|
|
tcx.sess.abort_if_errors();
|
|
}
|
|
|
|
impl<'a, 'tcx> euv::Delegate<'tcx> for CheckCrateVisitor<'a, 'tcx> {
|
|
fn consume(&mut self,
|
|
_consume_id: ast::NodeId,
|
|
consume_span: Span,
|
|
cmt: mc::cmt,
|
|
_mode: euv::ConsumeMode) {
|
|
let mut cur = &cmt;
|
|
loop {
|
|
match cur.cat {
|
|
mc::cat_static_item => {
|
|
if self.mode != Mode::Var {
|
|
// statics cannot be consumed by value at any time, that would imply
|
|
// that they're an initializer (what a const is for) or kept in sync
|
|
// over time (not feasible), so deny it outright.
|
|
self.tcx.sess.span_err(consume_span,
|
|
"cannot refer to other statics by value, use the \
|
|
address-of operator or a constant instead");
|
|
}
|
|
break;
|
|
}
|
|
mc::cat_deref(ref cmt, _, _) |
|
|
mc::cat_downcast(ref cmt, _) |
|
|
mc::cat_interior(ref cmt, _) => cur = cmt,
|
|
|
|
mc::cat_rvalue(..) |
|
|
mc::cat_upvar(..) |
|
|
mc::cat_local(..) => break
|
|
}
|
|
}
|
|
}
|
|
fn borrow(&mut self,
|
|
borrow_id: ast::NodeId,
|
|
borrow_span: Span,
|
|
cmt: mc::cmt<'tcx>,
|
|
_loan_region: ty::Region,
|
|
bk: ty::BorrowKind,
|
|
loan_cause: euv::LoanCause) {
|
|
let mut cur = &cmt;
|
|
let mut is_interior = false;
|
|
loop {
|
|
match cur.cat {
|
|
mc::cat_rvalue(..) => {
|
|
if loan_cause == euv::MatchDiscriminant {
|
|
// Ignore the dummy immutable borrow created by EUV.
|
|
break;
|
|
}
|
|
let mutbl = bk.to_mutbl_lossy();
|
|
if mutbl == ast::MutMutable && self.mode == Mode::StaticMut {
|
|
// Mutable slices are the only `&mut` allowed in globals,
|
|
// but only in `static mut`, nowhere else.
|
|
match cmt.ty.sty {
|
|
ty::ty_vec(_, _) => break,
|
|
_ => {}
|
|
}
|
|
}
|
|
self.record_borrow(borrow_id, mutbl);
|
|
break;
|
|
}
|
|
mc::cat_static_item => {
|
|
if is_interior && self.mode != Mode::Var {
|
|
// Borrowed statics can specifically *only* have their address taken,
|
|
// not any number of other borrows such as borrowing fields, reading
|
|
// elements of an array, etc.
|
|
self.tcx.sess.span_err(borrow_span,
|
|
"cannot refer to the interior of another \
|
|
static, use a constant instead");
|
|
}
|
|
break;
|
|
}
|
|
mc::cat_deref(ref cmt, _, _) |
|
|
mc::cat_downcast(ref cmt, _) |
|
|
mc::cat_interior(ref cmt, _) => {
|
|
is_interior = true;
|
|
cur = cmt;
|
|
}
|
|
|
|
mc::cat_upvar(..) |
|
|
mc::cat_local(..) => break
|
|
}
|
|
}
|
|
}
|
|
|
|
fn decl_without_init(&mut self,
|
|
_id: ast::NodeId,
|
|
_span: Span) {}
|
|
fn mutate(&mut self,
|
|
_assignment_id: ast::NodeId,
|
|
_assignment_span: Span,
|
|
_assignee_cmt: mc::cmt,
|
|
_mode: euv::MutateMode) {}
|
|
|
|
fn matched_pat(&mut self,
|
|
_: &ast::Pat,
|
|
_: mc::cmt,
|
|
_: euv::MatchMode) {}
|
|
|
|
fn consume_pat(&mut self,
|
|
_consume_pat: &ast::Pat,
|
|
_cmt: mc::cmt,
|
|
_mode: euv::ConsumeMode) {}
|
|
}
|