Rollup of 11 pull requests

.azure-pipelines/steps/run.yml

@@ -74,8 +74,9 @@ steps:
 # images, etc.
 - bash: |
     set -e
+    source src/ci/shared.sh
     sudo apt-get install -y python3-setuptools
-    pip3 install awscli --upgrade --user
+    retry pip3 install awscli --upgrade --user
     echo "##vso[task.prependpath]$HOME/.local/bin"
   displayName: Install awscli (Linux)
   condition: and(succeeded(), eq(variables['Agent.OS'], 'Linux'))

README.md

@@ -130,9 +130,9 @@ build.
 
 MSVC builds of Rust additionally require an installation of Visual Studio 2017
 (or later) so `rustc` can use its linker.  The simplest way is to get the
-[Visual Studio Build Tools] and check the “C++ build tools” workload.
+[Visual Studio], check the “C++ build tools” and “Windows 10 SDK” workload.
 
-[Visual Studio Build Tools]: https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019
+[Visual Studio]: https://visualstudio.microsoft.com/downloads/
 
 (If you're installing cmake yourself, be careful that “C++ CMake tools for
 Windows” doesn't get included under “Individual components”.)

src/libcore/iter/traits/iterator.rs

@@ -1495,13 +1495,13 @@ pub trait Iterator {
         let mut left: B = Default::default();
         let mut right: B = Default::default();
 
-        for x in self {
+        self.for_each(|x| {
             if f(&x) {
                 left.extend(Some(x))
             } else {
                 right.extend(Some(x))
             }
-        }
+        });
 
         (left, right)
     }

src/libcore/slice/mod.rs

@@ -5420,7 +5420,7 @@ macro_rules! impl_marker_for {
 }
 
 impl_marker_for!(BytewiseEquality,
-                 u8 i8 u16 i16 u32 i32 u64 i64 usize isize char bool);
+                 u8 i8 u16 i16 u32 i32 u64 i64 u128 i128 usize isize char bool);
 
 #[doc(hidden)]
 unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {

src/libcore/str/mod.rs

@@ -4000,11 +4000,11 @@ impl str {
     /// # Examples
     ///
     /// ```
-    /// let mut s = String::from("Grüße, Jürgen ❤");
+    /// let mut s = String::from("GRÜßE, JÜRGEN ❤");
     ///
     /// s.make_ascii_lowercase();
     ///
-    /// assert_eq!("grüße, jürgen ❤", s);
+    /// assert_eq!("grÜße, jÜrgen ❤", s);
     /// ```
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     pub fn make_ascii_lowercase(&mut self) {

src/librustc/session/config.rs

@@ -227,13 +227,17 @@ impl OutputType {
     }
 }
 
+/// The type of diagnostics output to generate.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum ErrorOutputType {
+    /// Output meant for the consumption of humans.
     HumanReadable(HumanReadableErrorType),
+    /// Output that's consumed by other tools such as `rustfix` or the `RLS`.
     Json {
-        /// Render the json in a human readable way (with indents and newlines)
+        /// Render the JSON in a human readable way (with indents and newlines).
         pretty: bool,
-        /// The way the `rendered` field is created
+        /// The JSON output includes a `rendered` field that includes the rendered
+        /// human output.
         json_rendered: HumanReadableErrorType,
     },
 }

src/librustc_errors/diagnostic_builder.rs

@@ -348,7 +348,7 @@ impl<'a> DiagnosticBuilder<'a> {
 
     /// Convenience function for internal use, clients should use one of the
     /// struct_* methods on Handler.
-    pub fn new_with_code(handler: &'a Handler,
+    crate fn new_with_code(handler: &'a Handler,
                          level: Level,
                          code: Option<DiagnosticId>,
                          message: &str)

src/librustc_errors/emitter.rs

@@ -1,3 +1,12 @@
+//! The current rustc diagnostics emitter.
+//!
+//! An `Emitter` takes care of generating the output from a `DiagnosticBuilder` struct.
+//!
+//! There are various `Emitter` implementations that generate different output formats such as
+//! JSON and human readable output.
+//!
+//! The output types are defined in `librustc::session::config::ErrorOutputType`.
+
 use Destination::*;
 
 use syntax_pos::{SourceFile, Span, MultiSpan};

