Auto merge of #104325 - GuillaumeGomez:rollup-19bzwoa, r=GuillaumeGomez

Rollup of 8 pull requests

Successful merges:

 - #104110 (prevent uninitialized access in black_box for zero-sized-types)
 - #104117 (Mark `trait_upcasting` feature no longer incomplete.)
 - #104144 (Suggest removing unnecessary `.` to use a floating point literal)
 - #104250 (Migrate no result page link color to CSS variables)
 - #104261 (More accurately report error when formal and expected signature types differ)
 - #104263 (Add a reference to ilog2 in leading_zeros integer docs)
 - #104308 (Remove the old `ValidAlign` name)
 - #104319 (Fix non clickable source link)

Failed merges:

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

Author: bors

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -340,17 +340,26 @@ impl<'ll, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'_, 'll, 'tcx> {
 
             sym::black_box => {
                 args[0].val.store(self, result);
-
+                let result_val_span = [result.llval];
                 // We need to "use" the argument in some way LLVM can't introspect, and on
                 // targets that support it we can typically leverage inline assembly to do
                 // this. LLVM's interpretation of inline assembly is that it's, well, a black
                 // box. This isn't the greatest implementation since it probably deoptimizes
                 // more than we want, but it's so far good enough.
+                //
+                // For zero-sized types, the location pointed to by the result may be
+                // uninitialized. Do not "use" the result in this case; instead just clobber
+                // the memory.
+                let (constraint, inputs): (&str, &[_]) = if result.layout.is_zst() {
+                    ("~{memory}", &[])
+                } else {
+                    ("r,~{memory}", &result_val_span)
+                };
                 crate::asm::inline_asm_call(
                     self,
                     "",
-                    "r,~{memory}",
-                    &[result.llval],
+                    constraint,
+                    inputs,
                     self.type_void(),
                     true,
                     false,

compiler/rustc_feature/src/active.rs

@@ -512,9 +512,9 @@ declare_features! (
     (active, thread_local, "1.0.0", Some(29594), None),
     /// Allows defining `trait X = A + B;` alias items.
     (active, trait_alias, "1.24.0", Some(41517), None),
-    /// Allows upcasting trait objects via supertraits.
-    /// Trait upcasting is casting, e.g., `dyn Foo -> dyn Bar` where `Foo: Bar`.
-    (incomplete, trait_upcasting, "1.56.0", Some(65991), None),
+    /// Allows dyn upcasting trait objects via supertraits.
+    /// Dyn upcasting is casting, e.g., `dyn Foo -> dyn Bar` where `Foo: Bar`.
+    (active, trait_upcasting, "1.56.0", Some(65991), None),
     /// Allows #[repr(transparent)] on unions (RFC 2645).
     (active, transparent_unions, "1.37.0", Some(60405), None),
     /// Allows inconsistent bounds in where clauses.

compiler/rustc_hir_typeck/src/demand.rs

@@ -30,6 +30,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
         error: Option<TypeError<'tcx>>,
     ) {
+        if expr_ty == expected {
+            return;
+        }
+
         self.annotate_expected_due_to_let_ty(err, expr, error);
 
         // Use `||` to give these suggestions a precedence
@@ -43,7 +47,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             || self.suggest_block_to_brackets_peeling_refs(err, expr, expr_ty, expected)
             || self.suggest_copied_or_cloned(err, expr, expr_ty, expected)
             || self.suggest_into(err, expr, expr_ty, expected)
-            || self.suggest_option_to_bool(err, expr, expr_ty, expected);
+            || self.suggest_option_to_bool(err, expr, expr_ty, expected)
+            || self.suggest_floating_point_literal(err, expr, expected);
 
         self.note_type_is_not_clone(err, expected, expr_ty, expr);
         self.note_need_for_fn_pointer(err, expected, expr_ty);

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -597,6 +597,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
         };
 
