From 12aedc833ccec26e6a883ec52e98acfc6d41263b Mon Sep 17 00:00:00 2001 From: Ariel Ben-Yehuda Date: Sun, 5 Nov 2017 20:04:18 +0200 Subject: [PATCH] collect unused unsafe code FIXME: de-uglify --- src/librustc/dep_graph/dep_node.rs | 2 +- src/librustc/ich/impls_mir.rs | 1 + src/librustc/mir/mod.rs | 10 ++ src/librustc/ty/maps/mod.rs | 5 +- src/librustc/ty/maps/plumbing.rs | 2 +- src/librustc_mir/transform/check_unsafety.rs | 151 +++++++++++------- src/librustc_mir/transform/mod.rs | 2 +- ...sue-45107-unnecessary-unsafe-in-closure.rs | 35 ++++ ...45107-unnecessary-unsafe-in-closure.stderr | 71 ++++++++ src/test/ui/span/lint-unused-unsafe.stderr | 40 ++--- 10 files changed, 233 insertions(+), 86 deletions(-) create mode 100644 src/test/ui/issue-45107-unnecessary-unsafe-in-closure.rs create mode 100644 src/test/ui/issue-45107-unnecessary-unsafe-in-closure.stderr diff --git a/src/librustc/dep_graph/dep_node.rs b/src/librustc/dep_graph/dep_node.rs index 8e48513baa0..9bd566274fb 100644 --- a/src/librustc/dep_graph/dep_node.rs +++ b/src/librustc/dep_graph/dep_node.rs @@ -482,7 +482,7 @@ define_dep_nodes!( <'tcx> [] BorrowCheckKrate, [] BorrowCheck(DefId), [] MirBorrowCheck(DefId), - [] UnsafetyViolations(DefId), + [] UnsafetyCheckResult(DefId), [] Reachability, [] MirKeys, diff --git a/src/librustc/ich/impls_mir.rs b/src/librustc/ich/impls_mir.rs index 05436201e7a..8ae26d81442 100644 --- a/src/librustc/ich/impls_mir.rs +++ b/src/librustc/ich/impls_mir.rs @@ -34,6 +34,7 @@ impl_stable_hash_for!(struct mir::LocalDecl<'tcx> { impl_stable_hash_for!(struct mir::UpvarDecl { debug_name, by_ref }); impl_stable_hash_for!(struct mir::BasicBlockData<'tcx> { statements, terminator, is_cleanup }); impl_stable_hash_for!(struct mir::UnsafetyViolation { source_info, description, lint_node_id }); +impl_stable_hash_for!(struct mir::UnsafetyCheckResult { violations, unsafe_blocks }); impl<'gcx> HashStable> for mir::Terminator<'gcx> { diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs index 2fc27de137f..0fa40f56196 100644 --- a/src/librustc/mir/mod.rs +++ b/src/librustc/mir/mod.rs @@ -33,6 +33,7 @@ use std::cell::Ref; use std::fmt::{self, Debug, Formatter, Write}; use std::{iter, u32}; use std::ops::{Index, IndexMut}; +use std::rc::Rc; use std::vec::IntoIter; use syntax::ast::{self, Name}; use syntax_pos::Span; @@ -1683,6 +1684,15 @@ pub struct UnsafetyViolation { pub lint_node_id: Option, } +#[derive(Clone, Debug, PartialEq, Eq, Hash)] +pub struct UnsafetyCheckResult { + /// Violations that are propagated *upwards* from this function + pub violations: Rc<[UnsafetyViolation]>, + /// unsafe blocks in this function, along with whether they are used. This is + /// used for the "unused_unsafe" lint. + pub unsafe_blocks: Rc<[(ast::NodeId, bool)]>, +} + /// The layout of generator state #[derive(Clone, Debug, RustcEncodable, RustcDecodable)] pub struct GeneratorLayout<'tcx> { diff --git a/src/librustc/ty/maps/mod.rs b/src/librustc/ty/maps/mod.rs index 8a9c38fde32..b698985a927 100644 --- a/src/librustc/ty/maps/mod.rs +++ b/src/librustc/ty/maps/mod.rs @@ -171,9 +171,8 @@ define_maps! { <'tcx> /// expression defining the closure. [] fn closure_kind: ClosureKind(DefId) -> ty::ClosureKind, - /// Unsafety violations for this def ID. - [] fn unsafety_violations: UnsafetyViolations(DefId) - -> Rc<[mir::UnsafetyViolation]>, + /// The result of unsafety-checking this def-id. + [] fn unsafety_check_result: UnsafetyCheckResult(DefId) -> mir::UnsafetyCheckResult, /// The signature of functions and closures. [] fn fn_sig: FnSignature(DefId) -> ty::PolyFnSig<'tcx>, diff --git a/src/librustc/ty/maps/plumbing.rs b/src/librustc/ty/maps/plumbing.rs index fc5f9b88ef3..f457314f12d 100644 --- a/src/librustc/ty/maps/plumbing.rs +++ b/src/librustc/ty/maps/plumbing.rs @@ -720,7 +720,7 @@ pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>, DepKind::BorrowCheck => { force!