Rollup of 12 pull requests

compiler/rustc_arena/src/lib.rs

@@ -16,6 +16,7 @@
 #![feature(maybe_uninit_slice)]
 #![feature(min_specialization)]
 #![feature(decl_macro)]
+#![feature(pointer_byte_offsets)]
 #![feature(rustc_attrs)]
 #![cfg_attr(test, feature(test))]
 #![feature(strict_provenance)]
@@ -211,7 +212,7 @@ impl<T> TypedArena<T> {
 
         unsafe {
             if mem::size_of::<T>() == 0 {
-                self.ptr.set((self.ptr.get() as *mut u8).wrapping_offset(1) as *mut T);
+                self.ptr.set(self.ptr.get().wrapping_byte_add(1));
                 let ptr = ptr::NonNull::<T>::dangling().as_ptr();
                 // Don't drop the object. This `write` is equivalent to `forget`.
                 ptr::write(ptr, object);

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -273,7 +273,8 @@ impl<'tcx> BorrowExplanation<'tcx> {
             _ => {}
         }
     }
-    pub(crate) fn add_lifetime_bound_suggestion_to_diagnostic(
+
+    fn add_lifetime_bound_suggestion_to_diagnostic(
         &self,
         err: &mut Diagnostic,
         category: &ConstraintCategory<'tcx>,

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1,3 +1,4 @@
+use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::Node;
 use rustc_middle::hir::map::Map;
@@ -12,12 +13,11 @@ use rustc_middle::{
 };
 use rustc_span::source_map::DesugaringKind;
 use rustc_span::symbol::{kw, Symbol};
-use rustc_span::{BytePos, Span};
+use rustc_span::{sym, BytePos, Span};
 
 use crate::diagnostics::BorrowedContentSource;
 use crate::MirBorrowckCtxt;
 use rustc_const_eval::util::collect_writes::FindAssignments;
-use rustc_errors::{Applicability, Diagnostic};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub(crate) enum AccessKind {
@@ -614,6 +614,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                             "trait `IndexMut` is required to modify indexed content, \
                                 but it is not implemented for `{ty}`",
                         ));
+                        self.suggest_map_index_mut_alternatives(ty, &mut err);
                     }
                     _ => (),
                 }
@@ -627,6 +628,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         self.buffer_error(err);
     }
 
+    fn suggest_map_index_mut_alternatives(
+        &self,
+        ty: Ty<'_>,
+        err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>,
+    ) {
+        let Some(adt) = ty.ty_adt_def() else { return };
+        let did = adt.did();
+        if self.infcx.tcx.is_diagnostic_item(sym::HashMap, did)
+            || self.infcx.tcx.is_diagnostic_item(sym::BTreeMap, did)
+        {
+            err.help(format!("to modify a `{ty}`, use `.get_mut()`, `.insert()` or the entry API"));
+        }
+    }
+
     /// User cannot make signature of a trait mutable without changing the
     /// trait. So we find if this error belongs to a trait and if so we move
     /// suggestion to the trait or disable it if it is out of scope of this crate

compiler/rustc_lint/src/context.rs

@@ -865,9 +865,14 @@ pub trait LintContext: Sized {
 
                     if let Some(positional_arg_to_replace) = position_sp_to_replace {
                         let name = if is_formatting_arg { named_arg_name + "$" } else { named_arg_name };
-
+                        let span_to_replace = if let Ok(positional_arg_content) =
+                            self.sess().source_map().span_to_snippet(positional_arg_to_replace) && positional_arg_content.starts_with(":") {
+                            positional_arg_to_replace.shrink_to_lo()
+                        } else {
+                            positional_arg_to_replace
+                        };
                         db.span_suggestion_verbose(
-                            positional_arg_to_replace,
+                            span_to_replace,
                             "use the named argument by name to avoid ambiguity",
                             name,
                             Applicability::MaybeIncorrect,

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -2180,7 +2180,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         err.emit()
     }
 
