Rollup of 9 pull requests

compiler/rustc_builtin_macros/src/lib.rs

@@ -48,7 +48,7 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand, edition: Editi
     let mut register = |name, kind| {
         resolver.register_builtin_macro(
             Ident::with_dummy_span(name),
-            SyntaxExtension { is_builtin: true, ..SyntaxExtension::default(kind, edition) },
+            SyntaxExtension::default(kind, edition),
         )
     };
     macro register_bang($($name:ident: $f:expr,)*) {

compiler/rustc_expand/src/base.rs

@@ -728,9 +728,7 @@ pub struct SyntaxExtension {
     pub edition: Edition,
     /// Built-in macros have a couple of special properties like availability
     /// in `#[no_implicit_prelude]` modules, so we have to keep this flag.
-    pub is_builtin: bool,
-    /// We have to identify macros providing a `Copy` impl early for compatibility reasons.
-    pub is_derive_copy: bool,
+    pub builtin_name: Option<Symbol>,
 }
 
 impl SyntaxExtension {
@@ -758,8 +756,7 @@ impl SyntaxExtension {
             deprecation: None,
             helper_attrs: Vec::new(),
             edition,
-            is_builtin: false,
-            is_derive_copy: false,
+            builtin_name: None,
             kind,
         }
     }
@@ -785,7 +782,9 @@ impl SyntaxExtension {
             }
         }
 
-        let is_builtin = sess.contains_name(attrs, sym::rustc_builtin_macro);
+        let builtin_name = sess
+            .find_by_name(attrs, sym::rustc_builtin_macro)
+            .map(|a| a.value_str().unwrap_or(name));
         let (stability, const_stability) = attr::find_stability(&sess, attrs, span);
         if const_stability.is_some() {
             sess.parse_sess
@@ -803,8 +802,7 @@ impl SyntaxExtension {
             deprecation: attr::find_deprecation(&sess, attrs).map(|(d, _)| d),
             helper_attrs,
             edition,
-            is_builtin,
-            is_derive_copy: is_builtin && name == sym::Copy,
+            builtin_name,
         }
     }
 

compiler/rustc_feature/src/builtin_attrs.rs

@@ -442,7 +442,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // Internal attributes, Macro related:
     // ==========================================================================
 
-    rustc_attr!(rustc_builtin_macro, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_builtin_macro, AssumedUsed, template!(Word, NameValueStr: "name"), IMPL_DETAIL),
     rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), INTERNAL_UNSTABLE),
     rustc_attr!(
         rustc_macro_transparency, AssumedUsed,

compiler/rustc_resolve/src/diagnostics.rs

@@ -398,20 +398,30 @@ impl<'a> Resolver<'a> {
                 err.help("use the `|| { ... }` closure form instead");
                 err
             }
-            ResolutionError::AttemptToUseNonConstantValueInConstant(ident, sugg) => {
+            ResolutionError::AttemptToUseNonConstantValueInConstant(ident, sugg, current) => {
                 let mut err = struct_span_err!(
                     self.session,
                     span,
                     E0435,
                     "attempt to use a non-constant value in a constant"
                 );
-                err.span_suggestion(
-                    ident.span,
-                    &sugg,
-                    "".to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-                err.span_label(span, "non-constant value");
+                // let foo =...
+                //     ^^^ given this Span
+                // ------- get this Span to have an applicable suggestion
+                let sp =
+                    self.session.source_map().span_extend_to_prev_str(ident.span, current, true);
+                if sp.lo().0 == 0 {
+                    err.span_label(ident.span, &format!("this would need to be a `{}`", sugg));
+                } else {
+                    let sp = sp.with_lo(BytePos(sp.lo().0 - current.len() as u32));
+                    err.span_suggestion(
+                        sp,
+                        &format!("consider using `{}` instead of `{}`", sugg, current),
+                        format!("{} {}", sugg, ident),
+                        Applicability::MaybeIncorrect,
+                    );
+                    err.span_label(span, "non-constant value");
+                }
                 err
             }
             ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {

compiler/rustc_resolve/src/lib.rs

@@ -210,7 +210,11 @@ enum ResolutionError<'a> {
     /// Error E0434: can't capture dynamic environment in a fn item.
     CannotCaptureDynamicEnvironmentInFnItem,
     /// Error E0435: attempt to use a non-constant value in a constant.
-    AttemptToUseNonConstantValueInConstant(Ident, String),
+    AttemptToUseNonConstantValueInConstant(
+        Ident,
+        /* suggestion */ &'static str,
+        /* current */ &'static str,
+    ),
     /// Error E0530: `X` bindings cannot shadow `Y`s.
     BindingShadowsSomethingUnacceptable(&'static str, Symbol, &'a NameBinding<'a>),
     /// Error E0128: type parameters with a default cannot use forward-declared identifiers.
@@ -1443,7 +1447,7 @@ impl<'a> Resolver<'a> {
     }
 
