Auto merge of rust-lang#89608 - Manishearth:rollup-m7kd76f, r=Manishearth

Rollup of 12 pull requests

Successful merges:

 - rust-lang#87601 (Add functions to add unsigned and signed integers)
 - rust-lang#88523 (Expand documentation for `FpCategory`.)
 - rust-lang#89050 (refactor: VecDeques Drain fields to private)
 - rust-lang#89245 (refactor: make VecDeque's IterMut fields module-private, not just crate-private)
 - rust-lang#89324 (Rename `std::thread::available_conccurrency` to `std::thread::available_parallelism`)
 - rust-lang#89329 (print-type-sizes: skip field printing for primitives)
 - rust-lang#89501 (Note specific regions involved in 'borrowed data escapes' error)
 - rust-lang#89506 (librustdoc: Use correct heading levels.)
 - rust-lang#89528 (Fix suggestion to borrow when casting from pointer to reference)
 - rust-lang#89531 (library std, libc dependency update)
 - rust-lang#89588 (Add a test for generic_const_exprs)
 - rust-lang#89591 (fix: alloc-optimisation is only for rust llvm)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

Cargo.lock

@@ -1879,9 +1879,9 @@ checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
 
 [[package]]
 name = "libc"
-version = "0.2.99"
+version = "0.2.103"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7f823d141fe0a24df1e23b4af4e3c7ba9e5966ec514ea068c93024aa7deb765"
+checksum = "dd8f7255a17a627354f321ef0055d63b898c6fb27eff628af4d1b66b7331edf6"
 dependencies = [
  "rustc-std-workspace-core",
 ]

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -498,6 +498,27 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             diag.span_label(*span, format!("`{}` escapes the {} body here", fr_name, escapes_from));
         }
 
+        // Only show an extra note if we can find an 'error region' for both of the region
+        // variables. This avoids showing a noisy note that just mentions 'synthetic' regions
+        // that don't help the user understand the error.
+        if self.to_error_region(errci.fr).is_some()
+            && self.to_error_region(errci.outlived_fr).is_some()
+        {
+            let fr_region_name = self.give_region_a_name(errci.fr).unwrap();
+            fr_region_name.highlight_region_name(&mut diag);
+            let outlived_fr_region_name = self.give_region_a_name(errci.outlived_fr).unwrap();
+            outlived_fr_region_name.highlight_region_name(&mut diag);
+
+            diag.span_label(
+                *span,
+                format!(
+                    "{}requires that `{}` must outlive `{}`",
+                    category.description(),
+                    fr_region_name,
+                    outlived_fr_region_name,
+                ),
+            );
+        }
         diag
     }
 

compiler/rustc_middle/src/ty/layout.rs

@@ -1826,8 +1826,11 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
 
         match layout.variants {
             Variants::Single { index } => {
-                debug!("print-type-size `{:#?}` variant {}", layout, adt_def.variants[index].ident);
-                if !adt_def.variants.is_empty() {
+                if !adt_def.variants.is_empty() && layout.fields != FieldsShape::Primitive {
+                    debug!(
+                        "print-type-size `{:#?}` variant {}",
+                        layout, adt_def.variants[index].ident
+                    );
                     let variant_def = &adt_def.variants[index];
                     let fields: Vec<_> = variant_def.fields.iter().map(|f| f.ident.name).collect();
                     record(

compiler/rustc_typeck/src/check/cast.rs

@@ -351,7 +351,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                 );
                 let mut sugg = None;
                 let mut sugg_mutref = false;
-                if let ty::Ref(reg, _, mutbl) = *self.cast_ty.kind() {
+                if let ty::Ref(reg, cast_ty, mutbl) = *self.cast_ty.kind() {
                     if let ty::RawPtr(TypeAndMut { ty: expr_ty, .. }) = *self.expr_ty.kind() {
                         if fcx
                             .try_coerce(
@@ -366,7 +366,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                             )
                             .is_ok()
                         {
-                            sugg = Some(format!("&{}*", mutbl.prefix_str()));
+                            sugg = Some((format!("&{}*", mutbl.prefix_str()), cast_ty == expr_ty));
                         }
                     } else if let ty::Ref(expr_reg, expr_ty, expr_mutbl) = *self.expr_ty.kind() {
                         if expr_mutbl == Mutability::Not
@@ -400,7 +400,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                             )
                             .is_ok()
                     {
-                        sugg = Some(format!("&{}", mutbl.prefix_str()));
+                        sugg = Some((format!("&{}", mutbl.prefix_str()), false));
                     }
                 } else if let ty::RawPtr(TypeAndMut { mutbl, .. }) = *self.cast_ty.kind() {
                     if fcx
@@ -416,19 +416,47 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                         )
                         .is_ok()
                     {
-                        sugg = Some(format!("&{}", mutbl.prefix_str()));
+                        sugg = Some((format!("&{}", mutbl.prefix_str()), false));
                     }
                 }
                 if sugg_mutref {
                     err.span_label(self.span, "invalid cast");
                     err.span_note(self.expr.span, "this reference is immutable");
                     err.span_note(self.cast_span, "trying to cast to a mutable reference type");
-                } else if let Some(sugg) = sugg {
+                } else if let Some((sugg, remove_cast)) = sugg {
                     err.span_label(self.span, "invalid cast");
-                    err.span_suggestion_verbose(
-                        self.expr.span.shrink_to_lo(),
+
+                    let has_parens = fcx
+                        .tcx
+                        .sess
+                        .source_map()
+                        .span_to_snippet(self.expr.span)
+                        .map_or(false, |snip| snip.starts_with("("));
+
+                    // Very crude check to see whether the expression must be wrapped
+                    // in parentheses for the suggestion to work (issue #89497).
+                    // Can/should be extended in the future.
+                    let needs_parens = !has_parens
+                        && match self.expr.kind {
+                            hir::ExprKind::Cast(..) => true,
+                            _ => false,
+                        };
+
+                    let mut suggestion = vec![(self.expr.span.shrink_to_lo(), sugg)];
+                    if needs_parens {
+                        suggestion[0].1 += "(";
+                        suggestion.push((self.expr.span.shrink_to_hi(), ")".to_string()));
+                    }
+                    if remove_cast {
+                        suggestion.push((
+                            self.expr.span.shrink_to_hi().to(self.cast_span),
+                            String::new(),
+                        ));
+                    }
+
+                    err.multipart_suggestion_verbose(
                         "consider borrowing the value",
-                        sugg,
+                        suggestion,
                         Applicability::MachineApplicable,
                     );
                 } else if !matches!(

