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Correctly handle async blocks for NEEDLESS_PASS_BY_REF_MUT

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This commit is contained in:
Guillaume Gomez 2023-08-10 16:06:17 +02:00
parent add2722677
commit 42186af21e
1 changed files with 82 additions and 23 deletions
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105
clippy_lints/src/needless_pass_by_ref_mut.rs
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@ -5,14 +5,16 @@
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_qpath, FnKind, Visitor};
use rustc_hir::{Body, ExprKind, FnDecl, HirId, HirIdMap, HirIdSet, Impl, ItemKind, Mutability, Node, PatKind, QPath};
use rustc_hir::{
Body, Closure, Expr, ExprKind, FnDecl, HirId, HirIdMap, HirIdSet, Impl, ItemKind, Mutability, Node, PatKind, QPath,
};
use rustc_hir_typeck::expr_use_visitor as euv;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::map::associated_body;
use rustc_middle::hir::nested_filter::OnlyBodies;
use rustc_middle::mir::FakeReadCause;
use rustc_middle::ty::{self, Ty, UpvarId, UpvarPath};
use rustc_middle::ty::{self, Ty, TyCtxt, UpvarId, UpvarPath};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::def_id::LocalDefId;
use rustc_span::symbol::kw;
@ -147,22 +149,36 @@ fn check_fn(
// Collect variables mutably used and spans which will need dereferencings from the
// function body.
let MutablyUsedVariablesCtxt { mutably_used_vars, .. } = {
let mut ctx = MutablyUsedVariablesCtxt::default();
let mut ctx = MutablyUsedVariablesCtxt {
mutably_used_vars: HirIdSet::default(),
prev_bind: None,
prev_move_to_closure: HirIdSet::default(),
aliases: HirIdMap::default(),
async_closures: FxHashSet::default(),
tcx: cx.tcx,
};
let infcx = cx.tcx.infer_ctxt().build();
euv::ExprUseVisitor::new(&mut ctx, &infcx, fn_def_id, cx.param_env, cx.typeck_results()).consume_body(body);
if is_async {
let closures = ctx.async_closures.clone();
let hir = cx.tcx.hir();
for closure in closures {
ctx.prev_bind = None;
ctx.prev_move_to_closure.clear();
if let Some(body) = hir
.find_by_def_id(closure)
.and_then(associated_body)
.map(|(_, body_id)| hir.body(body_id))
{
euv::ExprUseVisitor::new(&mut ctx, &infcx, closure, cx.param_env, cx.typeck_results())
.consume_body(body);
let mut checked_closures = FxHashSet::default();
while !ctx.async_closures.is_empty() {
let closures = ctx.async_closures.clone();
ctx.async_closures.clear();
let hir = cx.tcx.hir();
for closure in closures {
if !checked_closures.insert(closure) {
continue;
}
ctx.prev_bind = None;
ctx.prev_move_to_closure.clear();
if let Some(body) = hir
.find_by_def_id(closure)
.and_then(associated_body)
.map(|(_, body_id)| hir.body(body_id))
{
euv::ExprUseVisitor::new(&mut ctx, &infcx, closure, cx.param_env, cx.typeck_results())
.consume_body(body);
}
}
}
}
@ -225,16 +241,16 @@ fn check_crate_post(&mut self, cx: &LateContext<'tcx>) {
}
}
#[derive(Default)]
struct MutablyUsedVariablesCtxt {
struct MutablyUsedVariablesCtxt<'tcx> {
mutably_used_vars: HirIdSet,
prev_bind: Option<HirId>,
prev_move_to_closure: HirIdSet,
aliases: HirIdMap<HirId>,
async_closures: FxHashSet<LocalDefId>,
tcx: TyCtxt<'tcx>,
}
impl MutablyUsedVariablesCtxt {
impl<'tcx> MutablyUsedVariablesCtxt<'tcx> {
fn add_mutably_used_var(&mut self, mut used_id: HirId) {
while let Some(id) = self.aliases.get(&used_id) {
self.mutably_used_vars.insert(used_id);
@ -242,9 +258,27 @@ fn add_mutably_used_var(&mut self, mut used_id: HirId) {
}
self.mutably_used_vars.insert(used_id);
}
fn would_be_alias_cycle(&self, alias: HirId, mut target: HirId) -> bool {
while let Some(id) = self.aliases.get(&target) {
if *id == alias {
return true;
}
target = *id;
}
false
}
fn add_alias(&mut self, alias: HirId, target: HirId) {
// This is to prevent alias loop.
if alias == target || self.would_be_alias_cycle(alias, target) {
return;
}
self.aliases.insert(alias, target);
}
}
impl<'tcx> euv::Delegate<'tcx> for MutablyUsedVariablesCtxt {
impl<'tcx> euv::Delegate<'tcx> for MutablyUsedVariablesCtxt<'tcx> {
fn consume(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId) {
if let euv::Place {
base:
@ -259,7 +293,7 @@ fn consume(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId) {
{
if let Some(bind_id) = self.prev_bind.take() {
if bind_id != *vid {
self.aliases.insert(bind_id, *vid);
self.add_alias(bind_id, *vid);
}
} else if !self.prev_move_to_closure.contains(vid)
&& matches!(base_ty.ref_mutability(), Some(Mutability::Mut))
@ -271,7 +305,7 @@ fn consume(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId) {
}
}
fn borrow(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId, borrow: ty::BorrowKind) {
fn borrow(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, id: HirId, borrow: ty::BorrowKind) {
self.prev_bind = None;
if let euv::Place {
base: euv::PlaceBase::Local(vid),
@ -289,6 +323,25 @@ fn borrow(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId, borrow: ty::Bo
{
self.add_mutably_used_var(*vid);
}
} else if borrow == ty::ImmBorrow {
// If there is an `async block`, it'll contain a call to a closure which we need to
// go into to ensure all "mutate" checks are found.
if let Node::Expr(Expr {
kind:
ExprKind::Call(
_,
[
Expr {
kind: ExprKind::Closure(Closure { def_id, .. }),
..
},
],
),
..
}) = self.tcx.hir().get(id)
{
self.async_closures.insert(*def_id);
}
}
}
@ -296,7 +349,12 @@ fn mutate(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId) {
self.prev_bind = None;
if let euv::Place {
projections,
base: euv::PlaceBase::Local(vid),
base:
euv::PlaceBase::Local(vid)
| euv::PlaceBase::Upvar(UpvarId {
var_path: UpvarPath { hir_id: vid },
..
}),
..
} = &cmt.place
{
@ -329,8 +387,9 @@ fn fake_read(
// Seems like we are inside an async function. We need to store the closure `DefId`
// to go through it afterwards.
self.async_closures.insert(inner);
self.aliases.insert(cmt.hir_id, *vid);
self.add_alias(cmt.hir_id, *vid);
self.prev_move_to_closure.insert(*vid);
self.prev_bind = None;
}
}
}