1 // Copyright 2017 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 use rustc_data_structures::fx::FxHashSet;
12 use rustc_data_structures::indexed_vec::IndexVec;
14 use rustc::ty::maps::Providers;
15 use rustc::ty::{self, TyCtxt};
17 use rustc::hir::def_id::DefId;
18 use rustc::lint::builtin::{SAFE_EXTERN_STATICS, SAFE_PACKED_BORROWS, UNUSED_UNSAFE};
20 use rustc::mir::visit::{PlaceContext, Visitor};
23 use syntax::symbol::Symbol;
28 pub struct UnsafetyChecker<'a, 'tcx: 'a> {
30 visibility_scope_info: &'a IndexVec<VisibilityScope, VisibilityScopeInfo>,
31 violations: Vec<UnsafetyViolation>,
32 source_info: SourceInfo,
33 tcx: TyCtxt<'a, 'tcx, 'tcx>,
34 param_env: ty::ParamEnv<'tcx>,
35 used_unsafe: FxHashSet<ast::NodeId>,
36 inherited_blocks: Vec<(ast::NodeId, bool)>,
39 impl<'a, 'gcx, 'tcx> UnsafetyChecker<'a, 'tcx> {
40 fn new(mir: &'a Mir<'tcx>,
41 visibility_scope_info: &'a IndexVec<VisibilityScope, VisibilityScopeInfo>,
42 tcx: TyCtxt<'a, 'tcx, 'tcx>,
43 param_env: ty::ParamEnv<'tcx>) -> Self {
46 visibility_scope_info,
48 source_info: SourceInfo {
50 scope: ARGUMENT_VISIBILITY_SCOPE
54 used_unsafe: FxHashSet(),
55 inherited_blocks: vec![],
60 impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> {
61 fn visit_terminator(&mut self,
63 terminator: &Terminator<'tcx>,
66 self.source_info = terminator.source_info;
67 match terminator.kind {
68 TerminatorKind::Goto { .. } |
69 TerminatorKind::SwitchInt { .. } |
70 TerminatorKind::Drop { .. } |
71 TerminatorKind::Yield { .. } |
72 TerminatorKind::Assert { .. } |
73 TerminatorKind::DropAndReplace { .. } |
74 TerminatorKind::GeneratorDrop |
75 TerminatorKind::Resume |
76 TerminatorKind::Abort |
77 TerminatorKind::Return |
78 TerminatorKind::Unreachable |
79 TerminatorKind::FalseEdges { .. } => {
80 // safe (at least as emitted during MIR construction)
83 TerminatorKind::Call { ref func, .. } => {
84 let func_ty = func.ty(self.mir, self.tcx);
85 let sig = func_ty.fn_sig(self.tcx);
86 if let hir::Unsafety::Unsafe = sig.unsafety() {
87 self.require_unsafe("call to unsafe function")
91 self.super_terminator(block, terminator, location);
94 fn visit_statement(&mut self,
96 statement: &Statement<'tcx>,
99 self.source_info = statement.source_info;
100 match statement.kind {
101 StatementKind::Assign(..) |
102 StatementKind::SetDiscriminant { .. } |
103 StatementKind::StorageLive(..) |
104 StatementKind::StorageDead(..) |
105 StatementKind::EndRegion(..) |
106 StatementKind::Validate(..) |
107 StatementKind::Nop => {
108 // safe (at least as emitted during MIR construction)
111 StatementKind::InlineAsm { .. } => {
112 self.require_unsafe("use of inline assembly")
115 self.super_statement(block, statement, location);
118 fn visit_rvalue(&mut self,
119 rvalue: &Rvalue<'tcx>,
122 if let &Rvalue::Aggregate(box ref aggregate, _) = rvalue {
124 &AggregateKind::Array(..) |
125 &AggregateKind::Tuple |
126 &AggregateKind::Adt(..) => {}
127 &AggregateKind::Closure(def_id, _) => {
128 let UnsafetyCheckResult {
129 violations, unsafe_blocks
130 } = self.tcx.unsafety_check_result(def_id);
131 self.register_violations(&violations, &unsafe_blocks);
133 &AggregateKind::Generator(def_id, _, interior) => {
134 let UnsafetyCheckResult {
135 violations, unsafe_blocks
136 } = self.tcx.unsafety_check_result(def_id);
137 self.register_violations(&violations, &unsafe_blocks);
138 if !interior.movable {
139 self.require_unsafe("construction of immovable generator")
144 self.super_rvalue(rvalue, location);
147 fn visit_place(&mut self,
149 context: PlaceContext<'tcx>,
150 location: Location) {
151 if let PlaceContext::Borrow { .. } = context {
152 if util::is_disaligned(self.tcx, self.mir, self.param_env, place) {
153 let source_info = self.source_info;
155 self.visibility_scope_info[source_info.scope].lint_root;
156 self.register_violations(&[UnsafetyViolation {
158 description: Symbol::intern("borrow of packed field").as_str(),
159 kind: UnsafetyViolationKind::BorrowPacked(lint_root)
165 &Place::Projection(box Projection {
168 let old_source_info = self.source_info;
169 if let &Place::Local(local) = base {
170 if self.mir.local_decls[local].internal {
171 // Internal locals are used in the `move_val_init` desugaring.