library/alloc/src/collections/vec_deque/drain.rs

@@ -18,10 +18,21 @@ pub struct Drain<
     T: 'a,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
 > {
-    pub(crate) after_tail: usize,
-    pub(crate) after_head: usize,
-    pub(crate) iter: Iter<'a, T>,
-    pub(crate) deque: NonNull<VecDeque<T, A>>,
+    after_tail: usize,
+    after_head: usize,
+    iter: Iter<'a, T>,
+    deque: NonNull<VecDeque<T, A>>,
+}
+
+impl<'a, T, A: Allocator> Drain<'a, T, A> {
+    pub(super) unsafe fn new(
+        after_tail: usize,
+        after_head: usize,
+        iter: Iter<'a, T>,
+        deque: NonNull<VecDeque<T, A>>,
+    ) -> Self {
+        Drain { after_tail, after_head, iter, deque }
+    }
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]

library/alloc/src/collections/vec_deque/iter_mut.rs

@@ -13,10 +13,21 @@ use super::{count, wrap_index, RingSlices};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct IterMut<'a, T: 'a> {
     // Internal safety invariant: the entire slice is dereferencable.
-    pub(crate) ring: *mut [T],
-    pub(crate) tail: usize,
-    pub(crate) head: usize,
-    pub(crate) phantom: PhantomData<&'a mut [T]>,
+    ring: *mut [T],
+    tail: usize,
+    head: usize,
+    phantom: PhantomData<&'a mut [T]>,
+}
+
+impl<'a, T> IterMut<'a, T> {
+    pub(super) unsafe fn new(
+        ring: *mut [T],
+        tail: usize,
+        head: usize,
+        phantom: PhantomData<&'a mut [T]>,
+    ) -> Self {
+        IterMut { ring, tail, head, phantom }
+    }
 }
 
 // SAFETY: we do nothing thread-local and there is no interior mutability,

library/alloc/src/collections/vec_deque/mod.rs

@@ -1000,12 +1000,9 @@ impl<T, A: Allocator> VecDeque<T, A> {
     pub fn iter_mut(&mut self) -> IterMut<'_, T> {
         // SAFETY: The internal `IterMut` safety invariant is established because the
         // `ring` we create is a dereferencable slice for lifetime '_.
-        IterMut {
-            tail: self.tail,
-            head: self.head,
-            ring: ptr::slice_from_raw_parts_mut(self.ptr(), self.cap()),
-            phantom: PhantomData,
-        }
+        let ring = ptr::slice_from_raw_parts_mut(self.ptr(), self.cap());
+
+        unsafe { IterMut::new(ring, self.tail, self.head, PhantomData) }
     }
 
     /// Returns a pair of slices which contain, in order, the contents of the
@@ -1192,12 +1189,9 @@ impl<T, A: Allocator> VecDeque<T, A> {
 
         // SAFETY: The internal `IterMut` safety invariant is established because the
         // `ring` we create is a dereferencable slice for lifetime '_.
-        IterMut {
-            tail,
-            head,
-            ring: ptr::slice_from_raw_parts_mut(self.ptr(), self.cap()),
-            phantom: PhantomData,
-        }
+        let ring = ptr::slice_from_raw_parts_mut(self.ptr(), self.cap());
+
+        unsafe { IterMut::new(ring, tail, head, PhantomData) }
     }
 
     /// Creates a draining iterator that removes the specified range in the
@@ -1269,19 +1263,17 @@ impl<T, A: Allocator> VecDeque<T, A> {
         // the drain is complete and the Drain destructor is run.
         self.head = drain_tail;
 
-        Drain {
-            deque: NonNull::from(&mut *self),
-            after_tail: drain_head,
-            after_head: head,
-            iter: Iter {
-                tail: drain_tail,
-                head: drain_head,
-                // Crucially, we only create shared references from `self` here and read from
-                // it.  We do not write to `self` nor reborrow to a mutable reference.
-                // Hence the raw pointer we created above, for `deque`, remains valid.
-                ring: unsafe { self.buffer_as_slice() },
-            },
-        }
+        let deque = NonNull::from(&mut *self);
+        let iter = Iter {
+            tail: drain_tail,
+            head: drain_head,
+            // Crucially, we only create shared references from `self` here and read from
+            // it.  We do not write to `self` nor reborrow to a mutable reference.
+            // Hence the raw pointer we created above, for `deque`, remains valid.
+            ring: unsafe { self.buffer_as_slice() },
+        };
+
+        unsafe { Drain::new(drain_head, head, iter, deque) }
     }
 
     /// Clears the `VecDeque`, removing all values.

library/core/src/lib.rs

@@ -142,6 +142,7 @@
 #![feature(link_llvm_intrinsics)]
 #![feature(llvm_asm)]
 #![feature(min_specialization)]
+#![feature(mixed_integer_ops)]
 #![cfg_attr(not(bootstrap), feature(must_not_suspend))]
 #![feature(negative_impls)]
 #![feature(never_type)]