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extract each lint into its own module

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Ada Alakbarova 2025-10-31 22:22:46 +01:00
parent 54a84c1d76
commit ccd51307df
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5 changed files with 701 additions and 640 deletions
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49
clippy_lints/src/ptr/cmp_null.rs Normal file
View file

@ -0,0 +1,49 @@
use super::CMP_NULL;
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::res::{MaybeDef, MaybeResPath};
use clippy_utils::sugg::Sugg;
use clippy_utils::{is_lint_allowed, sym};
use rustc_errors::Applicability;
use rustc_hir::{BinOpKind, Expr, ExprKind};
use rustc_lint::LateContext;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
op: BinOpKind,
l: &Expr<'_>,
r: &Expr<'_>,
) -> bool {
let non_null_path_snippet = match (
is_lint_allowed(cx, CMP_NULL, expr.hir_id),
is_null_path(cx, l),
is_null_path(cx, r),
) {
(false, true, false) if let Some(sugg) = Sugg::hir_opt(cx, r) => sugg.maybe_paren(),
(false, false, true) if let Some(sugg) = Sugg::hir_opt(cx, l) => sugg.maybe_paren(),
_ => return false,
};
let invert = if op == BinOpKind::Eq { "" } else { "!" };
span_lint_and_sugg(
cx,
CMP_NULL,
expr.span,
"comparing with null is better expressed by the `.is_null()` method",
"try",
format!("{invert}{non_null_path_snippet}.is_null()",),
Applicability::MachineApplicable,
);
true
}
fn is_null_path(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
if let ExprKind::Call(pathexp, []) = expr.kind {
matches!(
pathexp.basic_res().opt_diag_name(cx),
Some(sym::ptr_null | sym::ptr_null_mut)
)
} else {
false
}
}

655
clippy_lints/src/ptr/mod.rs
View file

@ -1,31 +1,11 @@
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then, span_lint_hir_and_then};
use clippy_utils::res::{MaybeDef, MaybeResPath};
use clippy_utils::source::SpanRangeExt;
use clippy_utils::sugg::Sugg;
use clippy_utils::visitors::contains_unsafe_block;
use clippy_utils::{get_expr_use_or_unification_node, is_lint_allowed, std_or_core, sym};
use hir::LifetimeKind;
use rustc_abi::ExternAbi;
use rustc_errors::{Applicability, MultiSpan};
use rustc_hir::hir_id::{HirId, HirIdMap};
use rustc_hir::intravisit::{Visitor, walk_expr};
use rustc_hir::{
self as hir, AnonConst, BinOpKind, BindingMode, Body, Expr, ExprKind, FnRetTy, FnSig, GenericArg, ImplItemKind,
ItemKind, Lifetime, Mutability, Node, Param, PatKind, QPath, TraitFn, TraitItem, TraitItemKind, TyKind,
};
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::traits::{Obligation, ObligationCause};
use rustc_hir::{BinOpKind, Body, Expr, ExprKind, ImplItemKind, ItemKind, Node, TraitFn, TraitItem, TraitItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::nested_filter;
use rustc_middle::ty::{self, Binder, ClauseKind, ExistentialPredicate, List, PredicateKind, Ty};
use rustc_session::declare_lint_pass;
use rustc_span::Span;
use rustc_span::symbol::Symbol;
use rustc_trait_selection::infer::InferCtxtExt as _;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
use std::{fmt, iter};
use crate::vec::is_allowed_vec_method;
mod cmp_null;
mod mut_from_ref;
mod ptr_arg;
mod ptr_eq;
declare_clippy_lint! {
/// ### What it does
@ -165,30 +145,8 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
return;
}
check_mut_from_ref(cx, sig, None);
if !matches!(sig.header.abi, ExternAbi::Rust) {
// Ignore `extern` functions with non-Rust calling conventions
return;
}
for arg in check_fn_args(
cx,
cx.tcx.fn_sig(item.owner_id).instantiate_identity().skip_binder(),
sig.decl.inputs,
&[],
)
.filter(|arg| arg.mutability() == Mutability::Not)
{
span_lint_hir_and_then(cx, PTR_ARG, arg.emission_id, arg.span, arg.build_msg(), |diag| {
diag.span_suggestion(
arg.span,
"change this to",
format!("{}{}", arg.ref_prefix, arg.deref_ty.display(cx)),
Applicability::Unspecified,
);
});
}
mut_from_ref::check(cx, sig, None);
ptr_arg::check_trait_item(cx, item.owner_id, sig);
}
}
@ -224,604 +182,21 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
_ => return,
};
check_mut_from_ref(cx, sig, Some(body));
if !matches!(sig.header.abi, ExternAbi::Rust) {
// Ignore `extern` functions with non-Rust calling conventions
return;
}
let decl = sig.decl;
