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Don't lint ptr_arg when return type uses Cow's lifetime

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Catherine 2023-06-24 03:03:05 -05:00
parent ce0a48a9b6
commit db4efe3f6d
3 changed files with 141 additions and 57 deletions
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105
clippy_lints/src/ptr.rs
View file

@ -5,6 +5,7 @@ use clippy_utils::source::snippet_opt;
use clippy_utils::ty::expr_sig; use clippy_utils::ty::expr_sig;
use clippy_utils::visitors::contains_unsafe_block; 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 clippy_utils::{get_expr_use_or_unification_node, is_lint_allowed, path_def_id, path_to_local, paths};
use hir::LifetimeName;
use if_chain::if_chain; use if_chain::if_chain;
use rustc_errors::{Applicability, MultiSpan}; use rustc_errors::{Applicability, MultiSpan};
use rustc_hir::def_id::DefId; use rustc_hir::def_id::DefId;
@ -15,6 +16,7 @@ use rustc_hir::{
ImplItemKind, ItemKind, Lifetime, Mutability, Node, Param, PatKind, QPath, TraitFn, TraitItem, TraitItemKind, ImplItemKind, ItemKind, Lifetime, Mutability, Node, Param, PatKind, QPath, TraitFn, TraitItem, TraitItemKind,
TyKind, Unsafety, TyKind, Unsafety,
}; };
use rustc_hir_analysis::hir_ty_to_ty;
use rustc_infer::infer::TyCtxtInferExt; use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::traits::{Obligation, ObligationCause}; use rustc_infer::traits::{Obligation, ObligationCause};
use rustc_lint::{LateContext, LateLintPass}; use rustc_lint::{LateContext, LateLintPass};
@ -166,6 +168,7 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
cx, cx,
cx.tcx.fn_sig(item.owner_id).subst_identity().skip_binder().inputs(), cx.tcx.fn_sig(item.owner_id).subst_identity().skip_binder().inputs(),
sig.decl.inputs, sig.decl.inputs,
&sig.decl.output,
&[], &[],
) )
.filter(|arg| arg.mutability() == Mutability::Not) .filter(|arg| arg.mutability() == Mutability::Not)
@ -218,7 +221,7 @@ impl<'tcx> LateLintPass<'tcx> for Ptr {
check_mut_from_ref(cx, sig, Some(body)); check_mut_from_ref(cx, sig, Some(body));
let decl = sig.decl; let decl = sig.decl;
let sig = cx.tcx.fn_sig(item_id).subst_identity().skip_binder(); let sig = cx.tcx.fn_sig(item_id).subst_identity().skip_binder();
let lint_args: Vec<_> = check_fn_args(cx, sig.inputs(), decl.inputs, body.params) let lint_args: Vec<_> = check_fn_args(cx, sig.inputs(), decl.inputs, &decl.output, body.params)
.filter(|arg| !is_trait_item || arg.mutability() == Mutability::Not) .filter(|arg| !is_trait_item || arg.mutability() == Mutability::Not)
.collect(); .collect();
let results = check_ptr_arg_usage(cx, body, &lint_args); let results = check_ptr_arg_usage(cx, body, &lint_args);
@ -407,29 +410,27 @@ impl<'tcx> DerefTy<'tcx> {
} }
} }
#[expect(clippy::too_many_lines)]
fn check_fn_args<'cx, 'tcx: 'cx>( fn check_fn_args<'cx, 'tcx: 'cx>(
cx: &'cx LateContext<'tcx>, cx: &'cx LateContext<'tcx>,
tys: &'tcx [Ty<'tcx>], tys: &'tcx [Ty<'tcx>],
hir_tys: &'tcx [hir::Ty<'tcx>], hir_tys: &'tcx [hir::Ty<'tcx>],
ret_ty: &'tcx FnRetTy<'tcx>,
params: &'tcx [Param<'tcx>], params: &'tcx [Param<'tcx>],
) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx { ) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx {
tys.iter() tys.iter()
.zip(hir_tys.iter()) .zip(hir_tys.iter())
.enumerate() .enumerate()
.filter_map(|(i, (ty, hir_ty))| { .filter_map(move |(i, (ty, hir_ty))| {
if_chain! { if let ty::Ref(_, ty, mutability) = *ty.kind()
if let ty::Ref(_, ty, mutability) = *ty.kind(); && let ty::Adt(adt, substs) = *ty.kind()
if let ty::Adt(adt, substs) = *ty.kind(); && let TyKind::Ref(lt, ref ty) = hir_ty.kind
