Rollup of 12 pull requests

src/doc/unstable-book/src/language-features/slice-patterns.md

@@ -1,8 +1,8 @@
 # `slice_patterns`
 
-The tracking issue for this feature is: [#23121]
+The tracking issue for this feature is: [#62254]
 
-[#23121]: https://github.com/rust-lang/rust/issues/23121
+[#62254]: https://github.com/rust-lang/rust/issues/62254
 
 ------------------------
 

src/liballoc/boxed.rs

@@ -367,23 +367,35 @@ impl<T: Clone> Clone for Box<T> {
     /// ```
     /// let x = Box::new(5);
     /// let y = x.clone();
+    ///
+    /// // The value is the same
+    /// assert_eq!(x, y);
+    ///
+    /// // But they are unique objects
+    /// assert_ne!(&*x as *const i32, &*y as *const i32);
     /// ```
     #[rustfmt::skip]
     #[inline]
     fn clone(&self) -> Box<T> {
         box { (**self).clone() }
     }
+
     /// Copies `source`'s contents into `self` without creating a new allocation.
     ///
     /// # Examples
     ///
     /// ```
     /// let x = Box::new(5);
     /// let mut y = Box::new(10);
+    /// let yp: *const i32 = &*y;
     ///
     /// y.clone_from(&x);
     ///
-    /// assert_eq!(*y, 5);
+    /// // The value is the same
+    /// assert_eq!(x, y);
+    ///
+    /// // And no allocation occurred
+    /// assert_eq!(yp, &*y);
     /// ```
     #[inline]
     fn clone_from(&mut self, source: &Box<T>) {

src/libcore/convert.rs

@@ -251,12 +251,12 @@ pub trait AsMut<T: ?Sized> {
 ///
 /// # Examples
 ///
-/// [`String`] implements `Into<Vec<u8>>`:
+/// [`String`] implements [`Into`]`<`[`Vec`]`<`[`u8`]`>>`:
 ///
 /// In order to express that we want a generic function to take all arguments that can be
 /// converted to a specified type `T`, we can use a trait bound of [`Into`]`<T>`.
 /// For example: The function `is_hello` takes all arguments that can be converted into a
-/// `Vec<u8>`.
+/// [`Vec`]`<`[`u8`]`>`.
 ///
 /// ```
 /// fn is_hello<T: Into<Vec<u8>>>(s: T) {
@@ -274,6 +274,7 @@ pub trait AsMut<T: ?Sized> {
 /// [`String`]: ../../std/string/struct.String.html
 /// [`From`]: trait.From.html
 /// [`Into`]: trait.Into.html
+/// [`Vec`]: ../../std/vec/struct.Vec.html
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Into<T>: Sized {
     /// Performs the conversion.
@@ -410,12 +411,12 @@ pub trait TryInto<T>: Sized {
 ///
 /// This is useful when you are doing a type conversion that may
 /// trivially succeed but may also need special handling.
-/// For example, there is no way to convert an `i64` into an `i32`
-/// using the [`From`] trait, because an `i64` may contain a value
-/// that an `i32` cannot represent and so the conversion would lose data.
-/// This might be handled by truncating the `i64` to an `i32` (essentially
-/// giving the `i64`'s value modulo `i32::MAX`) or by simply returning
-/// `i32::MAX`, or by some other method.  The `From` trait is intended
+/// For example, there is no way to convert an [`i64`] into an [`i32`]
+/// using the [`From`] trait, because an [`i64`] may contain a value
+/// that an [`i32`] cannot represent and so the conversion would lose data.
+/// This might be handled by truncating the [`i64`] to an [`i32`] (essentially
+/// giving the [`i64`]'s value modulo [`i32::MAX`]) or by simply returning
+/// [`i32::MAX`], or by some other method.  The [`From`] trait is intended
 /// for perfect conversions, so the `TryFrom` trait informs the
 /// programmer when a type conversion could go bad and lets them
 /// decide how to handle it.
@@ -425,8 +426,8 @@ pub trait TryInto<T>: Sized {
 /// - `TryFrom<T> for U` implies [`TryInto`]`<U> for T`
 /// - [`try_from`] is reflexive, which means that `TryFrom<T> for T`
 /// is implemented and cannot fail -- the associated `Error` type for
-/// calling `T::try_from()` on a value of type `T` is `Infallible`.
-/// When the `!` type is stablized `Infallible` and `!` will be
+/// calling `T::try_from()` on a value of type `T` is [`Infallible`].
+/// When the [`!`] type is stablized [`Infallible`] and [`!`] will be
 /// equivalent.
 ///
 /// `TryFrom<T>` can be implemented as follows:
@@ -451,7 +452,7 @@ pub trait TryInto<T>: Sized {
 ///
 /// # Examples
 ///
-/// As described, [`i32`] implements `TryFrom<i64>`:
+/// As described, [`i32`] implements `TryFrom<`[`i64`]`>`:
 ///
 /// ```
 /// use std::convert::TryFrom;
@@ -474,6 +475,8 @@ pub trait TryInto<T>: Sized {
 ///
 /// [`try_from`]: trait.TryFrom.html#tymethod.try_from
 /// [`TryInto`]: trait.TryInto.html
+/// [`i32::MAX`]: ../../std/i32/constant.MAX.html
+/// [`!`]: ../../std/primitive.never.html
 #[stable(feature = "try_from", since = "1.34.0")]
 pub trait TryFrom<T>: Sized {
     /// The type returned in the event of a conversion error.