let sig = cx.tcx.fn_sig(item_id).instantiate_identity().skip_binder();
let lint_args: Vec<_> = check_fn_args(cx, sig, decl.inputs, body.params)
.filter(|arg| !is_trait_item || arg.mutability() == Mutability::Not)
.collect();
let results = check_ptr_arg_usage(cx, body, &lint_args);
for (result, args) in iter::zip(&results, &lint_args).filter(|(r, _)| !r.skip) {
span_lint_hir_and_then(cx, PTR_ARG, args.emission_id, args.span, args.build_msg(), |diag| {
diag.multipart_suggestion(
"change this to",
iter::once((args.span, format!("{}{}", args.ref_prefix, args.deref_ty.display(cx))))
.chain(result.replacements.iter().map(|r| {
(
r.expr_span,
format!("{}{}", r.self_span.get_source_text(cx).unwrap(), r.replacement),
)
}))
.collect(),
Applicability::Unspecified,
);
});
}
mut_from_ref::check(cx, sig, Some(body));
ptr_arg::check_body(cx, body, item_id, sig, is_trait_item);
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Binary(op, l, r) = expr.kind
&& (op.node == BinOpKind::Eq || op.node == BinOpKind::Ne)
{
let non_null_path_snippet = match (
is_lint_allowed(cx, CMP_NULL, expr.hir_id),
is_null_path(cx, l),
is_null_path(cx, r),
) {
(false, true, false) if let Some(sugg) = Sugg::hir_opt(cx, r) => sugg.maybe_paren(),
(false, false, true) if let Some(sugg) = Sugg::hir_opt(cx, l) => sugg.maybe_paren(),
_ => return check_ptr_eq(cx, expr, op.node, l, r),
};
let invert = if op.node == BinOpKind::Eq { "" } else { "!" };
span_lint_and_sugg(
cx,
CMP_NULL,
expr.span,
"comparing with null is better expressed by the `.is_null()` method",
"try",
format!("{invert}{non_null_path_snippet}.is_null()",),
Applicability::MachineApplicable,
);
}
}
}
#[derive(Default)]
struct PtrArgResult {
skip: bool,
replacements: Vec<PtrArgReplacement>,
}
struct PtrArgReplacement {
expr_span: Span,
self_span: Span,
replacement: &'static str,
}
struct PtrArg<'tcx> {
idx: usize,
emission_id: HirId,
span: Span,
ty_name: Symbol,
method_renames: &'static [(Symbol, &'static str)],
ref_prefix: RefPrefix,
deref_ty: DerefTy<'tcx>,
}
impl PtrArg<'_> {
fn build_msg(&self) -> String {
format!(
"writing `&{}{}` instead of `&{}{}` involves a new object where a slice will do",
self.ref_prefix.mutability.prefix_str(),
self.ty_name,
self.ref_prefix.mutability.prefix_str(),
self.deref_ty.argless_str(),
)
}
fn mutability(&self) -> Mutability {
self.ref_prefix.mutability
}
}
struct RefPrefix {
lt: Lifetime,
mutability: Mutability,
}
impl fmt::Display for RefPrefix {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use fmt::Write;
f.write_char('&')?;
if !self.lt.is_anonymous() {
self.lt.ident.fmt(f)?;
f.write_char(' ')?;
}
f.write_str(self.mutability.prefix_str())
}
}
struct DerefTyDisplay<'a, 'tcx>(&'a LateContext<'tcx>, &'a DerefTy<'tcx>);
impl fmt::Display for DerefTyDisplay<'_, '_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use std::fmt::Write;
match self.1 {
DerefTy::Str => f.write_str("str"),
DerefTy::Path => f.write_str("Path"),
DerefTy::Slice(hir_ty, ty) => {
f.write_char('[')?;
match hir_ty.and_then(|s| s.get_source_text(self.0)) {
Some(s) => f.write_str(&s)?,
None => ty.fmt(f)?,
}
f.write_char(']')
},
}
}
}
enum DerefTy<'tcx> {
Str,
Path,
Slice(Option<Span>, Ty<'tcx>),
}
impl<'tcx> DerefTy<'tcx> {
fn ty(&self, cx: &LateContext<'tcx>) -> Ty<'tcx> {
match *self {
Self::Str => cx.tcx.types.str_,
Self::Path => Ty::new_adt(
cx.tcx,
cx.tcx.adt_def(cx.tcx.get_diagnostic_item(sym::Path).unwrap()),
List::empty(),
),
Self::Slice(_, ty) => Ty::new_slice(cx.tcx, ty),
}
}
fn argless_str(&self) -> &'static str {
match *self {
Self::Str => "str",
Self::Path => "Path",
Self::Slice(..) => "[_]",
}
}
fn display<'a>(&'a self, cx: &'a LateContext<'tcx>) -> DerefTyDisplay<'a, 'tcx> {
DerefTyDisplay(cx, self)
}
}
fn check_fn_args<'cx, 'tcx: 'cx>(
cx: &'cx LateContext<'tcx>,
fn_sig: ty::FnSig<'tcx>,
hir_tys: &'tcx [hir::Ty<'tcx>],
params: &'tcx [Param<'tcx>],
) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx {
iter::zip(fn_sig.inputs(), hir_tys)
.enumerate()
.filter_map(move |(i, (ty, hir_ty))| {
if let ty::Ref(_, ty, mutability) = *ty.kind()
&& let ty::Adt(adt, args) = *ty.kind()
&& let TyKind::Ref(lt, ref ty) = hir_ty.kind
&& let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind
// Check that the name as typed matches the actual name of the type.
