Auto merge of #50807 - kennytm:rollup, r=kennytm

Rollup of 17 pull requests

Successful merges:

 - #50170 (Implement From for more types on Cow)
 - #50638 (Don't unconditionally set CLOEXEC twice on every fd we open on Linux)
 - #50656 (Fix `fn main() -> impl Trait` for non-`Termination` trait)
 - #50669 (rustdoc: deprecate `#![doc(passes, plugins, no_default_passes)]`)
 - #50726 (read2: Use inner function instead of closure)
 - #50728 (Fix rustdoc panic with `impl Trait` in type parameters)
 - #50736 (env: remove unwrap in examples in favor of try op)
 - #50740 (Remove LazyBTreeMap.)
 - #50752 (Add missing error codes in libsyntax-ext asm)
 - #50779 (Make mutable_noalias and arg_align_attributes be tracked)
 - #50787 (Fix run-make wasm tests)
 - #50788 (Fix an ICE when casting a nonexistent const)
 - #50789 (Ensure libraries built in stage0 have unique metadata)
 - #50793 (tidy: Add a check for empty UI test files)
 - #50797 (fix a typo in signed-integer::from_str_radix())
 - #50808 (Stabilize num::NonZeroU*)
 - #50809 (GitHub: Stop treating Cargo.lock as a generated file.)

Failed merges:

.gitattributes

@@ -7,4 +7,4 @@
 src/etc/installer/gfx/* binary
 *.woff binary
 src/vendor/** -text
-Cargo.lock -merge
+Cargo.lock -merge linguist-generated=false

src/bootstrap/builder.rs

@@ -592,7 +592,15 @@ pub fn cargo(&self,
 
         // FIXME: Temporary fix for https://github.com/rust-lang/cargo/issues/3005
         // Force cargo to output binaries with disambiguating hashes in the name
-        cargo.env("__CARGO_DEFAULT_LIB_METADATA", &self.config.channel);
+        let metadata = if compiler.stage == 0 {
+            // Treat stage0 like special channel, whether it's a normal prior-
+            // release rustc or a local rebuild with the same version, so we
+            // never mix these libraries by accident.
+            "bootstrap"
+        } else {
+            &self.config.channel
+        };
+        cargo.env("__CARGO_DEFAULT_LIB_METADATA", &metadata);
 
         let stage;
         if compiler.stage == 0 && self.local_rebuild {

src/bootstrap/test.rs

@@ -838,7 +838,7 @@ fn run(self, builder: &Builder) {
     host: true
 });
 
-host_test!(RunMake {
+default_test!(RunMake {
     path: "src/test/run-make",
     mode: "run-make",
     suite: "run-make"
@@ -1041,7 +1041,7 @@ fn run(self, builder: &Builder) {
 
             // Only pass correct values for these flags for the `run-make` suite as it
             // requires that a C++ compiler was configured which isn't always the case.
-            if !builder.config.dry_run && mode == "run-make" {
+            if !builder.config.dry_run && suite == "run-make-fulldeps" {
                 let llvm_components = output(Command::new(&llvm_config).arg("--components"));
                 let llvm_cxxflags = output(Command::new(&llvm_config).arg("--cxxflags"));
                 cmd.arg("--cc").arg(builder.cc(target))
@@ -1054,13 +1054,13 @@ fn run(self, builder: &Builder) {
                 }
             }
         }
-        if mode == "run-make" && !builder.config.llvm_enabled {
+        if suite == "run-make-fulldeps" && !builder.config.llvm_enabled {
             builder.info(
                 &format!("Ignoring run-make test suite as they generally don't work without LLVM"));
             return;
         }
 
-        if mode != "run-make" {
+        if suite != "run-make-fulldeps" {
             cmd.arg("--cc").arg("")
                .arg("--cxx").arg("")
                .arg("--cflags").arg("")

src/liballoc/lib.rs

@@ -102,7 +102,6 @@
 #![feature(lang_items)]
 #![feature(libc)]
 #![feature(needs_allocator)]
-#![feature(nonzero)]
 #![feature(optin_builtin_traits)]
 #![feature(pattern)]
 #![feature(pin)]

src/liballoc/string.rs

@@ -2240,6 +2240,14 @@ fn from(s: String) -> Cow<'a, str> {
     }
 }
 
+#[stable(feature = "cow_from_string_ref", since = "1.28.0")]
+impl<'a> From<&'a String> for Cow<'a, str> {
+    #[inline]
+    fn from(s: &'a String) -> Cow<'a, str> {
+        Cow::Borrowed(s.as_str())
+    }
+}
+
 #[stable(feature = "cow_str_from_iter", since = "1.12.0")]
 impl<'a> FromIterator<char> for Cow<'a, str> {
     fn from_iter<I: IntoIterator<Item = char>>(it: I) -> Cow<'a, str> {

src/liballoc/vec.rs

@@ -2286,6 +2286,13 @@ fn from(v: Vec<T>) -> Cow<'a, [T]> {
     }
 }
 
+#[stable(feature = "cow_from_vec_ref", since = "1.28.0")]
+impl<'a, T: Clone> From<&'a Vec<T>> for Cow<'a, [T]> {
+    fn from(v: &'a Vec<T>) -> Cow<'a, [T]> {
+        Cow::Borrowed(v.as_slice())
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone {
     fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> {

src/libcore/lib.rs

@@ -171,7 +171,6 @@
 
 pub mod intrinsics;
 pub mod mem;
-pub mod nonzero;
 pub mod ptr;
 pub mod hint;
 
@@ -221,6 +220,7 @@ pub mod heap {
 
 // note: does not need to be public
 mod iter_private;
+mod nonzero;
 mod tuple;
 mod unit;
 

src/libcore/nonzero.rs

@@ -9,103 +9,13 @@
 // except according to those terms.
 
 //! Exposes the NonZero lang item which provides optimization hints.
-#![unstable(feature = "nonzero", reason = "deprecated", issue = "49137")]
-#![rustc_deprecated(reason = "use `std::ptr::NonNull` or `std::num::NonZero*` instead",
-                    since = "1.26.0")]
-#![allow(deprecated)]
 
 use ops::CoerceUnsized;
 