     fn is_builtin_macro(&mut self, res: Res) -> bool {
-        self.get_macro(res).map_or(false, |ext| ext.is_builtin)
+        self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some())
     }
 
     fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
@@ -2010,7 +2014,7 @@ impl<'a> Resolver<'a> {
                 // The macro is a proc macro derive
                 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
                     let ext = self.get_macro_by_def_id(def_id);
-                    if !ext.is_builtin
+                    if ext.builtin_name.is_none()
                         && ext.macro_kind() == MacroKind::Derive
                         && parent.expansion.outer_expn_is_descendant_of(span.ctxt())
                     {
@@ -2614,18 +2618,19 @@ impl<'a> Resolver<'a> {
                                             ConstantItemKind::Const => "const",
                                             ConstantItemKind::Static => "static",
                                         };
-                                        let sugg = format!(
-                                            "consider using `let` instead of `{}`",
-                                            kind_str
-                                        );
-                                        (span, AttemptToUseNonConstantValueInConstant(ident, sugg))
+                                        (
+                                            span,
+                                            AttemptToUseNonConstantValueInConstant(
+                                                ident, "let", kind_str,
+                                            ),
+                                        )
                                     } else {
-                                        let sugg = "consider using `const` instead of `let`";
                                         (
                                             rib_ident.span,
                                             AttemptToUseNonConstantValueInConstant(
                                                 original_rib_ident_def,
-                                                sugg.to_string(),
+                                                "const",
+                                                "let",
                                             ),
                                         )
                                     };

compiler/rustc_resolve/src/macros.rs

@@ -285,7 +285,7 @@ impl<'a> ResolverExpand for Resolver<'a> {
                                 helper_attrs.extend(
                                     ext.helper_attrs.iter().map(|name| Ident::new(*name, span)),
                                 );
-                                if ext.is_derive_copy {
+                                if ext.builtin_name == Some(sym::Copy) {
                                     self.containers_deriving_copy.insert(invoc_id);
                                 }
                                 ext
@@ -1089,9 +1089,9 @@ impl<'a> Resolver<'a> {
             edition,
         );
 
-        if result.is_builtin {
+        if let Some(builtin_name) = result.builtin_name {
             // The macro was marked with `#[rustc_builtin_macro]`.
-            if let Some(builtin_macro) = self.builtin_macros.get_mut(&item.ident.name) {
+            if let Some(builtin_macro) = self.builtin_macros.get_mut(&builtin_name) {
                 // The macro is a built-in, replace its expander function
                 // while still taking everything else from the source code.
                 // If we already loaded this builtin macro, give a better error message than 'no such builtin macro'.

compiler/rustc_span/src/source_map.rs

@@ -671,7 +671,9 @@ impl SourceMap {
             let pat = pat.to_owned() + ws;
             if let Ok(prev_source) = self.span_to_prev_source(sp) {
                 let prev_source = prev_source.rsplit(&pat).next().unwrap_or("").trim_start();
-                if !prev_source.is_empty() && (!prev_source.contains('\n') || accept_newlines) {
+                if prev_source.is_empty() && sp.lo().0 != 0 {
+                    return sp.with_lo(BytePos(sp.lo().0 - 1));
+                } else if !prev_source.contains('\n') || accept_newlines {
                     return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32));
                 }
             }

compiler/rustc_symbol_mangling/src/legacy.rs

@@ -56,7 +56,15 @@ pub(super) fn mangle(
     let hash = get_symbol_hash(tcx, instance, instance_ty, instantiating_crate);
 
     let mut printer = SymbolPrinter { tcx, path: SymbolPath::new(), keep_within_component: false }
-        .print_def_path(def_id, &[])
+        .print_def_path(
+            def_id,
+            if let ty::InstanceDef::DropGlue(_, _) = instance.def {
+                // Add the name of the dropped type to the symbol name
+                &*instance.substs
+            } else {
+                &[]
+            },
+        )
         .unwrap();
 
     if let ty::InstanceDef::VtableShim(..) = instance.def {

library/alloc/src/vec/mod.rs

@@ -990,6 +990,9 @@ impl<T, A: Allocator> Vec<T, A> {
         //   such that no value will be dropped twice in case `drop_in_place`
         //   were to panic once (if it panics twice, the program aborts).
         unsafe {
+            // Note: It's intentional that this is `>` and not `>=`.
+            //       Changing it to `>=` has negative performance
+            //       implications in some cases. See #78884 for more.
             if len > self.len {
                 return;
             }