// e.g. `fn foo(_: &Foo)` shouldn't trigger the lint when `Foo` is an alias for `Vec`
&& let [.., name] = path.segments
&& cx.tcx.item_name(adt.did()) == name.ident.name
{
let emission_id = params.get(i).map_or(hir_ty.hir_id, |param| param.hir_id);
let (method_renames, deref_ty) = match cx.tcx.get_diagnostic_name(adt.did()) {
Some(sym::Vec) => (
[(sym::clone, ".to_owned()")].as_slice(),
DerefTy::Slice(
if let Some(name_args) = name.args
&& let [GenericArg::Type(ty), ..] = name_args.args
{
Some(ty.span)
} else {
None
},
args.type_at(0),
),
),
_ if Some(adt.did()) == cx.tcx.lang_items().string() => (
[(sym::clone, ".to_owned()"), (sym::as_str, "")].as_slice(),
DerefTy::Str,
),
Some(sym::PathBuf) => (
[(sym::clone, ".to_path_buf()"), (sym::as_path, "")].as_slice(),
DerefTy::Path,
),
Some(sym::Cow) if mutability == Mutability::Not => {
if let Some(name_args) = name.args
&& let [GenericArg::Lifetime(lifetime), ty] = name_args.args
{
if let LifetimeKind::Param(param_def_id) = lifetime.kind
&& !lifetime.is_anonymous()
&& fn_sig
.output()
.walk()
.filter_map(ty::GenericArg::as_region)
.filter_map(|lifetime| match lifetime.kind() {
ty::ReEarlyParam(r) => Some(
cx.tcx
.generics_of(cx.tcx.parent(param_def_id.to_def_id()))
.region_param(r, cx.tcx)
.def_id,
),
ty::ReBound(_, r) => r.kind.get_id(),
ty::ReLateParam(r) => r.kind.get_id(),
ty::ReStatic
| ty::ReVar(_)
| ty::RePlaceholder(_)
| ty::ReErased
| ty::ReError(_) => None,
})
.any(|def_id| def_id.as_local().is_some_and(|def_id| def_id == param_def_id))
{
// `&Cow<'a, T>` when the return type uses 'a is okay
return None;
}
span_lint_hir_and_then(
cx,
PTR_ARG,
emission_id,
hir_ty.span,
"using a reference to `Cow` is not recommended",
|diag| {
diag.span_suggestion(
hir_ty.span,
"change this to",
match ty.span().get_source_text(cx) {
Some(s) => format!("&{}{s}", mutability.prefix_str()),
None => format!("&{}{}", mutability.prefix_str(), args.type_at(1)),
},
Applicability::Unspecified,
);
},
);
}
return None;
},
_ => return None,
};
return Some(PtrArg {
idx: i,
emission_id,
span: hir_ty.span,
ty_name: name.ident.name,
method_renames,
ref_prefix: RefPrefix { lt: *lt, mutability },
deref_ty,
});
}
None
})
}
fn check_mut_from_ref<'tcx>(cx: &LateContext<'tcx>, sig: &FnSig<'_>, body: Option<&Body<'tcx>>) {
let FnRetTy::Return(ty) = sig.decl.output else { return };
for (out, mutability, out_span) in get_lifetimes(ty) {
if mutability != Some(Mutability::Mut) {
continue;
}
let out_region = cx.tcx.named_bound_var(out.hir_id);
// `None` if one of the types contains `&'a mut T` or `T<'a>`.
// Else, contains all the locations of `&'a T` types.
let args_immut_refs: Option<Vec<Span>> = sig
.decl
.inputs
.iter()
.flat_map(get_lifetimes)
.filter(|&(lt, _, _)| cx.tcx.named_bound_var(lt.hir_id) == out_region)
.map(|(_, mutability, span)| (mutability == Some(Mutability::Not)).then_some(span))
.collect();
if let Some(args_immut_refs) = args_immut_refs
&& !args_immut_refs.is_empty()
&& body.is_none_or(|body| sig.header.is_unsafe() || contains_unsafe_block(cx, body.value))
{
span_lint_and_then(
cx,
MUT_FROM_REF,
out_span,
"mutable borrow from immutable input(s)",
|diag| {
let ms = MultiSpan::from_spans(args_immut_refs);
diag.span_note(ms, "immutable borrow here");
},
);
}
}
}
#[expect(clippy::too_many_lines)]
fn check_ptr_arg_usage<'tcx>(cx: &LateContext<'tcx>, body: &Body<'tcx>, args: &[PtrArg<'tcx>]) -> Vec<PtrArgResult> {
struct V<'cx, 'tcx> {
cx: &'cx LateContext<'tcx>,
/// Map from a local id to which argument it came from (index into `Self::args` and
/// `Self::results`)
bindings: HirIdMap<usize>,
/// The arguments being checked.
args: &'cx [PtrArg<'tcx>],
/// The results for each argument (len should match args.len)
results: Vec<PtrArgResult>,
/// The number of arguments which can't be linted. Used to return early.
skip_count: usize,
}
impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
type NestedFilter = nested_filter::OnlyBodies;
fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
self.cx.tcx
}
fn visit_anon_const(&mut self, _: &'tcx AnonConst) {}
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
if self.skip_count == self.args.len() {
return;
}
// Check if this is local we care about
let Some(&args_idx) = e.res_local_id().and_then(|id| self.bindings.get(&id)) else {
return walk_expr(self, e);
};
let args = &self.args[args_idx];
let result = &mut self.results[args_idx];
// Helper function to handle early returns.
let mut set_skip_flag = || {
if !result.skip {
self.skip_count += 1;
}
result.skip = true;
};
match get_expr_use_or_unification_node(self.cx.tcx, e) {
Some((Node::Stmt(_), _)) => (),
Some((Node::LetStmt(l), _)) => {
// Only trace simple bindings. e.g `let x = y;`
if let PatKind::Binding(BindingMode::NONE, id, ident, None) = l.pat.kind
// Let's not lint for the current parameter. The user may still intend to mutate
// (or, if not mutate, then perhaps call a method that's not otherwise available
// for) the referenced value behind the parameter through this local let binding
// with the underscore being only temporary.
&& !ident.name.as_str().starts_with('_')
{
self.bindings.insert(id, args_idx);
} else {
set_skip_flag();
}
},
Some((Node::Expr(use_expr), child_id)) => {
if let ExprKind::Index(e, ..) = use_expr.kind
&& e.hir_id == child_id
{
// Indexing works with both owned and its dereferenced type
return;
}
if let ExprKind::MethodCall(name, receiver, ..) = use_expr.kind
&& receiver.hir_id == child_id
{
let name = name.ident.name;
// Check if the method can be renamed.