-/// Unsafe trait to indicate what types are usable with the NonZero struct
-pub unsafe trait Zeroable {
-    /// Whether this value is zero
-    fn is_zero(&self) -> bool;
-}
-
-macro_rules! impl_zeroable_for_pointer_types {
-    ( $( $Ptr: ty )+ ) => {
-        $(
-            /// For fat pointers to be considered "zero", only the "data" part needs to be null.
-            unsafe impl<T: ?Sized> Zeroable for $Ptr {
-                #[inline]
-                fn is_zero(&self) -> bool {
-                    (*self).is_null()
-                }
-            }
-        )+
-    }
-}
-
-macro_rules! impl_zeroable_for_integer_types {
-    ( $( $Int: ty )+ ) => {
-        $(
-            unsafe impl Zeroable for $Int {
-                #[inline]
-                fn is_zero(&self) -> bool {
-                    *self == 0
-                }
-            }
-        )+
-    }
-}
-
-impl_zeroable_for_pointer_types! {
-    *const T
-    *mut T
-}
-
-impl_zeroable_for_integer_types! {
-    usize u8 u16 u32 u64 u128
-    isize i8 i16 i32 i64 i128
-}
-
 /// A wrapper type for raw pointers and integers that will never be
 /// NULL or 0 that might allow certain optimizations.
 #[lang = "non_zero"]
-#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Debug, Hash)]
-pub struct NonZero<T: Zeroable>(pub(crate) T);
-
-impl<T: Zeroable> NonZero<T> {
-    /// Creates an instance of NonZero with the provided value.
-    /// You must indeed ensure that the value is actually "non-zero".
-    #[inline]
-    pub const unsafe fn new_unchecked(inner: T) -> Self {
-        NonZero(inner)
-    }
-
-    /// Creates an instance of NonZero with the provided value.
-    #[inline]
-    pub fn new(inner: T) -> Option<Self> {
-        if inner.is_zero() {
-            None
-        } else {
-            Some(NonZero(inner))
-        }
-    }
-
-    /// Gets the inner value.
-    pub fn get(self) -> T {
-        self.0
-    }
-}
-
-impl<T: Zeroable+CoerceUnsized<U>, U: Zeroable> CoerceUnsized<NonZero<U>> for NonZero<T> {}
-
-impl<'a, T: ?Sized> From<&'a mut T> for NonZero<*mut T> {
-    fn from(reference: &'a mut T) -> Self {
-        NonZero(reference)
-    }
-}
-
-impl<'a, T: ?Sized> From<&'a mut T> for NonZero<*const T> {
-    fn from(reference: &'a mut T) -> Self {
-        let ptr: *mut T = reference;
-        NonZero(ptr)
-    }
-}
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+pub(crate) struct NonZero<T>(pub(crate) T);
 
-impl<'a, T: ?Sized> From<&'a T> for NonZero<*const T> {
-    fn from(reference: &'a T) -> Self {
-        NonZero(reference)
-    }
-}
+impl<T: CoerceUnsized<U>, U> CoerceUnsized<NonZero<U>> for NonZero<T> {}

src/libcore/num/mod.rs

@@ -16,15 +16,14 @@
 use fmt;
 use intrinsics;
 use mem;
-#[allow(deprecated)] use nonzero::NonZero;
+use nonzero::NonZero;
 use ops;
 use str::FromStr;
 
 macro_rules! impl_nonzero_fmt {
-    ( #[$stability: meta] ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
+    ( ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
         $(
-            #[$stability]
-            #[allow(deprecated)]
+            #[stable(feature = "nonzero", since = "1.28.0")]
             impl fmt::$Trait for $Ty {
                 #[inline]
                 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
@@ -36,7 +35,7 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 }
 
 macro_rules! nonzero_integers {
-    ( #[$stability: meta] #[$deprecation: meta] $( $Ty: ident($Int: ty); )+ ) => {
+    ( $( $Ty: ident($Int: ty); )+ ) => {
         $(
             /// An integer that is known not to equal zero.
             ///
@@ -47,27 +46,24 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
             /// use std::mem::size_of;
             /// assert_eq!(size_of::<Option<std::num::NonZeroU32>>(), size_of::<u32>());
             /// ```
-            #[$stability]
-            #[$deprecation]
-            #[allow(deprecated)]
+            #[stable(feature = "nonzero", since = "1.28.0")]
             #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
             pub struct $Ty(NonZero<$Int>);
 
-            #[allow(deprecated)]
             impl $Ty {
                 /// Create a non-zero without checking the value.
                 ///
                 /// # Safety
                 ///
                 /// The value must not be zero.
-                #[$stability]
+                #[stable(feature = "nonzero", since = "1.28.0")]
                 #[inline]
                 pub const unsafe fn new_unchecked(n: $Int) -> Self {
                     $Ty(NonZero(n))
                 }
 
                 /// Create a non-zero if the given value is not zero.
-                #[$stability]
+                #[stable(feature = "nonzero", since = "1.28.0")]
                 #[inline]
                 pub fn new(n: $Int) -> Option<Self> {
                     if n != 0 {
@@ -78,7 +74,7 @@ pub fn new(n: $Int) -> Option<Self> {
                 }
 
                 /// Returns the value as a primitive type.
-                #[$stability]
+                #[stable(feature = "nonzero", since = "1.28.0")]
                 #[inline]
                 pub fn get(self) -> $Int {
                     self.0 .0
@@ -87,7 +83,6 @@ pub fn get(self) -> $Int {
             }
 
             impl_nonzero_fmt! {
-                #[$stability]
                 (Debug, Display, Binary, Octal, LowerHex, UpperHex) for $Ty
             }
         )+
@@ -95,8 +90,6 @@ pub fn get(self) -> $Int {
 }
 
 nonzero_integers! {
-    #[unstable(feature = "nonzero", issue = "49137")]
-    #[allow(deprecated)]  // Redundant, works around "error: inconsistent lockstep iteration"
     NonZeroU8(u8);
     NonZeroU16(u16);
     NonZeroU32(u32);
@@ -105,19 +98,6 @@ pub fn get(self) -> $Int {
     NonZeroUsize(usize);
 }
 
-nonzero_integers! {
-    #[unstable(feature = "nonzero", issue = "49137")]
-    #[rustc_deprecated(since = "1.26.0", reason = "\
-        signed non-zero integers are considered for removal due to lack of known use cases. \
-        If you’re using them, please comment on https://github.com/rust-lang/rust/issues/49137")]
-    NonZeroI8(i8);
-    NonZeroI16(i16);
-    NonZeroI32(i32);
-    NonZeroI64(i64);
-    NonZeroI128(i128);
-    NonZeroIsize(isize);
-}
-
 /// Provides intentionally-wrapped arithmetic on `T`.
 ///
 /// Operations like `+` on `u32` values is intended to never overflow,
@@ -252,7 +232,7 @@ pub const fn max_value() -> Self {
 
  * `0-9`
  * `a-z`
- * `a-z`
+ * `A-Z`
 
 # Panics
 

src/libcore/ptr.rs

@@ -23,7 +23,7 @@
 use hash;
 use marker::{PhantomData, Unsize};
 use mem;
-#[allow(deprecated)] use nonzero::NonZero;
+use nonzero::NonZero;
 
 use cmp::Ordering::{self, Less, Equal, Greater};
 
@@ -2742,7 +2742,6 @@ fn ge(&self, other: &*mut T) -> bool { *self >= *other }
 #[unstable(feature = "ptr_internals", issue = "0",
            reason = "use NonNull instead and consider PhantomData<T> \
                      (if you also use #[may_dangle]), Send, and/or Sync")]
-#[allow(deprecated)]
 #[doc(hidden)]
 pub struct Unique<T: ?Sized> {
     pointer: NonZero<*const T>,
@@ -2790,7 +2789,6 @@ pub const fn empty() -> Self {
 }
 
 #[unstable(feature = "ptr_internals", issue = "0")]
-#[allow(deprecated)]
 impl<T: ?Sized> Unique<T> {
     /// Creates a new `Unique`.
     ///
@@ -2855,7 +2853,6 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 }
 
 #[unstable(feature = "ptr_internals", issue = "0")]
-#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a mut T> for Unique<T> {
     fn from(reference: &'a mut T) -> Self {
         Unique { pointer: NonZero(reference as _), _marker: PhantomData }
@@ -2863,7 +2860,6 @@ fn from(reference: &'a mut T) -> Self {
 }
 