src/librustc_errors/lib.rs

@@ -1,5 +1,10 @@
+//! Diagnostics creation and emission for `rustc`.
+//!
+//! This module contains the code for creating and emitting diagnostics.
+
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
+#![feature(crate_visibility_modifier)]
 #![allow(unused_attributes)]
 #![cfg_attr(unix, feature(libc))]
 #![feature(nll)]

src/librustc_metadata/creader.rs

@@ -614,7 +614,7 @@ impl<'a> CrateLoader<'a> {
             match decl {
                 ProcMacro::CustomDerive { trait_name, attributes, client } => {
                     let attrs = attributes.iter().cloned().map(Symbol::intern).collect::<Vec<_>>();
-                    (trait_name, SyntaxExtension::ProcMacroDerive(
+                    (trait_name, SyntaxExtension::Derive(
                         Box::new(ProcMacroDerive {
                             client,
                             attrs: attrs.clone(),
@@ -624,13 +624,13 @@ impl<'a> CrateLoader<'a> {
                     ))
                 }
                 ProcMacro::Attr { name, client } => {
-                    (name, SyntaxExtension::AttrProcMacro(
+                    (name, SyntaxExtension::Attr(
                         Box::new(AttrProcMacro { client }),
                         root.edition,
                     ))
                 }
                 ProcMacro::Bang { name, client } => {
-                    (name, SyntaxExtension::ProcMacro {
+                    (name, SyntaxExtension::Bang {
                         expander: Box::new(BangProcMacro { client }),
                         allow_internal_unstable: None,
                         edition: root.edition,

src/librustc_metadata/cstore_impl.rs

@@ -430,7 +430,7 @@ impl cstore::CStore {
             use syntax_ext::proc_macro_impl::BangProcMacro;
 
             let client = proc_macro::bridge::client::Client::expand1(proc_macro::quote);
-            let ext = SyntaxExtension::ProcMacro {
+            let ext = SyntaxExtension::Bang {
                 expander: Box::new(BangProcMacro { client }),
                 allow_internal_unstable: Some(vec![sym::proc_macro_def_site].into()),
                 edition: data.root.edition,

src/librustc_mir/transform/qualify_min_const_fn.rs

@@ -299,7 +299,7 @@ fn check_terminator(
 
         TerminatorKind::FalseEdges { .. } | TerminatorKind::SwitchInt { .. } => Err((
             span,
-            "`if`, `match`, `&&` and `||` are not stable in const fn".into(),
+            "loops and conditional expressions are not stable in const fn".into(),
         )),
         | TerminatorKind::Abort | TerminatorKind::Unreachable => {
             Err((span, "const fn with unreachable code is not stable".into()))

src/librustc_plugin/registry.rs

@@ -4,8 +4,9 @@ use rustc::lint::{EarlyLintPassObject, LateLintPassObject, LintId, Lint};
 use rustc::session::Session;
 use rustc::util::nodemap::FxHashMap;
 
-use syntax::ext::base::{SyntaxExtension, NamedSyntaxExtension, NormalTT, IdentTT};
+use syntax::ext::base::{SyntaxExtension, NamedSyntaxExtension};
 use syntax::ext::base::MacroExpanderFn;
+use syntax::ext::hygiene::Transparency;
 use syntax::symbol::{Symbol, sym};
 use syntax::ast;
 use syntax::feature_gate::AttributeType;
@@ -84,47 +85,26 @@ impl<'a> Registry<'a> {
     /// Register a syntax extension of any kind.
     ///
     /// This is the most general hook into `libsyntax`'s expansion behavior.
-    pub fn register_syntax_extension(&mut self, name: ast::Name, extension: SyntaxExtension) {
+    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`");
         }
-        self.syntax_exts.push((name, match extension {
-            NormalTT {
-                expander,
-                def_info: _,
-                allow_internal_unstable,
-                allow_internal_unsafe,
-                local_inner_macros,
-                unstable_feature,
-                edition,
-            } => {
-                let nid = ast::CRATE_NODE_ID;
-                NormalTT {
-                    expander,
-                    def_info: Some((nid, self.krate_span)),
-                    allow_internal_unstable,
-                    allow_internal_unsafe,
-                    local_inner_macros,
-                    unstable_feature,
-                    edition,
-                }
-            }
-            IdentTT { expander, span: _, allow_internal_unstable } => {
-                IdentTT { expander, span: Some(self.krate_span), allow_internal_unstable }
-            }
-            _ => extension,
-        }));
+        if let SyntaxExtension::LegacyBang { def_info: ref mut def_info @ None, .. } = extension {
+            *def_info = Some((ast::CRATE_NODE_ID, self.krate_span));
+        }
+        self.syntax_exts.push((name, extension));
     }
 