if let Some((_, replacement)) = args.method_renames.iter().find(|&&(x, _)| x == name) {
result.replacements.push(PtrArgReplacement {
expr_span: use_expr.span,
self_span: receiver.span,
replacement,
});
return;
}
// Some methods exist on both `[T]` and `Vec<T>`, such as `len`, where the receiver type
// doesn't coerce to a slice and our adjusted type check below isn't enough,
// but it would still be valid to call with a slice
if is_allowed_vec_method(use_expr) {
return;
}
}
// If the expression's type gets adjusted down to the deref type, we might as
// well have started with that deref type -- the lint should fire
let deref_ty = args.deref_ty.ty(self.cx);
let adjusted_ty = self.cx.typeck_results().expr_ty_adjusted(e).peel_refs();
if adjusted_ty == deref_ty {
return;
}
// If the expression's type is constrained by `dyn Trait`, see if the deref
// type implements the trait(s) as well, and if so, the lint should fire
if let ty::Dynamic(preds, ..) = adjusted_ty.kind()
&& matches_preds(self.cx, deref_ty, preds)
{
return;
}
set_skip_flag();
},
_ => set_skip_flag(),
#[expect(
clippy::collapsible_if,
reason = "the outer `if`s check the HIR, the inner ones run lints"
)]
if !cmp_null::check(cx, expr, op.node, l, r) {
ptr_eq::check(cx, op.node, l, r, expr.span);
}
}
}
let mut skip_count = 0;
let mut results = args.iter().map(|_| PtrArgResult::default()).collect::<Vec<_>>();
let mut v = V {
cx,
bindings: args
.iter()
.enumerate()
.filter_map(|(i, arg)| {
let param = &body.params[arg.idx];
match param.pat.kind {
PatKind::Binding(BindingMode::NONE, id, ident, None)
if !is_lint_allowed(cx, PTR_ARG, param.hir_id)
// Let's not lint for the current parameter. The user may still intend to mutate
// (or, if not mutate, then perhaps call a method that's not otherwise available
// for) the referenced value behind the parameter with the underscore being only
// temporary.
&& !ident.name.as_str().starts_with('_') =>
{
Some((id, i))
},
_ => {
skip_count += 1;
results[i].skip = true;
None
},
}
})
.collect(),
args,
results,
skip_count,
};
v.visit_expr(body.value);
v.results
}
fn matches_preds<'tcx>(
cx: &LateContext<'tcx>,
ty: Ty<'tcx>,
preds: &'tcx [ty::PolyExistentialPredicate<'tcx>],
) -> bool {
let infcx = cx.tcx.infer_ctxt().build(cx.typing_mode());
preds
.iter()
.all(|&p| match cx.tcx.instantiate_bound_regions_with_erased(p) {
ExistentialPredicate::Trait(p) => infcx
.type_implements_trait(p.def_id, [ty.into()].into_iter().chain(p.args.iter()), cx.param_env)
.must_apply_modulo_regions(),
ExistentialPredicate::Projection(p) => infcx.predicate_must_hold_modulo_regions(&Obligation::new(
cx.tcx,
ObligationCause::dummy(),
cx.param_env,
cx.tcx
.mk_predicate(Binder::dummy(PredicateKind::Clause(ClauseKind::Projection(
p.with_self_ty(cx.tcx, ty),
)))),
)),
ExistentialPredicate::AutoTrait(p) => infcx
.type_implements_trait(p, [ty], cx.param_env)
.must_apply_modulo_regions(),
})
}
struct LifetimeVisitor<'tcx> {
result: Vec<(&'tcx Lifetime, Option<Mutability>, Span)>,
}
impl<'tcx> Visitor<'tcx> for LifetimeVisitor<'tcx> {
fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx, hir::AmbigArg>) {
if let TyKind::Ref(lt, ref m) = ty.kind {
self.result.push((lt, Some(m.mutbl), ty.span));
}
hir::intravisit::walk_ty(self, ty);
}
fn visit_generic_arg(&mut self, generic_arg: &'tcx GenericArg<'tcx>) {
if let GenericArg::Lifetime(lt) = generic_arg {
self.result.push((lt, None, generic_arg.span()));
}
hir::intravisit::walk_generic_arg(self, generic_arg);
}
}
/// Visit `ty` and collect the all the lifetimes appearing in it, implicit or not.
///
/// The second field of the vector's elements indicate if the lifetime is attached to a
/// shared reference, a mutable reference, or neither.
fn get_lifetimes<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> Vec<(&'tcx Lifetime, Option<Mutability>, Span)> {
use hir::intravisit::VisitorExt as _;
let mut visitor = LifetimeVisitor { result: Vec::new() };
visitor.visit_ty_unambig(ty);
visitor.result
}
fn is_null_path(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
if let ExprKind::Call(pathexp, []) = expr.kind {
matches!(
pathexp.basic_res().opt_diag_name(cx),
Some(sym::ptr_null | sym::ptr_null_mut)
)
} else {
false
}
}
fn check_ptr_eq<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
op: BinOpKind,
left: &'tcx Expr<'_>,
right: &'tcx Expr<'_>,
) {
if expr.span.from_expansion() {
return;
}
// Remove one level of usize conversion if any
let (left, right, usize_peeled) = match (expr_as_cast_to_usize(cx, left), expr_as_cast_to_usize(cx, right)) {
(Some(lhs), Some(rhs)) => (lhs, rhs, true),
_ => (left, right, false),
};
// This lint concerns raw pointers
let (left_ty, right_ty) = (cx.typeck_results().expr_ty(left), cx.typeck_results().expr_ty(right));
if !left_ty.is_raw_ptr() || !right_ty.is_raw_ptr() {
return;
}
let ((left_var, left_casts_peeled), (right_var, right_casts_peeled)) =
(peel_raw_casts(cx, left, left_ty), peel_raw_casts(cx, right, right_ty));
if !(usize_peeled || left_casts_peeled || right_casts_peeled) {
return;
}
let mut app = Applicability::MachineApplicable;
let left_snip = Sugg::hir_with_context(cx, left_var, expr.span.ctxt(), "_", &mut app);
let right_snip = Sugg::hir_with_context(cx, right_var, expr.span.ctxt(), "_", &mut app);
{
let Some(top_crate) = std_or_core(cx) else { return };
let invert = if op == BinOpKind::Eq { "" } else { "!" };
span_lint_and_sugg(
cx,
PTR_EQ,
expr.span,
format!("use `{top_crate}::ptr::eq` when comparing raw pointers"),
"try",
format!("{invert}{top_crate}::ptr::eq({left_snip}, {right_snip})"),
app,
);
}
}
// If the given expression is a cast to a usize, return the lhs of the cast
// E.g., `foo as *const _ as usize` returns `foo as *const _`.