(borrowck, def_id!()); } DepKind::MirBorrowCheck => { force!(mir_borrowck, def_id!()); } - DepKind::UnsafetyViolations => { force!(unsafety_violations, def_id!()); } + DepKind::UnsafetyCheckResult => { force!(unsafety_check_result, def_id!()); } DepKind::Reachability => { force!(reachable_set, LOCAL_CRATE); } DepKind::MirKeys => { force!(mir_keys, LOCAL_CRATE); } DepKind::CrateVariances => { force!(crate_variances, LOCAL_CRATE); } diff --git a/src/librustc_mir/transform/check_unsafety.rs b/src/librustc_mir/transform/check_unsafety.rs index 30a60cc7590..53a4b2551fd 100644 --- a/src/librustc_mir/transform/check_unsafety.rs +++ b/src/librustc_mir/transform/check_unsafety.rs @@ -34,6 +34,7 @@ pub struct UnsafetyChecker<'a, 'tcx: 'a> { tcx: TyCtxt<'a, 'tcx, 'tcx>, param_env: ty::ParamEnv<'tcx>, used_unsafe: FxHashSet, + inherited_blocks: Vec<(ast::NodeId, bool)>, } impl<'a, 'gcx, 'tcx> UnsafetyChecker<'a, 'tcx> { @@ -52,6 +53,7 @@ impl<'a, 'gcx, 'tcx> UnsafetyChecker<'a, 'tcx> { tcx, param_env, used_unsafe: FxHashSet(), + inherited_blocks: vec![], } } } @@ -124,8 +126,11 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> { &AggregateKind::Adt(..) => {} &AggregateKind::Closure(def_id, _) | &AggregateKind::Generator(def_id, _, _) => { - let unsafety_violations = self.tcx.unsafety_violations(def_id); - self.register_violations(&unsafety_violations); + let UnsafetyCheckResult { + violations, unsafe_blocks + } = self.tcx.unsafety_check_result(def_id); + self.inherited_blocks.extend(unsafe_blocks.iter().cloned()); + self.register_violations(&violations, &unsafe_blocks); } } } @@ -194,7 +199,7 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> { source_info, description: "use of extern static", lint_node_id: Some(lint_root) - }]); + }], &[]); } } } @@ -227,41 +232,49 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> { let source_info = self.source_info; self.register_violations(&[UnsafetyViolation { source_info, description, lint_node_id: None - }]); + }], &[]); } - fn register_violations(&mut self, violations: &[UnsafetyViolation]) { - match self.visibility_scope_info[self.source_info.scope].safety { + fn register_violations(&mut self, + violations: &[UnsafetyViolation], + unsafe_blocks: &[(ast::NodeId, bool)]) { + let within_unsafe = match self.visibility_scope_info[self.source_info.scope].safety { Safety::Safe => { for violation in violations { if !self.violations.contains(violation) { self.violations.push(violation.clone()) } } + + false } - Safety::BuiltinUnsafe | Safety::FnUnsafe => {} + Safety::BuiltinUnsafe | Safety::FnUnsafe => true, Safety::ExplicitUnsafe(node_id) => { if !violations.is_empty() { self.used_unsafe.insert(node_id); } + true } - } + }; + self.inherited_blocks.extend(unsafe_blocks.iter().map(|&(node_id, is_used)| { + (node_id, is_used && !within_unsafe) + })); } } pub(crate) fn provide(providers: &mut Providers) { *providers = Providers { - unsafety_violations, + unsafety_check_result, ..