library/core/src/char/convert.rs

@@ -113,6 +113,48 @@ impl From<char> for u32 {
     }
 }
 
+#[stable(feature = "more_char_conversions", since = "1.51.0")]
+impl From<char> for u64 {
+    /// Converts a [`char`] into a [`u64`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::mem;
+    ///
+    /// let c = '👤';
+    /// let u = u64::from(c);
+    /// assert!(8 == mem::size_of_val(&u))
+    /// ```
+    #[inline]
+    fn from(c: char) -> Self {
+        // The char is casted to the value of the code point, then zero-extended to 64 bit.
+        // See [https://doc.rust-lang.org/reference/expressions/operator-expr.html#semantics]
+        c as u64
+    }
+}
+
+#[stable(feature = "more_char_conversions", since = "1.51.0")]
+impl From<char> for u128 {
+    /// Converts a [`char`] into a [`u128`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::mem;
+    ///
+    /// let c = '⚙';
+    /// let u = u128::from(c);
+    /// assert!(16 == mem::size_of_val(&u))
+    /// ```
+    #[inline]
+    fn from(c: char) -> Self {
+        // The char is casted to the value of the code point, then zero-extended to 128 bit.
+        // See [https://doc.rust-lang.org/reference/expressions/operator-expr.html#semantics]
+        c as u128
+    }
+}
+
 /// Maps a byte in 0x00..=0xFF to a `char` whose code point has the same value, in U+0000..=U+00FF.
 ///
 /// Unicode is designed such that this effectively decodes bytes

library/std/src/alloc.rs

@@ -166,8 +166,9 @@ impl System {
         match old_layout.size() {
             0 => self.alloc_impl(new_layout, zeroed),
 
-            // SAFETY: `new_size` is non-zero as `old_size` is greater than or equal to `new_size`
-            // as required by safety conditions. Other conditions must be upheld by the caller
+            // SAFETY: `new_size` is non-zero as `new_size` is greater than or equal to `old_size`
+            // as required by safety conditions and the `old_size == 0` case was handled in the
+            // previous match arm. Other conditions must be upheld by the caller
             old_size if old_layout.align() == new_layout.align() => unsafe {
                 let new_size = new_layout.size();
 

src/bootstrap/bootstrap.py

@@ -413,7 +413,7 @@ def download_stage0(self):
             lib_dir = "{}/lib".format(self.bin_root())
             for lib in os.listdir(lib_dir):
                 if lib.endswith(".so"):
-                    self.fix_bin_or_dylib("{}/{}".format(lib_dir, lib))
+                    self.fix_bin_or_dylib(os.path.join(lib_dir, lib), rpath_libz=True)
             with output(self.rustc_stamp()) as rust_stamp:
                 rust_stamp.write(self.date)
 
@@ -451,10 +451,15 @@ def download_stage0(self):
                 "{}/src/bootstrap/download-ci-llvm-stamp".format(top_level),
             ]).decode(sys.getdefaultencoding()).strip()
             llvm_assertions = self.get_toml('assertions', 'llvm') == 'true'
+            llvm_root = self.llvm_root()
+            llvm_lib = os.path.join(llvm_root, "lib")
             if self.program_out_of_date(self.llvm_stamp(), llvm_sha + str(llvm_assertions)):
                 self._download_ci_llvm(llvm_sha, llvm_assertions)
                 for binary in ["llvm-config", "FileCheck"]:
-                    self.fix_bin_or_dylib("{}/bin/{}".format(self.llvm_root(), binary))
+                    self.fix_bin_or_dylib(os.path.join(llvm_root, "bin", binary), rpath_libz=True)
+                for lib in os.listdir(llvm_lib):
+                    if lib.endswith(".so"):
+                        self.fix_bin_or_dylib(os.path.join(llvm_lib, lib), rpath_libz=True)
                 with output(self.llvm_stamp()) as llvm_stamp:
                     llvm_stamp.write(llvm_sha + str(llvm_assertions))
 
@@ -501,7 +506,7 @@ def _download_ci_llvm(self, llvm_sha, llvm_assertions):
                 match="rust-dev",
                 verbose=self.verbose)
 
-    def fix_bin_or_dylib(self, fname):
+    def fix_bin_or_dylib(self, fname, rpath_libz=False):
         """Modifies the interpreter section of 'fname' to fix the dynamic linker,
         or the RPATH section, to fix the dynamic library search path
 
