Rollup of 14 pull requests

src/liballoc/collections/btree/map.rs

@@ -75,10 +75,10 @@ use Entry::*;
 ///
 /// // look up the values associated with some keys.
 /// let to_find = ["Up!", "Office Space"];
-/// for book in &to_find {
-///     match movie_reviews.get(book) {
-///        Some(review) => println!("{}: {}", book, review),
-///        None => println!("{} is unreviewed.", book)
+/// for movie in &to_find {
+///     match movie_reviews.get(movie) {
+///        Some(review) => println!("{}: {}", movie, review),
+///        None => println!("{} is unreviewed.", movie)
 ///     }
 /// }
 ///

src/liballoc/collections/btree/node.rs

@@ -106,8 +106,8 @@ impl<K, V> LeafNode<K, V> {
         LeafNode {
             // As a general policy, we leave fields uninitialized if they can be, as this should
             // be both slightly faster and easier to track in Valgrind.
-            keys: uninitialized_array![_; CAPACITY],
-            vals: uninitialized_array![_; CAPACITY],
+            keys: uninit_array![_; CAPACITY],
+            vals: uninit_array![_; CAPACITY],
             parent: ptr::null(),
             parent_idx: MaybeUninit::uninit(),
             len: 0
@@ -159,7 +159,7 @@ impl<K, V> InternalNode<K, V> {
     unsafe fn new() -> Self {
         InternalNode {
             data: LeafNode::new(),
-            edges: uninitialized_array![_; 2*B],
+            edges: uninit_array![_; 2*B],
         }
     }
 }

src/liballoc/lib.rs

@@ -77,13 +77,15 @@
 #![feature(box_syntax)]
 #![feature(cfg_target_has_atomic)]
 #![feature(coerce_unsized)]
+#![cfg_attr(not(bootstrap), feature(const_in_array_repeat_expressions))]
 #![feature(dispatch_from_dyn)]
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
 #![feature(exact_size_is_empty)]
 #![feature(fmt_internals)]
 #![feature(fn_traits)]
 #![feature(fundamental)]
+#![feature(internal_uninit_const)]
 #![feature(lang_items)]
 #![feature(libc)]
 #![feature(nll)]

src/libcore/fmt/float.rs

@@ -12,10 +12,11 @@ fn float_to_decimal_common_exact<T>(fmt: &mut Formatter<'_>, num: &T,
     unsafe {
         let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
         let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 4]>::uninit();
-        // FIXME(#53491): Technically, this is calling `get_mut` on an uninitialized
-        // `MaybeUninit` (here and elsewhere in this file).  Revisit this once
+        // FIXME(#53491): This is calling `get_mut` on an uninitialized
+        // `MaybeUninit` (here and elsewhere in this file). Revisit this once
         // we decided whether that is valid or not.
-        // Using `freeze` is *not enough*; `flt2dec::Part` is an enum!
+        // We can do this only because we are libstd and coupled to the compiler.
+        // (FWIW, using `freeze` would not be enough; `flt2dec::Part` is an enum!)
         let formatted = flt2dec::to_exact_fixed_str(flt2dec::strategy::grisu::format_exact,
                                                     *num, sign, precision,
                                                     false, buf.get_mut(), parts.get_mut());

src/libcore/fmt/num.rs

@@ -51,7 +51,7 @@ trait GenericRadix {
         // characters for a base 2 number.
         let zero = T::zero();
         let is_nonnegative = x >= zero;
-        let mut buf = uninitialized_array![u8; 128];
+        let mut buf = [MaybeUninit::<u8>::uninit(); 128];
         let mut curr = buf.len();
         let base = T::from_u8(Self::BASE);
         if is_nonnegative {
@@ -189,7 +189,7 @@ static DEC_DIGITS_LUT: &[u8; 200] =
 macro_rules! impl_Display {
     ($($t:ident),* as $u:ident via $conv_fn:ident named $name:ident) => {
         fn $name(mut n: $u, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-            let mut buf = uninitialized_array![u8; 39];
+            let mut buf = [MaybeUninit::<u8>::uninit(); 39];
             let mut curr = buf.len() as isize;
             let buf_ptr = MaybeUninit::first_ptr_mut(&mut buf);
             let lut_ptr = DEC_DIGITS_LUT.as_ptr();

src/libcore/macros.rs

@@ -626,20 +626,37 @@ macro_rules! todo {
 /// Creates an array of [`MaybeUninit`].
 ///
 /// This macro constructs an uninitialized array of the type `[MaybeUninit<K>; N]`.
+/// It exists solely because bootstrap does not yet support const array-init expressions.
 ///
 /// [`MaybeUninit`]: mem/union.MaybeUninit.html
+// FIXME: Remove both versions of this macro once bootstrap is 1.38.
 #[macro_export]
 #[unstable(feature = "maybe_uninit_array", issue = "53491")]
-macro_rules! uninitialized_array {
+#[cfg(bootstrap)]
+macro_rules! uninit_array {
     // This `assume_init` is safe because an array of `MaybeUninit` does not
     // require initialization.
-    // FIXME(#49147): Could be replaced by an array initializer, once those can
-    // be any const expression.
     ($t:ty; $size:expr) => (unsafe {
         MaybeUninit::<[MaybeUninit<$t>; $size]>::uninit().assume_init()
     });
 }
 
