diff options
| -rw-r--r-- | clippy_lints/src/ptr.rs | 105 | ||||
| -rw-r--r-- | tests/ui/ptr_arg.rs | 33 | ||||
| -rw-r--r-- | tests/ui/ptr_arg.stderr | 60 |
3 files changed, 141 insertions, 57 deletions
diff --git a/clippy_lints/src/ptr.rs b/clippy_lints/src/ptr.rs index fc550936165..e8854394150 100644 --- a/clippy_lints/src/ptr.rs +++ b/clippy_lints/src/ptr.rs @@ -5,6 +5,7 @@ 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 hir::LifetimeName; use if_chain::if_chain; use rustc_errors::{Applicability, MultiSpan}; use rustc_hir::def_id::DefId; @@ -15,6 +16,7 @@ use rustc_hir::{ ImplItemKind, ItemKind, Lifetime, Mutability, Node, Param, PatKind, QPath, TraitFn, TraitItem, TraitItemKind, TyKind, Unsafety, }; +use rustc_hir_analysis::hir_ty_to_ty; use rustc_infer::infer::TyCtxtInferExt; use rustc_infer::traits::{Obligation, ObligationCause}; use rustc_lint::{LateContext, LateLintPass}; @@ -166,6 +168,7 @@ impl<'tcx> LateLintPass<'tcx> for Ptr { cx, cx.tcx.fn_sig(item.owner_id).subst_identity().skip_binder().inputs(), sig.decl.inputs, + &sig.decl.output, &[], ) .filter(|arg| arg.mutability() == Mutability::Not) @@ -218,7 +221,7 @@ impl<'tcx> LateLintPass<'tcx> for Ptr { check_mut_from_ref(cx, sig, Some(body)); let decl = sig.decl; 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) .collect(); 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>( cx: &'cx LateContext<'tcx>, tys: &'tcx [Ty<'tcx>], hir_tys: &'tcx [hir::Ty<'tcx>], + ret_ty: &'tcx FnRetTy<'tcx>, params: &'tcx [Param<'tcx>], ) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx { tys.iter() .zip(hir_tys.iter()) .enumerate() - .filter_map(|(i, (ty, hir_ty))| { - if_chain! { - if let ty::Ref(_, ty, mutability) = *ty.kind(); - if let ty::Adt(adt, substs) = *ty.kind(); - - if let TyKind::Ref(lt, ref ty) = hir_ty.kind; - if let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind; - + .filter_map(move |(i, (ty, hir_ty))| { + if let ty::Ref(_, ty, mutability) = *ty.kind() + && 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 // 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` - if let [.., name] = path.segments; - if cx.tcx.item_name(adt.did()) == name.ident.name; - - then { + && 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) => ( @@ -454,30 +455,65 @@ fn check_fn_args<'cx, 'tcx: 'cx>( DerefTy::Path, ), Some(sym::Cow) if mutability == Mutability::Not => { - let ty_name = name.args + if let Some((lifetime, ty)) = name.args .and_then(|args| { - args.args.iter().find_map(|a| match a { - GenericArg::Type(x) => Some(x), - _ => None, - }) + if let [GenericArg::Lifetime(lifetime), ty] = args.args { + return Some((lifetime, ty)); + } + None }) - .and_then(|arg| snippet_opt(cx, arg.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, - ); + { + if !lifetime.is_anonymous() + && let FnRetTy::Return(ret_ty) = ret_ty + && let ret_ty = hir_ty_to_ty(cx.tcx, ret_ty) + && ret_ty + .walk() + .filter_map(|arg| { + arg.as_region().and_then(|lifetime| { + match lifetime.kind() { + ty::ReEarlyBound(r) => Some(r.def_id), + ty::ReLateBound(_, r) => r.kind.get_id(), + ty::ReFree(r) => r.bound_region.get_id(), + ty::ReStatic + | 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, @@ -495,7 +531,6 @@ fn check_fn_args<'cx, 'tcx: 'cx>( }, deref_ty, }); - } } None }) diff --git a/tests/ui/ptr_arg.rs b/tests/ui/ptr_arg.rs index 5f54101ca15..709f74ee6aa 100644 --- a/tests/ui/ptr_arg.rs +++ b/tests/ui/ptr_arg.rs @@ -1,5 +1,10 @@ #![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)] 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(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!() + } +} diff --git a/tests/ui/ptr_arg.stderr b/tests/ui/ptr_arg.stderr index 6b4de98ce88..d663b070b9c 100644 --- a/tests/ui/ptr_arg.stderr +++ b/tests/ui/ptr_arg.stderr @@ -1,5 +1,5 @@ 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>) { | ^^^^^^^^^ 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` 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>) { | ^^^^^^^^^^^^^ help: change this to: `&mut [i64]` 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) { | ^^^^^^^ help: change this to: `&str` 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) { | ^^^^^^^^^^^ help: change this to: `&mut str` 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) { | ^^^^^^^^ help: change this to: `&Path` 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) { | ^^^^^^^^^^^^ help: change this to: `&mut Path` 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>); | ^^^^^^^^^ help: change this to: `&[i64]` 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> { | ^^^^^^^^ @@ -60,7 +60,7 @@ LL ~ x.to_owned() | 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 { | ^^^^^^^ @@ -76,7 +76,7 @@ LL ~ x.to_owned() | 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 { | ^^^^^^^^ @@ -92,7 +92,7 @@ LL ~ x.to_path_buf() | 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) { | ^^^^^^^ @@ -106,19 +106,19 @@ LL ~ let c = y; | 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]>) {} | ^^^^^^^^^^^ help: change this to: `&[i32]` 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) {} | ^^^^^^^ help: change this to: `&str` 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>) { | ^^^^^^^^ @@ -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 - --> $DIR/ptr_arg.rs:151:23 + --> $DIR/ptr_arg.rs:156:23 | 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 - --> $DIR/ptr_arg.rs:156:21 + --> $DIR/ptr_arg.rs:161:21 | 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 - --> $DIR/ptr_arg.rs:162:29 + --> $DIR/ptr_arg.rs:167:29 | LL | fn mut_vec_slice_methods(v: &mut Vec<u32>) { | ^^^^^^^^^^^^^ help: change this to: `&mut [u32]` 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) { | ^^^^^^^^^^^^^ help: change this to: `&mut [u32]` 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) { | ^^^^^^^^^^^ help: change this to: `&mut str` 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) { | ^^^^^^^^^^^^ 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 |