use clippy_utils::diagnostics::{span_lint_hir, span_lint_hir_and_then};
+use clippy_utils::mir::{visit_local_usage, LocalUsage, PossibleBorrowerMap};
use clippy_utils::source::snippet_opt;
-use clippy_utils::ty::{has_drop, is_copy, is_type_diagnostic_item, walk_ptrs_ty_depth};
+use clippy_utils::ty::{has_drop, is_copy, is_type_diagnostic_item, is_type_lang_item, walk_ptrs_ty_depth};
use clippy_utils::{fn_has_unsatisfiable_preds, match_def_path, paths};
use if_chain::if_chain;
-use rustc_data_structures::fx::FxHashMap;
use rustc_errors::Applicability;
use rustc_hir::intravisit::FnKind;
-use rustc_hir::{def_id, Body, FnDecl, HirId};
-use rustc_index::bit_set::{BitSet, HybridBitSet};
+use rustc_hir::{def_id, Body, FnDecl, HirId, LangItem};
use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::mir::{
- self, traversal,
- visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor as _},
- Mutability,
-};
-use rustc_middle::ty::{self, fold::TypeVisitor, Ty};
-use rustc_mir_dataflow::{Analysis, AnalysisDomain, CallReturnPlaces, GenKill, GenKillAnalysis, ResultsCursor};
+use rustc_middle::mir;
+use rustc_middle::ty::{self, Ty};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::{BytePos, Span};
use rustc_span::sym;
-use std::ops::ControlFlow;
macro_rules! unwrap_or_continue {
($x:expr) => {
let mir = cx.tcx.optimized_mir(def_id.to_def_id());
- let possible_origin = {
- let mut vis = PossibleOriginVisitor::new(mir);
- vis.visit_body(mir);
- vis.into_map(cx)
- };
- let maybe_storage_live_result = MaybeStorageLive
- .into_engine(cx.tcx, mir)
- .pass_name("redundant_clone")
- .iterate_to_fixpoint()
- .into_results_cursor(mir);
- let mut possible_borrower = {
- let mut vis = PossibleBorrowerVisitor::new(cx, mir, possible_origin);
- vis.visit_body(mir);
- vis.into_map(cx, maybe_storage_live_result)
- };
-
- for (bb, bbdata) in mir.basic_blocks().iter_enumerated() {
+ let mut possible_borrower = PossibleBorrowerMap::new(cx, mir);
+
+ for (bb, bbdata) in mir.basic_blocks.iter_enumerated() {
let terminator = bbdata.terminator();
if terminator.source_info.span.from_expansion() {
let from_borrow = match_def_path(cx, fn_def_id, &paths::CLONE_TRAIT_METHOD)
|| match_def_path(cx, fn_def_id, &paths::TO_OWNED_METHOD)
|| (match_def_path(cx, fn_def_id, &paths::TO_STRING_METHOD)
- && is_type_diagnostic_item(cx, arg_ty, sym::String));
+ && is_type_lang_item(cx, arg_ty, LangItem::String));
let from_deref = !from_borrow
&& (match_def_path(cx, fn_def_id, &paths::PATH_TO_PATH_BUF)
// `arg` is a reference as it is `.deref()`ed in the previous block.
// Look into the predecessor block and find out the source of deref.
- let ps = &mir.predecessors()[bb];
+ let ps = &mir.basic_blocks.predecessors()[bb];
if ps.len() != 1 {
continue;
}
unwrap_or_continue!(find_stmt_assigns_to(cx, mir, pred_arg, true, ps[0]));
let loc = mir::Location {
block: bb,
- statement_index: mir.basic_blocks()[bb].statements.len(),
+ statement_index: mir.basic_blocks[bb].statements.len(),
};
// This can be turned into `res = move local` if `arg` and `cloned` are not borrowed
diag.span_suggestion(
sugg_span,
"remove this",
- String::new(),
+ "",
app,
);
if clone_usage.cloned_used {
if let mir::TerminatorKind::Call { func, args, destination, .. } = kind;
if args.len() == 1;
if let mir::Operand::Move(mir::Place { local, .. }) = &args[0];
- if let ty::FnDef(def_id, _) = *func.ty(&*mir, cx.tcx).kind();
- if let (inner_ty, 1) = walk_ptrs_ty_depth(args[0].ty(&*mir, cx.tcx));
+ if let ty::FnDef(def_id, _) = *func.ty(mir, cx.tcx).kind();
+ if let (inner_ty, 1) = walk_ptrs_ty_depth(args[0].ty(mir, cx.tcx));
if !is_copy(cx, inner_ty);
then {
- Some((def_id, *local, inner_ty, destination.as_ref().map(|(dest, _)| dest)?.as_local()?))