+        let mk_trace = |span, (formal_ty, expected_ty), provided_ty| {
+            let mismatched_ty = if expected_ty == provided_ty {
+                // If expected == provided, then we must have failed to sup
+                // the formal type. Avoid printing out "expected Ty, found Ty"
+                // in that case.
+                formal_ty
+            } else {
+                expected_ty
+            };
+            TypeTrace::types(&self.misc(span), true, mismatched_ty, provided_ty)
+        };
+
         // The algorithm here is inspired by levenshtein distance and longest common subsequence.
         // We'll try to detect 4 different types of mistakes:
         // - An extra parameter has been provided that doesn't satisfy *any* of the other inputs
@@ -661,10 +673,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // A tuple wrap suggestion actually occurs within,
                         // so don't do anything special here.
                         err = self.err_ctxt().report_and_explain_type_error(
-                            TypeTrace::types(
-                                &self.misc(*lo),
-                                true,
-                                formal_and_expected_inputs[mismatch_idx.into()].1,
+                            mk_trace(
+                                *lo,
+                                formal_and_expected_inputs[mismatch_idx.into()],
                                 provided_arg_tys[mismatch_idx.into()].0,
                             ),
                             terr,
@@ -748,9 +759,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         errors.drain_filter(|error| {
                 let Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(Some(e))) = error else { return false };
                 let (provided_ty, provided_span) = provided_arg_tys[*provided_idx];
-                let (expected_ty, _) = formal_and_expected_inputs[*expected_idx];
-                let cause = &self.misc(provided_span);
-                let trace = TypeTrace::types(cause, true, expected_ty, provided_ty);
+                let trace = mk_trace(provided_span, formal_and_expected_inputs[*expected_idx], provided_ty);
                 if !matches!(trace.cause.as_failure_code(*e), FailureCode::Error0308(_)) {
                     self.err_ctxt().report_and_explain_type_error(trace, *e).emit();
                     return true;
@@ -774,8 +783,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         {
             let (formal_ty, expected_ty) = formal_and_expected_inputs[*expected_idx];
             let (provided_ty, provided_arg_span) = provided_arg_tys[*provided_idx];
-            let cause = &self.misc(provided_arg_span);
-            let trace = TypeTrace::types(cause, true, expected_ty, provided_ty);
+            let trace = mk_trace(provided_arg_span, (formal_ty, expected_ty), provided_ty);
             let mut err = self.err_ctxt().report_and_explain_type_error(trace, *err);
             self.emit_coerce_suggestions(
                 &mut err,
@@ -847,8 +855,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     let (formal_ty, expected_ty) = formal_and_expected_inputs[expected_idx];
                     let (provided_ty, provided_span) = provided_arg_tys[provided_idx];
                     if let Compatibility::Incompatible(error) = compatibility {
-                        let cause = &self.misc(provided_span);
-                        let trace = TypeTrace::types(cause, true, expected_ty, provided_ty);
+                        let trace = mk_trace(provided_span, (formal_ty, expected_ty), provided_ty);
                         if let Some(e) = error {
                             self.err_ctxt().note_type_err(
                                 &mut err,

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -374,7 +374,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 let annotation_span = ty.span;
                                 err.span_suggestion(
                                     annotation_span.with_hi(annotation_span.lo()),
-                                    format!("alternatively, consider changing the type annotation"),
+                                    "alternatively, consider changing the type annotation",
                                     suggest_annotation,
                                     Applicability::MaybeIncorrect,
                                 );
@@ -1204,6 +1204,48 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self, err))]
+    pub(crate) fn suggest_floating_point_literal(
+        &self,
+        err: &mut Diagnostic,
+        expr: &hir::Expr<'_>,
+        expected_ty: Ty<'tcx>,
+    ) -> bool {
+        if !expected_ty.is_floating_point() {
+            return false;
+        }
+        match expr.kind {
+            ExprKind::Struct(QPath::LangItem(LangItem::Range, ..), [start, end], _) => {
+                err.span_suggestion_verbose(
+                    start.span.shrink_to_hi().with_hi(end.span.lo()),
+                    "remove the unnecessary `.` operator for a floating point literal",
+                    '.',
+                    Applicability::MaybeIncorrect,
+                );
+                true
+            }
+            ExprKind::Struct(QPath::LangItem(LangItem::RangeFrom, ..), [start], _) => {
+                err.span_suggestion_verbose(
+                    expr.span.with_lo(start.span.hi()),
+                    "remove the unnecessary `.` operator for a floating point literal",
+                    '.',
+                    Applicability::MaybeIncorrect,
+                );
+                true
+            }
+            ExprKind::Struct(QPath::LangItem(LangItem::RangeTo, ..), [end], _) => {
+                err.span_suggestion_verbose(
+                    expr.span.until(end.span),
+                    "remove the unnecessary `.` operator and add an integer part for a floating point literal",
+                    "0.",
+                    Applicability::MaybeIncorrect,
+                );
+                true
+            }
+            _ => false,
+        }
+    }
+
     fn is_loop(&self, id: hir::HirId) -> bool {
         let node = self.tcx.hir().get(id);
         matches!(node, Node::Expr(Expr { kind: ExprKind::Loop(..), .. }))