fn expr_as_cast_to_usize<'tcx>(cx: &LateContext<'tcx>, cast_expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
if !cast_expr.span.from_expansion()
&& cx.typeck_results().expr_ty(cast_expr) == cx.tcx.types.usize
&& let ExprKind::Cast(expr, _) = cast_expr.kind
{
Some(expr)
} else {
None
}
}
// Peel raw casts if the remaining expression can be coerced to it, and whether casts have been
// peeled or not.
fn peel_raw_casts<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, expr_ty: Ty<'tcx>) -> (&'tcx Expr<'tcx>, bool) {
if !expr.span.from_expansion()
&& let ExprKind::Cast(inner, _) = expr.kind
&& let ty::RawPtr(target_ty, _) = expr_ty.kind()
&& let inner_ty = cx.typeck_results().expr_ty(inner)
&& let ty::RawPtr(inner_target_ty, _) | ty::Ref(_, inner_target_ty, _) = inner_ty.kind()
&& target_ty == inner_target_ty
{
(peel_raw_casts(cx, inner, inner_ty).0, true)
} else {
(expr, false)
}
}

75
clippy_lints/src/ptr/mut_from_ref.rs Normal file
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use super::MUT_FROM_REF;
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::visitors::contains_unsafe_block;
use rustc_errors::MultiSpan;
use rustc_hir::intravisit::Visitor;
use rustc_hir::{self as hir, Body, FnRetTy, FnSig, GenericArg, Lifetime, Mutability, TyKind};
use rustc_lint::LateContext;
use rustc_span::Span;
pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, sig: &FnSig<'_>, body: Option<&Body<'tcx>>) {
let FnRetTy::Return(ty) = sig.decl.output else { return };
for (out, mutability, out_span) in get_lifetimes(ty) {
if mutability != Some(Mutability::Mut) {
continue;
}
let out_region = cx.tcx.named_bound_var(out.hir_id);
// `None` if one of the types contains `&'a mut T` or `T<'a>`.
// Else, contains all the locations of `&'a T` types.
let args_immut_refs: Option<Vec<Span>> = sig
.decl
.inputs
.iter()
.flat_map(get_lifetimes)
.filter(|&(lt, _, _)| cx.tcx.named_bound_var(lt.hir_id) == out_region)
.map(|(_, mutability, span)| (mutability == Some(Mutability::Not)).then_some(span))
.collect();
if let Some(args_immut_refs) = args_immut_refs
&& !args_immut_refs.is_empty()
&& body.is_none_or(|body| sig.header.is_unsafe() || contains_unsafe_block(cx, body.value))
{
span_lint_and_then(
cx,
MUT_FROM_REF,
out_span,
"mutable borrow from immutable input(s)",
|diag| {
let ms = MultiSpan::from_spans(args_immut_refs);
diag.span_note(ms, "immutable borrow here");
},
);
}
}
}
struct LifetimeVisitor<'tcx> {
result: Vec<(&'tcx Lifetime, Option<Mutability>, Span)>,
}
impl<'tcx> Visitor<'tcx> for LifetimeVisitor<'tcx> {
fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx, hir::AmbigArg>) {
if let TyKind::Ref(lt, ref m) = ty.kind {
self.result.push((lt, Some(m.mutbl), ty.span));
}
hir::intravisit::walk_ty(self, ty);
}
fn visit_generic_arg(&mut self, generic_arg: &'tcx GenericArg<'tcx>) {
if let GenericArg::Lifetime(lt) = generic_arg {
self.result.push((lt, None, generic_arg.span()));
}
hir::intravisit::walk_generic_arg(self, generic_arg);
}
}
/// Visit `ty` and collect the all the lifetimes appearing in it, implicit or not.
///
/// The second field of the vector's elements indicate if the lifetime is attached to a
/// shared reference, a mutable reference, or neither.