+ Some((def_id, *local, inner_ty, destination.as_local()?))
} else {
None
}
by_ref: bool,
bb: mir::BasicBlock,
) -> Option<(mir::Local, CannotMoveOut)> {
- let rvalue = mir.basic_blocks()[bb].statements.iter().rev().find_map(|stmt| {
+ let rvalue = mir.basic_blocks[bb].statements.iter().rev().find_map(|stmt| {
if let mir::StatementKind::Assign(box (mir::Place { local, .. }, v)) = &stmt.kind {
return if *local == to_local { Some(v) } else { None };
}
None
})?;
- match (by_ref, &*rvalue) {
+ match (by_ref, rvalue) {
(true, mir::Rvalue::Ref(_, _, place)) | (false, mir::Rvalue::Use(mir::Operand::Copy(place))) => {
Some(base_local_and_movability(cx, mir, *place))
},
/// Whether the clone value is mutated.
clone_consumed_or_mutated: bool,
}
-fn visit_clone_usage(cloned: mir::Local, clone: mir::Local, mir: &mir::Body<'_>, bb: mir::BasicBlock) -> CloneUsage {
- struct V {
- cloned: mir::Local,
- clone: mir::Local,
- result: CloneUsage,
- }
- impl<'tcx> mir::visit::Visitor<'tcx> for V {
- fn visit_basic_block_data(&mut self, block: mir::BasicBlock, data: &mir::BasicBlockData<'tcx>) {
- let statements = &data.statements;
- for (statement_index, statement) in statements.iter().enumerate() {
- self.visit_statement(statement, mir::Location { block, statement_index });
- }
-
- self.visit_terminator(
- data.terminator(),
- mir::Location {
- block,
- statement_index: statements.len(),
- },
- );
- }
-
- fn visit_place(&mut self, place: &mir::Place<'tcx>, ctx: PlaceContext, loc: mir::Location) {
- let local = place.local;
-
- if local == self.cloned
- && !matches!(
- ctx,
- PlaceContext::MutatingUse(MutatingUseContext::Drop) | PlaceContext::NonUse(_)
- )
- {
- self.result.cloned_used = true;
- self.result.cloned_consume_or_mutate_loc = self.result.cloned_consume_or_mutate_loc.or_else(|| {
- matches!(
- ctx,
- PlaceContext::NonMutatingUse(NonMutatingUseContext::Move)
- | PlaceContext::MutatingUse(MutatingUseContext::Borrow)
- )
- .then(|| loc)
- });
- } else if local == self.clone {
- match ctx {
- PlaceContext::NonMutatingUse(NonMutatingUseContext::Move)
- | PlaceContext::MutatingUse(MutatingUseContext::Borrow) => {
- self.result.clone_consumed_or_mutated = true;
- },
- _ => {},
- }
- }
- }
- }
-
- let init = CloneUsage {
- cloned_used: false,
- cloned_consume_or_mutate_loc: None,
- // Consider non-temporary clones consumed.
- // TODO: Actually check for mutation of non-temporaries.
- clone_consumed_or_mutated: mir.local_kind(clone) != mir::LocalKind::Temp,
- };
- traversal::ReversePostorder::new(mir, bb)
- .skip(1)
- .fold(init, |usage, (tbb, tdata)| {
- // Short-circuit
- if (usage.cloned_used && usage.clone_consumed_or_mutated) ||
- // Give up on loops
- tdata.terminator().successors().any(|s| s == bb)
- {
- return CloneUsage {
- cloned_used: true,
- clone_consumed_or_mutated: true,
- ..usage
- };
- }
-
- let mut v = V {
- cloned,
- clone,
- result: usage,
- };
- v.visit_basic_block_data(tbb, tdata);
- v.result
- })
-}
-
-/// Determines liveness of each local purely based on `StorageLive`/`Dead`.