@@ -571,20 +576,22 @@ def fix_bin_or_dylib(self, fname):
             self.nix_deps_dir = nix_deps_dir
 
         patchelf = "{}/patchelf/bin/patchelf".format(nix_deps_dir)
+        patchelf_args = []
 
-        if fname.endswith(".so"):
-            # Dynamic library, patch RPATH to point to system dependencies.
+        if rpath_libz:
+            # Patch RPATH to add `zlib` dependency that stems from LLVM
             dylib_deps = ["zlib"]
             rpath_entries = [
                 # Relative default, all binary and dynamic libraries we ship
                 # appear to have this (even when `../lib` is redundant).
                 "$ORIGIN/../lib",
             ] + ["{}/{}/lib".format(nix_deps_dir, dep) for dep in dylib_deps]
-            patchelf_args = ["--set-rpath", ":".join(rpath_entries)]
-        else:
+            patchelf_args += ["--set-rpath", ":".join(rpath_entries)]
+        if not fname.endswith(".so"):
+            # Finally, set the corret .interp for binaries
             bintools_dir = "{}/stdenv.cc.bintools".format(nix_deps_dir)
             with open("{}/nix-support/dynamic-linker".format(bintools_dir)) as dynamic_linker:
-                patchelf_args = ["--set-interpreter", dynamic_linker.read().rstrip()]
+                patchelf_args += ["--set-interpreter", dynamic_linker.read().rstrip()]
 
         try:
             subprocess.check_output([patchelf] + patchelf_args + [fname])

src/librustdoc/clean/auto_trait.rs

@@ -84,14 +84,14 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
                         new_generics
                     });
 
-                let polarity;
+                let negative_polarity;
                 let new_generics = match result {
                     AutoTraitResult::PositiveImpl(new_generics) => {
-                        polarity = None;
+                        negative_polarity = false;
                         new_generics
                     }
                     AutoTraitResult::NegativeImpl => {
-                        polarity = Some(ImplPolarity::Negative);
+                        negative_polarity = true;
 
                         // For negative impls, we use the generic params, but *not* the predicates,
                         // from the original type. Otherwise, the displayed impl appears to be a
@@ -130,7 +130,7 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
                         trait_: Some(trait_ref.clean(self.cx).get_trait_type().unwrap()),
                         for_: ty.clean(self.cx),
                         items: Vec::new(),
-                        polarity,
+                        negative_polarity,
                         synthetic: true,
                         blanket_impl: None,
                     }),

src/librustdoc/clean/blanket_impl.rs

@@ -131,7 +131,7 @@ impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
                             .in_definition_order()
                             .collect::<Vec<_>>()
                             .clean(self.cx),
-                        polarity: None,
+                        negative_polarity: false,
                         synthetic: false,
                         blanket_impl: Some(trait_ref.self_ty().clean(self.cx)),
                     }),

src/librustdoc/clean/inline.rs

@@ -428,7 +428,7 @@ crate fn build_impl(
             trait_,
             for_,
             items: trait_items,
-            polarity: Some(polarity.clean(cx)),
+            negative_polarity: polarity.clean(cx),
             synthetic: false,
             blanket_impl: None,
         }),
@@ -441,60 +441,51 @@ crate fn build_impl(
 