+/// Creates an array of [`MaybeUninit`].
+///
+/// This macro constructs an uninitialized array of the type `[MaybeUninit<K>; N]`.
+/// It exists solely because bootstrap does not yet support const array-init expressions.
+///
+/// [`MaybeUninit`]: mem/union.MaybeUninit.html
+// FIXME: Just inline this version of the macro once bootstrap is 1.38.
+#[macro_export]
+#[unstable(feature = "maybe_uninit_array", issue = "53491")]
+#[cfg(not(bootstrap))]
+macro_rules! uninit_array {
+    ($t:ty; $size:expr) => (
+        [MaybeUninit::<$t>::UNINIT; $size]
+    );
+}
+
 /// Built-in macros to the compiler itself.
 ///
 /// These macros do not have any corresponding definition with a `macro_rules!`

src/libcore/mem/maybe_uninit.rs

@@ -252,6 +252,11 @@ impl<T> MaybeUninit<T> {
         MaybeUninit { uninit: () }
     }
 
+    /// A promotable constant, equivalent to `uninit()`.
+    #[unstable(feature = "internal_uninit_const", issue = "0",
+        reason = "hack to work around promotability")]
+    pub const UNINIT: Self = Self::uninit();
+
     /// Creates a new `MaybeUninit<T>` in an uninitialized state, with the memory being
     /// filled with `0` bytes. It depends on `T` whether that already makes for
     /// proper initialization. For example, `MaybeUninit<usize>::zeroed()` is initialized,

src/libcore/ptr/mod.rs

@@ -1043,7 +1043,7 @@ impl<T: ?Sized> *const T {
     }
 
     /// Cast to a pointer to a different type
-    #[unstable(feature = "ptr_cast", issue = "60602")]
+    #[stable(feature = "ptr_cast", since = "1.38.0")]
     #[inline]
     pub const fn cast<U>(self) -> *const U {
         self as _
@@ -1678,7 +1678,7 @@ impl<T: ?Sized> *mut T {
     }
 
     /// Cast to a pointer to a different type
-    #[unstable(feature = "ptr_cast", issue = "60602")]
+    #[stable(feature = "ptr_cast", since = "1.38.0")]
     #[inline]
     pub const fn cast<U>(self) -> *mut U {
         self as _

src/libcore/ptr/unique.rs

@@ -26,8 +26,8 @@ use crate::ptr::NonNull;
 /// Unlike `*mut T`, `Unique<T>` is covariant over `T`. This should always be correct
 /// for any type which upholds Unique's aliasing requirements.
 #[unstable(feature = "ptr_internals", issue = "0",
-           reason = "use NonNull instead and consider PhantomData<T> \
-                     (if you also use #[may_dangle]), Send, and/or Sync")]
+           reason = "use `NonNull` instead and consider `PhantomData<T>` \
+                     (if you also use `#[may_dangle]`), `Send`, and/or `Sync`")]
 #[doc(hidden)]
 #[repr(transparent)]
 #[rustc_layout_scalar_valid_range_start(1)]

src/libcore/slice/sort.rs

@@ -216,14 +216,14 @@ fn partition_in_blocks<T, F>(v: &mut [T], pivot: &T, is_less: &mut F) -> usize
     let mut block_l = BLOCK;
     let mut start_l = ptr::null_mut();
     let mut end_l = ptr::null_mut();
-    let mut offsets_l: [MaybeUninit<u8>; BLOCK] = uninitialized_array![u8; BLOCK];
+    let mut offsets_l = [MaybeUninit::<u8>::uninit(); BLOCK];
 
     // The current block on the right side (from `r.sub(block_r)` to `r`).
     let mut r = unsafe { l.add(v.len()) };
     let mut block_r = BLOCK;
     let mut start_r = ptr::null_mut();
     let mut end_r = ptr::null_mut();
-    let mut offsets_r: [MaybeUninit<u8>; BLOCK] = uninitialized_array![u8; BLOCK];
+    let mut offsets_r = [MaybeUninit::<u8>::uninit(); BLOCK];
 
     // FIXME: When we get VLAs, try creating one array of length `min(v.len(), 2 * BLOCK)` rather
     // than two fixed-size arrays of length `BLOCK`. VLAs might be more cache-efficient.