*providers }; } -struct UnusedUnsafeVisitor<'a, 'tcx: 'a> { - tcx: TyCtxt<'a, 'tcx, 'tcx>, - used_unsafe: FxHashSet +struct UnusedUnsafeVisitor<'a> { + used_unsafe: &'a FxHashSet, + unsafe_blocks: &'a mut Vec<(ast::NodeId, bool)>, } -impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'a, 'tcx> { +impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'a> { fn nested_visit_map<'this>(&'this mut self) -> hir::intravisit::NestedVisitorMap<'this, 'tcx> { @@ -272,50 +285,15 @@ impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'a, 'tcx> hir::intravisit::walk_block(self, block); if let hir::UnsafeBlock(hir::UserProvided) = block.rules { - if !self.used_unsafe.contains(&block.id) { - self.report_unused_unsafe(block); - } + self.unsafe_blocks.push((block.id, self.used_unsafe.contains(&block.id))); } } } -impl<'a, 'tcx> UnusedUnsafeVisitor<'a, 'tcx> { - /// Return the NodeId for an enclosing scope that is also `unsafe` - fn is_enclosed(&self, id: ast::NodeId) -> Option<(String, ast::NodeId)> { - let parent_id = self.tcx.hir.get_parent_node(id); - if parent_id != id { - if self.used_unsafe.contains(&parent_id) { - Some(("block".to_string(), parent_id)) - } else if let Some(hir::map::NodeItem(&hir::Item { - node: hir::ItemFn(_, hir::Unsafety::Unsafe, _, _, _, _), - .. - })) = self.tcx.hir.find(parent_id) { - Some(("fn".to_string(), parent_id)) - } else { - self.is_enclosed(parent_id) - } - } else { - None - } - } - - fn report_unused_unsafe(&self, block: &'tcx hir::Block) { - let mut db = self.tcx.struct_span_lint_node(UNUSED_UNSAFE, - block.id, - block.span, - "unnecessary `unsafe` block"); - db.span_label(block.span, "unnecessary `unsafe` block"); - if let Some((kind, id)) = self.is_enclosed(block.id) { - db.span_note(self.tcx.hir.span(id), - &format!("because it's nested under this `unsafe` {}", kind)); - } - db.emit(); - } -} - fn check_unused_unsafe<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId, - used_unsafe: FxHashSet) + used_unsafe: &FxHashSet, + unsafe_blocks: &'a mut Vec<(ast::NodeId, bool)>) { let body_id = tcx.hir.as_local_node_id(def_id).and_then(|node_id| { @@ -333,13 +311,12 @@ fn check_unused_unsafe<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, debug!("check_unused_unsafe({:?}, body={:?}, used_unsafe={:?})", def_id, body, used_unsafe); - hir::intravisit::Visitor::visit_body( - &mut UnusedUnsafeVisitor { tcx, used_unsafe }, - body); + let mut visitor = UnusedUnsafeVisitor { used_unsafe, unsafe_blocks }; + hir::intravisit::Visitor::visit_body(&mut visitor, body); } -fn unsafety_violations<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> - Rc<[UnsafetyViolation]> +fn unsafety_check_result<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) + -> UnsafetyCheckResult { debug!("unsafety_violations({:?})", def_id); @@ -351,7 +328,10 @@ fn unsafety_violations<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ClearOnDecode::Set(ref data) => data, ClearOnDecode::Clear => { debug!("unsafety_violations: {:?} - remote, skipping", def_id); - return Rc::new([]) + return UnsafetyCheckResult { + violations: Rc::new([]), + unsafe_blocks: Rc::new([]) + } } }; @@ -360,8 +340,43 @@ fn unsafety_violations<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> mir, visibility_scope_info, tcx, param_env); checker.visit_mir(mir); - check_unused_unsafe(tcx, def_id, checker.used_unsafe); - checker.violations.into() + check_unused_unsafe(tcx, def_id, &checker.used_unsafe, &mut checker.inherited_blocks); + UnsafetyCheckResult { + violations: checker.violations.into(), + unsafe_blocks: checker.inherited_blocks.into() + } +} + +/// Return the NodeId for an enclosing scope that is also `unsafe` +fn is_enclosed(tcx: TyCtxt, + used_unsafe: &FxHashSet, + id: ast::NodeId) -> Option<(String, ast::NodeId)> { + let parent_id = tcx.hir.get_parent_node(id); + if parent_id != id { + if used_unsafe.contains(&parent_id) { + Some(("block".to_string(), parent_id)) + } else if let Some(hir::map::NodeItem(&hir::Item { + node: hir::ItemFn(_, hir::Unsafety::Unsafe, _, _, _, _), + .. + })) = tcx.hir.find(parent_id) { + Some(("fn".to_string(), parent_id)) + } else { + is_enclosed(tcx, used_unsafe, parent_id) + } + } else { + None + } +} + +fn report_unused_unsafe(tcx: TyCtxt, used_unsafe: &FxHashSet, id: ast::NodeId) { + let span = tcx.hir.span(id); + let mut db = tcx.struct_span_lint_node(UNUSED_UNSAFE, id, span, "unnecessary `unsafe` block"); + db.span_label(span, "unnecessary `unsafe` block"); + if let Some((kind, id)) = is_enclosed(tcx, used_unsafe, id) { + db.span_note(tcx.hir.span(id), + &format!("because it's nested under this `unsafe` {}", kind)); + } + db.emit(); } pub fn check_unsafety<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) { @@ -372,9 +387,14 @@ pub fn check_unsafety<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) { _ => {} }; + let UnsafetyCheckResult { + violations, + unsafe_blocks + } = tcx.unsafety_check_result(def_id); + for &UnsafetyViolation { source_info, description, lint_node_id - } in &*tcx.unsafety_violations(def_id) { + } in violations.iter() { // Report an error. if let Some(lint_node_id) = lint_node_id { tcx.lint_node(SAFE_EXTERN_STATICS, @@ -390,4 +410,15 @@ pub fn check_unsafety<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) { .emit(); } } + + let mut unsafe_blocks: Vec<_> = unsafe_blocks.into_iter().collect(); + unsafe_blocks.sort(); + let used_unsafe: FxHashSet<_> = unsafe_blocks.iter() + .flat_map(|&&(id, used)| if used { Some(id) } else { None }) + .collect(); + for &(block_id, is_used) in unsafe_blocks { + if !is_used { + report_unused_unsafe(tcx, &used_unsafe, block_id); + } + } } diff --git a/src/librustc_mir/transform/mod.rs b/src/librustc_mir/transform/mod.rs index ad17cc5e58f..34cc3a289d1 100644 --- a/src/librustc_mir/transform/mod.rs +++ b/src/librustc_mir/transform/mod.rs @@ -111,7 +111,7 @@ fn mir_built<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx Stea fn mir_const<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx Steal> { // Unsafety check uses the raw mir, so make sure it is run - let _ = tcx.unsafety_violations(def_id); + let _ = tcx.unsafety_check_result(def_id); let source = MirSource::from_local_def_id(tcx, def_id); let mut mir = tcx.mir_built(def_id).steal(); diff --git a/src/test/ui/issue-45107-unnecessary-unsafe-in-closure.rs b/src/test/ui/issue-45107-unnecessary-unsafe-in-closure.rs new file mode 100644 index 00000000000..833fc2802a3 --- /dev/null +++ b/src/test/ui/issue-45107-unnecessary-unsafe-in-closure.rs @@ -0,0 +1,35 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#[deny(unused_unsafe)] +fn main() { + let mut v = Vec::::with_capacity(24); + + unsafe { + let f = |v: &mut Vec<_>| { + unsafe { + v.set_len(24); + |w: &mut Vec| { unsafe { + w.set_len(32); + } }; + } + |x: &mut Vec| { unsafe { + x.set_len(40); + } }; + }; + + v.set_len(0); + f(&mut v); + } + + |y: &mut Vec| { unsafe { + y.set_len(48); + } }; +} diff --git a/src/test/ui/issue-45107-unnecessary-unsafe-in-closure.stderr