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 ty::{self, Ty, TyCtxt};
24 use hir::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::TyFnDef(_, _, ref f) |
48 ty::TyFnPtr(ref f) => f.unsafety == hir::Unsafety::Unsafe,
53 struct EffectCheckVisitor<'a, 'tcx: 'a> {
54 tcx: TyCtxt<'a, 'tcx, 'tcx>,
56 /// Whether we're in an unsafe context.
57 unsafe_context: UnsafeContext,
60 impl<'a, 'tcx> EffectCheckVisitor<'a, 'tcx> {
61 fn require_unsafe(&mut self, span: Span, description: &str) {
62 if self.unsafe_context.push_unsafe_count > 0 { return; }
63 match self.unsafe_context.root {
66 span_err!(self.tcx.sess, span, E0133,
67 "{} requires unsafe function or block",
70 UnsafeBlock(block_id) => {
71 // OK, but record this.
72 debug!("effect: recording unsafe block as used: {}", block_id);
73 self.tcx.used_unsafe.borrow_mut().insert(block_id);
80 impl<'a, 'tcx, 'v> Visitor<'v> for EffectCheckVisitor<'a, 'tcx> {
81 fn visit_fn(&mut self, fn_kind: FnKind<'v>, fn_decl: &'v hir::FnDecl,
82 block: &'v hir::Block, span: Span, id: ast::NodeId) {
84 let (is_item_fn, is_unsafe_fn) = match fn_kind {
85 FnKind::ItemFn(_, _, unsafety, _, _, _, _) =>
86 (true, unsafety == hir::Unsafety::Unsafe),
87 FnKind::Method(_, sig, _, _) =>
88 (true, sig.unsafety == hir::Unsafety::Unsafe),
92 let old_unsafe_context = self.unsafe_context;
94 self.unsafe_context = UnsafeContext::new(UnsafeFn)
95 } else if is_item_fn {
96 self.unsafe_context = UnsafeContext::new(SafeContext)
99 intravisit::walk_fn(self, fn_kind, fn_decl, block, span, id);
101 self.unsafe_context = old_unsafe_context
104 fn visit_block(&mut self, block: &hir::Block) {
105 let old_unsafe_context = self.unsafe_context;
107 hir::UnsafeBlock(source) => {
108 // By default only the outermost `unsafe` block is
109 // "used" and so nested unsafe blocks are pointless
110 // (the inner ones are unnecessary and we actually
111 // warn about them). As such, there are two cases when
112 // we need to create a new context, when we're
113 // - outside `unsafe` and found a `unsafe` block
115 // - inside `unsafe`, found an `unsafe` block
116 // created internally to the compiler
118 // The second case is necessary to ensure that the
119 // compiler `unsafe` blocks don't accidentally "use"
120 // external blocks (e.g. `unsafe { println("") }`,
121 // expands to `unsafe { ... unsafe { ... } }` where
122 // the inner one is compiler generated).
123 if self.unsafe_context.root == SafeContext || source == hir::CompilerGenerated {
124 self.unsafe_context.root = UnsafeBlock(block.id)
127 hir::PushUnsafeBlock(..) => {
128 self.unsafe_context.push_unsafe_count =
129 self.unsafe_context.push_unsafe_count.checked_add(1).unwrap();
131 hir::PopUnsafeBlock(..) => {
132 self.unsafe_context.push_unsafe_count =
133 self.unsafe_context.push_unsafe_count.checked_sub(1).unwrap();
135 hir::DefaultBlock | hir::PushUnstableBlock | hir:: PopUnstableBlock => {}
138 intravisit::walk_block(self, block);
140 self.unsafe_context = old_unsafe_context
143 fn visit_expr(&mut self, expr: &hir::Expr) {
145 hir::ExprMethodCall(_, _, _) => {
146 let method_call = MethodCall::expr(expr.id);
147 let base_type = self.tcx.tables.borrow().method_map[&method_call].ty;
148 debug!("effect: method call case, base type is {:?}",
150 if type_is_unsafe_function(base_type) {
151 self.require_unsafe(expr.span,
152 "invocation of unsafe method")
155 hir::ExprCall(ref base, _) => {
156 let base_type = self.tcx.expr_ty_adjusted(base);
157 debug!("effect: call case, base type is {:?}",
159 if type_is_unsafe_function(base_type) {
160 self.require_unsafe(expr.span, "call to unsafe function")
163 hir::ExprUnary(hir::UnDeref, ref base) => {
164 let base_type = self.tcx.expr_ty_adjusted(base);
165 debug!("effect: unary case, base type is {:?}",
167 if let ty::TyRawPtr(_) = base_type.sty {
168 self.require_unsafe(expr.span, "dereference of raw pointer")
171 hir::ExprInlineAsm(..) => {
172 self.require_unsafe(expr.span, "use of inline assembly");
174 hir::ExprPath(..) => {
175 if let Def::Static(_, true) = self.tcx.expect_def(expr.id) {
176 self.require_unsafe(expr.span, "use of mutable static");
182 intravisit::walk_expr(self, expr);
186 pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
187 let _task = tcx.dep_graph.in_task(DepNode::EffectCheck);
189 let mut visitor = EffectCheckVisitor {
191 unsafe_context: UnsafeContext::new(SafeContext),
194 tcx.map.krate().visit_all_items(&mut visitor);