library/core/src/alloc/layout.rs

@@ -7,8 +7,8 @@
 use crate::cmp;
 use crate::error::Error;
 use crate::fmt;
-use crate::mem::{self, ValidAlign};
-use crate::ptr::NonNull;
+use crate::mem;
+use crate::ptr::{Alignment, NonNull};
 
 // While this function is used in one place and its implementation
 // could be inlined, the previous attempts to do so made rustc
@@ -46,7 +46,7 @@ pub struct Layout {
     //
     // (However, we do not analogously require `align >= sizeof(void*)`,
     //  even though that is *also* a requirement of `posix_memalign`.)
-    align: ValidAlign,
+    align: Alignment,
 }
 
 impl Layout {
@@ -71,11 +71,11 @@ impl Layout {
         }
 
         // SAFETY: just checked that align is a power of two.
-        Layout::from_size_valid_align(size, unsafe { ValidAlign::new_unchecked(align) })
+        Layout::from_size_alignment(size, unsafe { Alignment::new_unchecked(align) })
     }
 
     #[inline(always)]
-    const fn max_size_for_align(align: ValidAlign) -> usize {
+    const fn max_size_for_align(align: Alignment) -> usize {
         // (power-of-two implies align != 0.)
 
         // Rounded up size is:
@@ -95,7 +95,7 @@ impl Layout {
 
     /// Internal helper constructor to skip revalidating alignment validity.
     #[inline]
-    const fn from_size_valid_align(size: usize, align: ValidAlign) -> Result<Self, LayoutError> {
+    const fn from_size_alignment(size: usize, align: Alignment) -> Result<Self, LayoutError> {
         if size > Self::max_size_for_align(align) {
             return Err(LayoutError);
         }
@@ -117,7 +117,7 @@ impl Layout {
     #[rustc_allow_const_fn_unstable(ptr_alignment_type)]
     pub const unsafe fn from_size_align_unchecked(size: usize, align: usize) -> Self {
         // SAFETY: the caller is required to uphold the preconditions.
-        unsafe { Layout { size, align: ValidAlign::new_unchecked(align) } }
+        unsafe { Layout { size, align: Alignment::new_unchecked(align) } }
     }
 
     /// The minimum size in bytes for a memory block of this layout.
@@ -321,7 +321,7 @@ impl Layout {
         let alloc_size = padded_size.checked_mul(n).ok_or(LayoutError)?;
 
         // The safe constructor is called here to enforce the isize size limit.
-        Layout::from_size_valid_align(alloc_size, self.align).map(|layout| (layout, padded_size))
+        Layout::from_size_alignment(alloc_size, self.align).map(|layout| (layout, padded_size))
     }
 
     /// Creates a layout describing the record for `self` followed by
@@ -379,7 +379,7 @@ impl Layout {
         let new_size = offset.checked_add(next.size()).ok_or(LayoutError)?;
 
         // The safe constructor is called here to enforce the isize size limit.
-        let layout = Layout::from_size_valid_align(new_size, new_align)?;
+        let layout = Layout::from_size_alignment(new_size, new_align)?;
         Ok((layout, offset))
     }
 
@@ -400,7 +400,7 @@ impl Layout {
     pub fn repeat_packed(&self, n: usize) -> Result<Self, LayoutError> {
         let size = self.size().checked_mul(n).ok_or(LayoutError)?;
         // The safe constructor is called here to enforce the isize size limit.
-        Layout::from_size_valid_align(size, self.align)
+        Layout::from_size_alignment(size, self.align)
     }
 
