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Preserve explicit lifetime information when removing mut #16273

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19 changes: 14 additions & 5 deletions clippy_lints/src/needless_pass_by_ref_mut.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
use super::needless_pass_by_value::requires_exact_signature;
use clippy_config::Conf;
use clippy_utils::diagnostics::span_lint_hir_and_then;
use clippy_utils::source::snippet;
use clippy_utils::source::HasSession as _;
use clippy_utils::visitors::for_each_expr;
use clippy_utils::{inherits_cfg, is_from_proc_macro, is_self};
use core::ops::ControlFlow;
Expand All @@ -18,9 +18,9 @@ use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::mir::FakeReadCause;
use rustc_middle::ty::{self, Ty, TyCtxt, UpvarId, UpvarPath};
use rustc_session::impl_lint_pass;
use rustc_span::Span;
use rustc_span::def_id::LocalDefId;
use rustc_span::symbol::kw;
use rustc_span::{BytePos, Span};

declare_clippy_lint! {
/// ### What it does
Expand Down Expand Up @@ -269,6 +269,15 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessPassByRefMut<'tcx> {
// If the argument is never used mutably, we emit the warning.
let sp = input.span;
if let rustc_hir::TyKind::Ref(_, inner_ty) = input.kind {
let Some(after_mut_span) = cx.sess().source_map().span_extend_to_prev_str(
inner_ty.ty.span.shrink_to_lo(),
"mut",
true,
true,
) else {
return;
};
let mut_span = after_mut_span.with_lo(after_mut_span.lo() - BytePos(3));
let is_cfged = is_cfged.get_or_insert_with(|| inherits_cfg(cx.tcx, *fn_def_id));
span_lint_hir_and_then(
cx,
Expand All @@ -278,9 +287,9 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessPassByRefMut<'tcx> {
"this argument is a mutable reference, but not used mutably",
|diag| {
diag.span_suggestion(
sp,
"consider changing to".to_string(),
format!("&{}", snippet(cx, cx.tcx.hir_span(inner_ty.ty.hir_id), "_"),),
mut_span,
"consider removing this `mut`",
"",
Applicability::Unspecified,
);
if cx.effective_visibilities.is_exported(*fn_def_id) {
Expand Down
4 changes: 3 additions & 1 deletion tests/ui-toml/needless_pass_by_ref_mut/needless_pass_by_ref_mut.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,9 @@ error: this argument is a mutable reference, but not used mutably
--> tests/ui-toml/needless_pass_by_ref_mut/needless_pass_by_ref_mut.rs:5:19
|
LL | pub fn pub_foo(s: &mut Vec<u32>, b: &u32, x: &mut u32) {
| ^^^^^^^^^^^^^ help: consider changing to: `&Vec<u32>`
| ^----^^^^^^^^
| |
| help: consider removing this `mut`
|
= warning: changing this function will impact semver compatibility
= note: `-D clippy::needless-pass-by-ref-mut` implied by `-D warnings`
Expand Down
136 changes: 102 additions & 34 deletions tests/ui/needless_pass_by_ref_mut.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,9 @@ error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:12:11
|
LL | fn foo(s: &mut Vec<u32>, b: &u32, x: &mut u32) {
| ^^^^^^^^^^^^^ help: consider changing to: `&Vec<u32>`
| ^----^^^^^^^^
| |
| help: consider removing this `mut`
|
= note: `-D clippy::needless-pass-by-ref-mut` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::needless_pass_by_ref_mut)]`
Expand All @@ -11,203 +13,269 @@ error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:38:12
|
LL | fn foo6(s: &mut Vec<u32>) {
| ^^^^^^^^^^^^^ help: consider changing to: `&Vec<u32>`
| ^----^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:49:12
|
LL | fn bar(&mut self) {}
| ^^^^^^^^^ help: consider changing to: `&self`
| ^----^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:52:29
|
LL | fn mushroom(&self, vec: &mut Vec<i32>) -> usize {
| ^^^^^^^^^^^^^ help: consider changing to: `&Vec<i32>`
| ^----^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:130:16
|
LL | async fn a1(x: &mut i32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:135:16
|
LL | async fn a2(x: &mut i32, y: String) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:140:16
|
LL | async fn a3(x: &mut i32, y: String, z: String) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:145:16
|
LL | async fn a4(x: &mut i32, y: i32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:150:24
|
LL | async fn a5(x: i32, y: &mut i32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:155:24
|
LL | async fn a6(x: i32, y: &mut i32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:160:32
|
LL | async fn a7(x: i32, y: i32, z: &mut i32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:165:24
|
LL | async fn a8(x: i32, a: &mut i32, y: i32, z: &mut i32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:165:45
|
LL | async fn a8(x: i32, a: &mut i32, y: i32, z: &mut i32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:201:16
|
LL | fn cfg_warn(s: &mut u32) {}
| ^^^^^^^^ help: consider changing to: `&u32`
| ^----^^^
| |
| help: consider removing this `mut`
|
= note: this is cfg-gated and may require further changes