&& let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind
if let TyKind::Ref(lt, ref ty) = hir_ty.kind;
if let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind;
// Check that the name as typed matches the actual name of the type. // 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` // e.g. `fn foo(_: &Foo)` shouldn't trigger the lint when `Foo` is an alias for `Vec`
if let [.., name] = path.segments; && let [.., name] = path.segments
if cx.tcx.item_name(adt.did()) == name.ident.name; && cx.tcx.item_name(adt.did()) == name.ident.name
{
then {
let emission_id = params.get(i).map_or(hir_ty.hir_id, |param| param.hir_id); 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()) { let (method_renames, deref_ty) = match cx.tcx.get_diagnostic_name(adt.did()) {
Some(sym::Vec) => ( Some(sym::Vec) => (
@ -454,30 +455,65 @@ fn check_fn_args<'cx, 'tcx: 'cx>(
DerefTy::Path, DerefTy::Path,
), ),
Some(sym::Cow) if mutability == Mutability::Not => { Some(sym::Cow) if mutability == Mutability::Not => {
let ty_name = name.args if let Some((lifetime, ty)) = name.args
.and_then(|args| { .and_then(|args| {
args.args.iter().find_map(|a| match a { if let [GenericArg::Lifetime(lifetime), ty] = args.args {
GenericArg::Type(x) => Some(x), return Some((lifetime, ty));
_ => None, }
}) None
}) })
.and_then(|arg| snippet_opt(cx, arg.span)) {
.unwrap_or_else(|| substs.type_at(1).to_string()); if !lifetime.is_anonymous()
span_lint_hir_and_then( && let FnRetTy::Return(ret_ty) = ret_ty
cx, && let ret_ty = hir_ty_to_ty(cx.tcx, ret_ty)
PTR_ARG, && ret_ty
emission_id, .walk()
hir_ty.span, .filter_map(|arg| {
"using a reference to `Cow` is not recommended", arg.as_region().and_then(|lifetime| {
|diag| { match lifetime.kind() {
diag.span_suggestion( ty::ReEarlyBound(r) => Some(r.def_id),
hir_ty.span, ty::ReLateBound(_, r) => r.kind.get_id(),
"change this to", ty::ReFree(r) => r.bound_region.get_id(),
format!("&{}{ty_name}", mutability.prefix_str()), ty::ReStatic
Applicability::Unspecified, | ty::ReVar(_)
); | ty::RePlaceholder(_)
| ty::ReErased
| ty::ReError(_) => None,
}
})
})
.any(|def_id| {
matches!(
lifetime.res,
LifetimeName::Param(param_def_id) if 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;
} }
);
let ty_name =
snippet_opt(cx, ty.span()).unwrap_or_else(|| substs.type_at(1).to_string());
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",
format!("&{}{ty_name}", mutability.prefix_str()),
Applicability::Unspecified,
);
}
);
}
return None; return None;
}, },
_ => return None, _ => return None,
@ -495,7 +531,6 @@ fn check_fn_args<'cx, 'tcx: 'cx>(
}, },
deref_ty, deref_ty,
}); });
}
} }
None None
}) })

33
tests/ui/ptr_arg.rs
View file

@ -1,5 +1,10 @@
#![feature(lint_reasons)] #![feature(lint_reasons)]
#![allow(unused, clippy::many_single_char_names, clippy::redundant_clone)] #![allow(
unused,
clippy::many_single_char_names,
clippy::needless_lifetimes,
clippy::redundant_clone
)]
#![warn(clippy::ptr_arg)] #![warn(clippy::ptr_arg)]
use std::borrow::Cow; use std::borrow::Cow;
@ -235,3 +240,29 @@ fn dyn_trait(a: &mut Vec<u32>, b: &mut String, c: &mut PathBuf) {
takes_dyn(b); takes_dyn(b);
takes_dyn(c); takes_dyn(c);
} }
mod issue_9218 {
use std::borrow::Cow;
fn cow_non_elided_lifetime<'a>(input: &Cow<'a, str>) -> &'a str {
todo!()
}
// This one has an anonymous lifetime so it's not okay
fn cow_elided_lifetime<'a>(input: &'a Cow<str>) -> &'a str {
todo!()
}
// These two's return types don't use use 'a so it's not okay
fn cow_bad_ret_ty_1<'a>(input: &'a Cow<'a, str>) -> &'static str {
todo!()
}
fn cow_bad_ret_ty_2<'a, 'b>(input: &'a Cow<'a, str>) -> &'b str {
todo!()
}
// Inferred to be `&'a str`, afaik.