 fn build_module(cx: &DocContext<'_>, did: DefId, visited: &mut FxHashSet<DefId>) -> clean::Module {
     let mut items = Vec::new();
-    fill_in(cx, did, &mut items, visited);
-    return clean::Module { items, is_crate: false };
-
-    fn fill_in(
-        cx: &DocContext<'_>,
-        did: DefId,
-        items: &mut Vec<clean::Item>,
-        visited: &mut FxHashSet<DefId>,
-    ) {
-        // If we're re-exporting a re-export it may actually re-export something in
-        // two namespaces, so the target may be listed twice. Make sure we only
-        // visit each node at most once.
-        for &item in cx.tcx.item_children(did).iter() {
-            if item.vis == ty::Visibility::Public {
-                if let Some(def_id) = item.res.mod_def_id() {
-                    if did == def_id || !visited.insert(def_id) {
-                        continue;
-                    }
+
+    // If we're re-exporting a re-export it may actually re-export something in
+    // two namespaces, so the target may be listed twice. Make sure we only
+    // visit each node at most once.
+    for &item in cx.tcx.item_children(did).iter() {
+        if item.vis == ty::Visibility::Public {
+            if let Some(def_id) = item.res.mod_def_id() {
+                if did == def_id || !visited.insert(def_id) {
+                    continue;
                 }
-                if let Res::PrimTy(p) = item.res {
-                    // Primitive types can't be inlined so generate an import instead.
-                    items.push(clean::Item {
-                        name: None,
-                        attrs: clean::Attributes::default(),
-                        source: clean::Span::dummy(),
-                        def_id: DefId::local(CRATE_DEF_INDEX),
-                        visibility: clean::Public,
-                        kind: box clean::ImportItem(clean::Import::new_simple(
-                            item.ident.name,
-                            clean::ImportSource {
-                                path: clean::Path {
-                                    global: false,
-                                    res: item.res,
-                                    segments: vec![clean::PathSegment {
-                                        name: clean::PrimitiveType::from(p).as_sym(),
-                                        args: clean::GenericArgs::AngleBracketed {
-                                            args: Vec::new(),
-                                            bindings: Vec::new(),
-                                        },
-                                    }],
-                                },
-                                did: None,
+            }
+            if let Res::PrimTy(p) = item.res {
+                // Primitive types can't be inlined so generate an import instead.
+                items.push(clean::Item {
+                    name: None,
+                    attrs: clean::Attributes::default(),
+                    source: clean::Span::dummy(),
+                    def_id: DefId::local(CRATE_DEF_INDEX),
+                    visibility: clean::Public,
+                    kind: box clean::ImportItem(clean::Import::new_simple(
+                        item.ident.name,
+                        clean::ImportSource {
+                            path: clean::Path {
+                                global: false,
+                                res: item.res,
+                                segments: vec![clean::PathSegment {
+                                    name: clean::PrimitiveType::from(p).as_sym(),
+                                    args: clean::GenericArgs::AngleBracketed {
+                                        args: Vec::new(),
+                                        bindings: Vec::new(),
+                                    },
+                                }],
                             },
-                            true,
-                        )),
-                    });
-                } else if let Some(i) =
-                    try_inline(cx, did, item.res, item.ident.name, None, visited)
-                {
-                    items.extend(i)
-                }
+                            did: None,
+                        },
+                        true,
+                    )),
+                });
+            } else if let Some(i) = try_inline(cx, did, item.res, item.ident.name, None, visited) {
+                items.extend(i)
             }
         }
     }
+
+    clean::Module { items, is_crate: false }
 }
 
 crate fn print_inlined_const(cx: &DocContext<'_>, did: DefId) -> String {

src/librustdoc/clean/mod.rs

@@ -2069,13 +2069,14 @@ impl Clean<Item> for hir::Variant<'_> {
     }
 }
 
-impl Clean<ImplPolarity> for ty::ImplPolarity {
-    fn clean(&self, _: &DocContext<'_>) -> ImplPolarity {
+impl Clean<bool> for ty::ImplPolarity {
+    /// Returns whether the impl has negative polarity.
+    fn clean(&self, _: &DocContext<'_>) -> bool {
         match self {
             &ty::ImplPolarity::Positive |
             // FIXME: do we want to do something else here?
-            &ty::ImplPolarity::Reservation => ImplPolarity::Positive,
-            &ty::ImplPolarity::Negative => ImplPolarity::Negative,
+            &ty::ImplPolarity::Reservation => false,
+            &ty::ImplPolarity::Negative => true,
         }
     }
 }
@@ -2116,7 +2117,7 @@ fn clean_impl(impl_: &hir::Item<'_>, cx: &DocContext<'_>) -> Vec<Item> {
             trait_,
             for_,
             items,
-            polarity: Some(cx.tcx.impl_polarity(def_id).clean(cx)),
+            negative_polarity: cx.tcx.impl_polarity(def_id).clean(cx),
             synthetic: false,
             blanket_impl: None,
         });

src/librustdoc/clean/types.rs

@@ -175,9 +175,11 @@ impl Item {
     }
 
     crate fn is_crate(&self) -> bool {
-        matches!(*self.kind,
+        matches!(
+            *self.kind,
             StrippedItem(box ModuleItem(Module { is_crate: true, .. }))
-            | ModuleItem(Module { is_crate: true, .. }))
+                | ModuleItem(Module { is_crate: true, .. })
+        )
     }
     crate fn is_mod(&self) -> bool {
         self.type_() == ItemType::Module
@@ -1226,6 +1228,7 @@ crate enum Type {
     BareFunction(Box<BareFunctionDecl>),
     Tuple(Vec<Type>),
     Slice(Box<Type>),
+    /// The `String` field is about the size or the constant representing the array's length.
     Array(Box<Type>, String),
     Never,
     RawPointer(Mutability, Box<Type>),
@@ -1857,12 +1860,6 @@ crate struct Constant {
     crate is_literal: bool,
 }
 