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:206:20
|
LL | fn cfg_warn(s: &mut u32) {}
| ^^^^^^^^ help: consider changing to: `&u32`
| ^----^^^
| |
| help: consider removing this `mut`
|
= note: this is cfg-gated and may require further changes

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:219:39
|
LL | async fn inner_async2(x: &mut i32, y: &mut u32) {
| ^^^^^^^^ help: consider changing to: `&u32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:228:26
|
LL | async fn inner_async3(x: &mut i32, y: &mut u32) {
| ^^^^^^^^ help: consider changing to: `&i32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:248:30
|
LL | async fn call_in_closure1(n: &mut str) {
| ^^^^^^^^ help: consider changing to: `&str`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:268:16
|
LL | fn closure2(n: &mut usize) -> impl '_ + FnMut() -> usize {
| ^^^^^^^^^^ help: consider changing to: `&usize`
| ^----^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:280:22
|
LL | async fn closure4(n: &mut usize) {
| ^^^^^^^^^^ help: consider changing to: `&usize`
| ^----^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:335:12
|
LL | fn bar(&mut self) {}
| ^^^^^^^^^ help: consider changing to: `&self`
| ^----^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:338:18
|
LL | async fn foo(&mut self, u: &mut i32, v: &mut u32) {
| ^^^^^^^^^ help: consider changing to: `&self`
| ^----^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:338:45
|
LL | async fn foo(&mut self, u: &mut i32, v: &mut u32) {
| ^^^^^^^^ help: consider changing to: `&u32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:347:46
|
LL | async fn foo2(&mut self, u: &mut i32, v: &mut u32) {
| ^^^^^^^^ help: consider changing to: `&u32`
| ^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:364:18
|
LL | fn _empty_tup(x: &mut (())) {}
| ^^^^^^^^^ help: consider changing to: `&()`
| ^^----^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:366:19
|
LL | fn _single_tup(x: &mut ((i32,))) {}
| ^^^^^^^^^^^^^ help: consider changing to: `&(i32,)`
| ^^----^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:368:18
|
LL | fn _multi_tup(x: &mut ((i32, u32))) {}
| ^^^^^^^^^^^^^^^^^ help: consider changing to: `&(i32, u32)`
| ^^----^^^^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:370:11
|
LL | fn _fn(x: &mut (fn())) {}
| ^^^^^^^^^^^ help: consider changing to: `&fn()`
| ^^----^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:373:23
|
LL | fn _extern_rust_fn(x: &mut extern "Rust" fn()) {}
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing to: `&extern "Rust" fn()`
| ^----^^^^^^^^^^^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:375:20
|
LL | fn _extern_c_fn(x: &mut extern "C" fn()) {}
| ^^^^^^^^^^^^^^^^^^^^ help: consider changing to: `&extern "C" fn()`
| ^----^^^^^^^^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:377:18
|
LL | fn _unsafe_fn(x: &mut unsafe fn()) {}
| ^^^^^^^^^^^^^^^^ help: consider changing to: `&unsafe fn()`
| ^----^^^^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:379:25
|
LL | fn _unsafe_extern_fn(x: &mut unsafe extern "C" fn()) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing to: `&unsafe extern "C" fn()`
| ^----^^^^^^^^^^^^^^^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:381:20
|
LL | fn _fn_with_arg(x: &mut unsafe extern "C" fn(i32)) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing to: `&unsafe extern "C" fn(i32)`
| ^----^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| help: consider removing this `mut`

error: this argument is a mutable reference, but not used mutably
--> tests/ui/needless_pass_by_ref_mut.rs:383:20
|
LL | fn _fn_with_ret(x: &mut unsafe extern "C" fn() -> (i32)) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing to: `&unsafe extern "C" fn() -> (i32)`
| ^----^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| help: consider removing this `mut`

error: aborting due to 34 previous errors

6 changes: 6 additions & 0 deletions tests/ui/needless_pass_by_ref_mut2.fixed
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Original file line number Diff line number Diff line change
Expand Up @@ -24,3 +24,9 @@ async fn inner_async4(u: &mut i32, v: &u32) {
}

fn main() {}

//~v needless_pass_by_ref_mut
fn issue16267<'a>(msg: &str, slice: &'a [i32]) -> &'a [i32] {
println!("{msg}");
&slice[0..5]
}
6 changes: 6 additions & 0 deletions tests/ui/needless_pass_by_ref_mut2.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,3 +24,9 @@ async fn inner_async4(u: &mut i32, v: &mut u32) {
}

fn main() {}

//~v needless_pass_by_ref_mut
fn issue16267<'a>(msg: &str, slice: &'a mut [i32]) -> &'a [i32] {
println!("{msg}");
&slice[0..5]
}
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