src/libcore/lib.rs

@@ -74,6 +74,7 @@
 #![feature(concat_idents)]
 #![feature(const_fn)]
 #![feature(const_fn_union)]
+#![feature(custom_inner_attributes)]
 #![feature(doc_cfg)]
 #![feature(doc_spotlight)]
 #![feature(extern_types)]

src/libcore/mem/mod.rs

@@ -552,6 +552,12 @@ pub fn swap<T>(x: &mut T, y: &mut T) {
 ///         mem::take(&mut self.buf)
 ///     }
 /// }
+///
+/// let mut buffer = Buffer { buf: vec![0, 1] };
+/// assert_eq!(buffer.buf.len(), 2);
+///
+/// assert_eq!(buffer.get_and_reset(), vec![0, 1]);
+/// assert_eq!(buffer.buf.len(), 0);
 /// ```
 ///
 /// [`Clone`]: ../../std/clone/trait.Clone.html
@@ -586,17 +592,17 @@ pub fn take<T: Default>(dest: &mut T) -> T {
 /// struct Buffer<T> { buf: Vec<T> }
 ///
 /// impl<T> Buffer<T> {
-///     fn get_and_reset(&mut self) -> Vec<T> {
+///     fn replace_index(&mut self, i: usize, v: T) -> T {
 ///         // error: cannot move out of dereference of `&mut`-pointer
-///         let buf = self.buf;
-///         self.buf = Vec::new();
-///         buf
+///         let t = self.buf[i];
+///         self.buf[i] = v;
+///         t
 ///     }
 /// }
 /// ```
 ///
-/// Note that `T` does not necessarily implement [`Clone`], so it can't even clone and reset
-/// `self.buf`. But `replace` can be used to disassociate the original value of `self.buf` from
+/// Note that `T` does not necessarily implement [`Clone`], so we can't even clone `self.buf[i]` to
+/// avoid the move. But `replace` can be used to disassociate the original value at that index from
 /// `self`, allowing it to be returned:
 ///
 /// ```
@@ -605,10 +611,16 @@ pub fn take<T: Default>(dest: &mut T) -> T {
 ///
 /// # struct Buffer<T> { buf: Vec<T> }
 /// impl<T> Buffer<T> {
-///     fn get_and_reset(&mut self) -> Vec<T> {
-///         mem::replace(&mut self.buf, Vec::new())
+///     fn replace_index(&mut self, i: usize, v: T) -> T {
+///         mem::replace(&mut self.buf[i], v)
 ///     }
 /// }
+///
+/// let mut buffer = Buffer { buf: vec![0, 1] };
+/// assert_eq!(buffer.buf[0], 0);
+///
+/// assert_eq!(buffer.replace_index(0, 2), 0);
+/// assert_eq!(buffer.buf[0], 2);
 /// ```
 ///
 /// [`Clone`]: ../../std/clone/trait.Clone.html

src/librustc_codegen_ssa/back/link.rs

@@ -653,10 +653,14 @@ fn link_natively<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
             linker_error.emit();
 