-    pub(crate) fn add_missing_lifetime_specifiers_label(
+    fn add_missing_lifetime_specifiers_label(
         &mut self,
         err: &mut Diagnostic,
         lifetime_refs: Vec<MissingLifetime>,

library/alloc/src/macros.rs

@@ -107,6 +107,8 @@ macro_rules! vec {
 /// format!("test");
 /// format!("hello {}", "world!");
 /// format!("x = {}, y = {y}", 10, y = 30);
+/// let (x, y) = (1, 2);
+/// format!("{x} + {y} = 3");
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]

library/alloc/src/vec/into_iter.rs

@@ -4,7 +4,6 @@ use crate::alloc::{Allocator, Global};
 use crate::raw_vec::RawVec;
 use core::array;
 use core::fmt;
-use core::intrinsics::arith_offset;
 use core::iter::{
     FusedIterator, InPlaceIterable, SourceIter, TrustedLen, TrustedRandomAccessNoCoerce,
 };
@@ -154,7 +153,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
             // purposefully don't use 'ptr.offset' because for
             // vectors with 0-size elements this would return the
             // same pointer.
-            self.ptr = unsafe { arith_offset(self.ptr as *const i8, 1) as *mut T };
+            self.ptr = self.ptr.wrapping_byte_add(1);
 
             // Make up a value of this ZST.
             Some(unsafe { mem::zeroed() })
@@ -184,7 +183,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
             // SAFETY: due to unchecked casts of unsigned amounts to signed offsets the wraparound
             // effectively results in unsigned pointers representing positions 0..usize::MAX,
             // which is valid for ZSTs.
-            self.ptr = unsafe { arith_offset(self.ptr as *const i8, step_size as isize) as *mut T }
+            self.ptr = self.ptr.wrapping_byte_add(step_size);
         } else {
             // SAFETY: the min() above ensures that step_size is in bounds
             self.ptr = unsafe { self.ptr.add(step_size) };
@@ -217,7 +216,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
                 return Err(unsafe { array::IntoIter::new_unchecked(raw_ary, 0..len) });
             }
 
-            self.ptr = unsafe { arith_offset(self.ptr as *const i8, N as isize) as *mut T };
+            self.ptr = self.ptr.wrapping_byte_add(N);
             // Safety: ditto
             return Ok(unsafe { MaybeUninit::array_assume_init(raw_ary) });
         }
@@ -267,7 +266,7 @@ impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
             None
         } else if mem::size_of::<T>() == 0 {
             // See above for why 'ptr.offset' isn't used
-            self.end = unsafe { arith_offset(self.end as *const i8, -1) as *mut T };
+            self.end = self.ptr.wrapping_byte_sub(1);
 
             // Make up a value of this ZST.
             Some(unsafe { mem::zeroed() })
@@ -283,9 +282,7 @@ impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
         let step_size = self.len().min(n);
         if mem::size_of::<T>() == 0 {
             // SAFETY: same as for advance_by()
-            self.end = unsafe {
-                arith_offset(self.end as *const i8, step_size.wrapping_neg() as isize) as *mut T
-            }
+            self.end = self.end.wrapping_byte_sub(step_size);
         } else {
             // SAFETY: same as for advance_by()
             self.end = unsafe { self.end.sub(step_size) };

library/alloc/src/vec/mod.rs

@@ -59,7 +59,7 @@ use core::cmp::Ordering;
 use core::convert::TryFrom;
 use core::fmt;
 use core::hash::{Hash, Hasher};
-use core::intrinsics::{arith_offset, assume};
+use core::intrinsics::assume;
 use core::iter;
 #[cfg(not(no_global_oom_handling))]
 use core::iter::FromIterator;
@@ -2678,7 +2678,7 @@ impl<T, A: Allocator> IntoIterator for Vec<T, A> {
             let alloc = ManuallyDrop::new(ptr::read(me.allocator()));
             let begin = me.as_mut_ptr();
             let end = if mem::size_of::<T>() == 0 {
-                arith_offset(begin as *const i8, me.len() as isize) as *const T
+                begin.wrapping_byte_add(me.len())
             } else {
                 begin.add(me.len()) as *const T
             };

library/core/src/iter/adapters/by_ref_sized.rs

@@ -1,4 +1,4 @@
-use crate::ops::Try;
+use crate::ops::{NeverShortCircuit, Try};
 
 /// Like `Iterator::by_ref`, but requiring `Sized` so it can forward generics.
 ///
@@ -8,36 +8,40 @@ use crate::ops::Try;
 #[derive(Debug)]
 pub struct ByRefSized<'a, I>(pub &'a mut I);
 