172 // We want to check unsafety against the source info of the
173 // desugaring, rather than the source info of the RHS.
174 self.source_info = self.mir.local_decls[local].source_info;
177 let base_ty = base.ty(self.mir, self.tcx).to_ty(self.tcx);
179 ty::TyRawPtr(..) => {
180 self.require_unsafe("dereference of raw pointer")
182 ty::TyAdt(adt, _) => {
184 if context == PlaceContext::Store ||
185 context == PlaceContext::AsmOutput ||
186 context == PlaceContext::Drop
188 let elem_ty = match elem {
189 &ProjectionElem::Field(_, ty) => ty,
191 self.source_info.span,
192 "non-field projection {:?} from union?",
195 if elem_ty.moves_by_default(self.tcx, self.param_env,
196 self.source_info.span) {
198 "assignment to non-`Copy` union field")
200 // write to non-move union, safe
203 self.require_unsafe("access to union field")
209 self.source_info = old_source_info;
211 &Place::Local(..) => {
214 &Place::Static(box Static { def_id, ty: _ }) => {
215 if self.tcx.is_static_mut(def_id) {
216 self.require_unsafe("use of mutable static");
217 } else if self.tcx.is_foreign_item(def_id) {
218 let source_info = self.source_info;
220 self.visibility_scope_info[source_info.scope].lint_root;
221 self.register_violations(&[UnsafetyViolation {
223 description: Symbol::intern("use of extern static").as_str(),
224 kind: UnsafetyViolationKind::ExternStatic(lint_root)
229 self.super_place(place, context, location);
233 impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
234 fn require_unsafe(&mut self,
235 description: &'static str)
237 let source_info = self.source_info;
238 self.register_violations(&[UnsafetyViolation {
240 description: Symbol::intern(description).as_str(),
241 kind: UnsafetyViolationKind::General,
245 fn register_violations(&mut self,
246 violations: &[UnsafetyViolation],
247 unsafe_blocks: &[(ast::NodeId, bool)]) {
248 let within_unsafe = match self.visibility_scope_info[self.source_info.scope].safety {
250 for violation in violations {
251 if !self.violations.contains(violation) {
252 self.violations.push(violation.clone())
258 Safety::BuiltinUnsafe | Safety::FnUnsafe => true,
259 Safety::ExplicitUnsafe(node_id) => {
260 if !violations.is_empty() {
261 self.used_unsafe.insert(node_id);
266 self.inherited_blocks.extend(unsafe_blocks.iter().map(|&(node_id, is_used)| {
267 (node_id, is_used && !within_unsafe)
272 pub(crate) fn provide(providers: &mut Providers) {
273 *providers = Providers {
274 unsafety_check_result,
275 unsafe_derive_on_repr_packed,
280 struct UnusedUnsafeVisitor<'a> {
281 used_unsafe: &'a FxHashSet<ast::NodeId>,
282 unsafe_blocks: &'a mut Vec<(ast::NodeId, bool)>,
285 impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'a> {
286 fn nested_visit_map<'this>(&'this mut self) ->
287 hir::intravisit::NestedVisitorMap<'this, 'tcx>
289 hir::intravisit::NestedVisitorMap::None
292 fn visit_block(&mut self, block: &'tcx hir::Block) {
293 hir::intravisit::walk_block(self, block);
295 if let hir::UnsafeBlock(hir::UserProvided) = block.rules {
296 self.unsafe_blocks.push((block.id, self.used_unsafe.contains(&block.id)));
301 fn check_unused_unsafe<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
303 used_unsafe: &FxHashSet<ast::NodeId>,
304 unsafe_blocks: &'a mut Vec<(ast::NodeId, bool)>)
307 tcx.hir.as_local_node_id(def_id).and_then(|node_id| {
308 tcx.hir.maybe_body_owned_by(node_id)
311 let body_id = match body_id {
314 debug!("check_unused_unsafe({:?}) - no body found", def_id);
318 let body = tcx.hir.body(body_id);
319 debug!("check_unused_unsafe({:?}, body={:?}, used_unsafe={:?})",
320 def_id, body, used_unsafe);
322 let mut visitor = UnusedUnsafeVisitor { used_unsafe, unsafe_blocks };
323 hir::intravisit::Visitor::visit_body(&mut visitor, body);
326 fn unsafety_check_result<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId)
327 -> UnsafetyCheckResult
329 debug!("unsafety_violations({:?})", def_id);
331 // NB: this borrow is valid because all the consumers of
332 // `mir_built` force this.
