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Only lint mut_from_ref when unsafe code is used

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This commit is contained in:
Jason Newcomb 2022-04-06 10:56:06 -04:00
parent cf1e2e9c1c
commit ddd3af2273
4 changed files with 89 additions and 35 deletions
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56
clippy_lints/src/ptr.rs
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@ -3,6 +3,7 @@
use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::source::snippet_opt;
use clippy_utils::ty::expr_sig;
use clippy_utils::visitors::contains_unsafe_block;
use clippy_utils::{get_expr_use_or_unification_node, is_lint_allowed, path_def_id, path_to_local, paths};
use if_chain::if_chain;
use rustc_errors::Applicability;
@ -10,9 +11,9 @@ use rustc_hir::def_id::DefId;
use rustc_hir::hir_id::HirIdMap;
use rustc_hir::intravisit::{walk_expr, Visitor};
use rustc_hir::{
self as hir, AnonConst, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnDecl, FnRetTy, GenericArg,
self as hir, AnonConst, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnRetTy, FnSig, GenericArg,
ImplItemKind, ItemKind, Lifetime, LifetimeName, Mutability, Node, Param, ParamName, PatKind, QPath, TraitFn,
TraitItem, TraitItemKind, TyKind,
TraitItem, TraitItemKind, TyKind, Unsafety,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::nested_filter;
@ -145,7 +146,7 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
return;
}
check_mut_from_ref(cx, sig.decl);
check_mut_from_ref(cx, sig, None);
for arg in check_fn_args(
cx,
cx.tcx.fn_sig(item.def_id).skip_binder().inputs(),
@ -170,10 +171,10 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
fn check_body(&mut self, cx: &LateContext<'tcx>, body: &'tcx Body<'_>) {
let hir = cx.tcx.hir();
let mut parents = hir.parent_iter(body.value.hir_id);
let (item_id, decl, is_trait_item) = match parents.next() {
let (item_id, sig, is_trait_item) = match parents.next() {
Some((_, Node::Item(i))) => {
if let ItemKind::Fn(sig, ..) = &i.kind {
(i.def_id, sig.decl, false)
(i.def_id, sig, false)
} else {
return;
}
@ -185,14 +186,14 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
return;
}
if let ImplItemKind::Fn(sig, _) = &i.kind {
(i.def_id, sig.decl, false)
(i.def_id, sig, false)
} else {
return;
}
},
Some((_, Node::TraitItem(i))) => {
if let TraitItemKind::Fn(sig, _) = &i.kind {
(i.def_id, sig.decl, true)
(i.def_id, sig, true)
} else {
return;
}
@ -200,7 +201,8 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
_ => return,
};
check_mut_from_ref(cx, decl);
check_mut_from_ref(cx, sig, Some(body));
let decl = sig.decl;
let sig = cx.tcx.fn_sig(item_id).skip_binder();
let lint_args: Vec<_> = check_fn_args(cx, sig.inputs(), decl.inputs, body.params)
.filter(|arg| !is_trait_item || arg.mutability() == Mutability::Not)
@ -478,31 +480,31 @@ fn check_fn_args<'cx, 'tcx: 'cx>(
})
}
fn check_mut_from_ref(cx: &LateContext<'_>, decl: &FnDecl<'_>) {
if let FnRetTy::Return(ty) = decl.output {
if let Some((out, Mutability::Mut, _)) = get_rptr_lm(ty) {
let mut immutables = vec![];
for (_, mutbl, argspan) in decl
.inputs
.iter()
.filter_map(get_rptr_lm)
.filter(|&(lt, _, _)| lt.name == out.name)
{
if mutbl == Mutability::Mut {
return;
}
immutables.push(argspan);
}
if immutables.is_empty() {
return;
}
fn check_mut_from_ref<'tcx>(cx: &LateContext<'tcx>, sig: &FnSig<'_>, body: Option<&'tcx Body<'_>>) {
if let FnRetTy::Return(ty) = sig.decl.output
&& let Some((out, Mutability::Mut, _)) = get_rptr_lm(ty)
{
let args: Option<Vec<_>> = sig
.decl
.inputs
.iter()
.filter_map(get_rptr_lm)
.filter(|&(lt, _, _)| lt.name == out.name)
.map(|(_, mutability, span)| (mutability == Mutability::Not).then(|| span))
.collect();
if let Some(args) = args
&& !args.is_empty()
&& body.map_or(true, |body| {
sig.header.unsafety == Unsafety::Unsafe || contains_unsafe_block(cx, &body.value)
})
{
span_lint_and_then(
cx,
MUT_FROM_REF,
ty.span,
"mutable borrow from immutable input(s)",
|diag| {
let ms = MultiSpan::from_spans(immutables);
let ms = MultiSpan::from_spans(args);
diag.span_note(ms, "immutable borrow here");
},
);