+// The following implementations use UFCS-style, rather than trusting autoderef,
+// to avoid accidentally calling the `&mut Iterator` implementations.
+
 #[unstable(feature = "std_internals", issue = "none")]
 impl<I: Iterator> Iterator for ByRefSized<'_, I> {
     type Item = I::Item;
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
-        self.0.next()
+        I::next(self.0)
     }
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        self.0.size_hint()
+        I::size_hint(self.0)
     }
 
     #[inline]
     fn advance_by(&mut self, n: usize) -> Result<(), usize> {
-        self.0.advance_by(n)
+        I::advance_by(self.0, n)
     }
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        self.0.nth(n)
+        I::nth(self.0, n)
     }
 
     #[inline]
     fn fold<B, F>(self, init: B, f: F) -> B
     where
         F: FnMut(B, Self::Item) -> B,
     {
-        self.0.fold(init, f)
+        // `fold` needs ownership, so this can't forward directly.
+        I::try_fold(self.0, init, NeverShortCircuit::wrap_mut_2(f)).0
     }
 
     #[inline]
@@ -46,33 +50,34 @@ impl<I: Iterator> Iterator for ByRefSized<'_, I> {
         F: FnMut(B, Self::Item) -> R,
         R: Try<Output = B>,
     {
-        self.0.try_fold(init, f)
+        I::try_fold(self.0, init, f)
     }
 }
 
 #[unstable(feature = "std_internals", issue = "none")]
 impl<I: DoubleEndedIterator> DoubleEndedIterator for ByRefSized<'_, I> {
     #[inline]
     fn next_back(&mut self) -> Option<Self::Item> {
-        self.0.next_back()
+        I::next_back(self.0)
     }
 
     #[inline]
     fn advance_back_by(&mut self, n: usize) -> Result<(), usize> {
-        self.0.advance_back_by(n)
+        I::advance_back_by(self.0, n)
     }
 
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
-        self.0.nth_back(n)
+        I::nth_back(self.0, n)
     }
 
     #[inline]
     fn rfold<B, F>(self, init: B, f: F) -> B
     where
         F: FnMut(B, Self::Item) -> B,
     {
-        self.0.rfold(init, f)
+        // `rfold` needs ownership, so this can't forward directly.
+        I::try_rfold(self.0, init, NeverShortCircuit::wrap_mut_2(f)).0
     }
 
     #[inline]
@@ -81,6 +86,6 @@ impl<I: DoubleEndedIterator> DoubleEndedIterator for ByRefSized<'_, I> {
         F: FnMut(B, Self::Item) -> R,
         R: Try<Output = B>,
     {
-        self.0.try_rfold(init, f)
+        I::try_rfold(self.0, init, f)
     }
 }

library/core/src/marker.rs

@@ -343,7 +343,7 @@ pub trait StructuralEq {
 /// If you try to implement `Copy` on a struct or enum containing non-`Copy` data, you will get
 /// the error [E0204].
 ///
-/// [E0204]: ../../error-index.html#E0204
+/// [E0204]: ../../error_codes/E0204.html
 ///
 /// ## When *should* my type be `Copy`?
 ///

library/core/src/ops/drop.rs

@@ -156,7 +156,7 @@ pub trait Drop {
     /// handled by the compiler, but when using unsafe code, can sometimes occur
     /// unintentionally, particularly when using [`ptr::drop_in_place`].
     ///
-    /// [E0040]: ../../error-index.html#E0040
+    /// [E0040]: ../../error_codes/E0040.html
     /// [`panic!`]: crate::panic!
     /// [`mem::drop`]: drop
     /// [`ptr::drop_in_place`]: crate::ptr::drop_in_place

library/core/src/ptr/const_ptr.rs

@@ -249,7 +249,7 @@ impl<T: ?Sized> *const T {
         let offset = dest_addr.wrapping_sub(self_addr);
 
         // This is the canonical desugarring of this operation
-        self.cast::<u8>().wrapping_offset(offset).cast::<T>()
+        self.wrapping_byte_offset(offset)
     }
 
     /// Creates a new pointer by mapping `self`'s address to a new one.

library/core/src/ptr/mut_ptr.rs

@@ -255,7 +255,7 @@ impl<T: ?Sized> *mut T {
         let offset = dest_addr.wrapping_sub(self_addr);
 