fn cow_good_ret_ty<'a>(input: &'a Cow<'a, str>) -> &str {
todo!()
}
}

60
tests/ui/ptr_arg.stderr
View file

@ -1,5 +1,5 @@
error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:8:14 --> $DIR/ptr_arg.rs:13:14
| |
LL | fn do_vec(x: &Vec<i64>) { LL | fn do_vec(x: &Vec<i64>) {
| ^^^^^^^^^ help: change this to: `&[i64]` | ^^^^^^^^^ help: change this to: `&[i64]`
@ -7,43 +7,43 @@ LL | fn do_vec(x: &Vec<i64>) {
= note: `-D clippy::ptr-arg` implied by `-D warnings` = note: `-D clippy::ptr-arg` implied by `-D warnings`
error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:12:18 --> $DIR/ptr_arg.rs:17:18
| |
LL | fn do_vec_mut(x: &mut Vec<i64>) { LL | fn do_vec_mut(x: &mut Vec<i64>) {
| ^^^^^^^^^^^^^ help: change this to: `&mut [i64]` | ^^^^^^^^^^^^^ help: change this to: `&mut [i64]`
error: writing `&String` instead of `&str` involves a new object where a slice will do error: writing `&String` instead of `&str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:16:14 --> $DIR/ptr_arg.rs:21:14
| |
LL | fn do_str(x: &String) { LL | fn do_str(x: &String) {
| ^^^^^^^ help: change this to: `&str` | ^^^^^^^ help: change this to: `&str`
error: writing `&mut String` instead of `&mut str` involves a new object where a slice will do error: writing `&mut String` instead of `&mut str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:20:18 --> $DIR/ptr_arg.rs:25:18
| |
LL | fn do_str_mut(x: &mut String) { LL | fn do_str_mut(x: &mut String) {
| ^^^^^^^^^^^ help: change this to: `&mut str` | ^^^^^^^^^^^ help: change this to: `&mut str`
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:24:15 --> $DIR/ptr_arg.rs:29:15
| |
LL | fn do_path(x: &PathBuf) { LL | fn do_path(x: &PathBuf) {
| ^^^^^^^^ help: change this to: `&Path` | ^^^^^^^^ help: change this to: `&Path`
error: writing `&mut PathBuf` instead of `&mut Path` involves a new object where a slice will do error: writing `&mut PathBuf` instead of `&mut Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:28:19 --> $DIR/ptr_arg.rs:33:19
| |
LL | fn do_path_mut(x: &mut PathBuf) { LL | fn do_path_mut(x: &mut PathBuf) {
| ^^^^^^^^^^^^ help: change this to: `&mut Path` | ^^^^^^^^^^^^ help: change this to: `&mut Path`
error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:36:18 --> $DIR/ptr_arg.rs:41:18
| |
LL | fn do_vec(x: &Vec<i64>); LL | fn do_vec(x: &Vec<i64>);
| ^^^^^^^^^ help: change this to: `&[i64]` | ^^^^^^^^^ help: change this to: `&[i64]`
error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:49:14 --> $DIR/ptr_arg.rs:54:14
| |
LL | fn cloned(x: &Vec<u8>) -> Vec<u8> { LL | fn cloned(x: &Vec<u8>) -> Vec<u8> {
| ^^^^^^^^ | ^^^^^^^^
@ -60,7 +60,7 @@ LL ~ x.to_owned()
| |
error: writing `&String` instead of `&str` involves a new object where a slice will do error: writing `&String` instead of `&str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:58:18 --> $DIR/ptr_arg.rs:63:18
| |
LL | fn str_cloned(x: &String) -> String { LL | fn str_cloned(x: &String) -> String {
| ^^^^^^^ | ^^^^^^^
@ -76,7 +76,7 @@ LL ~ x.to_owned()
| |
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:66:19 --> $DIR/ptr_arg.rs:71:19
| |
LL | fn path_cloned(x: &PathBuf) -> PathBuf { LL | fn path_cloned(x: &PathBuf) -> PathBuf {
| ^^^^^^^^ | ^^^^^^^^
@ -92,7 +92,7 @@ LL ~ x.to_path_buf()
| |
error: writing `&String` instead of `&str` involves a new object where a slice will do error: writing `&String` instead of `&str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:74:44 --> $DIR/ptr_arg.rs:79:44
| |
LL | fn false_positive_capacity(x: &Vec<u8>, y: &String) { LL | fn false_positive_capacity(x: &Vec<u8>, y: &String) {
| ^^^^^^^ | ^^^^^^^
@ -106,19 +106,19 @@ LL ~ let c = y;
| |
error: using a reference to `Cow` is not recommended error: using a reference to `Cow` is not recommended