 #[unstable(feature = "ptr_internals", issue = "0")]
-#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a T> for Unique<T> {
     fn from(reference: &'a T) -> Self {
         Unique { pointer: NonZero(reference as _), _marker: PhantomData }
@@ -2896,7 +2892,7 @@ fn from(p: NonNull<T>) -> Self {
 /// provide a public API that follows the normal shared XOR mutable rules of Rust.
 #[stable(feature = "nonnull", since = "1.25.0")]
 pub struct NonNull<T: ?Sized> {
-    #[allow(deprecated)] pointer: NonZero<*const T>,
+    pointer: NonZero<*const T>,
 }
 
 /// `NonNull` pointers are not `Send` because the data they reference may be aliased.
@@ -2923,7 +2919,6 @@ pub fn dangling() -> Self {
     }
 }
 
-#[allow(deprecated)]
 impl<T: ?Sized> NonNull<T> {
     /// Creates a new `NonNull`.
     ///
@@ -3054,7 +3049,6 @@ fn from(unique: Unique<T>) -> Self {
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]
-#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a mut T> for NonNull<T> {
     fn from(reference: &'a mut T) -> Self {
         NonNull { pointer: NonZero(reference as _) }
@@ -3062,7 +3056,6 @@ fn from(reference: &'a mut T) -> Self {
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]
-#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a T> for NonNull<T> {
     fn from(reference: &'a T) -> Self {
         NonNull { pointer: NonZero(reference as _) }

src/libcore/tests/lib.rs

@@ -26,7 +26,6 @@
 #![feature(iterator_step_by)]
 #![feature(iterator_flatten)]
 #![feature(iterator_repeat_with)]
-#![feature(nonzero)]
 #![feature(pattern)]
 #![feature(range_is_empty)]
 #![feature(raw)]

src/librustc/infer/higher_ranked/mod.rs

@@ -19,10 +19,10 @@
 use super::combine::CombineFields;
 use super::region_constraints::{TaintDirections};
 
-use rustc_data_structures::lazy_btree_map::LazyBTreeMap;
 use ty::{self, TyCtxt, Binder, TypeFoldable};
 use ty::error::TypeError;
 use ty::relate::{Relate, RelateResult, TypeRelation};
+use std::collections::BTreeMap;
 use syntax_pos::Span;
 use util::nodemap::{FxHashMap, FxHashSet};
 
@@ -247,8 +247,7 @@ fn generalize_region<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
                                              snapshot: &CombinedSnapshot<'a, 'tcx>,
                                              debruijn: ty::DebruijnIndex,
                                              new_vars: &[ty::RegionVid],
-                                             a_map: &LazyBTreeMap<ty::BoundRegion,
-                                                                  ty::Region<'tcx>>,
+                                             a_map: &BTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
                                              r0: ty::Region<'tcx>)
                                              -> ty::Region<'tcx> {
             // Regions that pre-dated the LUB computation stay as they are.
@@ -344,8 +343,7 @@ fn generalize_region<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
                                              snapshot: &CombinedSnapshot<'a, 'tcx>,
                                              debruijn: ty::DebruijnIndex,
                                              new_vars: &[ty::RegionVid],
-                                             a_map: &LazyBTreeMap<ty::BoundRegion,
-                                                                  ty::Region<'tcx>>,
+                                             a_map: &BTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
                                              a_vars: &[ty::RegionVid],
                                              b_vars: &[ty::RegionVid],
                                              r0: ty::Region<'tcx>)
@@ -414,7 +412,7 @@ fn generalize_region<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
 
         fn rev_lookup<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
                                       span: Span,
-                                      a_map: &LazyBTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
+                                      a_map: &BTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
                                       r: ty::Region<'tcx>) -> ty::Region<'tcx>
         {
             for (a_br, a_r) in a_map {
@@ -437,7 +435,7 @@ fn fresh_bound_variable<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
 }
 
 fn var_ids<'a, 'gcx, 'tcx>(fields: &CombineFields<'a, 'gcx, 'tcx>,
-                           map: &LazyBTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
+                           map: &BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
                            -> Vec<ty::RegionVid> {
     map.iter()
        .map(|(_, &r)| match *r {

src/librustc/infer/mod.rs

@@ -28,9 +28,9 @@
 use ty::fold::TypeFoldable;
 use ty::relate::RelateResult;
 use traits::{self, ObligationCause, PredicateObligations};
-use rustc_data_structures::lazy_btree_map::LazyBTreeMap;
 use rustc_data_structures::unify as ut;
 use std::cell::{Cell, RefCell, Ref, RefMut};
+use std::collections::BTreeMap;
 use std::fmt;
 use syntax::ast;
 use errors::DiagnosticBuilder;
@@ -198,7 +198,7 @@ pub struct InferCtxt<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 
 /// A map returned by `skolemize_late_bound_regions()` indicating the skolemized
 /// region that each late-bound region was replaced with.
-pub type SkolemizationMap<'tcx> = LazyBTreeMap<ty::BoundRegion, ty::Region<'tcx>>;
+pub type SkolemizationMap<'tcx> = BTreeMap<ty::BoundRegion, ty::Region<'tcx>>;
 
 /// See `error_reporting` module for more details
 #[derive(Clone, Debug)]
@@ -1235,7 +1235,7 @@ pub fn replace_late_bound_regions_with_fresh_var<T>(
         span: Span,
         lbrct: LateBoundRegionConversionTime,
         value: &ty::Binder<T>)
-        -> (T, LazyBTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
+        -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
         where T : TypeFoldable<'tcx>
     {
         self.tcx.replace_late_bound_regions(

src/librustc/lib.rs

@@ -56,7 +56,6 @@
 #![feature(never_type)]
 #![feature(exhaustive_patterns)]
 #![feature(non_exhaustive)]
-#![feature(nonzero)]
 #![feature(proc_macro_internals)]
 #![feature(quote)]
 #![feature(optin_builtin_traits)]

src/librustc/session/config.rs

@@ -1239,9 +1239,9 @@ fn parse_cross_lang_lto(slot: &mut CrossLangLto, v: Option<&str>) -> bool {
           "print the result of the translation item collection pass"),
     mir_opt_level: usize = (1, parse_uint, [TRACKED],
           "set the MIR optimization level (0-3, default: 1)"),
-    mutable_noalias: bool = (false, parse_bool, [UNTRACKED],
+    mutable_noalias: bool = (false, parse_bool, [TRACKED],
           "emit noalias metadata for mutable references"),
-    arg_align_attributes: bool = (false, parse_bool, [UNTRACKED],
+    arg_align_attributes: bool = (false, parse_bool, [TRACKED],
           "emit align metadata for reference arguments"),
     dump_mir: Option<String> = (None, parse_opt_string, [UNTRACKED],
           "dump MIR state at various points in translation"),

src/librustc/ty/fold.rs

@@ -43,7 +43,7 @@
 use hir::def_id::DefId;
 use ty::{self, Binder, Ty, TyCtxt, TypeFlags};
 
-use rustc_data_structures::lazy_btree_map::LazyBTreeMap;
+use std::collections::BTreeMap;
 use std::fmt;
 use util::nodemap::FxHashSet;
 