-#[derive(Copy, Clone)]
-struct MaybeStorageLive;
-
-impl<'tcx> AnalysisDomain<'tcx> for MaybeStorageLive {
- type Domain = BitSet<mir::Local>;
- const NAME: &'static str = "maybe_storage_live";
-
- fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
- // bottom = dead
- BitSet::new_empty(body.local_decls.len())
- }
-
- fn initialize_start_block(&self, body: &mir::Body<'tcx>, state: &mut Self::Domain) {
- for arg in body.args_iter() {
- state.insert(arg);
- }
- }
-}
-
-impl<'tcx> GenKillAnalysis<'tcx> for MaybeStorageLive {
- type Idx = mir::Local;
- fn statement_effect(&self, trans: &mut impl GenKill<Self::Idx>, stmt: &mir::Statement<'tcx>, _: mir::Location) {
- match stmt.kind {
- mir::StatementKind::StorageLive(l) => trans.gen(l),
- mir::StatementKind::StorageDead(l) => trans.kill(l),
- _ => (),
- }
- }
-
- fn terminator_effect(
- &self,
- _trans: &mut impl GenKill<Self::Idx>,
- _terminator: &mir::Terminator<'tcx>,
- _loc: mir::Location,
- ) {
- }
-
- fn call_return_effect(
- &self,
- _trans: &mut impl GenKill<Self::Idx>,
- _block: mir::BasicBlock,
- _return_places: CallReturnPlaces<'_, 'tcx>,
- ) {
- // Nothing to do when a call returns successfully
- }
-}
-
-/// Collects the possible borrowers of each local.
-/// For example, `b = &a; c = &a;` will make `b` and (transitively) `c`
-/// possible borrowers of `a`.
-struct PossibleBorrowerVisitor<'a, 'tcx> {
- possible_borrower: TransitiveRelation,
- body: &'a mir::Body<'tcx>,
- cx: &'a LateContext<'tcx>,
- possible_origin: FxHashMap<mir::Local, HybridBitSet<mir::Local>>,
-}
-
-impl<'a, 'tcx> PossibleBorrowerVisitor<'a, 'tcx> {
- fn new(
- cx: &'a LateContext<'tcx>,
- body: &'a mir::Body<'tcx>,
- possible_origin: FxHashMap<mir::Local, HybridBitSet<mir::Local>>,
- ) -> Self {
- Self {
- possible_borrower: TransitiveRelation::default(),
- cx,
- body,
- possible_origin,
- }
- }
-
- fn into_map(
- self,
- cx: &LateContext<'tcx>,
- maybe_live: ResultsCursor<'tcx, 'tcx, MaybeStorageLive>,
- ) -> PossibleBorrowerMap<'a, 'tcx> {
- let mut map = FxHashMap::default();
- for row in (1..self.body.local_decls.len()).map(mir::Local::from_usize) {
- if is_copy(cx, self.body.local_decls[row].ty) {
- continue;
- }
-
- let mut borrowers = self.possible_borrower.reachable_from(row, self.body.local_decls.len());
- borrowers.remove(mir::Local::from_usize(0));
- if !borrowers.is_empty() {
- map.insert(row, borrowers);
- }
- }
-
- let bs = BitSet::new_empty(self.body.local_decls.len());
- PossibleBorrowerMap {
- map,
- maybe_live,
- bitset: (bs.clone(), bs),
- }
- }
-}
-
-impl<'a, 'tcx> mir::visit::Visitor<'tcx> for PossibleBorrowerVisitor<'a, 'tcx> {
- fn visit_assign(&mut self, place: &mir::Place<'tcx>, rvalue: &mir::Rvalue<'_>, _location: mir::Location) {
- let lhs = place.local;
- match rvalue {
- mir::Rvalue::Ref(_, _, borrowed) => {
- self.possible_borrower.add(borrowed.local, lhs);
- },
- other => {
- if ContainsRegion
- .visit_ty(place.ty(&self.body.local_decls, self.cx.tcx).ty)
- .is_continue()
- {
- return;
- }
- rvalue_locals(other, |rhs| {
- if lhs != rhs {
- self.possible_borrower.add(rhs, lhs);
- }
- });
- },
- }
- }
-
- fn visit_terminator(&mut self, terminator: &mir::Terminator<'_>, _loc: mir::Location) {
- if let mir::TerminatorKind::Call {
- args,
- destination: Some((mir::Place { local: dest, .. }, _)),
- ..