     /// Creates a layout describing the record for `self` followed by
@@ -414,7 +414,7 @@ impl Layout {
     pub fn extend_packed(&self, next: Self) -> Result<Self, LayoutError> {
         let new_size = self.size().checked_add(next.size()).ok_or(LayoutError)?;
         // The safe constructor is called here to enforce the isize size limit.
-        Layout::from_size_valid_align(new_size, self.align)
+        Layout::from_size_alignment(new_size, self.align)
     }
 
     /// Creates a layout describing the record for a `[T; n]`.
@@ -425,10 +425,10 @@ impl Layout {
     #[inline]
     pub fn array<T>(n: usize) -> Result<Self, LayoutError> {
         // Reduce the amount of code we need to monomorphize per `T`.
-        return inner(mem::size_of::<T>(), ValidAlign::of::<T>(), n);
+        return inner(mem::size_of::<T>(), Alignment::of::<T>(), n);
 
         #[inline]
-        fn inner(element_size: usize, align: ValidAlign, n: usize) -> Result<Layout, LayoutError> {
+        fn inner(element_size: usize, align: Alignment, n: usize) -> Result<Layout, LayoutError> {
             // We need to check two things about the size:
             //  - That the total size won't overflow a `usize`, and
             //  - That the total size still fits in an `isize`.
@@ -443,7 +443,7 @@ impl Layout {
 
             // SAFETY: We just checked above that the `array_size` will not
             // exceed `isize::MAX` even when rounded up to the alignment.
-            // And `ValidAlign` guarantees it's a power of two.
+            // And `Alignment` guarantees it's a power of two.
             unsafe { Ok(Layout::from_size_align_unchecked(array_size, align.as_usize())) }
         }
     }

library/core/src/mem/mod.rs

@@ -21,11 +21,6 @@ mod maybe_uninit;
 #[stable(feature = "maybe_uninit", since = "1.36.0")]
 pub use maybe_uninit::MaybeUninit;
 
-// FIXME: This is left here for now to avoid complications around pending reverts.
-// Once <https://github.com/rust-lang/rust/issues/101899> is fully resolved,
-// this should be removed and the references in `alloc::Layout` updated.
-pub(crate) use ptr::Alignment as ValidAlign;
-
 mod transmutability;
 #[unstable(feature = "transmutability", issue = "99571")]
 pub use transmutability::{Assume, BikeshedIntrinsicFrom};

library/core/src/num/int_macros.rs

@@ -107,6 +107,9 @@ macro_rules! int_impl {
 
         /// Returns the number of leading zeros in the binary representation of `self`.
         ///
+        /// Depending on what you're doing with the value, you might also be interested in the
+        /// [`ilog2`] function which returns a consistent number, even if the type widens.
+        ///
         /// # Examples
         ///
         /// Basic usage:
@@ -116,6 +119,7 @@ macro_rules! int_impl {
         ///
         /// assert_eq!(n.leading_zeros(), 0);
         /// ```
+        #[doc = concat!("[`ilog2`]: ", stringify!($SelfT), "::ilog2")]
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \

library/core/src/num/uint_macros.rs

@@ -109,6 +109,9 @@ macro_rules! uint_impl {
 
         /// Returns the number of leading zeros in the binary representation of `self`.
         ///
+        /// Depending on what you're doing with the value, you might also be interested in the
+        /// [`ilog2`] function which returns a consistent number, even if the type widens.
+        ///
         /// # Examples
         ///
         /// Basic usage:
@@ -118,6 +121,7 @@ macro_rules! uint_impl {
         ///
         /// assert_eq!(n.leading_zeros(), 2);
         /// ```
+        #[doc = concat!("[`ilog2`]: ", stringify!($SelfT), "::ilog2")]
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \

src/librustdoc/html/static/css/rustdoc.css

@@ -183,8 +183,6 @@ h4.code-header {
 	font-weight: 600;
 	margin: 0;
 	padding: 0;
-	/* position notable traits in mobile mode within the header */
-	position: relative;
 }
 
 #crate-search,