fn get_lifetimes<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> Vec<(&'tcx Lifetime, Option<Mutability>, Span)> {
use hir::intravisit::VisitorExt as _;
let mut visitor = LifetimeVisitor { result: Vec::new() };
visitor.visit_ty_unambig(ty);
visitor.result
}

475
clippy_lints/src/ptr/ptr_arg.rs Normal file
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use super::PTR_ARG;
use clippy_utils::diagnostics::span_lint_hir_and_then;
use clippy_utils::res::MaybeResPath;
use clippy_utils::source::SpanRangeExt;
use clippy_utils::{get_expr_use_or_unification_node, is_lint_allowed, sym};
use hir::LifetimeKind;
use rustc_abi::ExternAbi;
use rustc_errors::Applicability;
use rustc_hir::hir_id::{HirId, HirIdMap};
use rustc_hir::intravisit::{Visitor, walk_expr};
use rustc_hir::{
self as hir, AnonConst, BindingMode, Body, Expr, ExprKind, FnSig, GenericArg, Lifetime, Mutability, Node, OwnerId,
Param, PatKind, QPath, TyKind,
};
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::traits::{Obligation, ObligationCause};
use rustc_lint::LateContext;
use rustc_middle::hir::nested_filter;
use rustc_middle::ty::{self, Binder, ClauseKind, ExistentialPredicate, List, PredicateKind, Ty};
use rustc_span::Span;
use rustc_span::symbol::Symbol;
use rustc_trait_selection::infer::InferCtxtExt as _;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
use std::{fmt, iter};
use crate::vec::is_allowed_vec_method;
pub(super) fn check_body<'tcx>(
cx: &LateContext<'tcx>,
body: &Body<'tcx>,
item_id: OwnerId,
sig: &FnSig<'tcx>,
is_trait_item: bool,
) {
if !matches!(sig.header.abi, ExternAbi::Rust) {
// Ignore `extern` functions with non-Rust calling conventions
return;
}
let decl = sig.decl;
let sig = cx.tcx.fn_sig(item_id).instantiate_identity().skip_binder();
let lint_args: Vec<_> = check_fn_args(cx, sig, decl.inputs, body.params)
.filter(|arg| !is_trait_item || arg.mutability() == Mutability::Not)
.collect();
let results = check_ptr_arg_usage(cx, body, &lint_args);
for (result, args) in iter::zip(&results, &lint_args).filter(|(r, _)| !r.skip) {
span_lint_hir_and_then(cx, PTR_ARG, args.emission_id, args.span, args.build_msg(), |diag| {
diag.multipart_suggestion(
"change this to",
iter::once((args.span, format!("{}{}", args.ref_prefix, args.deref_ty.display(cx))))
.chain(result.replacements.iter().map(|r| {
(
r.expr_span,
format!("{}{}", r.self_span.get_source_text(cx).unwrap(), r.replacement),
)
}))
.collect(),
Applicability::Unspecified,
);
});
}
}
pub(super) fn check_trait_item<'tcx>(cx: &LateContext<'tcx>, item_id: OwnerId, sig: &FnSig<'tcx>) {
if !matches!(sig.header.abi, ExternAbi::Rust) {
// Ignore `extern` functions with non-Rust calling conventions
return;
}
for arg in check_fn_args(
cx,
cx.tcx.fn_sig(item_id).instantiate_identity().skip_binder(),
sig.decl.inputs,
&[],
)
.filter(|arg| arg.mutability() == Mutability::Not)
{
span_lint_hir_and_then(cx, PTR_ARG, arg.emission_id, arg.span, arg.build_msg(), |diag| {
diag.span_suggestion(
arg.span,
"change this to",
format!("{}{}", arg.ref_prefix, arg.deref_ty.display(cx)),
Applicability::Unspecified,
);
});
}
}
#[derive(Default)]
struct PtrArgResult {
skip: bool,
replacements: Vec<PtrArgReplacement>,
}
struct PtrArgReplacement {
expr_span: Span,
self_span: Span,
replacement: &'static str,
}
struct PtrArg<'tcx> {
idx: usize,
emission_id: HirId,
span: Span,
ty_name: Symbol,
method_renames: &'static [(Symbol, &'static str)],
ref_prefix: RefPrefix,
deref_ty: DerefTy<'tcx>,
}
impl PtrArg<'_> {
fn build_msg(&self) -> String {
format!(
"writing `&{}{}` instead of `&{}{}` involves a new object where a slice will do",
self.ref_prefix.mutability.prefix_str(),
self.ty_name,
self.ref_prefix.mutability.prefix_str(),
self.deref_ty.argless_str(),
)
}
fn mutability(&self) -> Mutability {
self.ref_prefix.mutability
}
}
struct RefPrefix {
lt: Lifetime,
mutability: Mutability,
}
impl fmt::Display for RefPrefix {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use fmt::Write;
f.write_char('&')?;
if !self.lt.is_anonymous() {
self.lt.ident.fmt(f)?;
f.write_char(' ')?;
}
f.write_str(self.mutability.prefix_str())
}
}
struct DerefTyDisplay<'a, 'tcx>(&'a LateContext<'tcx>, &'a DerefTy<'tcx>);
impl fmt::Display for DerefTyDisplay<'_, '_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use std::fmt::Write;
match self.1 {
DerefTy::Str => f.write_str("str"),
DerefTy::Path => f.write_str("Path"),
DerefTy::Slice(hir_ty, ty) => {
f.write_char('[')?;
match hir_ty.and_then(|s| s.get_source_text(self.0)) {
Some(s) => f.write_str(&s)?,
None => ty.fmt(f)?,
}
f.write_char(']')
},
}
}
}
enum DerefTy<'tcx> {
Str,
Path,
Slice(Option<Span>, Ty<'tcx>),
}
impl<'tcx> DerefTy<'tcx> {
fn ty(&self, cx: &LateContext<'tcx>) -> Ty<'tcx> {
match *self {
Self::Str => cx.tcx.types.str_,
Self::Path => Ty::new_adt(
cx.tcx,
cx.tcx.adt_def(cx.tcx.get_diagnostic_item(sym::Path).unwrap()),
List::empty(),
),
Self::Slice(_, ty) => Ty::new_slice(cx.tcx, ty),
}
}
fn argless_str(&self) -> &'static str {
match *self {
Self::Str => "str",
Self::Path => "Path",
Self::Slice(..) => "[_]",
}
}
fn display<'a>(&'a self, cx: &'a LateContext<'tcx>) -> DerefTyDisplay<'a, 'tcx> {
DerefTyDisplay(cx, self)
}
}
fn check_fn_args<'cx, 'tcx: 'cx>(
cx: &'cx LateContext<'tcx>,
fn_sig: ty::FnSig<'tcx>,
hir_tys: &'tcx [hir::Ty<'tcx>],
params: &'tcx [Param<'tcx>],
) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx {
iter::zip(fn_sig.inputs(), hir_tys)
.enumerate()
.filter_map(move |(i, (ty, hir_ty))| {
if let ty::Ref(_, ty, mutability) = *ty.kind()
&& let ty::Adt(adt, args) = *ty.kind()
&& let TyKind::Ref(lt, ref ty) = hir_ty.kind
&& let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind
// Check that the name as typed matches the actual name of the type.