-#[derive(Clone, PartialEq, Debug)]
-crate enum ImplPolarity {
-    Positive,
-    Negative,
-}
-
 #[derive(Clone, Debug)]
 crate struct Impl {
     crate unsafety: hir::Unsafety,
@@ -1871,7 +1868,7 @@ crate struct Impl {
     crate trait_: Option<Type>,
     crate for_: Type,
     crate items: Vec<Item>,
-    crate polarity: Option<ImplPolarity>,
+    crate negative_polarity: bool,
     crate synthetic: bool,
     crate blanket_impl: Option<Type>,
 }

src/librustdoc/html/format.rs

@@ -870,7 +870,7 @@ impl clean::Impl {
             }
 
             if let Some(ref ty) = self.trait_ {
-                if self.polarity == Some(clean::ImplPolarity::Negative) {
+                if self.negative_polarity {
                     write!(f, "!")?;
                 }
 

src/librustdoc/html/render/mod.rs

@@ -4327,16 +4327,15 @@ fn sidebar_assoc_items(cx: &Context<'_>, it: &clean::Item) -> String {
 
                 let mut ret = impls
                     .iter()
-                    .filter_map(|i| {
-                        let is_negative_impl = is_negative_impl(i.inner_impl());
-                        if let Some(ref i) = i.inner_impl().trait_ {
+                    .filter_map(|it| {
+                        if let Some(ref i) = it.inner_impl().trait_ {
                             let i_display = format!("{:#}", i.print());
                             let out = Escape(&i_display);
                             let encoded = small_url_encode(&format!("{:#}", i.print()));
                             let generated = format!(
                                 "<a href=\"#impl-{}\">{}{}</a>",
                                 encoded,
-                                if is_negative_impl { "!" } else { "" },
+                                if it.inner_impl().negative_polarity { "!" } else { "" },
                                 out
                             );
                             if links.insert(generated.clone()) { Some(generated) } else { None }
@@ -4503,10 +4502,6 @@ fn extract_for_impl_name(item: &clean::Item) -> Option<(String, String)> {
     }
 }
 
-fn is_negative_impl(i: &clean::Impl) -> bool {
-    i.polarity == Some(clean::ImplPolarity::Negative)
-}
-
 fn sidebar_trait(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item, t: &clean::Trait) {
     let mut sidebar = String::new();
 

src/librustdoc/json/conversions.rs

@@ -422,7 +422,7 @@ impl From<clean::Impl> for Impl {
             trait_,
             for_,
             items,
-            polarity,
+            negative_polarity,
             synthetic,
             blanket_impl,
         } = impl_;
@@ -436,7 +436,7 @@ impl From<clean::Impl> for Impl {
             trait_: trait_.map(Into::into),
             for_: for_.into(),
             items: ids(items),
-            negative: polarity == Some(clean::ImplPolarity::Negative),
+            negative: negative_polarity,
             synthetic,
             blanket_impl: blanket_impl.map(Into::into),
         }

src/librustdoc/theme.rs

@@ -70,7 +70,10 @@ impl Events {
     }
 
     fn is_comment(&self) -> bool {
-        matches!(self, Events::StartLineComment(_) | Events::StartComment(_) | Events::EndComment(_))
+        matches!(
+            self,
+            Events::StartLineComment(_) | Events::StartComment(_) | Events::EndComment(_)
+        )
     }
 }
 

src/test/ui/error-codes/E0435.fixed

@@ -0,0 +1,6 @@
+// run-rustfix
+fn main () {
+    #[allow(non_upper_case_globals)]
+    const foo: usize = 42;
+    let _: [u8; foo]; //~ ERROR E0435
+}

src/test/ui/error-codes/E0435.rs

@@ -1,4 +1,6 @@
+// run-rustfix
 fn main () {
-    let foo = 42u32;
+    #[allow(non_upper_case_globals)]
+    let foo: usize = 42;
     let _: [u8; foo]; //~ ERROR E0435
 }

src/test/ui/error-codes/E0435.stderr

@@ -1,8 +1,8 @@
 error[E0435]: attempt to use a non-constant value in a constant
-  --> $DIR/E0435.rs:3:17
+  --> $DIR/E0435.rs:5:17
    |
-LL |     let foo = 42u32;
-   |         --- help: consider using `const` instead of `let`
+LL |     let foo: usize = 42;
+   |     ------- help: consider using `const` instead of `let`: `const foo`
 LL |     let _: [u8; foo];
    |                 ^^^ non-constant value
 

src/test/ui/impl-trait/bindings.stderr

@@ -2,33 +2,33 @@ error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/bindings.rs:5:29
    |
 LL |     const foo: impl Clone = x;
-   |           ---               ^ non-constant value
-   |           |
-   |           help: consider using `let` instead of `const`
+   |     ---------               ^ non-constant value
+   |     |
+   |     help: consider using `let` instead of `const`: `let foo`
 