- } = &terminator.kind
- {
- // TODO add doc
- // If the call returns something with lifetimes,
- // let's conservatively assume the returned value contains lifetime of all the arguments.
- // For example, given `let y: Foo<'a> = foo(x)`, `y` is considered to be a possible borrower of `x`.
-
- let mut immutable_borrowers = vec![];
- let mut mutable_borrowers = vec![];
-
- for op in args {
- match op {
- mir::Operand::Copy(p) | mir::Operand::Move(p) => {
- if let ty::Ref(_, _, Mutability::Mut) = self.body.local_decls[p.local].ty.kind() {
- mutable_borrowers.push(p.local);
- } else {
- immutable_borrowers.push(p.local);
- }
- },
- mir::Operand::Constant(..) => (),
- }
- }
-
- let mut mutable_variables: Vec<mir::Local> = mutable_borrowers
- .iter()
- .filter_map(|r| self.possible_origin.get(r))
- .flat_map(HybridBitSet::iter)
- .collect();
-
- if ContainsRegion.visit_ty(self.body.local_decls[*dest].ty).is_break() {
- mutable_variables.push(*dest);
- }
-
- for y in mutable_variables {
- for x in &immutable_borrowers {
- self.possible_borrower.add(*x, y);
- }
- for x in &mutable_borrowers {
- self.possible_borrower.add(*x, y);
- }
- }
- }
- }
-}
-
-/// Collect possible borrowed for every `&mut` local.
-/// For example, `_1 = &mut _2` generate _1: {_2,...}
-/// Known Problems: not sure all borrowed are tracked
-struct PossibleOriginVisitor<'a, 'tcx> {
- possible_origin: TransitiveRelation,
- body: &'a mir::Body<'tcx>,
-}
-
-impl<'a, 'tcx> PossibleOriginVisitor<'a, 'tcx> {
- fn new(body: &'a mir::Body<'tcx>) -> Self {
- Self {
- possible_origin: TransitiveRelation::default(),
- body,
- }
- }
-
- fn into_map(self, cx: &LateContext<'tcx>) -> FxHashMap<mir::Local, HybridBitSet<mir::Local>> {
- let mut map = FxHashMap::default();
- for row in (1..self.body.local_decls.len()).map(mir::Local::from_usize) {
- if is_copy(cx, self.body.local_decls[row].ty) {
- continue;
- }
-
- let mut borrowers = self.possible_origin.reachable_from(row, self.body.local_decls.len());
- borrowers.remove(mir::Local::from_usize(0));
- if !borrowers.is_empty() {
- map.insert(row, borrowers);
- }
- }
- map
- }
-}
-
-impl<'a, 'tcx> mir::visit::Visitor<'tcx> for PossibleOriginVisitor<'a, 'tcx> {
- fn visit_assign(&mut self, place: &mir::Place<'tcx>, rvalue: &mir::Rvalue<'_>, _location: mir::Location) {
- let lhs = place.local;
- match rvalue {
- // Only consider `&mut`, which can modify origin place
- mir::Rvalue::Ref(_, rustc_middle::mir::BorrowKind::Mut { .. }, borrowed) |
- // _2: &mut _;
- // _3 = move _2
- mir::Rvalue::Use(mir::Operand::Move(borrowed)) |
- // _3 = move _2 as &mut _;
- mir::Rvalue::Cast(_, mir::Operand::Move(borrowed), _)
- => {
- self.possible_origin.add(lhs, borrowed.local);
- },
- _ => {},
- }
- }
-}
-
-struct ContainsRegion;
-
-impl TypeVisitor<'_> for ContainsRegion {
- type BreakTy = ();
-
- fn visit_region(&mut self, _: ty::Region<'_>) -> ControlFlow<Self::BreakTy> {
- ControlFlow::BREAK
- }
-}
-
-fn rvalue_locals(rvalue: &mir::Rvalue<'_>, mut visit: impl FnMut(mir::Local)) {
- use rustc_middle::mir::Rvalue::{Aggregate, BinaryOp, Cast, CheckedBinaryOp, Repeat, UnaryOp, Use};
-
- let mut visit_op = |op: &mir::Operand<'_>| match op {
- mir::Operand::Copy(p) | mir::Operand::Move(p) => visit(p.local),
- mir::Operand::Constant(..) => (),
- };
-
- match rvalue {
- Use(op) | Repeat(op, _) | Cast(_, op, _) | UnaryOp(_, op) => visit_op(op),
- Aggregate(_, ops) => ops.iter().for_each(visit_op),
- BinaryOp(_, box (lhs, rhs)) | CheckedBinaryOp(_, box (lhs, rhs)) => {
- visit_op(lhs);
- visit_op(rhs);
+fn visit_clone_usage(cloned: mir::Local, clone: mir::Local, mir: &mir::Body<'_>, bb: mir::BasicBlock) -> CloneUsage {
+ if let Some((
+ LocalUsage {
+ local_use_locs: cloned_use_locs,
+ local_consume_or_mutate_locs: cloned_consume_or_mutate_locs,
},
- _ => (),
- }
-}
-
-/// Result of `PossibleBorrowerVisitor`.