@@ -332,7 +332,7 @@ struct RegionReplacer<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     current_depth: u32,
     fld_r: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a),
-    map: LazyBTreeMap<ty::BoundRegion, ty::Region<'tcx>>
+    map: BTreeMap<ty::BoundRegion, ty::Region<'tcx>>
 }
 
 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
@@ -347,7 +347,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     pub fn replace_late_bound_regions<T,F>(self,
         value: &Binder<T>,
         mut f: F)
-        -> (T, LazyBTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
+        -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
         where F : FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
               T : TypeFoldable<'tcx>,
     {
@@ -460,7 +460,7 @@ fn new<F>(tcx: TyCtxt<'a, 'gcx, 'tcx>, fld_r: &'a mut F)
             tcx,
             current_depth: 1,
             fld_r,
-            map: LazyBTreeMap::default()
+            map: BTreeMap::default()
         }
     }
 }

src/librustc_data_structures/lazy_btree_map.rs

-// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-use std::collections::btree_map;
-use std::collections::BTreeMap;
-
-/// A thin wrapper around BTreeMap that avoids allocating upon creation.
-///
-/// Vec, HashSet and HashMap all have the nice feature that they don't do any
-/// heap allocation when creating a new structure of the default size. In
-/// contrast, BTreeMap *does* allocate in that situation. The compiler uses
-/// B-Tree maps in some places such that many maps are created but few are
-/// inserted into, so having a BTreeMap alternative that avoids allocating on
-/// creation is a performance win.
-///
-/// Only a fraction of BTreeMap's functionality is currently supported.
-/// Additional functionality should be added on demand.
-#[derive(Debug)]
-pub struct LazyBTreeMap<K, V>(Option<BTreeMap<K, V>>);
-
-impl<K, V> LazyBTreeMap<K, V> {
-    pub fn new() -> LazyBTreeMap<K, V> {
-        LazyBTreeMap(None)
-    }
-
-    pub fn iter(&self) -> Iter<K, V> {
-        Iter(self.0.as_ref().map(|btm| btm.iter()))
-    }
-
-    pub fn is_empty(&self) -> bool {
-        self.0.as_ref().map_or(true, |btm| btm.is_empty())
-    }
-}
-
-impl<K: Ord, V> LazyBTreeMap<K, V> {
-    fn instantiate(&mut self) -> &mut BTreeMap<K, V> {
-        if let Some(ref mut btm) = self.0 {
-            btm
-        } else {
-            let btm = BTreeMap::new();
-            self.0 = Some(btm);
-            self.0.as_mut().unwrap()
-        }
-    }
-
-    pub fn insert(&mut self, key: K, value: V) -> Option<V> {
-        self.instantiate().insert(key, value)
-    }
-
-    pub fn entry(&mut self, key: K) -> btree_map::Entry<K, V> {
-        self.instantiate().entry(key)
-    }
-
-    pub fn values<'a>(&'a self) -> Values<'a, K, V> {
-        Values(self.0.as_ref().map(|btm| btm.values()))
-    }
-}
-
-impl<K: Ord, V> Default for LazyBTreeMap<K, V> {
-    fn default() -> LazyBTreeMap<K, V> {
-        LazyBTreeMap::new()
-    }
-}
-
-impl<'a, K: 'a, V: 'a> IntoIterator for &'a LazyBTreeMap<K, V> {
-    type Item = (&'a K, &'a V);
-    type IntoIter = Iter<'a, K, V>;
-
-    fn into_iter(self) -> Iter<'a, K, V> {
-        self.iter()
-    }
-}
-
-pub struct Iter<'a, K: 'a, V: 'a>(Option<btree_map::Iter<'a, K, V>>);
-
-impl<'a, K: 'a, V: 'a> Iterator for Iter<'a, K, V> {
-    type Item = (&'a K, &'a V);
-
-    fn next(&mut self) -> Option<(&'a K, &'a V)> {
-        self.0.as_mut().and_then(|iter| iter.next())
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.0.as_ref().map_or_else(|| (0, Some(0)), |iter| iter.size_hint())
-    }
-}
-
-pub struct Values<'a, K: 'a, V: 'a>(Option<btree_map::Values<'a, K, V>>);
-
-impl<'a, K, V> Iterator for Values<'a, K, V> {
-    type Item = &'a V;
-
-    fn next(&mut self) -> Option<&'a V> {
-        self.0.as_mut().and_then(|values| values.next())
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.0.as_ref().map_or_else(|| (0, Some(0)), |values| values.size_hint())
-    }
-}
-

src/librustc_data_structures/lib.rs

@@ -21,7 +21,6 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 
 #![feature(collections_range)]
-#![feature(nonzero)]
 #![feature(unboxed_closures)]
 #![feature(fn_traits)]
 #![feature(unsize)]
@@ -61,7 +60,6 @@
 pub mod graph;
 pub mod indexed_set;
 pub mod indexed_vec;
-pub mod lazy_btree_map;
 pub mod obligation_forest;
 pub mod sip128;
 pub mod snapshot_map;

src/librustc_mir/lib.rs

@@ -30,7 +30,6 @@
 #![feature(exhaustive_patterns)]
 #![feature(range_contains)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(nonzero)]
 #![feature(inclusive_range_methods)]
 #![feature(crate_visibility_modifier)]
 #![feature(never_type)]

src/librustc_passes/rvalue_promotion.rs

@@ -275,7 +275,7 @@ fn check_expr<'a, 'tcx>(v: &mut CheckCrateVisitor<'a, 'tcx>, e: &hir::Expr, node
         hir::ExprCast(ref from, _) => {
             debug!("Checking const cast(id={})", from.id);
             match v.tables.cast_kinds().get(from.hir_id) {
-                None => span_bug!(e.span, "no kind for cast"),
+                None => v.tcx.sess.delay_span_bug(e.span, "no kind for cast"),
                 Some(&CastKind::PtrAddrCast) | Some(&CastKind::FnPtrAddrCast) => {
                     v.promotable = false;
                 }

src/librustc_typeck/check/mod.rs

@@ -1031,13 +1031,13 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
     let mut fcx = FnCtxt::new(inherited, param_env, body.value.id);
     *fcx.ps.borrow_mut() = UnsafetyState::function(fn_sig.unsafety, fn_id);
 
-    let ret_ty = fn_sig.output();
-    fcx.require_type_is_sized(ret_ty, decl.output.span(), traits::SizedReturnType);
-    let ret_ty = fcx.instantiate_anon_types_from_return_value(fn_id, &ret_ty);
-    fcx.ret_coercion = Some(RefCell::new(CoerceMany::new(ret_ty)));
+    let declared_ret_ty = fn_sig.output();
+    fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType);
+    let revealed_ret_ty = fcx.instantiate_anon_types_from_return_value(fn_id, &declared_ret_ty);
+    fcx.ret_coercion = Some(RefCell::new(CoerceMany::new(revealed_ret_ty)));
     fn_sig = fcx.tcx.mk_fn_sig(
         fn_sig.inputs().iter().cloned(),
-        ret_ty,
+        revealed_ret_ty,
         fn_sig.variadic,
         fn_sig.unsafety,
         fn_sig.abi
@@ -1119,7 +1119,7 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
         actual_return_ty = fcx.next_diverging_ty_var(
             TypeVariableOrigin::DivergingFn(span));
     }
-    fcx.demand_suptype(span, ret_ty, actual_return_ty);
+    fcx.demand_suptype(span, revealed_ret_ty, actual_return_ty);
 