     /// Register a macro of the usual kind.
     ///
     /// This is a convenience wrapper for `register_syntax_extension`.
-    /// It builds for you a `NormalTT` that calls `expander`,
+    /// It builds for you a `SyntaxExtension::LegacyBang` that calls `expander`,
     /// and also takes care of interning the macro's name.
     pub fn register_macro(&mut self, name: &str, expander: MacroExpanderFn) {
-        self.register_syntax_extension(Symbol::intern(name), NormalTT {
+        self.register_syntax_extension(Symbol::intern(name), SyntaxExtension::LegacyBang {
             expander: Box::new(expander),
             def_info: None,
+            transparency: Transparency::SemiTransparent,
             allow_internal_unstable: None,
             allow_internal_unsafe: false,
             local_inner_macros: false,

src/librustc_resolve/macros.rs

@@ -242,8 +242,7 @@ impl<'a> base::Resolver for Resolver<'a> {
     fn check_unused_macros(&self) {
         for did in self.unused_macros.iter() {
             let id_span = match *self.macro_map[did] {
-                SyntaxExtension::NormalTT { def_info, .. } |
-                SyntaxExtension::DeclMacro { def_info, .. } => def_info,
+                SyntaxExtension::LegacyBang { def_info, .. } => def_info,
                 _ => None,
             };
             if let Some((id, span)) = id_span {
@@ -587,7 +586,7 @@ impl<'a> Resolver<'a> {
                         match self.resolve_macro_to_res(derive, MacroKind::Derive,
                                                         &parent_scope, true, force) {
                             Ok((_, ext)) => {
-                                if let SyntaxExtension::ProcMacroDerive(_, helpers, _) = &*ext {
+                                if let SyntaxExtension::Derive(_, helpers, _) = &*ext {
                                     if helpers.contains(&ident.name) {
                                         let binding =
                                             (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),

src/librustc_typeck/astconv.rs

@@ -2155,6 +2155,17 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
         result_ty
     }
 
+    /// Returns the `DefId` of the constant parameter that the provided expression is a path to.
+    pub fn const_param_def_id(&self, expr: &hir::Expr) -> Option<DefId> {
+        match &expr.node {
+            ExprKind::Path(hir::QPath::Resolved(_, path)) => match path.res {
+                Res::Def(DefKind::ConstParam, did) => Some(did),
+                _ => None,
+            },
+            _ => None,
+        }
+    }
+
     pub fn ast_const_to_const(
         &self,
         ast_const: &hir::AnonConst,
@@ -2185,19 +2196,17 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
             }
         }
 
-        if let ExprKind::Path(ref qpath) = expr.node {
-            if let hir::QPath::Resolved(_, ref path) = qpath {
-                if let Res::Def(DefKind::ConstParam, def_id) = path.res {
-                    let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
-                    let item_id = tcx.hir().get_parent_node(node_id);
-                    let item_def_id = tcx.hir().local_def_id(item_id);
-                    let generics = tcx.generics_of(item_def_id);
-                    let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(node_id)];
-                    let name = tcx.hir().name(node_id).as_interned_str();
-                    const_.val = ConstValue::Param(ty::ParamConst::new(index, name));
-                }
-            }
-        };
+        if let Some(def_id) = self.const_param_def_id(expr) {
+            // Find the name and index of the const parameter by indexing the generics of the
+            // parent item and construct a `ParamConst`.
+            let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
+            let item_id = tcx.hir().get_parent_node(node_id);
+            let item_def_id = tcx.hir().local_def_id(item_id);
+            let generics = tcx.generics_of(item_def_id);
+            let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(node_id)];
+            let name = tcx.hir().name(node_id).as_interned_str();
+            const_.val = ConstValue::Param(ty::ParamConst::new(index, name));
+        }
 
         tcx.mk_const(const_)
     }

src/librustc_typeck/check/mod.rs

@@ -2504,6 +2504,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         ty
     }
 