 error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/bindings.rs:11:33
    |
 LL |         const foo: impl Clone = x;
-   |               ---               ^ non-constant value
-   |               |
-   |               help: consider using `let` instead of `const`
+   |         ---------               ^ non-constant value
+   |         |
+   |         help: consider using `let` instead of `const`: `let foo`
 
 error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/bindings.rs:18:33
    |
 LL |         const foo: impl Clone = x;
-   |               ---               ^ non-constant value
-   |               |
-   |               help: consider using `let` instead of `const`
+   |         ---------               ^ non-constant value
+   |         |
+   |         help: consider using `let` instead of `const`: `let foo`
 
 error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/bindings.rs:25:33
    |
 LL |         const foo: impl Clone = x;
-   |               ---               ^ non-constant value
-   |               |
-   |               help: consider using `let` instead of `const`
+   |         ---------               ^ non-constant value
+   |         |
+   |         help: consider using `let` instead of `const`: `let foo`
 
 warning: the feature `impl_trait_in_bindings` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/bindings.rs:1:12

src/test/ui/issues/issue-27433.fixed

@@ -0,0 +1,7 @@
+// run-rustfix
+fn main() {
+    let foo = 42u32;
+    #[allow(unused_variables, non_snake_case)]
+    let FOO : u32 = foo;
+                   //~^ ERROR attempt to use a non-constant value in a constant
+}

src/test/ui/issues/issue-27433.rs

@@ -1,5 +1,7 @@
+// run-rustfix
 fn main() {
     let foo = 42u32;
+    #[allow(unused_variables, non_snake_case)]
     const FOO : u32 = foo;
                    //~^ ERROR attempt to use a non-constant value in a constant
 }

src/test/ui/issues/issue-27433.stderr

@@ -1,10 +1,10 @@
 error[E0435]: attempt to use a non-constant value in a constant
-  --> $DIR/issue-27433.rs:3:23
+  --> $DIR/issue-27433.rs:5:23
    |
 LL |     const FOO : u32 = foo;
-   |           ---         ^^^ non-constant value
-   |           |
-   |           help: consider using `let` instead of `const`
+   |     ---------         ^^^ non-constant value
+   |     |
+   |     help: consider using `let` instead of `const`: `let FOO`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-3521-2.fixed

@@ -0,0 +1,9 @@
+// run-rustfix
+fn main() {
+    let foo = 100;
+
+    let y: isize = foo + 1;
+    //~^ ERROR attempt to use a non-constant value in a constant
+
+    println!("{}", y);
+}

src/test/ui/issues/issue-3521-2.rs

@@ -1,3 +1,4 @@
+// run-rustfix
 fn main() {
     let foo = 100;
 

src/test/ui/issues/issue-3521-2.stderr

@@ -1,10 +1,10 @@
 error[E0435]: attempt to use a non-constant value in a constant
-  --> $DIR/issue-3521-2.rs:4:23
+  --> $DIR/issue-3521-2.rs:5:23
    |
 LL |     static y: isize = foo + 1;
-   |            -          ^^^ non-constant value
-   |            |
-   |            help: consider using `let` instead of `static`
+   |     --------          ^^^ non-constant value
+   |     |
+   |     help: consider using `let` instead of `static`: `let y`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-3521.fixed

@@ -0,0 +1,13 @@
+// run-rustfix
+fn main() {
+    #[allow(non_upper_case_globals)]
+    const foo: isize = 100;
+
+    #[derive(Debug)]
+    enum Stuff {
+        Bar = foo
+        //~^ ERROR attempt to use a non-constant value in a constant
+    }
+
+    println!("{:?}", Stuff::Bar);
+}

src/test/ui/issues/issue-3521.rs

@@ -1,5 +1,7 @@
+// run-rustfix
 fn main() {
-    let foo = 100;
+    #[allow(non_upper_case_globals)]
+    let foo: isize = 100;
 