     // Check that the main return type implements the termination trait.
     if let Some(term_id) = fcx.tcx.lang_items().termination() {
@@ -1127,7 +1127,7 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
             if id == fn_id {
                 match entry_type {
                     config::EntryMain => {
-                        let substs = fcx.tcx.mk_substs(iter::once(Kind::from(ret_ty)));
+                        let substs = fcx.tcx.mk_substs(iter::once(Kind::from(declared_ret_ty)));
                         let trait_ref = ty::TraitRef::new(term_id, substs);
                         let return_ty_span = decl.output.span();
                         let cause = traits::ObligationCause::new(

src/librustdoc/clean/mod.rs

@@ -1754,16 +1754,39 @@ pub struct Generics {
 
 impl Clean<Generics> for hir::Generics {
     fn clean(&self, cx: &DocContext) -> Generics {
+        // Synthetic type-parameters are inserted after normal ones.
+        // In order for normal parameters to be able to refer to synthetic ones,
+        // scans them first.
+        fn is_impl_trait(param: &hir::GenericParam) -> bool {
+            if let hir::GenericParam::Type(ref tp) = param {
+                tp.synthetic == Some(hir::SyntheticTyParamKind::ImplTrait)
+            } else {
+                false
+            }
+        }
+        let impl_trait_params = self.params
+            .iter()
+            .filter(|p| is_impl_trait(p))
+            .map(|p| {
+                let p = p.clean(cx);
+                if let GenericParamDef::Type(ref tp) = p {
+                    cx.impl_trait_bounds
+                        .borrow_mut()
+                        .insert(tp.did, tp.bounds.clone());
+                } else {
+                    unreachable!()
+                }
+                p
+            })
+            .collect::<Vec<_>>();
+
         let mut params = Vec::with_capacity(self.params.len());
-        for p in &self.params {
+        for p in self.params.iter().filter(|p| !is_impl_trait(p)) {
             let p = p.clean(cx);
-            if let GenericParamDef::Type(ref tp) = p {
-                if tp.synthetic == Some(hir::SyntheticTyParamKind::ImplTrait) {
-                    cx.impl_trait_bounds.borrow_mut().insert(tp.did, tp.bounds.clone());
-                }
-            }
             params.push(p);
         }
+        params.extend(impl_trait_params);
+
         let mut g = Generics {
             params,
             where_predicates: self.where_clause.predicates.clean(cx)

src/librustdoc/lib.rs

@@ -654,6 +654,20 @@ fn rust_input<R, F>(cratefile: PathBuf,
 
         krate.version = crate_version;
 
+        let diag = core::new_handler(error_format, None);
+
+        fn report_deprecated_attr(name: &str, diag: &errors::Handler) {
+            let mut msg = diag.struct_warn(&format!("the `#![doc({})]` attribute is \
+                                                     considered deprecated", name));
+            msg.warn("please see https://github.com/rust-lang/rust/issues/44136");
+
+            if name == "no_default_passes" {
+                msg.help("you may want to use `#![doc(document_private_items)]`");
+            }
+
+            msg.emit();
+        }
+
         // Process all of the crate attributes, extracting plugin metadata along
         // with the passes which we are supposed to run.
         for attr in krate.module.as_ref().unwrap().attrs.lists("doc") {
@@ -661,18 +675,34 @@ fn rust_input<R, F>(cratefile: PathBuf,
             let name = name.as_ref().map(|s| &s[..]);
             if attr.is_word() {
                 if name == Some("no_default_passes") {
+                    report_deprecated_attr("no_default_passes", &diag);
                     default_passes = false;
                 }
             } else if let Some(value) = attr.value_str() {
                 let sink = match name {
-                    Some("passes") => &mut passes,
-                    Some("plugins") => &mut plugins,
+                    Some("passes") => {
+                        report_deprecated_attr("passes = \"...\"", &diag);
+                        &mut passes
+                    },
+                    Some("plugins") => {
+                        report_deprecated_attr("plugins = \"...\"", &diag);
+                        &mut plugins
+                    },
                     _ => continue,
                 };
                 for p in value.as_str().split_whitespace() {
                     sink.push(p.to_string());
                 }
             }
+
+            if attr.is_word() && name == Some("document_private_items") {
+                default_passes = false;
+
+                passes = vec![
+                    String::from("collapse-docs"),
+                    String::from("unindent-comments"),
+                ];
+            }
         }
 
         if default_passes {

src/libstd/env.rs

@@ -49,9 +49,11 @@
 /// ```
 /// use std::env;
 ///
-/// // We assume that we are in a valid directory.
-/// let path = env::current_dir().unwrap();
-/// println!("The current directory is {}", path.display());
+/// fn main() -> std::io::Result<()> {
+///     let path = env::current_dir()?;
+///     println!("The current directory is {}", path.display());
+///     Ok(())
+/// }
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn current_dir() -> io::Result<PathBuf> {
@@ -441,15 +443,18 @@ pub struct JoinPathsError {
 /// Joining paths on a Unix-like platform:
 ///
 /// ```
-/// # if cfg!(unix) {
 /// use std::env;
 /// use std::ffi::OsString;
 /// use std::path::Path;
 ///
-/// let paths = [Path::new("/bin"), Path::new("/usr/bin")];
-/// let path_os_string = env::join_paths(paths.iter()).unwrap();
-/// assert_eq!(path_os_string, OsString::from("/bin:/usr/bin"));
+/// fn main() -> Result<(), env::JoinPathsError> {
+/// # if cfg!(unix) {
+///     let paths = [Path::new("/bin"), Path::new("/usr/bin")];
+///     let path_os_string = env::join_paths(paths.iter())?;
+///     assert_eq!(path_os_string, OsString::from("/bin:/usr/bin"));
 /// # }
+///     Ok(())
+/// }
 /// ```
 ///
 /// Joining a path containing a colon on a Unix-like platform results in an error:
@@ -471,11 +476,15 @@ pub struct JoinPathsError {
 /// use std::env;
 /// use std::path::PathBuf;
 ///
-/// if let Some(path) = env::var_os("PATH") {
-///     let mut paths = env::split_paths(&path).collect::<Vec<_>>();
-///     paths.push(PathBuf::from("/home/xyz/bin"));
-///     let new_path = env::join_paths(paths).unwrap();
-///     env::set_var("PATH", &new_path);
+/// fn main() -> Result<(), env::JoinPathsError> {
+///     if let Some(path) = env::var_os("PATH") {
+///         let mut paths = env::split_paths(&path).collect::<Vec<_>>();
+///         paths.push(PathBuf::from("/home/xyz/bin"));
+///         let new_path = env::join_paths(paths)?;
+///         env::set_var("PATH", &new_path);
+///     }
+///
+///     Ok(())
 /// }
 /// ```
 #[stable(feature = "env", since = "1.0.0")]

src/libstd/ffi/c_str.rs

@@ -682,6 +682,14 @@ impl Borrow<CStr> for CString {
     fn borrow(&self) -> &CStr { self }
 }
 
