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intrinsicck.rs
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intrinsicck.rs
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// 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.
use metadata::csearch;
use middle::def::DefFn;
use middle::subst::Subst;
use middle::ty::{TransmuteRestriction, ctxt, ty_bare_fn};
use middle::ty;
use syntax::abi::RustIntrinsic;
use syntax::ast::DefId;
use syntax::ast;
use syntax::ast_map::NodeForeignItem;
use syntax::codemap::Span;
use syntax::parse::token;
use syntax::visit::Visitor;
use syntax::visit;
fn type_size_is_affected_by_type_parameters(tcx: &ty::ctxt, typ: ty::t)
-> bool {
let mut result = false;
ty::maybe_walk_ty(typ, |typ| {
match ty::get(typ).sty {
ty::ty_uniq(_) | ty::ty_ptr(_) | ty::ty_rptr(..) |
ty::ty_bare_fn(..) | ty::ty_closure(..) => {
false
}
ty::ty_param(_) => {
result = true;
// No need to continue; we now know the result.
false
}
ty::ty_enum(did, ref substs) => {
for enum_variant in (*ty::enum_variants(tcx, did)).iter() {
for argument_type in enum_variant.args.iter() {
let argument_type = argument_type.subst(tcx, substs);
result = result ||
type_size_is_affected_by_type_parameters(
tcx,
argument_type);
}
}
// Don't traverse substitutions.
false
}
ty::ty_struct(did, ref substs) => {
for field in ty::struct_fields(tcx, did, substs).iter() {
result = result ||
type_size_is_affected_by_type_parameters(tcx,
field.mt.ty);
}
// Don't traverse substitutions.
false
}
_ => true,
}
});
result
}
struct IntrinsicCheckingVisitor<'a, 'tcx: 'a> {
tcx: &'a ctxt<'tcx>,
}
impl<'a, 'tcx> IntrinsicCheckingVisitor<'a, 'tcx> {
fn def_id_is_transmute(&self, def_id: DefId) -> bool {
let intrinsic = match ty::get(ty::lookup_item_type(self.tcx, def_id).ty).sty {
ty::ty_bare_fn(ref bfty) => bfty.abi == RustIntrinsic,
_ => return false
};
if def_id.krate == ast::LOCAL_CRATE {
match self.tcx.map.get(def_id.node) {
NodeForeignItem(ref item) if intrinsic => {
token::get_ident(item.ident) ==
token::intern_and_get_ident("transmute")
}
_ => false,
}
} else {
match csearch::get_item_path(self.tcx, def_id).last() {
Some(ref last) if intrinsic => {
token::get_name(last.name()) ==
token::intern_and_get_ident("transmute")
}
_ => false,
}
}
}
fn check_transmute(&self, span: Span, from: ty::t, to: ty::t, id: ast::NodeId) {
if type_size_is_affected_by_type_parameters(self.tcx, from) {
span_err!(self.tcx.sess, span, E0139,
"cannot transmute from a type that contains type parameters");
}
if type_size_is_affected_by_type_parameters(self.tcx, to) {
span_err!(self.tcx.sess, span, E0140,
"cannot transmute to a type that contains type parameters");
}
let restriction = TransmuteRestriction {
span: span,
from: from,
to: to,
id: id,
};
self.tcx.transmute_restrictions.borrow_mut().push(restriction);
}
}
impl<'a, 'tcx, 'v> Visitor<'v> for IntrinsicCheckingVisitor<'a, 'tcx> {
fn visit_expr(&mut self, expr: &ast::Expr) {
match expr.node {
ast::ExprPath(..) => {
match ty::resolve_expr(self.tcx, expr) {
DefFn(did, _) if self.def_id_is_transmute(did) => {
let typ = ty::node_id_to_type(self.tcx, expr.id);
match ty::get(typ).sty {
ty_bare_fn(ref bare_fn_ty)
if bare_fn_ty.abi == RustIntrinsic => {
if let ty::FnConverging(to) = bare_fn_ty.sig.output {
let from = bare_fn_ty.sig.inputs[0];
self.check_transmute(expr.span, from, to, expr.id);
}
}
_ => {
self.tcx
.sess
.span_bug(expr.span,
"transmute wasn't a bare fn?!");
}
}
}
_ => {}
}
}
_ => {}
}
visit::walk_expr(self, expr);
}
}
pub fn check_crate(tcx: &ctxt) {
visit::walk_crate(&mut IntrinsicCheckingVisitor { tcx: tcx },
tcx.map.krate());
}