             if sess.target.target.options.is_like_msvc && linker_not_found {
-                sess.note_without_error("the msvc targets depend on the msvc linker \
-                    but `link.exe` was not found");
-                sess.note_without_error("please ensure that VS 2013, VS 2015 or VS 2017 \
-                    was installed with the Visual C++ option");
+                sess.note_without_error(
+                    "the msvc targets depend on the msvc linker \
+                     but `link.exe` was not found",
+                );
+                sess.note_without_error(
+                    "please ensure that VS 2013, VS 2015, VS 2017 or VS 2019 \
+                     was installed with the Visual C++ option",
+                );
             }
             sess.abort_if_errors();
         }

src/librustc_interface/util.rs

@@ -642,14 +642,14 @@ pub fn build_output_filenames(
                 );
                 None
             } else {
+                if !sess.opts.cg.extra_filename.is_empty() {
+                    sess.warn("ignoring -C extra-filename flag due to -o flag");
+                }
                 Some(out_file.clone())
             };
             if *odir != None {
                 sess.warn("ignoring --out-dir flag due to -o flag");
             }
-            if !sess.opts.cg.extra_filename.is_empty() {
-                sess.warn("ignoring -C extra-filename flag due to -o flag");
-            }
 
             OutputFilenames {
                 out_directory: out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),

src/librustc_mir/interpret/cast.rs

@@ -1,7 +1,7 @@
 use rustc::ty::{self, Ty, TypeAndMut};
 use rustc::ty::layout::{self, TyLayout, Size};
 use rustc::ty::adjustment::{PointerCast};
-use syntax::ast::{FloatTy, IntTy, UintTy};
+use syntax::ast::FloatTy;
 use syntax::symbol::sym;
 
 use rustc_apfloat::ieee::{Single, Double};
@@ -151,7 +151,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
                     "Unexpected cast from type {:?}", src_layout.ty
                 );
                 match val.to_bits_or_ptr(src_layout.size, self) {
-                    Err(ptr) => self.cast_from_ptr(ptr, dest_layout.ty),
+                    Err(ptr) => self.cast_from_ptr(ptr, src_layout, dest_layout),
                     Ok(data) => self.cast_from_int(data, src_layout, dest_layout),
                 }
             }
@@ -239,17 +239,25 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
     fn cast_from_ptr(
         &self,
         ptr: Pointer<M::PointerTag>,
-        ty: Ty<'tcx>
+        src_layout: TyLayout<'tcx>,
+        dest_layout: TyLayout<'tcx>,
     ) -> InterpResult<'tcx, Scalar<M::PointerTag>> {
         use rustc::ty::TyKind::*;
-        match ty.sty {
+
+        match dest_layout.ty.sty {
             // Casting to a reference or fn pointer is not permitted by rustc,
             // no need to support it here.
-            RawPtr(_) |
-            Int(IntTy::Isize) |
-            Uint(UintTy::Usize) => Ok(ptr.into()),
-            Int(_) | Uint(_) => err!(ReadPointerAsBytes),
-            _ => err!(Unimplemented(format!("ptr to {:?} cast", ty))),
+            RawPtr(_) => Ok(ptr.into()),
+            Int(_) | Uint(_) => {
+                let size = self.memory.pointer_size();
+
+                match self.force_bits(Scalar::Ptr(ptr), size) {
+                    Ok(bits) => self.cast_from_int(bits, src_layout, dest_layout),
+                    Err(_) if dest_layout.size == size => Ok(ptr.into()),
+                    Err(e) => Err(e),
+                }
+            }
+            _ => bug!("invalid MIR: ptr to {:?} cast", dest_layout.ty)
         }
     }
 

src/librustc_plugin/registry.rs

@@ -6,7 +6,7 @@ use rustc::util::nodemap::FxHashMap;
 
 use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind, NamedSyntaxExtension};
 use syntax::ext::base::MacroExpanderFn;
-use syntax::symbol::{Symbol, sym};
+use syntax::symbol::Symbol;
 use syntax::ast;
 use syntax::feature_gate::AttributeType;
 use syntax_pos::Span;
@@ -85,9 +85,6 @@ impl<'a> Registry<'a> {
     ///
     /// This is the most general hook into `libsyntax`'s expansion behavior.
     pub fn register_syntax_extension(&mut self, name: ast::Name, mut extension: SyntaxExtension) {
-        if name == sym::macro_rules {
-            panic!("user-defined macros may not be named `macro_rules`");
-        }
         if extension.def_info.is_none() {
             extension.def_info = Some((ast::CRATE_NODE_ID, self.krate_span));
         }

