From eb03ea4435fe93f4688d1a0ae61e266cfa53f845 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jana=20D=C3=B6nszelmann?= Date: Wed, 3 Dec 2025 16:20:30 +0100 Subject: [PATCH 1/2] Revert "implement and test `Iterator::{exactly_one, collect_array}`" This reverts commit 699184bba4f5e6df163d5d08883e09509ac79e86. --- library/core/src/iter/traits/iterator.rs | 56 ------------------------ 1 file changed, 56 deletions(-) diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index f898382086512..29230b1665380 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -4034,62 +4034,6 @@ pub trait Iterator { { unreachable!("Always specialized"); } - - /// Checks if the iterator contains *exactly* one element. - /// If so, returns this one element. - /// - /// See also [`collect_array`](Iterator::collect_array) for lengths other than `1`. - /// - /// # Examples - /// - /// ``` - /// #![feature(exact_length_collection)] - /// - /// assert_eq!([1].into_iter().exactly_one(), Some(1)); - /// assert_eq!([].into_iter().exactly_one(), None::<()>); - /// - /// // There is exactly one even integer in the array: - /// assert_eq!([1, 2, 3].into_iter().filter(|x| x % 2 == 0).exactly_one(), Some(2)); - /// // But there are two odds, which is too many: - /// assert_eq!([1, 2, 3].into_iter().filter(|x| x % 2 == 1).exactly_one(), None); - /// ``` - #[inline] - #[unstable(feature = "exact_length_collection", issue = "149266")] - fn exactly_one(self) -> Option - where - Self: Sized, - { - self.collect_array::<1>().map(|[i]| i) - } - - /// Checks if an iterator has *exactly* `N` elements. - /// If so, returns those `N` elements in an array. - /// - /// See also [`exactly_one`](Iterator::exactly_one) when expecting a single element. - /// - /// # Examples - /// - /// ``` - /// #![feature(exact_length_collection)] - /// - /// assert_eq!([1, 2, 3, 4].into_iter().collect_array(), Some([1, 2, 3, 4])); - /// assert_eq!([1, 2].into_iter().chain([3, 4]).collect_array(), Some([1, 2, 3, 4])); - /// - /// // Iterator contains too few elements: - /// assert_eq!([1, 2].into_iter().collect_array::<4>(), None); - /// // Iterator contains too many elements: - /// assert_eq!([1, 2, 3, 4, 5].into_iter().collect_array::<4>(), None); - /// // Taking 4 makes it work again: - /// assert_eq!([1, 2, 3, 4, 5].into_iter().take(4).collect_array(), Some([1, 2, 3, 4])); - /// ``` - #[inline] - #[unstable(feature = "exact_length_collection", issue = "149266")] - fn collect_array(mut self) -> Option<[Self::Item; N]> - where - Self: Sized, - { - self.next_chunk().ok().filter(|_| self.next().is_none()) - } } trait SpecIterEq: Iterator { From c3407323ada81bac2341fa3947fd00660bf7729b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jana=20D=C3=B6nszelmann?= Date: Wed, 3 Dec 2025 16:22:57 +0100 Subject: [PATCH 2/2] Revert "fixup warnings around the compiler" This reverts commit f20175293aa8372766250e56e2570f3c06640e0b. --- compiler/rustc_codegen_ssa/src/back/metadata.rs | 3 +-- src/librustdoc/html/format.rs | 6 ++---- src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs | 6 ++---- tests/ui/const-generics/type-dependent/issue-71805.rs | 4 ++-- tests/ui/mir/mir-inlining/ice-issue-77564.rs | 7 +++---- 5 files changed, 10 insertions(+), 16 deletions(-) diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs index 5a49d0f07a490..6dff79374f20f 100644 --- a/compiler/rustc_codegen_ssa/src/back/metadata.rs +++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs @@ -86,8 +86,7 @@ impl MetadataLoader for DefaultMetadataLoader { format!("failed to parse aix dylib '{}': {}", path.display(), e) })?; - // FIXME: rewrite in terms of `#![feature(exact_length_collection)]`. See: #149266 - match Itertools::exactly_one(archive.members()) { + match archive.members().exactly_one() { Ok(lib) => { let lib = lib.map_err(|e| { format!