Rollup of 15 pull requests

compiler/rustc_arena/src/lib.rs

@@ -11,7 +11,6 @@
     html_root_url = "https://doc.rust-lang.org/nightly/",
     test(no_crate_inject, attr(deny(warnings)))
 )]
-#![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
 #![feature(new_uninit)]
 #![feature(maybe_uninit_slice)]
@@ -24,7 +23,6 @@ use smallvec::SmallVec;
 use std::alloc::Layout;
 use std::cell::{Cell, RefCell};
 use std::cmp;
-use std::intrinsics;
 use std::marker::{PhantomData, Send};
 use std::mem::{self, MaybeUninit};
 use std::ptr;
@@ -122,7 +120,7 @@ impl<T> TypedArena<T> {
 
         unsafe {
             if mem::size_of::<T>() == 0 {
-                self.ptr.set(intrinsics::arith_offset(self.ptr.get() as *mut u8, 1) as *mut T);
+                self.ptr.set((self.ptr.get() as *mut u8).wrapping_offset(1) as *mut T);
                 let ptr = mem::align_of::<T>() as *mut T;
                 // Don't drop the object. This `write` is equivalent to `forget`.
                 ptr::write(ptr, object);

compiler/rustc_ast/src/lib.rs

@@ -5,17 +5,13 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/", test(attr(deny(warnings))))]
-#![feature(bool_to_option)]
 #![feature(box_syntax)]
 #![feature(const_fn)] // For the `transmute` in `P::new`
 #![feature(const_panic)]
-#![feature(const_fn_transmute)]
 #![feature(crate_visibility_modifier)]
 #![feature(label_break_value)]
 #![feature(nll)]
 #![feature(or_patterns)]
-#![feature(try_trait)]
-#![feature(unicode_internals)]
 #![recursion_limit = "256"]
 
 #[macro_use]

compiler/rustc_ast_lowering/src/item.rs

@@ -27,7 +27,7 @@ pub(super) struct ItemLowerer<'a, 'lowering, 'hir> {
 impl ItemLowerer<'_, '_, '_> {
     fn with_trait_impl_ref(&mut self, impl_ref: &Option<TraitRef>, f: impl FnOnce(&mut Self)) {
         let old = self.lctx.is_in_trait_impl;
-        self.lctx.is_in_trait_impl = if let &None = impl_ref { false } else { true };
+        self.lctx.is_in_trait_impl = impl_ref.is_some();
         f(self);
         self.lctx.is_in_trait_impl = old;
     }

compiler/rustc_codegen_ssa/src/lib.rs

@@ -8,8 +8,6 @@
 #![feature(or_patterns)]
 #![feature(trusted_len)]
 #![feature(associated_type_bounds)]
-#![feature(const_fn)] // for rustc_index::newtype_index
-#![feature(const_panic)] // for rustc_index::newtype_index
 #![recursion_limit = "256"]
 
 //! This crate contains codegen code that is used by all codegen backends (LLVM and others).

compiler/rustc_data_structures/src/lib.rs

@@ -8,10 +8,10 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![allow(incomplete_features)]
+#![feature(array_windows)]
 #![feature(control_flow_enum)]
 #![feature(in_band_lifetimes)]
 #![feature(unboxed_closures)]
-#![feature(generators)]
 #![feature(generator_trait)]
 #![feature(fn_traits)]
 #![feature(int_bits_const)]
@@ -27,7 +27,7 @@
 #![feature(thread_id_value)]
 #![feature(extend_one)]
 #![feature(const_panic)]
-#![feature(const_generics)]
+#![feature(min_const_generics)]
 #![feature(once_cell)]
 #![allow(rustc::default_hash_types)]
 

compiler/rustc_data_structures/src/sorted_map.rs

@@ -34,7 +34,7 @@ impl<K: Ord, V> SortedMap<K, V> {
     /// and that there are no duplicates.
     #[inline]
     pub fn from_presorted_elements(elements: Vec<(K, V)>) -> SortedMap<K, V> {
-        debug_assert!(elements.windows(2).all(|w| w[0].0 < w[1].0));
+        debug_assert!(elements.array_windows().all(|[fst, snd]| fst.0 < snd.0));
 