+    /// Returns the `DefId` of the constant parameter that the provided expression is a path to.
+    pub fn const_param_def_id(&self, hir_c: &hir::AnonConst) -> Option<DefId> {
+        AstConv::const_param_def_id(self, &self.tcx.hir().body(hir_c.body).value)
+    }
+
     pub fn to_const(&self, ast_c: &hir::AnonConst, ty: Ty<'tcx>) -> &'tcx ty::Const<'tcx> {
         AstConv::ast_const_to_const(self, ast_c, ty)
     }
@@ -4479,19 +4484,24 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             }
             ExprKind::Repeat(ref element, ref count) => {
                 let count_def_id = tcx.hir().local_def_id_from_hir_id(count.hir_id);
-                let param_env = ty::ParamEnv::empty();
-                let substs = InternalSubsts::identity_for_item(tcx.global_tcx(), count_def_id);
-                let instance = ty::Instance::resolve(
-                    tcx.global_tcx(),
-                    param_env,
-                    count_def_id,
-                    substs,
-                ).unwrap();
-                let global_id = GlobalId {
-                    instance,
-                    promoted: None
+                let count = if self.const_param_def_id(count).is_some() {
+                    Ok(self.to_const(count, self.tcx.type_of(count_def_id)))
+                } else {
+                    let param_env = ty::ParamEnv::empty();
+                    let substs = InternalSubsts::identity_for_item(tcx.global_tcx(), count_def_id);
+                    let instance = ty::Instance::resolve(
+                        tcx.global_tcx(),
+                        param_env,
+                        count_def_id,
+                        substs,
+                    ).unwrap();
+                    let global_id = GlobalId {
+                        instance,
+                        promoted: None
+                    };
+
+                    tcx.const_eval(param_env.and(global_id))
                 };
-                let count = tcx.const_eval(param_env.and(global_id));
 
                 let uty = match expected {
                     ExpectHasType(uty) => {

src/librustdoc/clean/inline.rs

@@ -471,7 +471,7 @@ fn build_macro(cx: &DocContext<'_>, did: DefId, name: ast::Name) -> clean::ItemE
         }
         LoadedMacro::ProcMacro(ext) => {
             let helpers = match &*ext {
-                &SyntaxExtension::ProcMacroDerive(_, ref syms, ..) => { syms.clean(cx) }
+                &SyntaxExtension::Derive(_, ref syms, ..) => { syms.clean(cx) }
                 _ => Vec::new(),
             };
 

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -433,7 +433,7 @@ fn macro_resolve(cx: &DocContext<'_>, path_str: &str) -> Option<Res> {
             if let Res::Def(DefKind::Macro(MacroKind::ProcMacroStub), _) = res {
                 // skip proc-macro stubs, they'll cause `get_macro` to crash
             } else {
-                if let SyntaxExtension::DeclMacro { .. } = *resolver.get_macro(res) {
+                if let SyntaxExtension::LegacyBang { .. } = *resolver.get_macro(res) {
                     return Some(res.map_id(|_| panic!("unexpected id")));
                 }
             }

src/libstd/primitive_docs.rs

@@ -482,8 +482,8 @@ mod prim_pointer { }
 /// an array. Indeed, this provides most of the API for working with arrays.
 /// Slices have a dynamic size and do not coerce to arrays.
 ///
-/// There is no way to move elements out of an array. See [`mem::replace`][replace]
-/// for an alternative.
+/// You can move elements out of an array with a slice pattern. If you want
+/// one element, see [`mem::replace`][replace].
 ///
 /// # Examples
 ///
@@ -525,6 +525,16 @@ mod prim_pointer { }
 /// for x in &array { }
 /// ```
 ///
+/// You can use a slice pattern to move elements out of an array:
+///
+/// ```
+/// fn move_away(_: String) { /* Do interesting things. */ }
+///
+/// let [john, roa] = ["John".to_string(), "Roa".to_string()];
+/// move_away(john);
+/// move_away(roa);
+/// ```
+///
 /// [slice]: primitive.slice.html
 /// [copy]: marker/trait.Copy.html
 /// [clone]: clone/trait.Clone.html