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

[rust-log-analyzer]

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

Click to see the possible cause of the failure (guessed by this bot)

    = 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: `-D unstable-name-collisions` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unstable_name_collisions)]`
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)]
    |

error: 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:258:14
    |
258 |             .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] serde_json test:false 2.334
    Checking icu_locale_core v2.0.0
[RUSTC-TIMING] chalk_solve test:false 5.378
---
    Checking icu_normalizer v2.0.0
error: a method with this name may be added to the standard library in the future
    --> src/tools/rust-analyzer/crates/hir-def/src/nameres/collector.rs:2216:14
     |
2216 |             .dedup_by(|a, b| {
     |              ^^^^^^^^
     |
     = 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 test:false 0.337
    Checking icu_properties v2.0.1
error: 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:104:14
    |
104 |             .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] windows_sys test:false 7.628
    Checking line-index v0.1.2
[RUSTC-TIMING] line_index test:false 0.247

[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?