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Consider splitting needless_lifetimes into cases that do and do not require '_ #13514

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dtolnay opened this issue Oct 6, 2024 · 5 comments · May be fixed by #13960
Open

Consider splitting needless_lifetimes into cases that do and do not require '_ #13514

dtolnay opened this issue Oct 6, 2024 · 5 comments · May be fixed by #13960

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@dtolnay
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dtolnay commented Oct 6, 2024

Description

I think the suggested code changes from needless_lifetimes are consistently good improvements when they look like this, involving only deleting characters:

warning: the following explicit lifetimes could be elided: 'a
   --> src/de.rs:339:11
    |
339 | impl<'de, 'a> EnumAccess<'de> for &'a mut Deserializer<'de> {
    |           ^^                       ^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
help: elide the lifetimes
    |
339 - impl<'de, 'a> EnumAccess<'de> for &'a mut Deserializer<'de> {
339 + impl<'de> EnumAccess<'de> for &mut Deserializer<'de> {

and a mixed bag when they look like this:

warning: the following explicit lifetimes could be elided: 'a
   --> src/de.rs:197:19
    |
197 |         impl<'de, 'a> de::SeqAccess<'de> for SeqAccess<'a, 'de> {
    |                   ^^                                   ^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
help: elide the lifetimes
    |
197 -         impl<'de, 'a> de::SeqAccess<'de> for SeqAccess<'a, 'de> {
197 +         impl<'de> de::SeqAccess<'de> for SeqAccess<'_, 'de> {
    |

I would love to be able to deny the first category and allow the second category.

Another possible way to draw a distinction is whether the lint pertains to an already-named lifetime. In SeqAccess<'a, 'de> a name has already been chosen for that 'a lifetime in the location where the type is defined, so the impl isn't responsible for inventing a whole new name. Whereas in &'a mut Deserializer<'de>, the impl is needlessly inventing a brand new name for this 'a lifetime. I think this "already-named" framing is slightly different than the "does it require '_" framing, considering cases like impl Trait for dyn Trait + '_. I am not sure which of the two would make the best split.

Version

rustc 1.83.0-nightly (9096f4faf 2024-10-05)
binary: rustc
commit-hash: 9096f4fafa2ac2d771f866337b4ee7064cde8575
commit-date: 2024-10-05
host: aarch64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0

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@ojeda
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ojeda commented Oct 12, 2024

Yeah, it may be a good idea to split some of these -- in the PR, @Alexendoo seemed to have similar thoughts:

The change seems like a natural extension but it does make me wonder if we should split the lint into cases that need '_ and ones that don't, but that can be separate since we already suggest '_ sometimes

@alice-i-cecile
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Seconding this request. The introduction of '_ lifetimes is a lateral move at best IMO.

We tested this lint in the Bevy repo here: bevyengine/bevy#15907 (comment). As discussed, the loss of encoded information with the choice of lifetime names is quite painful.

@ojeda ojeda mentioned this issue Oct 14, 2024
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@waywardmonkeys waywardmonkeys mentioned this issue Nov 1, 2024
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@orlp
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orlp commented Nov 15, 2024

I'd love if it this was implemented, clippy just suggested this monstrosity to me:

error: the following explicit lifetimes could be elided: 'k
   --> crates/polars-utils/src/idx_map/bytes_idx_map.rs:136:10
    |
136 | impl<'a, 'k, V> VacantEntry<'a, 'k, V> {
    |          ^^                     ^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
    = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
help: elide the lifetimes
    |
136 - impl<'a, 'k, V> VacantEntry<'a, 'k, V> {
136 + impl<'a, V> VacantEntry<'a, '_, V> {

@ojeda
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ojeda commented Nov 16, 2024

For Linux, we would have needed this: https://lore.kernel.org/rust-for-linux/[email protected]/