src/librustc/hir/def_id.rs

@@ -69,14 +69,14 @@ impl CrateNum {
     pub fn as_usize(self) -> usize {
         match self {
             CrateNum::Index(id) => id.as_usize(),
-            _ => bug!("tried to get index of nonstandard crate {:?}", self),
+            _ => bug!("tried to get index of non-standard crate {:?}", self),
         }
     }
 
     pub fn as_u32(self) -> u32 {
         match self {
             CrateNum::Index(id) => id.as_u32(),
-            _ => bug!("tried to get index of nonstandard crate {:?}", self),
+            _ => bug!("tried to get index of non-standard crate {:?}", self),
         }
     }
 

src/librustc/hir/lowering.rs

@@ -1693,8 +1693,8 @@ impl<'a> LoweringContext<'a> {
                         if pos == ImplTraitPosition::Binding &&
                             nightly_options::is_nightly_build() {
                             help!(err,
-                                  "add #![feature(impl_trait_in_bindings)] to the crate attributes \
-                                   to enable");
+                                  "add `#![feature(impl_trait_in_bindings)]` to the crate \
+                                   attributes to enable");
                         }
                         err.emit();
                         hir::TyKind::Err

src/librustc_incremental/assert_dep_graph.rs

@@ -190,7 +190,7 @@ fn check_paths<'tcx>(tcx: TyCtxt<'tcx>, if_this_changed: &Sources, then_this_wou
         for &(target_span, _, _, _) in then_this_would_need {
             tcx.sess.span_err(
                 target_span,
-                "no #[rustc_if_this_changed] annotation detected");
+                "no `#[rustc_if_this_changed]` annotation detected");
 
         }
         return;

src/librustc_incremental/persist/dirty_clean.rs

@@ -610,7 +610,7 @@ impl FindAllAttrs<'tcx> {
         for attr in &self.found_attrs {
             if !checked_attrs.contains(&attr.id) {
                 self.tcx.sess.span_err(attr.span, &format!("found unchecked \
-                    #[rustc_dirty]/#[rustc_clean] attribute"));
+                    `#[rustc_dirty]` / `#[rustc_clean]` attribute"));
             }
         }
     }

src/librustc_incremental/persist/fs.rs

@@ -538,7 +538,7 @@ fn find_source_directory_in_iter<I>(iter: I,
         if source_directories_already_tried.contains(&session_dir) ||
            !is_session_directory(&directory_name) ||
            !is_finalized(&directory_name) {
-            debug!("find_source_directory_in_iter - ignoring.");
+            debug!("find_source_directory_in_iter - ignoring");
             continue
         }
 
@@ -693,7 +693,7 @@ pub fn garbage_collect_session_directories(sess: &Session) -> io::Result<()> {
             let timestamp = match extract_timestamp_from_session_dir(lock_file_name) {
                 Ok(timestamp) => timestamp,
                 Err(()) => {
-                    debug!("Found lock-file with malformed timestamp: {}",
+                    debug!("found lock-file with malformed timestamp: {}",
                         crate_directory.join(&lock_file_name).display());
                     // Ignore it
                     continue
@@ -746,7 +746,7 @@ pub fn garbage_collect_session_directories(sess: &Session) -> io::Result<()> {
         let timestamp = match extract_timestamp_from_session_dir(directory_name) {
             Ok(timestamp) => timestamp,
             Err(()) => {
-                debug!("Found session-dir with malformed timestamp: {}",
+                debug!("found session-dir with malformed timestamp: {}",
                         crate_directory.join(directory_name).display());
                 // Ignore it
                 continue

src/librustc_lint/builtin.rs

@@ -591,7 +591,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
         if !self.impling_types.as_ref().unwrap().contains(&item.hir_id) {
             cx.span_lint(MISSING_DEBUG_IMPLEMENTATIONS,
                          item.span,
-                         "type does not implement `fmt::Debug`; consider adding #[derive(Debug)] \
+                         "type does not implement `fmt::Debug`; consider adding `#[derive(Debug)]` \
                           or a manual implementation")
         }
     }
@@ -867,7 +867,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
                 if attr::contains_name(&it.attrs, sym::no_mangle) {
                     // Const items do not refer to a particular location in memory, and therefore
                     // don't have anything to attach a symbol to
-                    let msg = "const items should never be #[no_mangle]";
+                    let msg = "const items should never be `#[no_mangle]`";
                     let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
 