-struct PossibleBorrowerMap<'a, 'tcx> {
- /// Mapping `Local -> its possible borrowers`
- map: FxHashMap<mir::Local, HybridBitSet<mir::Local>>,
- maybe_live: ResultsCursor<'a, 'tcx, MaybeStorageLive>,
- // Caches to avoid allocation of `BitSet` on every query
- bitset: (BitSet<mir::Local>, BitSet<mir::Local>),
-}
-
-impl PossibleBorrowerMap<'_, '_> {
- /// Returns true if the set of borrowers of `borrowed` living at `at` matches with `borrowers`.
- fn only_borrowers(&mut self, borrowers: &[mir::Local], borrowed: mir::Local, at: mir::Location) -> bool {
- self.maybe_live.seek_after_primary_effect(at);
-
- self.bitset.0.clear();
- let maybe_live = &mut self.maybe_live;
- if let Some(bitset) = self.map.get(&borrowed) {
- for b in bitset.iter().filter(move |b| maybe_live.contains(*b)) {
- self.bitset.0.insert(b);
- }
- } else {
- return false;
- }
-
- self.bitset.1.clear();
- for b in borrowers {
- self.bitset.1.insert(*b);
+ LocalUsage {
+ local_use_locs: _,
+ local_consume_or_mutate_locs: clone_consume_or_mutate_locs,
+ },
+ )) = visit_local_usage(
+ &[cloned, clone],
+ mir,
+ mir::Location {
+ block: bb,
+ statement_index: mir.basic_blocks[bb].statements.len(),
+ },
+ )
+ .map(|mut vec| (vec.remove(0), vec.remove(0)))
+ {
+ CloneUsage {
+ cloned_used: !cloned_use_locs.is_empty(),
+ cloned_consume_or_mutate_loc: cloned_consume_or_mutate_locs.first().copied(),
+ // Consider non-temporary clones consumed.
+ // TODO: Actually check for mutation of non-temporaries.
+ clone_consumed_or_mutated: mir.local_kind(clone) != mir::LocalKind::Temp
+ || !clone_consume_or_mutate_locs.is_empty(),
}
-
- self.bitset.0 == self.bitset.1
- }
-
- fn local_is_alive_at(&mut self, local: mir::Local, at: mir::Location) -> bool {
- self.maybe_live.seek_after_primary_effect(at);
- self.maybe_live.contains(local)
- }
-}
-
-#[derive(Default)]
-struct TransitiveRelation {
- relations: FxHashMap<mir::Local, Vec<mir::Local>>,
-}
-impl TransitiveRelation {
- fn add(&mut self, a: mir::Local, b: mir::Local) {
- self.relations.entry(a).or_default().push(b);
- }
-
- fn reachable_from(&self, a: mir::Local, domain_size: usize) -> HybridBitSet<mir::Local> {
- let mut seen = HybridBitSet::new_empty(domain_size);
- let mut stack = vec![a];
- while let Some(u) = stack.pop() {
- if let Some(edges) = self.relations.get(&u) {
- for &v in edges {
- if seen.insert(v) {
- stack.push(v);
- }
- }
- }
+ } else {
+ CloneUsage {
+ cloned_used: true,
+ cloned_consume_or_mutate_loc: None,
+ clone_consumed_or_mutated: true,
}
- seen
}
}
projects / rust.git / blobdiff