In the end, we decided to allow the lint instead for the time being: https://lore.kernel.org/rust-for-linux/[email protected]/

intel-lab-lkp pushed a commit to intel-lab-lkp/linux that referenced this issue Nov 21, 2024
@ojeda @intel-lab-lkp
rust: allow clippy::needless_lifetimes
a306fa8 
In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Signed-off-by: Miguel Ojeda <[email protected]>
ojeda added a commit to Rust-for-Linux/linux that referenced this issue Nov 24, 2024
@ojeda
rust: allow clippy::needless_lifetimes
60fc1e6 
In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
@dj8yfo dj8yfo mentioned this issue Nov 28, 2024
Merged
@FreezyLemon FreezyLemon mentioned this issue Dec 5, 2024
Merged
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Dec 11, 2024
@ojeda
rust: allow clippy::needless_lifetimes
27c7a1e 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Dec 12, 2024
@ojeda
rust: allow clippy::needless_lifetimes
e8b039f 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Kaz205 pushed a commit to Kaz205/linux that referenced this issue Dec 12, 2024
@ojeda
rust: allow clippy::needless_lifetimes
4500dae 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this issue Dec 12, 2024
@ojeda @gregkh
rust: allow clippy::needless_lifetimes
6dad973 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Dec 13, 2024
@ojeda
rust: allow clippy::needless_lifetimes
17bc15e 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this issue Dec 13, 2024
@ojeda @gregkh
rust: allow clippy::needless_lifetimes
b93872e 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Dec 14, 2024
@ojeda
rust: allow clippy::needless_lifetimes
3dcbbb4 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
gregkh pushed a commit to gregkh/linux that referenced this issue Dec 14, 2024
@ojeda @gregkh
rust: allow clippy::needless_lifetimes
a7e0e29 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Dec 15, 2024
@ojeda
rust: allow clippy::needless_lifetimes
708bf22 
commit 60fc1e6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
kongwoojin pushed a commit to kongwoojin/linux-kernel that referenced this issue Dec 17, 2024
@ojeda @kongwoojin
rust: allow clippy::needless_lifetimes
3fd67a5 
commit 60fc1e6750133620e404d40b93df5afe32e3e6c6 upstream.

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
@nicoburns
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nicoburns commented Dec 30, 2024 •
edited
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I'm also not entirely happy with this lint. It seems helpful when the lifetime name is something meaningless like 'a, but can hurt code readability when the lifetime has a useful name like 'de (serde) or 'dom (servo).

johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Jan 3, 2025
@ojeda
rust: allow clippy::needless_lifetimes
425a6ce 
[ Upstream commit 60fc1e6 ]

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Jan 4, 2025
@ojeda
rust: allow clippy::needless_lifetimes
58d1860 
[ Upstream commit 60fc1e6 ]

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Jan 5, 2025
@ojeda
rust: allow clippy::needless_lifetimes
ee0a425 
[ Upstream commit 60fc1e6 ]

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Jan 6, 2025
@ojeda
rust: allow clippy::needless_lifetimes
3602ff9 
[ Upstream commit 60fc1e6 ]

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
mj22226 pushed a commit to mj22226/linux that referenced this issue Jan 6, 2025
@ojeda @gregkh
rust: allow clippy::needless_lifetimes
cb041fe 
[ Upstream commit 60fc1e6 ]

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Jan 7, 2025
@ojeda
rust: allow clippy::needless_lifetimes
6cb6061 
[ Upstream commit 60fc1e6 ]

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
@Alexendoo Alexendoo linked a pull request Jan 7, 2025 that will close this issue
Open
johnny-mnemonic pushed a commit to linux-ia64/linux-stable-rc that referenced this issue Jan 9, 2025
@ojeda
rust: allow clippy::needless_lifetimes
0e05821 
[ Upstream commit 60fc1e6 ]

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has
been extended [1] to suggest eliding `impl` lifetimes, e.g.

    error: the following explicit lifetimes could be elided: 'a
    --> rust/kernel/list.rs:647:6
        |
    647 | impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
        |      ^^                                                                  ^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
        = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
        = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
    help: elide the lifetimes
        |
    647 - impl<'a, T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'a, T, ID> {}
    647 + impl<T: ?Sized + ListItem<ID>, const ID: u64> FusedIterator for Iter<'_, T, ID> {}

A possibility would have been to clean them -- the RFC patch [2] did
this, while asking if we wanted these cleanups. There is an open issue
[3] in Clippy about being able to differentiate some of the new cases,
e.g. those that do not involve introducing `'_`. Thus it seems others
feel similarly.

Thus, for the time being, we decided to `allow` the lint.

Link: rust-lang/rust-clippy#13286 [1]
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
Link: rust-lang/rust-clippy#13514 [3]
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Andreas Hindborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
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Split needless_lifetime '_ suggestions into elidable_lifetime_names Alexendoo/rust-clippy
5 participants
@orlp @nicoburns @ojeda @dtolnay @alice-i-cecile