         SortedMap { data: elements }
     }
@@ -159,7 +159,7 @@ impl<K: Ord, V> SortedMap<K, V> {
             return;
         }
 
-        debug_assert!(elements.windows(2).all(|w| w[0].0 < w[1].0));
+        debug_assert!(elements.array_windows().all(|[fst, snd]| fst.0 < snd.0));
 
         let start_index = self.lookup_index_for(&elements[0].0);
 

compiler/rustc_driver/src/args.rs

@@ -4,8 +4,7 @@ use std::fs;
 use std::io;
 
 pub fn arg_expand(arg: String) -> Result<Vec<String>, Error> {
-    if arg.starts_with('@') {
-        let path = &arg[1..];
+    if let Some(path) = arg.strip_prefix('@') {
         let file = match fs::read_to_string(path) {
             Ok(file) => file,
             Err(ref err) if err.kind() == io::ErrorKind::InvalidData => {

compiler/rustc_expand/src/lib.rs

@@ -1,5 +1,4 @@
 #![feature(bool_to_option)]
-#![feature(cow_is_borrowed)]
 #![feature(crate_visibility_modifier)]
 #![feature(decl_macro)]
 #![feature(or_patterns)]

compiler/rustc_infer/src/lib.rs

@@ -13,7 +13,6 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
-#![feature(bindings_after_at)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
@@ -23,7 +22,6 @@
 #![feature(never_type)]
 #![feature(or_patterns)]
 #![feature(in_band_lifetimes)]
-#![feature(crate_visibility_modifier)]
 #![recursion_limit = "512"] // For rustdoc
 
 #[macro_use]

compiler/rustc_lint/src/lib.rs

@@ -27,6 +27,7 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![cfg_attr(test, feature(test))]
+#![feature(array_windows)]
 #![feature(bool_to_option)]
 #![feature(box_syntax)]
 #![feature(crate_visibility_modifier)]

compiler/rustc_lint/src/nonstandard_style.rs

@@ -70,9 +70,9 @@ fn is_camel_case(name: &str) -> bool {
     // ones (some scripts don't have a concept of upper/lowercase)
     !name.chars().next().unwrap().is_lowercase()
         && !name.contains("__")
-        && !name.chars().collect::<Vec<_>>().windows(2).any(|pair| {
+        && !name.chars().collect::<Vec<_>>().array_windows().any(|&[fst, snd]| {
             // contains a capitalisable character followed by, or preceded by, an underscore
-            char_has_case(pair[0]) && pair[1] == '_' || char_has_case(pair[1]) && pair[0] == '_'
+            char_has_case(fst) && snd == '_' || char_has_case(snd) && fst == '_'
         })
 }
 

compiler/rustc_middle/src/lib.rs

@@ -23,33 +23,29 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![feature(array_windows)]
 #![feature(backtrace)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(cmp_min_max_by)]
 #![feature(const_fn)]
 #![feature(const_panic)]
-#![feature(const_fn_transmute)]
 #![feature(core_intrinsics)]
 #![feature(discriminant_kind)]
-#![feature(drain_filter)]
 #![feature(never_type)]
-#![feature(exhaustive_patterns)]
 #![feature(extern_types)]
 #![feature(nll)]
 #![feature(once_cell)]
 #![feature(option_expect_none)]
 #![feature(or_patterns)]
 #![feature(min_specialization)]
 #![feature(trusted_len)]
-#![feature(stmt_expr_attributes)]
 #![feature(test)]
 #![feature(in_band_lifetimes)]
 #![feature(crate_visibility_modifier)]
 #![feature(associated_type_bounds)]
 #![feature(rustc_attrs)]
-#![feature(hash_raw_entry)]
 #![feature(int_error_matching)]
 #![recursion_limit = "512"]
 

compiler/rustc_middle/src/mir/mod.rs

@@ -2286,7 +2286,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
 /// Constants
 ///
 /// Two constants are equal if they are the same constant. Note that
-/// this does not necessarily mean that they are `==` in Rust -- in
+/// this does not necessarily mean that they are `==` in Rust. In
 /// particular, one must be wary of `NaN`!
 