+#[stable(feature = "cstring_from_cow_cstr", since = "1.28.0")]
+impl<'a> From<Cow<'a, CStr>> for CString {
+    #[inline]
+    fn from(s: Cow<'a, CStr>) -> Self {
+        s.into_owned()
+    }
+}
+
 #[stable(feature = "box_from_c_str", since = "1.17.0")]
 impl<'a> From<&'a CStr> for Box<CStr> {
     fn from(s: &'a CStr) -> Box<CStr> {
@@ -706,6 +714,30 @@ fn from(s: CString) -> Box<CStr> {
     }
 }
 
+#[stable(feature = "cow_from_cstr", since = "1.28.0")]
+impl<'a> From<CString> for Cow<'a, CStr> {
+    #[inline]
+    fn from(s: CString) -> Cow<'a, CStr> {
+        Cow::Owned(s)
+    }
+}
+
+#[stable(feature = "cow_from_cstr", since = "1.28.0")]
+impl<'a> From<&'a CStr> for Cow<'a, CStr> {
+    #[inline]
+    fn from(s: &'a CStr) -> Cow<'a, CStr> {
+        Cow::Borrowed(s)
+    }
+}
+
+#[stable(feature = "cow_from_cstr", since = "1.28.0")]
+impl<'a> From<&'a CString> for Cow<'a, CStr> {
+    #[inline]
+    fn from(s: &'a CString) -> Cow<'a, CStr> {
+        Cow::Borrowed(s.as_c_str())
+    }
+}
+
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<CString> for Arc<CStr> {
     #[inline]

src/libstd/ffi/os_str.rs

@@ -664,6 +664,38 @@ fn from(s: &OsStr) -> Rc<OsStr> {
     }
 }
 
+#[stable(feature = "cow_from_osstr", since = "1.28.0")]
+impl<'a> From<OsString> for Cow<'a, OsStr> {
+    #[inline]
+    fn from(s: OsString) -> Cow<'a, OsStr> {
+        Cow::Owned(s)
+    }
+}
+
+#[stable(feature = "cow_from_osstr", since = "1.28.0")]
+impl<'a> From<&'a OsStr> for Cow<'a, OsStr> {
+    #[inline]
+    fn from(s: &'a OsStr) -> Cow<'a, OsStr> {
+        Cow::Borrowed(s)
+    }
+}
+
+#[stable(feature = "cow_from_osstr", since = "1.28.0")]
+impl<'a> From<&'a OsString> for Cow<'a, OsStr> {
+    #[inline]
+    fn from(s: &'a OsString) -> Cow<'a, OsStr> {
+        Cow::Borrowed(s.as_os_str())
+    }
+}
+
+#[stable(feature = "osstring_from_cow_osstr", since = "1.28.0")]
+impl<'a> From<Cow<'a, OsStr>> for OsString {
+    #[inline]
+    fn from(s: Cow<'a, OsStr>) -> Self {
+        s.into_owned()
+    }
+}
+
 #[stable(feature = "box_default_extra", since = "1.17.0")]
 impl Default for Box<OsStr> {
     fn default() -> Box<OsStr> {

src/libstd/lib.rs

@@ -277,7 +277,6 @@
 #![feature(needs_panic_runtime)]
 #![feature(never_type)]
 #![feature(exhaustive_patterns)]
-#![feature(nonzero)]
 #![feature(num_bits_bytes)]
 #![feature(old_wrapping)]
 #![feature(on_unimplemented)]

src/libstd/num.rs

@@ -21,12 +21,8 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::num::Wrapping;
 
-#[unstable(feature = "nonzero", issue = "49137")]
-#[allow(deprecated)]
-pub use core::num::{
-    NonZeroU8, NonZeroI8, NonZeroU16, NonZeroI16, NonZeroU32, NonZeroI32,
-    NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize,
-};
+#[stable(feature = "nonzero", since = "1.28.0")]
+pub use core::num::{NonZeroU8, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU128, NonZeroUsize};
 
 #[cfg(test)] use fmt;
 #[cfg(test)] use ops::{Add, Sub, Mul, Div, Rem};

src/libstd/path.rs

@@ -1504,6 +1504,22 @@ fn from(s: PathBuf) -> Cow<'a, Path> {
     }
 }
 
+#[stable(feature = "cow_from_pathbuf_ref", since = "1.28.0")]
+impl<'a> From<&'a PathBuf> for Cow<'a, Path> {
+    #[inline]
+    fn from(p: &'a PathBuf) -> Cow<'a, Path> {
+        Cow::Borrowed(p.as_path())
+    }
+}
+
+#[stable(feature = "pathbuf_from_cow_path", since = "1.28.0")]
+impl<'a> From<Cow<'a, Path>> for PathBuf {
+    #[inline]
+    fn from(p: Cow<'a, Path>) -> Self {
+        p.into_owned()
+    }
+}
+
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<PathBuf> for Arc<Path> {
     #[inline]

src/libstd/sys/unix/fd.rs

@@ -154,6 +154,13 @@ unsafe fn cvt_pwrite64(fd: c_int, buf: *const c_void, count: usize, offset: i64)
         }
     }
 
+    #[cfg(target_os = "linux")]
+    pub fn get_cloexec(&self) -> io::Result<bool> {
+        unsafe {
+            Ok((cvt(libc::fcntl(self.fd, libc::F_GETFD))? & libc::FD_CLOEXEC) != 0)
+        }
+    }
+
     #[cfg(not(any(target_env = "newlib",
                   target_os = "solaris",
                   target_os = "emscripten",

src/libstd/sys/unix/fs.rs

@@ -441,15 +441,48 @@ pub fn open_c(path: &CStr, opts: &OpenOptions) -> io::Result<File> {
 
         // Currently the standard library supports Linux 2.6.18 which did not
         // have the O_CLOEXEC flag (passed above). If we're running on an older
-        // Linux kernel then the flag is just ignored by the OS, so we continue
-        // to explicitly ask for a CLOEXEC fd here.
+        // Linux kernel then the flag is just ignored by the OS. After we open
+        // the first file, we check whether it has CLOEXEC set. If it doesn't,
+        // we will explicitly ask for a CLOEXEC fd for every further file we
+        // open, if it does, we will skip that step.
         //
         // The CLOEXEC flag, however, is supported on versions of macOS/BSD/etc
         // that we support, so we only do this on Linux currently.
-        if cfg!(target_os = "linux") {
-            fd.set_cloexec()?;
+        #[cfg(target_os = "linux")]
+        fn ensure_cloexec(fd: &FileDesc) -> io::Result<()> {
+            use sync::atomic::{AtomicUsize, Ordering};
+
+            const OPEN_CLOEXEC_UNKNOWN: usize = 0;
+            const OPEN_CLOEXEC_SUPPORTED: usize = 1;
+            const OPEN_CLOEXEC_NOTSUPPORTED: usize = 2;
+            static OPEN_CLOEXEC: AtomicUsize = AtomicUsize::new(OPEN_CLOEXEC_UNKNOWN);
+
+            let need_to_set;
+            match OPEN_CLOEXEC.load(Ordering::Relaxed) {
+                OPEN_CLOEXEC_UNKNOWN => {
+                    need_to_set = !fd.get_cloexec()?;
+                    OPEN_CLOEXEC.store(if need_to_set {
+                        OPEN_CLOEXEC_NOTSUPPORTED
+                    } else {
+                        OPEN_CLOEXEC_SUPPORTED
+                    }, Ordering::Relaxed);
+                },
+                OPEN_CLOEXEC_SUPPORTED => need_to_set = false,
+                OPEN_CLOEXEC_NOTSUPPORTED => need_to_set = true,
+                _ => unreachable!(),
+            }
+            if need_to_set {
+                fd.set_cloexec()?;
+            }
+            Ok(())
+        }
+
+        #[cfg(not(target_os = "linux"))]
+        fn ensure_cloexec(_: &FileDesc) -> io::Result<()> {
+            Ok(())
         }
 