b/src/test/ui/issue-45107-unnecessary-unsafe-in-closure.stderr new file mode 100644 index 00000000000..5c58b19c7fb --- /dev/null +++ b/src/test/ui/issue-45107-unnecessary-unsafe-in-closure.stderr @@ -0,0 +1,71 @@ +error: unnecessary `unsafe` block + --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:17:13 + | +17 | / unsafe { +18 | | v.set_len(24); +19 | | |w: &mut Vec| { unsafe { +20 | | w.set_len(32); +21 | | } }; +22 | | } + | |_____________^ unnecessary `unsafe` block + | +note: lint level defined here + --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:11:8 + | +11 | #[deny(unused_unsafe)] + | ^^^^^^^^^^^^^ +note: because it's nested under this `unsafe` block + --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:15:5 + | +15 | / unsafe { +16 | | let f = |v: &mut Vec<_>| { +17 | | unsafe { +18 | | v.set_len(24); +... | +29 | | f(&mut v); +30 | | } + | |_____^ + +error: unnecessary `unsafe` block + --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:19:38 + | +19 | |w: &mut Vec| { unsafe { + | ______________________________________^ +20 | | w.set_len(32); +21 | | } }; + | |_________________^ unnecessary `unsafe` block + | +note: because it's nested under this `unsafe` block + --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:17:13 + | +17 | / unsafe { +18 | | v.set_len(24); +19 | | |w: &mut Vec| { unsafe { +20 | | w.set_len(32); +21 | | } }; +22 | | } + | |_____________^ + +error: unnecessary `unsafe` block + --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:23:34 + | +23 | |x: &mut Vec| { unsafe { + | __________________________________^ +24 | | x.set_len(40); +25 | | } }; + | |_____________^ unnecessary `unsafe` block + | +note: because it's nested under this `unsafe` block + --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:15:5 + | +15 | / unsafe { +16 | | let f = |v: &mut Vec<_>| { +17 | | unsafe { +18 | | v.set_len(24); +... | +29 | | f(&mut v); +30 | | } + | |_____^ + +error: aborting due to 6 previous errors + diff --git a/src/test/ui/span/lint-unused-unsafe.stderr b/src/test/ui/span/lint-unused-unsafe.stderr index 1fa5f94aa4c..f4998e08907 100644 --- a/src/test/ui/span/lint-unused-unsafe.stderr +++ b/src/test/ui/span/lint-unused-unsafe.stderr @@ -64,26 +64,6 @@ note: because it's nested under this `unsafe` block 36 | | } | |_____^ -error: unnecessary `unsafe` block - --> $DIR/lint-unused-unsafe.rs:40:9 - | -40 | / unsafe { //~ ERROR: unnecessary `unsafe` block -41 | | unsf() -42 | | } - | |_________^ unnecessary `unsafe` block - | -note: because it's nested under this `unsafe` fn - --> $DIR/lint-unused-unsafe.rs:38:1 - | -38 | / unsafe fn bad7() { -39 | | unsafe { //~ ERROR: unnecessary `unsafe` block -40 | | unsafe { //~ ERROR: unnecessary `unsafe` block -41 | | unsf() -42 | | } -43 | | } -44 | | } - | |_^ - error: unnecessary `unsafe` block --> $DIR/lint-unused-unsafe.rs:39:5 | @@ -106,5 +86,25 @@ note: because it's nested under this `unsafe` fn 44 | | } | |_^ +error: unnecessary `unsafe` block + --> $DIR/lint-unused-unsafe.rs:40:9 + | +40 | / unsafe { //~ ERROR: unnecessary `unsafe` block +41 | | unsf() +42 | | } + | |_________^ unnecessary `unsafe` block + | +note: because it's nested under this `unsafe` fn + --> $DIR/lint-unused-unsafe.rs:38:1 + | +38 | / unsafe fn bad7() { +39 | | unsafe { //~ ERROR: unnecessary `unsafe` block +40 | | unsafe { //~ ERROR: unnecessary `unsafe` block +41 | | unsf() +42 | | } +43 | | } +44 | | } + | |_^ + error: aborting due to 8 previous errors