("failed to parse aix dylib '{}': {}", path.display(), e) diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs index 2b9562f26574a..eee13ff2b0dc0 100644 --- a/src/librustdoc/html/format.rs +++ b/src/librustdoc/html/format.rs @@ -1126,8 +1126,7 @@ pub(crate) fn print_impl( } if impl_.kind.is_fake_variadic() && let Some(generics) = ty.generics() - // FIXME: rewrite in terms of `#![feature(exact_length_collection)]`. See: #149266 - && let Ok(inner_type) = Itertools::exactly_one(generics) + && let Ok(inner_type) = generics.exactly_one() { let last = ty.last(); if f.alternate() { @@ -1207,8 +1206,7 @@ impl clean::Impl { } } else if let clean::Type::Path { path } = type_ && let Some(generics) = path.generics() - // FIXME: rewrite in terms of `#![feature(exact_length_collection)]`. See: #149266 - && let Ok(ty) = Itertools::exactly_one(generics) + && let Ok(ty) = generics.exactly_one() && self.kind.is_fake_variadic() { print_anchor(path.def_id(), path.last(), cx).fmt(f)?; diff --git a/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs b/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs index 08e7c7593cb27..0d783fde33131 100644 --- a/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs +++ b/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs @@ -92,8 +92,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualNonExhaustive { (matches!(v.data, VariantData::Unit(_, _)) && is_doc_hidden(cx.tcx.hir_attrs(v.hir_id))) .then_some((v.def_id, v.span)) }); - // FIXME: rewrite in terms of `#![feature(exact_length_collection)]`. See: #149266 - if let Ok((id, span)) = Itertools::exactly_one(iter) + if let Ok((id, span)) = iter.exactly_one() && !find_attr!(cx.tcx.hir_attrs(item.hir_id()), AttributeKind::NonExhaustive(..)) { self.potential_enums.push((item.owner_id.def_id, id, item.span, span)); @@ -105,8 +104,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualNonExhaustive { .iter() .filter(|field| !cx.effective_visibilities.is_exported(field.def_id)); if fields.len() > 1 - // FIXME: rewrite in terms of `#![feature(exact_length_collection)]`. See: #149266 - && let Ok(field) = Itertools::exactly_one(private_fields) + && let Ok(field) = private_fields.exactly_one() && let TyKind::Tup([]) = field.ty.kind { span_lint_and_then( diff --git a/tests/ui/const-generics/type-dependent/issue-71805.rs b/tests/ui/const-generics/type-dependent/issue-71805.rs index de04a809da60f..27c101df107c8 100644 --- a/tests/ui/const-generics/type-dependent/issue-71805.rs +++ b/tests/ui/const-generics/type-dependent/issue-71805.rs @@ -4,7 +4,7 @@ use std::mem::MaybeUninit; trait CollectSlice<'a>: Iterator { fn inner_array(&mut self) -> [Self::Item; N]; - fn custom_collect_array(&mut self) -> [Self::Item; N] { + fn collect_array(&mut self) -> [Self::Item; N] { let result = self.inner_array(); assert!(self.next().is_none()); result @@ -34,5 +34,5 @@ where fn main() { let mut foos = [0u64; 9].iter().cloned(); - let _bar: [u64; 9] = foos.custom_collect_array::<9_usize>(); + let _bar: [u64; 9] = foos.collect_array::<9_usize>(); } diff --git a/tests/ui/mir/mir-inlining/ice-issue-77564.rs b/tests/ui/mir/mir-inlining/ice-issue-77564.rs index 256ff295184d7..fce6d1d174f66 100644 --- a/tests/ui/mir/mir-inlining/ice-issue-77564.rs +++ b/tests/ui/mir/mir-inlining/ice-issue-77564.rs @@ -29,11 +29,10 @@ where fn main() { assert_eq!( - CollectArray::collect_array( - &mut [[1, 2], [3, 4]] + [[1, 2], [3, 4]] .iter() - .map(|row| CollectArray::collect_array(&mut row.iter())) - ), + .map(|row| row.iter().collect_array()) + .collect_array(), [[&1, &2], [&3, &4]] ); }