// e.g. `fn foo(_: &Foo)` shouldn't trigger the lint when `Foo` is an alias for `Vec`
&& let [.., name] = path.segments
&& cx.tcx.item_name(adt.did()) == name.ident.name
{
let emission_id = params.get(i).map_or(hir_ty.hir_id, |param| param.hir_id);
let (method_renames, deref_ty) = match cx.tcx.get_diagnostic_name(adt.did()) {
Some(sym::Vec) => (
[(sym::clone, ".to_owned()")].as_slice(),
DerefTy::Slice(
if let Some(name_args) = name.args
&& let [GenericArg::Type(ty), ..] = name_args.args
{
Some(ty.span)
} else {
None
},
args.type_at(0),
),
),
_ if Some(adt.did()) == cx.tcx.lang_items().string() => (
[(sym::clone, ".to_owned()"), (sym::as_str, "")].as_slice(),
DerefTy::Str,
),
Some(sym::PathBuf) => (
[(sym::clone, ".to_path_buf()"), (sym::as_path, "")].as_slice(),
DerefTy::Path,
),
Some(sym::Cow) if mutability == Mutability::Not => {
if let Some(name_args) = name.args
&& let [GenericArg::Lifetime(lifetime), ty] = name_args.args
{
if let LifetimeKind::Param(param_def_id) = lifetime.kind
&& !lifetime.is_anonymous()
&& fn_sig
.output()
.walk()
.filter_map(ty::GenericArg::as_region)
.filter_map(|lifetime| match lifetime.kind() {
ty::ReEarlyParam(r) => Some(
cx.tcx
.generics_of(cx.tcx.parent(param_def_id.to_def_id()))
.region_param(r, cx.tcx)
.def_id,
),
ty::ReBound(_, r) => r.kind.get_id(),
ty::ReLateParam(r) => r.kind.get_id(),
ty::ReStatic
| ty::ReVar(_)
| ty::RePlaceholder(_)
| ty::ReErased
| ty::ReError(_) => None,
})
.any(|def_id| def_id.as_local().is_some_and(|def_id| def_id == param_def_id))
{
// `&Cow<'a, T>` when the return type uses 'a is okay
return None;
}
span_lint_hir_and_then(
cx,
PTR_ARG,
emission_id,
hir_ty.span,
"using a reference to `Cow` is not recommended",
|diag| {
diag.span_suggestion(
hir_ty.span,
"change this to",
match ty.span().get_source_text(cx) {
Some(s) => format!("&{}{s}", mutability.prefix_str()),
None => format!("&{}{}", mutability.prefix_str(), args.type_at(1)),
},
Applicability::Unspecified,
);
},
);
}
return None;
},
_ => return None,
};
return Some(PtrArg {
idx: i,
emission_id,
span: hir_ty.span,
ty_name: name.ident.name,
method_renames,
ref_prefix: RefPrefix { lt: *lt, mutability },
deref_ty,
});
}
None
})
}
#[expect(clippy::too_many_lines)]
fn check_ptr_arg_usage<'tcx>(cx: &LateContext<'tcx>, body: &Body<'tcx>, args: &[PtrArg<'tcx>]) -> Vec<PtrArgResult> {
struct V<'cx, 'tcx> {
cx: &'cx LateContext<'tcx>,
/// Map from a local id to which argument it came from (index into `Self::args` and
/// `Self::results`)
bindings: HirIdMap<usize>,
/// The arguments being checked.
args: &'cx [PtrArg<'tcx>],
/// The results for each argument (len should match args.len)
results: Vec<PtrArgResult>,
/// The number of arguments which can't be linted. Used to return early.
skip_count: usize,
}
impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
type NestedFilter = nested_filter::OnlyBodies;
fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
self.cx.tcx
}
fn visit_anon_const(&mut self, _: &'tcx AnonConst) {}
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
if self.skip_count == self.args.len() {
return;
}
// Check if this is local we care about
let Some(&args_idx) = e.res_local_id().and_then(|id| self.bindings.get(&id)) else {
return walk_expr(self, e);
};
let args = &self.args[args_idx];
let result = &mut self.results[args_idx];
// Helper function to handle early returns.
let mut set_skip_flag = || {
if !result.skip {
self.skip_count += 1;
}
result.skip = true;
};
match get_expr_use_or_unification_node(self.cx.tcx, e) {
Some((Node::Stmt(_), _)) => (),
Some((Node::LetStmt(l), _)) => {
// Only trace simple bindings. e.g `let x = y;`
if let PatKind::Binding(BindingMode::NONE, id, ident, None) = l.pat.kind
// Let's not lint for the current parameter. The user may still intend to mutate
// (or, if not mutate, then perhaps call a method that's not otherwise available
// for) the referenced value behind the parameter through this local let binding
// with the underscore being only temporary.
&& !ident.name.as_str().starts_with('_')
{
self.bindings.insert(id, args_idx);
} else {
set_skip_flag();
}
},
Some((Node::Expr(use_expr), child_id)) => {
if let ExprKind::Index(e, ..) = use_expr.kind
&& e.hir_id == child_id
{
// Indexing works with both owned and its dereferenced type
return;
}
if let ExprKind::MethodCall(name, receiver, ..) = use_expr.kind
&& receiver.hir_id == child_id
{
let name = name.ident.name;
// Check if the method can be renamed.