     #[derive(Debug)]
     enum Stuff {

src/test/ui/issues/issue-3521.stderr

@@ -1,8 +1,8 @@
 error[E0435]: attempt to use a non-constant value in a constant
-  --> $DIR/issue-3521.rs:6:15
+  --> $DIR/issue-3521.rs:8:15
    |
-LL |     let foo = 100;
-   |         --- help: consider using `const` instead of `let`
+LL |     let foo: isize = 100;
+   |     ------- help: consider using `const` instead of `let`: `const foo`
 ...
 LL |         Bar = foo
    |               ^^^ non-constant value

src/test/ui/issues/issue-3668-2.fixed

@@ -0,0 +1,8 @@
+// run-rustfix
+#![allow(unused_variables, dead_code)]
+fn f(x:isize) {
+    let child: isize = x + 1;
+    //~^ ERROR attempt to use a non-constant value in a constant
+}
+
+fn main() {}

src/test/ui/issues/issue-3668-2.rs

@@ -1,3 +1,5 @@
+// run-rustfix
+#![allow(unused_variables, dead_code)]
 fn f(x:isize) {
     static child: isize = x + 1;
     //~^ ERROR attempt to use a non-constant value in a constant

src/test/ui/issues/issue-3668-2.stderr

@@ -1,10 +1,10 @@
 error[E0435]: attempt to use a non-constant value in a constant
-  --> $DIR/issue-3668-2.rs:2:27
+  --> $DIR/issue-3668-2.rs:4:27
    |
 LL |     static child: isize = x + 1;
-   |            -----          ^ non-constant value
-   |            |
-   |            help: consider using `let` instead of `static`
+   |     ------------          ^ non-constant value
+   |     |
+   |     help: consider using `let` instead of `static`: `let child`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-3668.stderr

@@ -2,9 +2,9 @@ error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/issue-3668.rs:8:34
    |
 LL |        static childVal: Box<P> = self.child.get();
-   |               --------           ^^^^ non-constant value
-   |               |
-   |               help: consider using `let` instead of `static`
+   |        ---------------           ^^^^ non-constant value
+   |        |
+   |        help: consider using `let` instead of `static`: `let childVal`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-42060.stderr

@@ -2,15 +2,15 @@ error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/issue-42060.rs:3:23
    |
 LL |     let thing = ();
-   |         ----- help: consider using `const` instead of `let`
+   |     --------- help: consider using `const` instead of `let`: `const thing`
 LL |     let other: typeof(thing) = thing;
    |                       ^^^^^ non-constant value
 
 error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/issue-42060.rs:9:13
    |
 LL |     let q = 1;
-   |         - help: consider using `const` instead of `let`
+   |     ----- help: consider using `const` instead of `let`: `const q`
 LL |     <typeof(q)>::N
    |             ^ non-constant value
 

src/test/ui/issues/issue-44239.fixed

@@ -0,0 +1,11 @@
+// run-rustfix
+#![allow(dead_code, non_upper_case_globals)]
+fn main() {
+    const n: usize = 0;
+
+    struct Foo;
+    impl Foo {
+        const N: usize = n;
+        //~^ ERROR attempt to use a non-constant value
+    }
+}

src/test/ui/issues/issue-44239.rs

@@ -1,5 +1,7 @@
+// run-rustfix
+#![allow(dead_code, non_upper_case_globals)]
 fn main() {
-    let n = 0;
+    let n: usize = 0;
 
     struct Foo;
     impl Foo {

src/test/ui/issues/issue-44239.stderr

@@ -1,8 +1,8 @@
 error[E0435]: attempt to use a non-constant value in a constant
-  --> $DIR/issue-44239.rs:6:26
+  --> $DIR/issue-44239.rs:8:26
    |
-LL |     let n = 0;
-   |         - help: consider using `const` instead of `let`
+LL |     let n: usize = 0;
+   |     ----- help: consider using `const` instead of `let`: `const n`
 ...
 LL |         const N: usize = n;
    |                          ^ non-constant value

src/test/ui/non-constant-expr-for-arr-len.stderr

@@ -2,9 +2,9 @@ error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/non-constant-expr-for-arr-len.rs:5:22
    |
 LL |     fn bar(n: usize) {
-   |            - help: consider using `const` instead of `let`
+   |            - this would need to be a `const`
 LL |         let _x = [0; n];
-   |                      ^ non-constant value
+   |                      ^
 
 error: aborting due to previous error
 

src/test/ui/repeat_count.stderr

@@ -2,7 +2,7 @@ error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/repeat_count.rs:5:17
    |
 LL |     let n = 1;
-   |         - help: consider using `const` instead of `let`
+   |     ----- help: consider using `const` instead of `let`: `const n`
 LL |     let a = [0; n];
    |                 ^ non-constant value
 

src/test/ui/type/type-dependent-def-issue-49241.stderr

@@ -2,9 +2,9 @@ error[E0435]: attempt to use a non-constant value in a constant
   --> $DIR/type-dependent-def-issue-49241.rs:3:22
    |
 LL |     const l: usize = v.count();
-   |           -          ^ non-constant value
-   |           |
-   |           help: consider using `let` instead of `const`
+   |     -------          ^ non-constant value
+   |     |
+   |     help: consider using `let` instead of `const`: `let l`
 
 error: aborting due to previous error