+        ensure_cloexec(&fd)?;
         Ok(File(fd))
     }
 

src/libstd/sys/unix/pipe.rs

@@ -100,24 +100,6 @@ pub fn read2(p1: AnonPipe,
         // wait for either pipe to become readable using `poll`
         cvt_r(|| unsafe { libc::poll(fds.as_mut_ptr(), 2, -1) })?;
 
-        // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
-        // EAGAIN. If we hit EOF, then this will happen because the underlying
-        // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
-        // this case we flip the other fd back into blocking mode and read
-        // whatever's leftover on that file descriptor.
-        let read = |fd: &FileDesc, dst: &mut Vec<u8>| {
-            match fd.read_to_end(dst) {
-                Ok(_) => Ok(true),
-                Err(e) => {
-                    if e.raw_os_error() == Some(libc::EWOULDBLOCK) ||
-                       e.raw_os_error() == Some(libc::EAGAIN) {
-                        Ok(false)
-                    } else {
-                        Err(e)
-                    }
-                }
-            }
-        };
         if fds[0].revents != 0 && read(&p1, v1)? {
             p2.set_nonblocking(false)?;
             return p2.read_to_end(v2).map(|_| ());
@@ -127,4 +109,23 @@ pub fn read2(p1: AnonPipe,
             return p1.read_to_end(v1).map(|_| ());
         }
     }
+
+    // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
+    // EAGAIN. If we hit EOF, then this will happen because the underlying
+    // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
+    // this case we flip the other fd back into blocking mode and read
+    // whatever's leftover on that file descriptor.
+    fn read(fd: &FileDesc, dst: &mut Vec<u8>) -> Result<bool, io::Error> {
+        match fd.read_to_end(dst) {
+            Ok(_) => Ok(true),
+            Err(e) => {
+                if e.raw_os_error() == Some(libc::EWOULDBLOCK) ||
+                   e.raw_os_error() == Some(libc::EAGAIN) {
+                    Ok(false)
+                } else {
+                    Err(e)
+                }
+            }
+        }
+    }
 }

src/libsyntax_ext/asm.rs

@@ -179,9 +179,11 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                     let (constraint, _str_style) = panictry!(p.parse_str());
 
                     if constraint.as_str().starts_with("=") {
-                        cx.span_err(p.prev_span, "input operand constraint contains '='");
+                        span_err_if_not_stage0!(cx, p.prev_span, E0662,
+                                                "input operand constraint contains '='");
                     } else if constraint.as_str().starts_with("+") {
-                        cx.span_err(p.prev_span, "input operand constraint contains '+'");
+                        span_err_if_not_stage0!(cx, p.prev_span, E0663,
+                                                "input operand constraint contains '+'");
                     }
 
                     panictry!(p.expect(&token::OpenDelim(token::Paren)));
@@ -203,7 +205,8 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                     if OPTIONS.iter().any(|&opt| s == opt) {
                         cx.span_warn(p.prev_span, "expected a clobber, found an option");
                     } else if s.as_str().starts_with("{") || s.as_str().ends_with("}") {
-                        cx.span_err(p.prev_span, "clobber should not be surrounded by braces");
+                        span_err_if_not_stage0!(cx, p.prev_span, E0664,
+                                                "clobber should not be surrounded by braces");
                     }
 
                     clobs.push(s);

