rust/src/librustc/middle/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 dep_graph::DepNode;
use hir::def::Def;
use hir::def_id::DefId;
use infer::InferCtxt;
use traits::Reveal;
use ty::{self, Ty, TyCtxt};
use ty::layout::{LayoutError, Pointer, SizeSkeleton};
use syntax::abi::Abi::RustIntrinsic;
use syntax::ast;
use syntax_pos::Span;
use hir::intravisit::{self, Visitor, FnKind, NestedVisitorMap};
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use hir;
pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
let mut visitor = ItemVisitor {
tcx: tcx
};
tcx.visit_all_item_likes_in_krate(DepNode::IntrinsicCheck, &mut visitor.as_deep_visitor());
}
struct ItemVisitor<'a, 'tcx: 'a> {
tcx: TyCtxt<'a, 'tcx, 'tcx>
}
impl<'a, 'tcx> ItemVisitor<'a, 'tcx> {
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fn visit_const(&mut self, item_id: ast::NodeId, expr: &'tcx hir::Expr) {
let param_env = ty::ParameterEnvironment::for_item(self.tcx, item_id);
self.tcx.infer_ctxt(None, Some(param_env), Reveal::All).enter(|infcx| {
let mut visitor = ExprVisitor {
infcx: &infcx
};
visitor.visit_expr(expr);
});
}
}
struct ExprVisitor<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
infcx: &'a InferCtxt<'a, 'gcx, 'tcx>
}
impl<'a, 'gcx, 'tcx> ExprVisitor<'a, 'gcx, 'tcx> {
fn def_id_is_transmute(&self, def_id: DefId) -> bool {
let intrinsic = match self.infcx.tcx.item_type(def_id).sty {
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ty::TyFnDef(.., ref bfty) => bfty.abi == RustIntrinsic,
_ => return false
};
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intrinsic && self.infcx.tcx.item_name(def_id) == "transmute"
}
fn check_transmute(&self, span: Span, from: Ty<'gcx>, to: Ty<'gcx>, id: ast::NodeId) {
let sk_from = SizeSkeleton::compute(from, self.infcx);
let sk_to = SizeSkeleton::compute(to, self.infcx);
// Check for same size using the skeletons.
if let (Ok(sk_from), Ok(sk_to)) = (sk_from, sk_to) {
if sk_from.same_size(sk_to) {
return;
}
match (&from.sty, sk_to) {
(&ty::TyFnDef(..), SizeSkeleton::Known(size_to))
if size_to == Pointer.size(&self.infcx.tcx.data_layout) => {
// FIXME #19925 Remove this warning after a release cycle.
let msg = format!("`{}` is now zero-sized and has to be cast \
to a pointer before transmuting to `{}`",
from, to);
self.infcx.tcx.sess.add_lint(
::lint::builtin::TRANSMUTE_FROM_FN_ITEM_TYPES, id, span, msg);
return;
}
_ => {}
}
}
// Try to display a sensible error with as much information as possible.
let skeleton_string = |ty: Ty<'gcx>, sk| {
match sk {
Ok(SizeSkeleton::Known(size)) => {
format!("{} bits", size.bits())
}
Ok(SizeSkeleton::Pointer { tail, .. }) => {
format!("pointer to {}", tail)
}
Err(LayoutError::Unknown(bad)) => {
if bad == ty {
format!("size can vary")
} else {
format!("size can vary because of {}", bad)
}
}
Err(err) => err.to_string()
}
};
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struct_span_err!(self.infcx.tcx.sess, span, E0512,
"transmute called with differently sized types: \
{} ({}) to {} ({})",
from, skeleton_string(from, sk_from),
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to, skeleton_string(to, sk_to))
.span_label(span,
&format!("transmuting between {} and {}",
skeleton_string(from, sk_from),
skeleton_string(to, sk_to)))
.emit();
}
}
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impl<'a, 'tcx> Visitor<'tcx> for ItemVisitor<'a, 'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::OnlyBodies(&self.tcx.map)
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}
// const, static and N in [T; N].
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fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
self.tcx.infer_ctxt(None, None, Reveal::All).enter(|infcx| {
let mut visitor = ExprVisitor {
infcx: &infcx
};
visitor.visit_expr(expr);
});
}
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fn visit_trait_item(&mut self, item: &'tcx hir::TraitItem) {
if let hir::TraitItemKind::Const(_, Some(ref expr)) = item.node {
self.visit_const(item.id, expr);
} else {
intravisit::walk_trait_item(self, item);
}
}
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fn visit_impl_item(&mut self, item: &'tcx hir::ImplItem) {
if let hir::ImplItemKind::Const(_, ref expr) = item.node {
self.visit_const(item.id, expr);
} else {
intravisit::walk_impl_item(self, item);
}
}
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fn visit_fn(&mut self, fk: FnKind<'tcx>, fd: &'tcx hir::FnDecl,
b: hir::ExprId, s: Span, id: ast::NodeId) {
if let FnKind::Closure(..) = fk {
span_bug!(s, "intrinsicck: closure outside of function")
}
let param_env = ty::ParameterEnvironment::for_item(self.tcx, id);
self.tcx.infer_ctxt(None, Some(param_env), Reveal::All).enter(|infcx| {
let mut visitor = ExprVisitor {
infcx: &infcx
};
visitor.visit_fn(fk, fd, b, s, id);
});
}
}
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impl<'a, 'gcx, 'tcx> Visitor<'gcx> for ExprVisitor<'a, 'gcx, 'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
NestedVisitorMap::OnlyBodies(&self.infcx.tcx.map)
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}
fn visit_expr(&mut self, expr: &'gcx hir::Expr) {
let def = if let hir::ExprPath(ref qpath) = expr.node {
self.infcx.tcx.tables().qpath_def(qpath, expr.id)
} else {
Def::Err
};
match def {
Def::Fn(did) if self.def_id_is_transmute(did) => {
let typ = self.infcx.tcx.tables().node_id_to_type(expr.id);
match typ.sty {
ty::TyFnDef(.., ref bare_fn_ty) if bare_fn_ty.abi == RustIntrinsic => {
let from = bare_fn_ty.sig.skip_binder().inputs()[0];
let to = bare_fn_ty.sig.skip_binder().output();
self.check_transmute(expr.span, from, to, expr.id);
}
_ => {
span_bug!(expr.span, "transmute wasn't a bare fn?!");
}
}
}
_ => {}
}
intravisit::walk_expr(self, expr);
}
}