--> $DIR/ptr_arg.rs:88:25 --> $DIR/ptr_arg.rs:93:25
| |
LL | fn test_cow_with_ref(c: &Cow<[i32]>) {} LL | fn test_cow_with_ref(c: &Cow<[i32]>) {}
| ^^^^^^^^^^^ help: change this to: `&[i32]` | ^^^^^^^^^^^ help: change this to: `&[i32]`
error: writing `&String` instead of `&str` involves a new object where a slice will do error: writing `&String` instead of `&str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:117:66 --> $DIR/ptr_arg.rs:122:66
| |
LL | fn some_allowed(#[allow(clippy::ptr_arg)] _v: &Vec<u32>, _s: &String) {} LL | fn some_allowed(#[allow(clippy::ptr_arg)] _v: &Vec<u32>, _s: &String) {}
| ^^^^^^^ help: change this to: `&str` | ^^^^^^^ help: change this to: `&str`
error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:146:21 --> $DIR/ptr_arg.rs:151:21
| |
LL | fn foo_vec(vec: &Vec<u8>) { LL | fn foo_vec(vec: &Vec<u8>) {
| ^^^^^^^^ | ^^^^^^^^
@ -131,7 +131,7 @@ LL ~ let _ = vec.to_owned().clone();
| |
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:151:23 --> $DIR/ptr_arg.rs:156:23
| |
LL | fn foo_path(path: &PathBuf) { LL | fn foo_path(path: &PathBuf) {
| ^^^^^^^^ | ^^^^^^^^
@ -144,7 +144,7 @@ LL ~ let _ = path.to_path_buf().clone();
| |
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:156:21 --> $DIR/ptr_arg.rs:161:21
| |
LL | fn foo_str(str: &PathBuf) { LL | fn foo_str(str: &PathBuf) {
| ^^^^^^^^ | ^^^^^^^^
@ -157,28 +157,46 @@ LL ~ let _ = str.to_path_buf().clone();
| |
error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:162:29 --> $DIR/ptr_arg.rs:167:29
| |
LL | fn mut_vec_slice_methods(v: &mut Vec<u32>) { LL | fn mut_vec_slice_methods(v: &mut Vec<u32>) {
| ^^^^^^^^^^^^^ help: change this to: `&mut [u32]` | ^^^^^^^^^^^^^ help: change this to: `&mut [u32]`
error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:224:17 --> $DIR/ptr_arg.rs:229:17
| |
LL | fn dyn_trait(a: &mut Vec<u32>, b: &mut String, c: &mut PathBuf) { LL | fn dyn_trait(a: &mut Vec<u32>, b: &mut String, c: &mut PathBuf) {
| ^^^^^^^^^^^^^ help: change this to: `&mut [u32]` | ^^^^^^^^^^^^^ help: change this to: `&mut [u32]`
error: writing `&mut String` instead of `&mut str` involves a new object where a slice will do error: writing `&mut String` instead of `&mut str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:224:35 --> $DIR/ptr_arg.rs:229:35
| |
LL | fn dyn_trait(a: &mut Vec<u32>, b: &mut String, c: &mut PathBuf) { LL | fn dyn_trait(a: &mut Vec<u32>, b: &mut String, c: &mut PathBuf) {
| ^^^^^^^^^^^ help: change this to: `&mut str` | ^^^^^^^^^^^ help: change this to: `&mut str`
error: writing `&mut PathBuf` instead of `&mut Path` involves a new object where a slice will do error: writing `&mut PathBuf` instead of `&mut Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:224:51 --> $DIR/ptr_arg.rs:229:51
| |
LL | fn dyn_trait(a: &mut Vec<u32>, b: &mut String, c: &mut PathBuf) { LL | fn dyn_trait(a: &mut Vec<u32>, b: &mut String, c: &mut PathBuf) {
| ^^^^^^^^^^^^ help: change this to: `&mut Path` | ^^^^^^^^^^^^ help: change this to: `&mut Path`
error: aborting due to 20 previous errors error: using a reference to `Cow` is not recommended
--> $DIR/ptr_arg.rs:252:39
|
LL | fn cow_elided_lifetime<'a>(input: &'a Cow<str>) -> &'a str {
| ^^^^^^^^^^^^ help: change this to: `&str`
error: using a reference to `Cow` is not recommended
--> $DIR/ptr_arg.rs:257:36
|
LL | fn cow_bad_ret_ty_1<'a>(input: &'a Cow<'a, str>) -> &'static str {
| ^^^^^^^^^^^^^^^^ help: change this to: `&str`
error: using a reference to `Cow` is not recommended
--> $DIR/ptr_arg.rs:260:40
|
LL | fn cow_bad_ret_ty_2<'a, 'b>(input: &'a Cow<'a, str>) -> &'b str {
| ^^^^^^^^^^^^^^^^ help: change this to: `&str`
error: aborting due to 23 previous errors