src/libsyntax_ext/diagnostics.rs

@@ -38,6 +38,58 @@
 asm!("nop" : "r"(a));
 ```
 
+Considering that this would be a long explanation, we instead recommend you to
+take a look at the unstable book:
+https://doc.rust-lang.org/unstable-book/language-features/asm.html
+"##,
+
+E0662: r##"
+An invalid input operand constraint was passed to the `asm` macro (third line).
+
+Erroneous code example:
+
+```compile_fail,E0662
+asm!("xor %eax, %eax"
+     :
+     : "=test"("a")
+    );
+```
+
+Considering that this would be a long explanation, we instead recommend you to
+take a look at the unstable book:
+https://doc.rust-lang.org/unstable-book/language-features/asm.html
+"##,
+
+E0663: r##"
+An invalid input operand constraint was passed to the `asm` macro (third line).
+
+Erroneous code example:
+
+```compile_fail,E0663
+asm!("xor %eax, %eax"
+     :
+     : "+test"("a")
+    );
+```
+
+Considering that this would be a long explanation, we instead recommend you to
+take a look at the unstable book:
+https://doc.rust-lang.org/unstable-book/language-features/asm.html
+"##,
+
+E0664: r##"
+A clobber was surrounded by braces in the `asm` macro.
+
+Erroneous code example:
+
+```compile_fail,E0663
+asm!("mov $$0x200, %eax"
+     :
+     :
+     : "{eax}"
+    );
+```
+
 Considering that this would be a long explanation, we instead recommend you to
 take a look at the unstable book:
 https://doc.rust-lang.org/unstable-book/language-features/asm.html

src/test/run-make/cross-lang-lto/Makefile → src/test/run-make-fulldeps/cross-lang-lto/Makefile

@@ -2,7 +2,7 @@
 # min-llvm-version 4.0
 # ignore-mingw
 
--include ../../run-make-fulldeps/tools.mk
+-include ../tools.mk
 
 # This test makes sure that the expected .llvmbc sections for use by
 # linker-based LTO are available in object files when compiling with

src/test/run-pass/ctfe/tuple-struct-constructors.rs

@@ -10,11 +10,9 @@
 
 // https://github.com/rust-lang/rust/issues/41898
 
-#![feature(nonzero, const_fn)]
-extern crate core;
-use core::nonzero::NonZero;
+use std::num::NonZeroU64;
 
 fn main() {
-    const FOO: NonZero<u64> = unsafe { NonZero::new_unchecked(2) };
+    const FOO: NonZeroU64 = unsafe { NonZeroU64::new_unchecked(2) };
     if let FOO = FOO {}
 }

src/test/run-pass/enum-null-pointer-opt.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(nonzero, core)]
-
 use std::mem::size_of;
 use std::num::NonZeroUsize;
 use std::ptr::NonNull;

src/test/run-pass/rfc-1937-termination-trait/termination-trait-for-impl-termination.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(termination_trait_lib)]
+
+fn main() -> impl std::process::Termination { }

src/test/rustdoc-ui/deprecated-attrs.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-pass
+
+#![doc(no_default_passes, passes = "collapse-docs unindent-comments")]
+
+struct SomeStruct;
+
+pub struct OtherStruct;

src/test/rustdoc-ui/deprecated-attrs.stderr

+warning: the `#![doc(no_default_passes)]` attribute is considered deprecated
+  |
+  = warning: please see https://github.com/rust-lang/rust/issues/44136
+  = help: you may want to use `#![doc(document_private_items)]`
+
+warning: the `#![doc(passes = "...")]` attribute is considered deprecated
+  |
+  = warning: please see https://github.com/rust-lang/rust/issues/44136
+

src/test/rustdoc/universal-impl-trait.rs

@@ -8,10 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(universal_impl_trait)]
 #![crate_name = "foo"]
 
 use std::io::Read;
+use std::borrow::Borrow;
 
 // @has foo/fn.foo.html
 // @has - //pre 'foo('
@@ -51,3 +51,15 @@ pub fn qux(_qux: impl IntoIterator<Item = S<impl Read>>) {
 // @has - 'method</a>('
 // @matches - '_x: impl <a class="trait" href="[^"]+/trait\.Debug\.html"'
 impl<T> Trait for S<T> {}
+
+// @has foo/fn.much_universe.html
+// @matches - 'T:.+Borrow.+impl .+trait\.Trait\.html'
+// @matches - 'U:.+IntoIterator.+= impl.+Iterator\.html.+= impl.+Clone\.html'
+// @matches - '_: impl .+trait\.Read\.html.+ \+ .+trait\.Clone\.html'
+pub fn much_universe<
+    T: Borrow<impl Trait>,
+    U: IntoIterator<Item = impl Iterator<Item = impl Clone>>,
+>(
+    _: impl Read + Clone,
+) {
+}

src/test/ui/E0662.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-stage1
+
+#![feature(asm)]
+
+fn main() {
+    asm!("xor %eax, %eax"
+         :
+         : "=test"("a") //~ ERROR E0662
+        );
+}

src/test/ui/E0662.stderr

+error[E0662]: input operand constraint contains '='
+  --> $DIR/E0662.rs:18:12
+   |
+LL |          : "=test"("a") //~ ERROR E0662
+   |            ^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0662`.

src/test/ui/E0663.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-stage1
+
+#![feature(asm)]
+
+fn main() {
+    asm!("xor %eax, %eax"
+         :
+         : "+test"("a") //~ ERROR E0663
+        );
+}

src/test/ui/E0663.stderr

+error[E0663]: input operand constraint contains '+'
+  --> $DIR/E0663.rs:18:12
+   |
+LL |          : "+test"("a") //~ ERROR E0663
+   |            ^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0663`.

src/test/ui/E0664.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-stage1
+
+#![feature(asm)]
+
+fn main() {
+    asm!("mov $$0x200, %eax"
+         :
+         :
+         : "{eax}" //~ ERROR E0664
+        );
+}

src/test/ui/E0664.stderr

+error[E0664]: clobber should not be surrounded by braces
+  --> $DIR/E0664.rs:19:12
+   |
+LL |          : "{eax}" //~ ERROR E0664
+   |            ^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0664`.

src/test/ui/issue-50599.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    const N: u32 = 1_000;
+    const M: usize = (f64::from(N) * std::f64::LOG10_2) as usize; //~ ERROR cannot find value
+    let mut digits = [0u32; M];
+}

src/test/ui/issue-50599.stderr

+error[E0425]: cannot find value `LOG10_2` in module `std::f64`
+  --> $DIR/issue-50599.rs:13:48
+   |
+LL |     const M: usize = (f64::from(N) * std::f64::LOG10_2) as usize; //~ ERROR cannot find value
+   |                                                ^^^^^^^ not found in `std::f64`
+help: possible candidates are found in other modules, you can import them into scope
+   |
+LL | use std::f32::consts::LOG10_2;
+   |
+LL | use std::f64::consts::LOG10_2;
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0425`.

src/test/ui/print_type_sizes/niche-filling.rs

@@ -22,7 +22,6 @@
 // padding and overall computed sizes can be quite different.
 
 #![feature(start)]
-#![feature(nonzero)]
 #![allow(dead_code)]
 
 use std::num::NonZeroU32;

src/test/ui/rfc-1937-termination-trait/termination-trait-impl-trait.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Tests that an `impl Trait` that is not `impl Termination` will not work.
+fn main() -> impl Copy { }
+//~^ ERROR `main` has invalid return type `impl std::marker::Copy`

src/test/ui/rfc-1937-termination-trait/termination-trait-impl-trait.stderr

+error[E0277]: `main` has invalid return type `impl std::marker::Copy`
+  --> $DIR/termination-trait-impl-trait.rs:12:14
+   |
+LL | fn main() -> impl Copy { }
+   |              ^^^^^^^^^ `main` can only return types that implement `std::process::Termination`
+   |
+   = help: consider using `()`, or a `Result`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

src/tools/compiletest/src/main.rs

@@ -614,8 +614,8 @@ pub fn is_test(file_name: &OsString) -> bool {
 }
 
 pub fn make_test(config: &Config, testpaths: &TestPaths) -> test::TestDescAndFn {
-
     let early_props = if config.mode == Mode::RunMake {
+        // Allow `ignore` directives to be in the Makefile.
         EarlyProps::from_file(config, &testpaths.file.join("Makefile"))
     } else {
         EarlyProps::from_file(config, &testpaths.file)

src/tools/tidy/src/ui_tests.rs

@@ -10,32 +10,49 @@
 
 //! Tidy check to ensure that there are no stray `.stderr` files in UI test directories.
 
+use std::fs;
 use std::path::Path;
 
 pub fn check(path: &Path, bad: &mut bool) {
-    super::walk_many(&[&path.join("test/ui"), &path.join("test/ui-fulldeps")],
-                     &mut |_| false,
-                     &mut |file_path| {
-        if let Some(ext) = file_path.extension() {
-            if ext == "stderr" || ext == "stdout" {
-                // Test output filenames have the format:
-                // $testname.stderr
-                // $testname.$mode.stderr
-                // $testname.$revision.stderr
-                // $testname.$revision.$mode.stderr
-                //
-                // For now, just make sure that there is a corresponding
-                // $testname.rs file.
-                let testname = file_path.file_name().unwrap()
-                                        .to_str().unwrap()
-                                        .splitn(2, '.').next().unwrap();
-                if !file_path.with_file_name(testname)
-                             .with_extension("rs")
-                             .exists() {
-                    println!("Stray file with UI testing output: {:?}", file_path);
-                    *bad = true;
+    super::walk_many(
+        &[&path.join("test/ui"), &path.join("test/ui-fulldeps")],
+        &mut |_| false,
+        &mut |file_path| {
+            if let Some(ext) = file_path.extension() {
+                if ext == "stderr" || ext == "stdout" {
+                    // Test output filenames have the format:
+                    // $testname.stderr
+                    // $testname.$mode.stderr
+                    // $testname.$revision.stderr
+                    // $testname.$revision.$mode.stderr
+                    //
+                    // For now, just make sure that there is a corresponding
+                    // $testname.rs file.
+                    let testname = file_path
+                        .file_name()
+                        .unwrap()
+                        .to_str()
+                        .unwrap()
+                        .splitn(2, '.')
+                        .next()
+                        .unwrap();
+                    if !file_path
+                        .with_file_name(testname)
+                        .with_extension("rs")
+                        .exists()
+                    {
+                        println!("Stray file with UI testing output: {:?}", file_path);
+                        *bad = true;
+                    }
+
+                    if let Ok(metadata) = fs::metadata(file_path) {
+                        if metadata.len() == 0 {
+                            println!("Empty file with UI testing output: {:?}", file_path);
+                            *bad = true;
+                        }
+                    }
                 }
             }
-        }
-    });
+        },
+    );
 }