add Iterator::dedup and friends

[Qelxiros]

Tracking issue: #83747

[rustbot]

r? @ibraheemdev

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[rustbot]

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

[ibraheemdev]

r? libs-api

[dtolnay]

Thanks for the PR!

I expect that this is going to be blocked on compiler work (#89151) for the same reason as this other pending Iterator method: #141994.

View changes since this review

[rustbot]

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[Qelxiros]

@dtolnay That's my expectation as well. Should I continue to fix the failing checks, or will that work become obsolete when #89151 is resolved?

[dtolnay]

That's right, compiler improvements are supposed to make those errors no longer occur.

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[rust-log-analyzer]

The job pr-check-1 failed! Check out the build log: (web) (plain enhanced) (plain)

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---
    = warning: once this associated item is added to the standard library, the ambiguity may cause an error or change in behavior!
    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
    = help: call with fully qualified syntax `itertools::Itertools::dedup(...)` to keep using the current method
    = note: `#[warn(unstable_name_collisions)]` (part of `#[warn(future_incompatible)]`) on by default
help: add `#![feature(iter_dedup)]` to the crate attributes to enable `std::iter::Iterator::dedup`
   --> src/tools/rust-analyzer/crates/hir-def/src/lib.rs:12:1
    |
 12 + #![feature(iter_dedup)]
    |

warning: a method with this name may be added to the standard library in the future
   --> src/tools/rust-analyzer/crates/hir-def/src/item_scope.rs:259:14
    |
259 |             .dedup()
    |              ^^^^^
    |
    = warning: once this associated item is added to the standard library, the ambiguity may cause an error or change in behavior!
    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
    = help: call with fully qualified syntax `itertools::Itertools::dedup(...)` to keep using the current method
help: add `#![feature(iter_dedup)]` to the crate attributes to enable `std::iter::Iterator::dedup`
   --> src/tools/rust-analyzer/crates/hir-def/src/lib.rs:12:1
    |
 12 + #![feature(iter_dedup)]
    |

[RUSTC-TIMING] typed_arena test:false 0.148
    Checking test-fixture v0.0.0 (/checkout/src/tools/rust-analyzer/crates/test-fixture)
[RUSTC-TIMING] test_fixture test:false 0.877
---
    Checking ra-ap-rustc_next_trait_solver v0.143.0
warning: a method with this name may be added to the standard library in the future
   --> src/tools/rust-analyzer/crates/hir-def/src/import_map.rs:105:14
    |
105 |             .dedup_by(|&(_, (_, lhs, _)), &(_, (_, rhs, _))| lhs.eq_ignore_ascii_case(rhs));
    |              ^^^^^^^^
    |
    = warning: once this associated item is added to the standard library, the ambiguity may cause an error or change in behavior!
    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
    = help: call with fully qualified syntax `itertools::Itertools::dedup_by(...)` to keep using the current method
help: add `#![feature(iter_dedup)]` to the crate attributes to enable `std::iter::Iterator::dedup_by`
   --> src/tools/rust-analyzer/crates/hir-def/src/lib.rs:12:1
    |
 12 + #![feature(iter_dedup)]
    |

[RUSTC-TIMING] yoke_derive test:false 3.061
    Checking yoke v0.8.0
[RUSTC-TIMING] yoke test:false 0.340
---
[RUSTC-TIMING] xshell test:false 0.425
warning: a method with this name may be added to the standard library in the future
   --> src/tools/rust-analyzer/crates/ide-db/src/text_edit.rs:128:34
    |
128 |         self.indels = iter_merge.dedup_by(|a, b| a == b && !a.delete.is_empty()).cloned().collect();
    |                                  ^^^^^^^^
    |
    = warning: once this associated item is added to the standard library, the ambiguity may cause an error or change in behavior!
    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
    = help: call with fully qualified syntax `itertools::Itertools::dedup_by(...)` to keep using the current method
    = note: `#[warn(unstable_name_collisions)]` (part of `#[warn(future_incompatible)]`) on by default
help: add `#![feature(iter_dedup)]` to the crate attributes to enable `std::iter::Iterator::dedup_by`
   --> src/tools/rust-analyzer/crates/ide-db/src/lib.rs:7:1
    |
  7 + #![feature(iter_dedup)]
    |

[RUSTC-TIMING] criterion_plot test:false 0.660
    Checking bit-set v0.8.0
[RUSTC-TIMING] proc_macro2 test:false 0.855
---
    = warning: once this associated item is added to the standard library, the ambiguity may cause an error or change in behavior!
    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
    = help: call with fully qualified syntax `itertools::Itertools::dedup(...)` to keep using the current method
    = note: `#[warn(unstable_name_collisions)]` (part of `#[warn(future_incompatible)]`) on by default
help: add `#![feature(iter_dedup)]` to the crate attributes to enable `std::iter::Iterator::dedup`
   --> src/tools/rust-analyzer/xtask/src/main.rs:19:1
    |
 19 + #![feature(iter_dedup)]
    |

[RUSTC-TIMING] xtask test:true 3.070
warning: `xtask` (bin "xtask" test) generated 1 warning
[RUSTC-TIMING] xtask test:false 3.002
warning: `xtask` (bin "xtask") generated 1 warning (1 duplicate)
[RUSTC-TIMING] rust_analyzer_proc_macro_srv test:false 0.540
[RUSTC-TIMING] bench test:false 0.216
[RUSTC-TIMING] tidy test:true 0.084