if let Some((_, replacement)) = args.method_renames.iter().find(|&&(x, _)| x == name) {
result.replacements.push(PtrArgReplacement {
expr_span: use_expr.span,
self_span: receiver.span,
replacement,
});
return;
}
// Some methods exist on both `[T]` and `Vec<T>`, such as `len`, where the receiver type
// doesn't coerce to a slice and our adjusted type check below isn't enough,
// but it would still be valid to call with a slice
if is_allowed_vec_method(use_expr) {
return;
}
}
// If the expression's type gets adjusted down to the deref type, we might as
// well have started with that deref type -- the lint should fire
let deref_ty = args.deref_ty.ty(self.cx);
let adjusted_ty = self.cx.typeck_results().expr_ty_adjusted(e).peel_refs();
if adjusted_ty == deref_ty {
return;
}
// If the expression's type is constrained by `dyn Trait`, see if the deref
// type implements the trait(s) as well, and if so, the lint should fire
if let ty::Dynamic(preds, ..) = adjusted_ty.kind()
&& matches_preds(self.cx, deref_ty, preds)
{
return;
}
set_skip_flag();
},
_ => set_skip_flag(),
}
}
}
let mut skip_count = 0;
let mut results = args.iter().map(|_| PtrArgResult::default()).collect::<Vec<_>>();
let mut v = V {
cx,
bindings: args
.iter()
.enumerate()
.filter_map(|(i, arg)| {
let param = &body.params[arg.idx];
match param.pat.kind {
PatKind::Binding(BindingMode::NONE, id, ident, None)
if !is_lint_allowed(cx, PTR_ARG, param.hir_id)
// Let's not lint for the current parameter. The user may still intend to mutate
// (or, if not mutate, then perhaps call a method that's not otherwise available
// for) the referenced value behind the parameter with the underscore being only
// temporary.
&& !ident.name.as_str().starts_with('_') =>
{
Some((id, i))
},
_ => {
skip_count += 1;
results[i].skip = true;
None
},
}
})
.collect(),
args,
results,
skip_count,
};
v.visit_expr(body.value);
v.results
}
fn matches_preds<'tcx>(
cx: &LateContext<'tcx>,
ty: Ty<'tcx>,
preds: &'tcx [ty::PolyExistentialPredicate<'tcx>],
) -> bool {
let infcx = cx.tcx.infer_ctxt().build(cx.typing_mode());
preds
.iter()
.all(|&p| match cx.tcx.instantiate_bound_regions_with_erased(p) {
ExistentialPredicate::Trait(p) => infcx
.type_implements_trait(p.def_id, [ty.into()].into_iter().chain(p.args.iter()), cx.param_env)
.must_apply_modulo_regions(),
ExistentialPredicate::Projection(p) => infcx.predicate_must_hold_modulo_regions(&Obligation::new(
cx.tcx,
ObligationCause::dummy(),
cx.param_env,
cx.tcx
.mk_predicate(Binder::dummy(PredicateKind::Clause(ClauseKind::Projection(
p.with_self_ty(cx.tcx, ty),
)))),
)),
ExistentialPredicate::AutoTrait(p) => infcx
.type_implements_trait(p, [ty], cx.param_env)
.must_apply_modulo_regions(),
})
}

87
clippy_lints/src/ptr/ptr_eq.rs Normal file
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@ -0,0 +1,87 @@
use super::PTR_EQ;
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::std_or_core;
use clippy_utils::sugg::Sugg;
use rustc_errors::Applicability;
use rustc_hir::{BinOpKind, Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
use rustc_span::Span;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
op: BinOpKind,
left: &'tcx Expr<'_>,
right: &'tcx Expr<'_>,
span: Span,
) {
if span.from_expansion() {
return;
}
// Remove one level of usize conversion if any
let (left, right, usize_peeled) = match (expr_as_cast_to_usize(cx, left), expr_as_cast_to_usize(cx, right)) {
(Some(lhs), Some(rhs)) => (lhs, rhs, true),
_ => (left, right, false),
};
// This lint concerns raw pointers
let (left_ty, right_ty) = (cx.typeck_results().expr_ty(left), cx.typeck_results().expr_ty(right));
if !left_ty.is_raw_ptr() || !right_ty.is_raw_ptr() {
return;
}
let ((left_var, left_casts_peeled), (right_var, right_casts_peeled)) =
(peel_raw_casts(cx, left, left_ty), peel_raw_casts(cx, right, right_ty));
if !(usize_peeled || left_casts_peeled || right_casts_peeled) {
return;
}
let mut app = Applicability::MachineApplicable;
let ctxt = span.ctxt();
let left_snip = Sugg::hir_with_context(cx, left_var, ctxt, "_", &mut app);
let right_snip = Sugg::hir_with_context(cx, right_var, ctxt, "_", &mut app);
{
let Some(top_crate) = std_or_core(cx) else { return };
let invert = if op == BinOpKind::Eq { "" } else { "!" };
span_lint_and_sugg(
cx,
PTR_EQ,
span,
format!("use `{top_crate}::ptr::eq` when comparing raw pointers"),
"try",
format!("{invert}{top_crate}::ptr::eq({left_snip}, {right_snip})"),
app,
);
}
}
// If the given expression is a cast to a usize, return the lhs of the cast
// E.g., `foo as *const _ as usize` returns `foo as *const _`.
fn expr_as_cast_to_usize<'tcx>(cx: &LateContext<'tcx>, cast_expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
if !cast_expr.span.from_expansion()
&& cx.typeck_results().expr_ty(cast_expr) == cx.tcx.types.usize
&& let ExprKind::Cast(expr, _) = cast_expr.kind
{
Some(expr)
} else {
None
}
}
// Peel raw casts if the remaining expression can be coerced to it, and whether casts have been
// peeled or not.
fn peel_raw_casts<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, expr_ty: Ty<'tcx>) -> (&'tcx Expr<'tcx>, bool) {
if !expr.span.from_expansion()
&& let ExprKind::Cast(inner, _) = expr.kind
&& let ty::RawPtr(target_ty, _) = expr_ty.kind()
&& let inner_ty = cx.typeck_results().expr_ty(inner)
&& let ty::RawPtr(inner_target_ty, _) | ty::Ref(_, inner_target_ty, _) = inner_ty.kind()
&& target_ty == inner_target_ty
{
(peel_raw_casts(cx, inner, inner_ty).0, true)
} else {
(expr, false)
}
}