                     // account for "pub const" (#45562)
@@ -1358,7 +1358,7 @@ impl EarlyLintPass for EllipsisInclusiveRangePatterns {
 declare_lint! {
     UNNAMEABLE_TEST_ITEMS,
     Warn,
-    "detects an item that cannot be named being marked as #[test_case]",
+    "detects an item that cannot be named being marked as `#[test_case]`",
     report_in_external_macro: true
 }
 

src/librustc_lint/lib.rs

@@ -481,9 +481,9 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
     store.register_removed("resolve_trait_on_defaulted_unit",
         "converted into hard error, see https://github.com/rust-lang/rust/issues/48950");
     store.register_removed("private_no_mangle_fns",
-        "no longer a warning, #[no_mangle] functions always exported");
+        "no longer a warning, `#[no_mangle]` functions always exported");
     store.register_removed("private_no_mangle_statics",
-        "no longer a warning, #[no_mangle] statics always exported");
+        "no longer a warning, `#[no_mangle]` statics always exported");
     store.register_removed("bad_repr",
         "replaced with a generic attribute input check");
     store.register_removed("duplicate_matcher_binding_name",

src/librustc_lint/unused.rs

@@ -24,7 +24,7 @@ use log::debug;
 declare_lint! {
     pub UNUSED_MUST_USE,
     Warn,
-    "unused result of a type flagged as #[must_use]",
+    "unused result of a type flagged as `#[must_use]`",
     report_in_external_macro: true
 }
 
@@ -316,7 +316,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAttributes {
 
         let name = attr.name_or_empty();
         if !attr::is_used(attr) {
-            debug!("Emitting warning for: {:?}", attr);
+            debug!("emitting warning for: {:?}", attr);
             cx.span_lint(UNUSED_ATTRIBUTES, attr.span, "unused attribute");
             // Is it a builtin attribute that must be used at the crate level?
             let known_crate = attr_info.map(|&&(_, ty, ..)| {
@@ -332,7 +332,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAttributes {
                 let msg = match attr.style {
                     ast::AttrStyle::Outer => {
                         "crate-level attribute should be an inner attribute: add an exclamation \
-                         mark: #![foo]"
+                         mark: `#![foo]`"
                     }
                     ast::AttrStyle::Inner => "crate-level attribute should be in the root module",
                 };
@@ -570,9 +570,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAllocation {
             if let adjustment::Adjust::Borrow(adjustment::AutoBorrow::Ref(_, m)) = adj.kind {
                 let msg = match m {
                     adjustment::AutoBorrowMutability::Immutable =>
-                        "unnecessary allocation, use & instead",
+                        "unnecessary allocation, use `&` instead",
                     adjustment::AutoBorrowMutability::Mutable { .. }=>
-                        "unnecessary allocation, use &mut instead"
+                        "unnecessary allocation, use `&mut` instead"
                 };
                 cx.span_lint(UNUSED_ALLOCATION, e.span, msg);
             }

src/librustc_metadata/creader.rs

@@ -938,14 +938,14 @@ impl<'a> CrateLoader<'a> {
             }
             match global_allocator {
                 Some(Some(other_crate)) => {
-                    self.sess.err(&format!("the #[global_allocator] in {} \
+                    self.sess.err(&format!("the `#[global_allocator]` in {} \
                                             conflicts with this global \
                                             allocator in: {}",
                                            other_crate,
                                            data.root.name));
                 }
                 Some(None) => {
-                    self.sess.err(&format!("the #[global_allocator] in this \
+                    self.sess.err(&format!("the `#[global_allocator]` in this \
                                             crate conflicts with global \
                                             allocator in: {}", data.root.name));
                 }
@@ -971,7 +971,7 @@ impl<'a> CrateLoader<'a> {
         if !has_default {
             self.sess.err("no global memory allocator found but one is \
                            required; link to std or \
-                           add #[global_allocator] to a static item \
+                           add `#[global_allocator]` to a static item \
                            that implements the GlobalAlloc trait.");
         }
         self.sess.allocator_kind.set(Some(AllocatorKind::DefaultLib));

src/librustc_metadata/error_codes.rs

@@ -7,7 +7,8 @@ E0454: r##"
 A link name was given with an empty name. Erroneous code example:
 
 ```ignore (cannot-test-this-because-rustdoc-stops-compile-fail-before-codegen)
-#[link(name = "")] extern {} // error: #[link(name = "")] given with empty name
+#[link(name = "")] extern {}
+// error: `#[link(name = "")]` given with empty name
 ```
 
 The rust compiler cannot link to an external library if you don't give it its
@@ -61,7 +62,7 @@ A link was used without a name parameter. Erroneous code example:
 
 ```ignore (cannot-test-this-because-rustdoc-stops-compile-fail-before-codegen)
 #[link(kind = "dylib")] extern {}
-// error: #[link(...)] specified without `name = "foo"`
+// error: `#[link(...)]` specified without `name = "foo"`
 ```
 
 Please add the name parameter to allow the rust compiler to find the library