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::*;
15 use dep_graph::DepNode;
17 use middle::ty::{self, Ty};
18 use middle::ty::MethodCall;
21 use syntax::codemap::Span;
23 use rustc_front::intravisit;
24 use rustc_front::intravisit::{FnKind, Visitor};
26 #[derive(Copy, Clone)]
27 struct UnsafeContext {
28 push_unsafe_count: usize,
29 root: RootUnsafeContext,
33 fn new(root: RootUnsafeContext) -> UnsafeContext {
34 UnsafeContext { root: root, push_unsafe_count: 0 }
38 #[derive(Copy, Clone, PartialEq)]
39 enum RootUnsafeContext {
42 UnsafeBlock(ast::NodeId),
45 fn type_is_unsafe_function(ty: Ty) -> bool {
47 ty::TyBareFn(_, ref f) => f.unsafety == hir::Unsafety::Unsafe,
52 struct EffectCheckVisitor<'a, 'tcx: 'a> {
53 tcx: &'a ty::ctxt<'tcx>,
55 /// Whether we're in an unsafe context.
56 unsafe_context: UnsafeContext,
59 impl<'a, 'tcx> EffectCheckVisitor<'a, 'tcx> {
60 fn require_unsafe(&mut self, span: Span, description: &str) {
61 if self.unsafe_context.push_unsafe_count > 0 { return; }
62 match self.unsafe_context.root {
65 span_err!(self.tcx.sess, span, E0133,
66 "{} requires unsafe function or block",
69 UnsafeBlock(block_id) => {
70 // OK, but record this.
71 debug!("effect: recording unsafe block as used: {}", block_id);
72 self.tcx.used_unsafe.borrow_mut().insert(block_id);
79 impl<'a, 'tcx, 'v> Visitor<'v> for EffectCheckVisitor<'a, 'tcx> {
80 fn visit_fn(&mut self, fn_kind: FnKind<'v>, fn_decl: &'v hir::FnDecl,
81 block: &'v hir::Block, span: Span, _: ast::NodeId) {
83 let (is_item_fn, is_unsafe_fn) = match fn_kind {
84 FnKind::ItemFn(_, _, unsafety, _, _, _) =>
85 (true, unsafety == hir::Unsafety::Unsafe),
86 FnKind::Method(_, sig, _) =>
87 (true, sig.unsafety == hir::Unsafety::Unsafe),
91 let old_unsafe_context = self.unsafe_context;
93 self.unsafe_context = UnsafeContext::new(UnsafeFn)
94 } else if is_item_fn {
95 self.unsafe_context = UnsafeContext::new(SafeContext)
98 intravisit::walk_fn(self, fn_kind, fn_decl, block, span);
100 self.unsafe_context = old_unsafe_context
103 fn visit_block(&mut self, block: &hir::Block) {
104 let old_unsafe_context = self.unsafe_context;
106 hir::UnsafeBlock(source) => {
107 // By default only the outermost `unsafe` block is
108 // "used" and so nested unsafe blocks are pointless
109 // (the inner ones are unnecessary and we actually
110 // warn about them). As such, there are two cases when
111 // we need to create a new context, when we're
112 // - outside `unsafe` and found a `unsafe` block
114 // - inside `unsafe`, found an `unsafe` block
115 // created internally to the compiler
117 // The second case is necessary to ensure that the
118 // compiler `unsafe` blocks don't accidentally "use"
119 // external blocks (e.g. `unsafe { println("") }`,
120 // expands to `unsafe { ... unsafe { ... } }` where
121 // the inner one is compiler generated).
122 if self.unsafe_context.root == SafeContext || source == hir::CompilerGenerated {
123 self.unsafe_context.root = UnsafeBlock(block.id)
126 hir::PushUnsafeBlock(..) => {
127 self.unsafe_context.push_unsafe_count =
128 self.unsafe_context.push_unsafe_count.checked_add(1).unwrap();
130 hir::PopUnsafeBlock(..) => {
131 self.unsafe_context.push_unsafe_count =
132 self.unsafe_context.push_unsafe_count.checked_sub(1).unwrap();
134 hir::DefaultBlock | hir::PushUnstableBlock | hir:: PopUnstableBlock => {}
137 intravisit::walk_block(self, block);
139 self.unsafe_context = old_unsafe_context
142 fn visit_expr(&mut self, expr: &hir::Expr) {
144 hir::ExprMethodCall(_, _, _) => {
145 let method_call = MethodCall::expr(expr.id);
146 let base_type = self.tcx.tables.borrow().method_map[&method_call].ty;
147 debug!("effect: method call case, base type is {:?}",
149 if type_is_unsafe_function(base_type) {
150 self.require_unsafe(expr.span,
151 "invocation of unsafe method")
154 hir::ExprCall(ref base, _) => {
155 let base_type = self.tcx.expr_ty_adjusted(base);
156 debug!("effect: call case, base type is {:?}",
158 if type_is_unsafe_function(base_type) {
159 self.require_unsafe(expr.span, "call to unsafe function")
162 hir::ExprUnary(hir::UnDeref, ref base) => {
163 let base_type = self.tcx.expr_ty_adjusted(base);
164 debug!("effect: unary case, base type is {:?}",
166 if let ty::TyRawPtr(_) = base_type.sty {
167 self.require_unsafe(expr.span, "dereference of raw pointer")
170 hir::ExprInlineAsm(..) => {
171 self.require_unsafe(expr.span, "use of inline assembly");
173 hir::ExprPath(..) => {
174 if let Def::Static(_, true) = self.tcx.resolve_expr(expr) {
175 self.require_unsafe(expr.span, "use of mutable static");
181 intravisit::walk_expr(self, expr);
185 pub fn check_crate(tcx: &ty::ctxt) {
186 let _task = tcx.dep_graph.in_task(DepNode::EffectCheck);
188 let mut visitor = EffectCheckVisitor {
190 unsafe_context: UnsafeContext::new(SafeContext),
193 tcx.map.krate().visit_all_items(&mut visitor);