 #[derive(Clone, Copy, PartialEq, TyEncodable, TyDecodable, HashStable)]

compiler/rustc_middle/src/ty/context.rs

@@ -2419,7 +2419,7 @@ impl<'tcx> TyCtxt<'tcx> {
         eps: &[ExistentialPredicate<'tcx>],
     ) -> &'tcx List<ExistentialPredicate<'tcx>> {
         assert!(!eps.is_empty());
-        assert!(eps.windows(2).all(|w| w[0].stable_cmp(self, &w[1]) != Ordering::Greater));
+        assert!(eps.array_windows().all(|[a, b]| a.stable_cmp(self, b) != Ordering::Greater));
         self._intern_existential_predicates(eps)
     }
 

compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs

@@ -492,8 +492,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             {
                 if let Ok(pat_snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(pat_span)
                 {
-                    if pat_snippet.starts_with('&') {
-                        let pat_snippet = pat_snippet[1..].trim_start();
+                    if let Some(stripped) = pat_snippet.strip_prefix('&') {
+                        let pat_snippet = stripped.trim_start();
                         let (suggestion, to_remove) = if pat_snippet.starts_with("mut")
                             && pat_snippet["mut".len()..].starts_with(rustc_lexer::is_whitespace)
                         {

compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs

@@ -631,9 +631,8 @@ fn suggest_ampmut<'tcx>(
                 let lt_name = &src[1..ws_pos];
                 let ty = &src[ws_pos..];
                 return (assignment_rhs_span, format!("&{} mut {}", lt_name, ty));
-            } else if src.starts_with('&') {
-                let borrowed_expr = &src[1..];
-                return (assignment_rhs_span, format!("&mut {}", borrowed_expr));
+            } else if let Some(stripped) = src.strip_prefix('&') {
+                return (assignment_rhs_span, format!("&mut {}", stripped));
             }
         }
     }

compiler/rustc_mir/src/dataflow/framework/graphviz.rs

@@ -1,6 +1,7 @@
 //! A helpful diagram for debugging dataflow problems.
 
 use std::borrow::Cow;
+use std::lazy::SyncOnceCell;
 use std::{io, ops, str};
 
 use regex::Regex;
@@ -570,6 +571,13 @@ where
     }
 }
 
+macro_rules! regex {
+    ($re:literal $(,)?) => {{
+        static RE: SyncOnceCell<regex::Regex> = SyncOnceCell::new();
+        RE.get_or_init(|| Regex::new($re).unwrap())
+    }};
+}
+
 fn diff_pretty<T, C>(new: T, old: T, ctxt: &C) -> String
 where
     T: DebugWithContext<C>,
@@ -578,7 +586,7 @@ where
         return String::new();
     }
 
-    let re = Regex::new("\t?\u{001f}([+-])").unwrap();
+    let re = regex!("\t?\u{001f}([+-])");
 
     let raw_diff = format!("{:#?}", DebugDiffWithAdapter { new, old, ctxt });
 

compiler/rustc_mir/src/lib.rs

@@ -6,27 +6,26 @@ Rust MIR: a lowered representation of Rust.
 
