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Fix async functions handling for needless_pass_by_ref_mut lint

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This commit is contained in:
Guillaume Gomez 2023-07-18 21:45:28 +02:00
parent 9f0cbfd7df
commit 8b0540bb46
1 changed files with 73 additions and 28 deletions
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101
clippy_lints/src/needless_pass_by_ref_mut.rs
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@ -3,14 +3,16 @@
use clippy_utils::source::snippet;
use clippy_utils::{is_from_proc_macro, is_self};
use if_chain::if_chain;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::Applicability;
use rustc_hir::intravisit::FnKind;
use rustc_hir::{Body, FnDecl, HirId, HirIdMap, HirIdSet, Impl, ItemKind, Mutability, Node, PatKind};
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::mir::FakeReadCause;
use rustc_middle::ty::{self, Ty};
use rustc_middle::ty::{self, Ty, UpvarId, UpvarPath};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::def_id::LocalDefId;
use rustc_span::symbol::kw;
@ -102,17 +104,17 @@ fn check_fn(
}
let hir_id = cx.tcx.hir().local_def_id_to_hir_id(fn_def_id);
match kind {
let is_async = match kind {
FnKind::ItemFn(.., header) => {
let attrs = cx.tcx.hir().attrs(hir_id);
if header.abi != Abi::Rust || requires_exact_signature(attrs) {
return;
}
header.is_async()
},
FnKind::Method(..) => (),
FnKind::Method(.., sig) => sig.header.is_async(),
FnKind::Closure => return,
}
};
// Exclude non-inherent impls
if let Some(Node::Item(item)) = cx.tcx.hir().find_parent(hir_id) {
@ -128,25 +130,6 @@ fn check_fn(
let fn_sig = cx.tcx.liberate_late_bound_regions(fn_def_id.to_def_id(), fn_sig);
// If there are no `&mut` argument, no need to go any further.
if !decl
.inputs
.iter()
.zip(fn_sig.inputs())
.zip(body.params)
.any(|((&input, &ty), arg)| !should_skip(cx, input, ty, arg))
{
return;
}
// 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 infcx = cx.tcx.infer_ctxt().build();
euv::ExprUseVisitor::new(&mut ctx, &infcx, fn_def_id, cx.param_env, cx.typeck_results()).consume_body(body);
ctx
};
let mut it = decl
.inputs
.iter()
@ -157,6 +140,32 @@ fn check_fn(
if it.peek().is_none() {
return;
}
// 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 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);
}
}
}
ctx
};
let show_semver_warning = self.avoid_breaking_exported_api && cx.effective_visibilities.is_exported(fn_def_id);
for ((&input, &_), arg) in it {
// Only take `&mut` arguments.
@ -197,7 +206,9 @@ fn check_fn(
struct MutablyUsedVariablesCtxt {
mutably_used_vars: HirIdSet,
prev_bind: Option<HirId>,
prev_move_to_closure: HirIdSet,
aliases: HirIdMap<HirId>,
async_closures: FxHashSet<LocalDefId>,
}
impl MutablyUsedVariablesCtxt {
@ -213,16 +224,27 @@ fn add_mutably_used_var(&mut self, mut used_id: HirId) {
impl<'tcx> euv::Delegate<'tcx> for MutablyUsedVariablesCtxt {
fn consume(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId) {
if let euv::Place {
base: euv::PlaceBase::Local(vid),
base:
euv::PlaceBase::Local(vid)
| euv::PlaceBase::Upvar(UpvarId {
var_path: UpvarPath { hir_id: vid },
..
}),
base_ty,
..
} = &cmt.place
{
if let Some(bind_id) = self.prev_bind.take() {
self.aliases.insert(bind_id, *vid);
} else if matches!(base_ty.ref_mutability(), Some(Mutability::Mut)) {
if bind_id != *vid {
self.aliases.insert(bind_id, *vid);
}
} else if !self.prev_move_to_closure.contains(vid)
&& matches!(base_ty.ref_mutability(), Some(Mutability::Mut))
{
self.add_mutably_used_var(*vid);
}
self.prev_bind = None;
self.prev_move_to_closure.remove(vid);
}
}
@ -265,7 +287,30 @@ fn copy(&mut self, _cmt: &euv::PlaceWithHirId<'tcx>, _id: HirId) {
self.prev_bind = None;
}
fn fake_read(&mut self, _: &rustc_hir_typeck::expr_use_visitor::PlaceWithHirId<'tcx>, _: FakeReadCause, _: HirId) {}
fn fake_read(
&mut self,
cmt: &rustc_hir_typeck::expr_use_visitor::PlaceWithHirId<'tcx>,
cause: FakeReadCause,
_id: HirId,
) {
if let euv::Place {
base:
euv::PlaceBase::Upvar(UpvarId {
var_path: UpvarPath { hir_id: vid },
..
}),
..
} = &cmt.place
{
if let FakeReadCause::ForLet(Some(inner)) = cause {
// 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.prev_move_to_closure.insert(*vid);
}
}
}
fn bind(&mut self, _cmt: &euv::PlaceWithHirId<'tcx>, id: HirId) {
self.prev_bind = Some(id);