Auto merge of #80867 - JohnTitor:rollup-tvqw555, r=JohnTitor

Rollup of 9 pull requests

Successful merges:

 - #79502 (Implement From<char> for u64 and u128.)
 - #79968 (Improve core::ptr::drop_in_place debuginfo)
 - #80774 (Fix safety comment)
 - #80801 (Use correct span for structured suggestion)
 - #80803 (Remove useless `fill_in` function)
 - #80820 (Support `download-ci-llvm` on NixOS)
 - #80825 (Remove under-used ImplPolarity enum)
 - #80850 (Allow #[rustc_builtin_macro = "name"])
 - #80857 (Add comment to `Vec::truncate` explaining `>` vs `>=`)

Failed merges:

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

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)),
                     }),