 #![feature(nll)]
 #![feature(in_band_lifetimes)]
+#![feature(array_windows)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(const_fn)]
 #![feature(const_panic)]
 #![feature(crate_visibility_modifier)]
 #![feature(decl_macro)]
-#![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
 #![feature(exhaustive_patterns)]
-#![feature(iter_order_by)]
 #![feature(never_type)]
 #![feature(min_specialization)]
 #![feature(trusted_len)]
 #![feature(try_blocks)]
-#![feature(associated_type_bounds)]
 #![feature(associated_type_defaults)]
 #![feature(stmt_expr_attributes)]
 #![feature(trait_alias)]
 #![feature(option_expect_none)]
 #![feature(or_patterns)]
+#![feature(once_cell)]
 #![recursion_limit = "256"]
 
 #[macro_use]

compiler/rustc_mir/src/monomorphize/partitioning/mod.rs

@@ -277,14 +277,8 @@ where
 
     symbols.sort_by_key(|sym| sym.1);
 
-    for pair in symbols.windows(2) {
-        let sym1 = &pair[0].1;
-        let sym2 = &pair[1].1;
-
+    for &[(mono_item1, ref sym1), (mono_item2, ref sym2)] in symbols.array_windows() {
         if sym1 == sym2 {
-            let mono_item1 = pair[0].0;
-            let mono_item2 = pair[1].0;
-
             let span1 = mono_item1.local_span(tcx);
             let span2 = mono_item2.local_span(tcx);
 

compiler/rustc_mir_build/src/lib.rs

@@ -1,7 +1,7 @@
 //! Construction of MIR from HIR.
 //!
 //! This crate also contains the match exhaustiveness and usefulness checking.
-
+#![feature(array_windows)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(const_fn)]

compiler/rustc_mir_build/src/thir/pattern/_match.rs

@@ -2299,19 +2299,19 @@ fn split_grouped_constructors<'p, 'tcx>(
                 // interval into a constructor.
                 split_ctors.extend(
                     borders
-                        .windows(2)
-                        .filter_map(|window| match (window[0], window[1]) {
-                            (Border::JustBefore(n), Border::JustBefore(m)) => {
+                        .array_windows()
+                        .filter_map(|&pair| match pair {
+                            [Border::JustBefore(n), Border::JustBefore(m)] => {
                                 if n < m {
                                     Some(IntRange { range: n..=(m - 1), ty, span })
                                 } else {
                                     None
                                 }
                             }
-                            (Border::JustBefore(n), Border::AfterMax) => {
+                            [Border::JustBefore(n), Border::AfterMax] => {
                                 Some(IntRange { range: n..=u128::MAX, ty, span })
                             }
-                            (Border::AfterMax, _) => None,
+                            [Border::AfterMax, _] => None,
                         })
                         .map(IntRange),
                 );

compiler/rustc_parse/src/lib.rs

@@ -3,7 +3,6 @@
 #![feature(bool_to_option)]
 #![feature(crate_visibility_modifier)]
 #![feature(bindings_after_at)]
-#![feature(try_blocks)]
 #![feature(or_patterns)]
 
 use rustc_ast as ast;

compiler/rustc_parse_format/src/lib.rs

@@ -11,8 +11,6 @@
 )]
 #![feature(nll)]
 #![feature(or_patterns)]
-#![feature(rustc_private)]
-#![feature(unicode_internals)]
 #![feature(bool_to_option)]
 
 pub use Alignment::*;

compiler/rustc_privacy/src/lib.rs

@@ -1,7 +1,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
-#![feature(or_patterns)]
 #![recursion_limit = "256"]
 
 use rustc_attr as attr;

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1418,9 +1418,9 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                         if snippet.starts_with('&') && !snippet.starts_with("&'") {
                             introduce_suggestion
                                 .push((param.span, format!("&{} {}", lt_name, &snippet[1..])));
-                        } else if snippet.starts_with("&'_ ") {
+                        } else if let Some(stripped) = snippet.strip_prefix("&'_ ") {
                             introduce_suggestion
-                                .push((param.span, format!("&{} {}", lt_name, &snippet[4..])));
+                                .push((param.span, format!("&{} {}", lt_name, stripped)));
                         }
                     }
                 }