1 // Copyright 2012-2013 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.
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.
11 //! Enforces the Rust effect system. Currently there is just one effect,
13 use self::RootUnsafeContext::*;
16 use middle::ty::{self, Ty};
17 use middle::ty::MethodCall;
20 use syntax::codemap::Span;
22 use rustc_front::intravisit;
23 use rustc_front::intravisit::{FnKind, Visitor};
25 #[derive(Copy, Clone)]
26 struct UnsafeContext {
27 push_unsafe_count: usize,
28 root: RootUnsafeContext,
32 fn new(root: RootUnsafeContext) -> UnsafeContext {
33 UnsafeContext { root: root, push_unsafe_count: 0 }
37 #[derive(Copy, Clone, PartialEq)]
38 enum RootUnsafeContext {
41 UnsafeBlock(ast::NodeId),
44 fn type_is_unsafe_function(ty: Ty) -> bool {
46 ty::TyBareFn(_, ref f) => f.unsafety == hir::Unsafety::Unsafe,
51 struct EffectCheckVisitor<'a, 'tcx: 'a> {
52 tcx: &'a ty::ctxt<'tcx>,
54 /// Whether we're in an unsafe context.
55 unsafe_context: UnsafeContext,
58 impl<'a, 'tcx> EffectCheckVisitor<'a, 'tcx> {
59 fn require_unsafe(&mut self, span: Span, description: &str) {
60 if self.unsafe_context.push_unsafe_count > 0 { return; }
61 match self.unsafe_context.root {
64 span_err!(self.tcx.sess, span, E0133,
65 "{} requires unsafe function or block",
68 UnsafeBlock(block_id) => {
69 // OK, but record this.
70 debug!("effect: recording unsafe block as used: {}", block_id);
71 self.tcx.used_unsafe.borrow_mut().insert(block_id);
78 impl<'a, 'tcx, 'v> Visitor<'v> for EffectCheckVisitor<'a, 'tcx> {
79 fn visit_fn(&mut self, fn_kind: FnKind<'v>, fn_decl: &'v hir::FnDecl,
80 block: &'v hir::Block, span: Span, _: ast::NodeId) {
82 let (is_item_fn, is_unsafe_fn) = match fn_kind {
83 FnKind::ItemFn(_, _, unsafety, _, _, _) =>
84 (true, unsafety == hir::Unsafety::Unsafe),
85 FnKind::Method(_, sig, _) =>
86 (true, sig.unsafety == hir::Unsafety::Unsafe),
90 let old_unsafe_context = self.unsafe_context;
92 self.unsafe_context = UnsafeContext::new(UnsafeFn)
93 } else if is_item_fn {
94 self.unsafe_context = UnsafeContext::new(SafeContext)
97 intravisit::walk_fn(self, fn_kind, fn_decl, block, span);
99 self.unsafe_context = old_unsafe_context
102 fn visit_block(&mut self, block: &hir::Block) {
103 let old_unsafe_context = self.unsafe_context;
105 hir::UnsafeBlock(source) => {
106 // By default only the outermost `unsafe` block is
107 // "used" and so nested unsafe blocks are pointless
108 // (the inner ones are unnecessary and we actually
109 // warn about them). As such, there are two cases when
110 // we need to create a new context, when we're
111 // - outside `unsafe` and found a `unsafe` block
113 // - inside `unsafe`, found an `unsafe` block
114 // created internally to the compiler
116 // The second case is necessary to ensure that the
117 // compiler `unsafe` blocks don't accidentally "use"
118 // external blocks (e.g. `unsafe { println("") }`,
119 // expands to `unsafe { ... unsafe { ... } }` where
120 // the inner one is compiler generated).
121 if self.unsafe_context.root == SafeContext || source == hir::CompilerGenerated {
122 self.unsafe_context.root = UnsafeBlock(block.id)
125 hir::PushUnsafeBlock(..) => {
126 self.unsafe_context.push_unsafe_count =
127 self.unsafe_context.push_unsafe_count.checked_add(1).unwrap();
129 hir::PopUnsafeBlock(..) => {
130 self.unsafe_context.push_unsafe_count =
131 self.unsafe_context.push_unsafe_count.checked_sub(1).unwrap();
133 hir::DefaultBlock | hir::PushUnstableBlock | hir:: PopUnstableBlock => {}
136 intravisit::walk_block(self, block);
138 self.unsafe_context = old_unsafe_context
141 fn visit_expr(&mut self, expr: &hir::Expr) {
143 hir::ExprMethodCall(_, _, _) => {
144 let method_call = MethodCall::expr(expr.id);
145 let base_type = self.tcx.tables.borrow().method_map[&method_call].ty;
146 debug!("effect: method call case, base type is {:?}",
148 if type_is_unsafe_function(base_type) {
149 self.require_unsafe(expr.span,
150 "invocation of unsafe method")
153 hir::ExprCall(ref base, _) => {
154 let base_type = self.tcx.expr_ty_adjusted(base);
155 debug!("effect: call case, base type is {:?}",
157 if type_is_unsafe_function(base_type) {
158 self.require_unsafe(expr.span, "call to unsafe function")
161 hir::ExprUnary(hir::UnDeref, ref base) => {
162 let base_type = self.tcx.expr_ty_adjusted(base);
163 debug!("effect: unary case, base type is {:?}",
165 if let ty::TyRawPtr(_) = base_type.sty {
166 self.require_unsafe(expr.span, "dereference of raw pointer")
169 hir::ExprInlineAsm(..) => {
170 self.require_unsafe(expr.span, "use of inline assembly");
172 hir::ExprPath(..) => {
173 if let Def::Static(_, true) = self.tcx.resolve_expr(expr) {
174 self.require_unsafe(expr.span, "use of mutable static");
180 intravisit::walk_expr(self, expr);
184 pub fn check_crate(tcx: &ty::ctxt) {
185 let mut visitor = EffectCheckVisitor {
187 unsafe_context: UnsafeContext::new(SafeContext),
190 tcx.map.krate().visit_all_items(&mut visitor);