src/librustc_resolve/macros.rs

@@ -19,9 +19,8 @@ use syntax::ext::base::{MacroKind, SyntaxExtension};
 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind};
 use syntax::ext::hygiene::Mark;
 use syntax::ext::tt::macro_rules;
-use syntax::feature_gate::{
-    feature_err, is_builtin_attr_name, AttributeGate, GateIssue, Stability, BUILTIN_ATTRIBUTES,
-};
+use syntax::feature_gate::{feature_err, emit_feature_err, is_builtin_attr_name};
+use syntax::feature_gate::{AttributeGate, GateIssue, Stability, BUILTIN_ATTRIBUTES};
 use syntax::symbol::{Symbol, kw, sym};
 use syntax::visit::Visitor;
 use syntax::util::lev_distance::find_best_match_for_name;
@@ -298,12 +297,25 @@ impl<'a> Resolver<'a> {
         let res = self.resolve_macro_to_res_inner(path, kind, parent_scope, trace, force);
 
         // Report errors and enforce feature gates for the resolved macro.
+        let features = self.session.features_untracked();
         if res != Err(Determinacy::Undetermined) {
             // Do not report duplicated errors on every undetermined resolution.
             for segment in &path.segments {
                 if let Some(args) = &segment.args {
                     self.session.span_err(args.span(), "generic arguments in macro path");
                 }
+                if kind == MacroKind::Attr && !features.rustc_attrs &&
+                   segment.ident.as_str().starts_with("rustc") {
+                    let msg = "attributes starting with `rustc` are \
+                               reserved for use by the `rustc` compiler";
+                    emit_feature_err(
+                        &self.session.parse_sess,
+                        sym::rustc_attrs,
+                        segment.ident.span,
+                        GateIssue::Language,
+                        msg,
+                    );
+                }
             }
         }
 
@@ -320,24 +332,15 @@ impl<'a> Resolver<'a> {
             }
             Res::NonMacroAttr(attr_kind) => {
                 if kind == MacroKind::Attr {
-                    let features = self.session.features_untracked();
                     if attr_kind == NonMacroAttrKind::Custom {
                         assert!(path.segments.len() == 1);
-                        let name = path.segments[0].ident.as_str();
-                        if name.starts_with("rustc_") {
-                            if !features.rustc_attrs {
-                                let msg = "unless otherwise specified, attributes with the prefix \
-                                           `rustc_` are reserved for internal compiler diagnostics";
-                                self.report_unknown_attribute(path.span, &name, msg,
-                                                              sym::rustc_attrs);
-                            }
-                        } else if !features.custom_attribute {
+                        if !features.custom_attribute {
                             let msg = format!("The attribute `{}` is currently unknown to the \
                                                compiler and may have meaning added to it in the \
                                                future", path);
                             self.report_unknown_attribute(
                                 path.span,
-                                &name,
+                                &path.segments[0].ident.as_str(),
                                 &msg,
                                 sym::custom_attribute,
                             );
@@ -1109,9 +1112,6 @@ impl<'a> Resolver<'a> {
                         current_legacy_scope: &mut LegacyScope<'a>) {
         self.local_macro_def_scopes.insert(item.id, self.current_module);
         let ident = item.ident;
-        if ident.name == sym::macro_rules {
-            self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
-        }
 
         let def_id = self.definitions.local_def_id(item.id);
         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,

src/librustc_target/spec/windows_msvc_base.rs

@@ -19,6 +19,10 @@ pub fn opts() -> TargetOptions {
         target_family: Some("windows".to_string()),
         is_like_windows: true,
         is_like_msvc: true,
+        // set VSLANG to 1033 can prevent link.exe from using
+        // language packs, and avoid generating Non-UTF-8 error
+        // messages if a link error occurred.
+        link_env: vec![("VSLANG".to_string(), "1033".to_string())],
         pre_link_args: args,
         crt_static_allows_dylibs: true,
         crt_static_respected: true,

src/librustc_typeck/check/_match.rs

@@ -458,7 +458,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 match ty.sty {
                                     ty::Array(..) | ty::Slice(..) => {
                                         err.help("the semantics of slice patterns changed \
-                                                  recently; see issue #23121");
+                                                  recently; see issue #62254");
                                     }
                                     _ => {}
                                 }