         // This is the canonical desugarring of this operation
-        self.cast::<u8>().wrapping_offset(offset).cast::<T>()
+        self.wrapping_byte_offset(offset)
     }
 
     /// Creates a new pointer by mapping `self`'s address to a new one.

library/core/src/slice/iter/macros.rs

@@ -64,7 +64,7 @@ macro_rules! iterator {
         // backwards by `n`. `n` must not exceed `self.len()`.
         macro_rules! zst_shrink {
             ($self: ident, $n: ident) => {
-                $self.end = ($self.end as * $raw_mut u8).wrapping_offset(-$n) as * $raw_mut T;
+                $self.end = $self.end.wrapping_byte_offset(-$n);
             }
         }
 

library/core/tests/atomic.rs

@@ -155,7 +155,7 @@ fn ptr_add_data() {
 
     assert_eq!(atom.fetch_ptr_sub(1, SeqCst), n.wrapping_add(1));
     assert_eq!(atom.load(SeqCst), n);
-    let bytes_from_n = |b| n.cast::<u8>().wrapping_add(b).cast::<i64>();
+    let bytes_from_n = |b| n.wrapping_byte_add(b);
 
     assert_eq!(atom.fetch_byte_add(1, SeqCst), n);
     assert_eq!(atom.load(SeqCst), bytes_from_n(1));

library/core/tests/iter/adapters/by_ref_sized.rs

@@ -0,0 +1,20 @@
+use core::iter::*;
+
+#[test]
+fn test_iterator_by_ref_sized() {
+    let a = ['a', 'b', 'c', 'd'];
+
+    let mut s = String::from("Z");
+    let mut it = a.iter().copied();
+    ByRefSized(&mut it).take(2).for_each(|x| s.push(x));
+    assert_eq!(s, "Zab");
+    ByRefSized(&mut it).fold((), |(), x| s.push(x));
+    assert_eq!(s, "Zabcd");
+
+    let mut s = String::from("Z");
+    let mut it = a.iter().copied();
+    ByRefSized(&mut it).rev().take(2).for_each(|x| s.push(x));
+    assert_eq!(s, "Zdc");
+    ByRefSized(&mut it).rfold((), |(), x| s.push(x));
+    assert_eq!(s, "Zdcba");
+}

library/core/tests/iter/adapters/mod.rs

@@ -1,4 +1,5 @@
 mod array_chunks;
+mod by_ref_sized;
 mod chain;
 mod cloned;
 mod copied;

library/core/tests/ptr.rs

@@ -650,7 +650,7 @@ fn thin_box() {
                     .unwrap_or_else(|| handle_alloc_error(layout))
                     .cast::<DynMetadata<T>>();
                 ptr.as_ptr().write(meta);
-                ptr.cast::<u8>().as_ptr().add(offset).cast::<Value>().write(value);
+                ptr.as_ptr().byte_add(offset).cast::<Value>().write(value);
                 Self { ptr, phantom: PhantomData }
             }
         }

library/std/src/io/error/repr_bitpacked.rs

@@ -269,10 +269,10 @@ where
         }
         TAG_SIMPLE_MESSAGE => ErrorData::SimpleMessage(&*ptr.cast::<SimpleMessage>().as_ptr()),
         TAG_CUSTOM => {
-            // It would be correct for us to use `ptr::sub` here (see the
+            // It would be correct for us to use `ptr::byte_sub` here (see the
             // comment above the `wrapping_add` call in `new_custom` for why),
             // but it isn't clear that it makes a difference, so we don't.
-            let custom = ptr.as_ptr().cast::<u8>().wrapping_sub(TAG_CUSTOM).cast::<Custom>();
+            let custom = ptr.as_ptr().wrapping_byte_sub(TAG_CUSTOM).cast::<Custom>();
             ErrorData::Custom(make_custom(custom))
         }
         _ => {

library/std/src/lib.rs

@@ -299,6 +299,7 @@
 #![feature(panic_can_unwind)]
 #![feature(panic_info_message)]
 #![feature(panic_internals)]
+#![feature(pointer_byte_offsets)]
 #![feature(pointer_is_aligned)]
 #![feature(portable_simd)]
 #![feature(prelude_2024)]