src/librustc_typeck/coherence/unsafety.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Unsafety checker: every impl either implements a trait defined in this
  12 //! crate or pertains to a type defined in this crate.
  13
  14 use rustc::ty::TyCtxt;
  15 use rustc::hir::itemlikevisit::ItemLikeVisitor;
  16 use rustc::hir::{self, Unsafety};
  17
  18 pub fn check<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
  19     let mut unsafety = UnsafetyChecker { tcx: tcx };
  20     tcx.hir.krate().visit_all_item_likes(&mut unsafety);
  21 }
  22
  23 struct UnsafetyChecker<'cx, 'tcx: 'cx> {
  24     tcx: TyCtxt<'cx, 'tcx, 'tcx>,
  25 }
  26
  27 impl<'cx, 'tcx, 'v> UnsafetyChecker<'cx, 'tcx> {
  28     fn check_unsafety_coherence(&mut self,
  29                                 item: &'v hir::Item,
  30                                 impl_generics: Option<&hir::Generics>,
  31                                 unsafety: hir::Unsafety,
  32                                 polarity: hir::ImplPolarity) {
  33         match self.tcx.impl_trait_ref(self.tcx.hir.local_def_id(item.id)) {
  34             None => {}
  35
  36             Some(trait_ref) => {
  37                 let trait_def = self.tcx.trait_def(trait_ref.def_id);
  38                 let unsafe_attr = impl_generics.and_then(|g| g.carries_unsafe_attr());
  39                 match (trait_def.unsafety, unsafe_attr, unsafety, polarity) {
  40                     (_, _, Unsafety::Unsafe, hir::ImplPolarity::Negative) => {
  41                         span_err!(self.tcx.sess,
  42                                   item.span,
  43                                   E0198,
  44                                   "negative implementations are not unsafe");
  45                     }
  46
  47                     (Unsafety::Normal, None, Unsafety::Unsafe, _) => {
  48                         span_err!(self.tcx.sess,
  49                                   item.span,
  50                                   E0199,
  51                                   "implementing the trait `{}` is not unsafe",
  52                                   trait_ref);
  53                     }
  54
  55                     (Unsafety::Unsafe, _, Unsafety::Normal, hir::ImplPolarity::Positive) => {
  56                         span_err!(self.tcx.sess,
  57                                   item.span,
  58                                   E0200,
  59                                   "the trait `{}` requires an `unsafe impl` declaration",
  60                                   trait_ref);
  61                     }
  62
  63                     (Unsafety::Normal, Some(g), Unsafety::Normal, hir::ImplPolarity::Positive) =>
  64                     {
  65                         span_err!(self.tcx.sess,
  66                                   item.span,
  67                                   E0569,
  68                                   "requires an `unsafe impl` declaration due to `#[{}]` attribute",
  69                                   g.attr_name());
  70                     }
  71
  72                     (_, _, Unsafety::Normal, hir::ImplPolarity::Negative) |
  73                     (Unsafety::Unsafe, _, Unsafety::Unsafe, hir::ImplPolarity::Positive) |
  74                     (Unsafety::Normal, Some(_), Unsafety::Unsafe, hir::ImplPolarity::Positive) |
  75                     (Unsafety::Normal, None, Unsafety::Normal, _) => {
  76                         // OK
  77                     }
  78                 }
  79             }
  80         }
  81     }
  82 }
  83
  84 impl<'cx, 'tcx, 'v> ItemLikeVisitor<'v> for UnsafetyChecker<'cx, 'tcx> {
  85     fn visit_item(&mut self, item: &'v hir::Item) {
  86         match item.node {
  87             hir::ItemDefaultImpl(unsafety, _) => {
  88                 self.check_unsafety_coherence(item, None, unsafety, hir::ImplPolarity::Positive);
  89             }
  90             hir::ItemImpl(unsafety, polarity, _, ref generics, ..) => {
  91                 self.check_unsafety_coherence(item, Some(generics), unsafety, polarity);
  92             }
  93             _ => {}
  94         }
  95     }
  96
  97     fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
  98     }
  99
 100     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
 101     }
 102 }