333 let mir = &tcx.mir_built(def_id).borrow();
335 let visibility_scope_info = match mir.visibility_scope_info {
336 ClearCrossCrate::Set(ref data) => data,
337 ClearCrossCrate::Clear => {
338 debug!("unsafety_violations: {:?} - remote, skipping", def_id);
339 return UnsafetyCheckResult {
340 violations: Rc::new([]),
341 unsafe_blocks: Rc::new([])
346 let param_env = tcx.param_env(def_id);
347 let mut checker = UnsafetyChecker::new(
348 mir, visibility_scope_info, tcx, param_env);
349 checker.visit_mir(mir);
351 check_unused_unsafe(tcx, def_id, &checker.used_unsafe, &mut checker.inherited_blocks);
352 UnsafetyCheckResult {
353 violations: checker.violations.into(),
354 unsafe_blocks: checker.inherited_blocks.into()
358 fn unsafe_derive_on_repr_packed<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) {
359 let lint_node_id = match tcx.hir.as_local_node_id(def_id) {
360 Some(node_id) => node_id,
361 None => bug!("checking unsafety for non-local def id {:?}", def_id)
364 // FIXME: when we make this a hard error, this should have its
366 let message = if !tcx.generics_of(def_id).types.is_empty() {
367 format!("#[derive] can't be used on a #[repr(packed)] struct with \
368 type parameters (error E0133)")
370 format!("#[derive] can't be used on a non-Copy #[repr(packed)] struct \
373 tcx.lint_node(SAFE_PACKED_BORROWS,
375 tcx.def_span(def_id),
379 /// Return the NodeId for an enclosing scope that is also `unsafe`
380 fn is_enclosed(tcx: TyCtxt,
381 used_unsafe: &FxHashSet<ast::NodeId>,
382 id: ast::NodeId) -> Option<(String, ast::NodeId)> {
383 let parent_id = tcx.hir.get_parent_node(id);
385 if used_unsafe.contains(&parent_id) {
386 Some(("block".to_string(), parent_id))
387 } else if let Some(hir::map::NodeItem(&hir::Item {
388 node: hir::ItemFn(_, hir::Unsafety::Unsafe, _, _, _, _),
390 })) = tcx.hir.find(parent_id) {
391 Some(("fn".to_string(), parent_id))
393 is_enclosed(tcx, used_unsafe, parent_id)
400 fn report_unused_unsafe(tcx: TyCtxt, used_unsafe: &FxHashSet<ast::NodeId>, id: ast::NodeId) {
401 let span = tcx.sess.codemap().def_span(tcx.hir.span(id));
402 let msg = "unnecessary `unsafe` block";
403 let mut db = tcx.struct_span_lint_node(UNUSED_UNSAFE, id, span, msg);
404 db.span_label(span, msg);
405 if let Some((kind, id)) = is_enclosed(tcx, used_unsafe, id) {
406 db.span_label(tcx.sess.codemap().def_span(tcx.hir.span(id)),
407 format!("because it's nested under this `unsafe` {}", kind));
412 fn builtin_derive_def_id<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Option<DefId> {
413 debug!("builtin_derive_def_id({:?})", def_id);
414 if let Some(impl_def_id) = tcx.impl_of_method(def_id) {
415 if tcx.has_attr(impl_def_id, "automatically_derived") {
416 debug!("builtin_derive_def_id({:?}) - is {:?}", def_id, impl_def_id);
419 debug!("builtin_derive_def_id({:?}) - not automatically derived", def_id);
423 debug!("builtin_derive_def_id({:?}) - not a method", def_id);
428 pub fn check_unsafety<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) {
429 debug!("check_unsafety({:?})", def_id);
431 // closures are handled by their parent fn.
432 if tcx.is_closure(def_id) {
436 let UnsafetyCheckResult {
439 } = tcx.unsafety_check_result(def_id);
441 for &UnsafetyViolation {
442 source_info, description, kind
443 } in violations.iter() {
446 UnsafetyViolationKind::General => {
448 tcx.sess, source_info.span, E0133,
449 "{} requires unsafe function or block", description)
450 .span_label(source_info.span, &description[..])
453 UnsafetyViolationKind::ExternStatic(lint_node_id) => {
454 tcx.lint_node(SAFE_EXTERN_STATICS,
457 &format!("{} requires unsafe function or \
458 block (error E0133)", &description[..]));
460 UnsafetyViolationKind::BorrowPacked(lint_node_id) => {
461 if let Some(impl_def_id) = builtin_derive_def_id(tcx, def_id) {
462 tcx.unsafe_derive_on_repr_packed(impl_def_id);
464 tcx.lint_node(SAFE_PACKED_BORROWS,
467 &format!("{} requires unsafe function or \
468 block (error E0133)", &description[..]));
474 let mut unsafe_blocks: Vec<_> = unsafe_blocks.into_iter().collect();
475 unsafe_blocks.sort();
476 let used_unsafe: FxHashSet<_> = unsafe_blocks.iter()
477 .flat_map(|&&(id, used)| if used { Some(id) } else { None })
479 for &(block_id, is_used) in unsafe_blocks {
481 report_unused_unsafe(tcx, &used_unsafe, block_id);