Auto merge of #45368 - kennytm:rollup, r=kennytm

Rollup of 10 pull requests

- Successful merges: #44138, #45082, #45098, #45181, #45217, #45281, #45325, #45326, #45340, #45354
- Failed merges:

23 files changed, 289 insertions, 122 deletions

diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 69e0f58f1cd..d6c83e3acfc 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -299,6 +299,7 @@ impl Config {
         let mut config = Config::default();
         config.llvm_enabled = true;
         config.llvm_optimize = true;
+        config.llvm_version_check = true;
         config.use_jemalloc = true;
         config.backtrace = true;
         config.rust_optimize = true;
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index 941ea96bbec..c37b1dad4c6 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -259,11 +259,14 @@ fn check_llvm_version(build: &Build, llvm_config: &Path) {
 
     let mut cmd = Command::new(llvm_config);
     let version = output(cmd.arg("--version"));
-    if version.starts_with("3.5") || version.starts_with("3.6") ||
-       version.starts_with("3.7") {
-        return
+    let mut parts = version.split('.').take(2)
+        .filter_map(|s| s.parse::<u32>().ok());
+    if let (Some(major), Some(minor)) = (parts.next(), parts.next()) {
+        if major > 3 || (major == 3 && minor >= 9) {
+            return
+        }
     }
-    panic!("\n\nbad LLVM version: {}, need >=3.5\n\n", version)
+    panic!("\n\nbad LLVM version: {}, need >=3.9\n\n", version)
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
diff --git a/src/ci/docker/x86_64-gnu-llvm-3.7/Dockerfile b/src/ci/docker/x86_64-gnu-llvm-3.9/Dockerfile
index e832a2445ba..6b818604898 100644
--- a/src/ci/docker/x86_64-gnu-llvm-3.7/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-llvm-3.9/Dockerfile
@@ -11,7 +11,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   cmake \
   sudo \
   gdb \
-  llvm-3.7-tools \
+  llvm-3.9-tools \
   libedit-dev \
   zlib1g-dev \
   xz-utils
@@ -19,7 +19,9 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+# using llvm-link-shared due to libffi issues -- see #34486
 ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
-      --llvm-root=/usr/lib/llvm-3.7
+      --llvm-root=/usr/lib/llvm-3.9 \
+      --enable-llvm-link-shared
 ENV RUST_CHECK_TARGET check
diff --git a/src/doc/unstable-book/src/language-features/lang-items.md b/src/doc/unstable-book/src/language-features/lang-items.md
index ecbc860e25c..0137a052a62 100644
--- a/src/doc/unstable-book/src/language-features/lang-items.md
+++ b/src/doc/unstable-book/src/language-features/lang-items.md
@@ -227,3 +227,95 @@ A third function, `rust_eh_unwind_resume`, is also needed if the `custom_unwind_
 flag is set in the options of the compilation target. It allows customizing the
 process of resuming unwind at the end of the landing pads. The language item's name
 is `eh_unwind_resume`.
+
+## List of all language items
+
+This is a list of all language items in Rust along with where they are located in
+the source code.
+
+- Primitives
+  - `i8`: `libcore/num/mod.rs`
+  - `i16`: `libcore/num/mod.rs`
+  - `i32`: `libcore/num/mod.rs`
+  - `i64`: `libcore/num/mod.rs`
+  - `i128`: `libcore/num/mod.rs`
+  - `isize`: `libcore/num/mod.rs`
+  - `u8`: `libcore/num/mod.rs`
+  - `u16`: `libcore/num/mod.rs`
+  - `u32`: `libcore/num/mod.rs`
+  - `u64`: `libcore/num/mod.rs`
+  - `u128`: `libcore/num/mod.rs`
+  - `usize`: `libcore/num/mod.rs`
+  - `f32`: `libstd/f32.rs`
+  - `f64`: `libstd/f64.rs`
+  - `char`: `libstd_unicode/char.rs`
+  - `slice`: `liballoc/slice.rs`
+  - `str`: `liballoc/str.rs`
+  - `const_ptr`: `libcore/ptr.rs`
+  - `mut_ptr`: `libcore/ptr.rs`
+  - `unsafe_cell`: `libcore/cell.rs`
+- Runtime
+  - `start`: `libstd/rt.rs`
+  - `eh_personality`: `libpanic_unwind/emcc.rs` (EMCC)
+  - `eh_personality`: `libpanic_unwind/seh64_gnu.rs` (SEH64 GNU)
+  - `eh_personality`: `libpanic_unwind/seh.rs` (SEH)
+  - `eh_unwind_resume`: `libpanic_unwind/seh64_gnu.rs` (SEH64 GNU)
+  - `eh_unwind_resume`: `libpanic_unwind/gcc.rs` (GCC)
+  - `msvc_try_filter`: `libpanic_unwind/seh.rs` (SEH)
+  - `panic`: `libcore/panicking.rs`
+  - `panic_bounds_check`: `libcore/panicking.rs`
+  - `panic_fmt`: `libcore/panicking.rs`
+  - `panic_fmt`: `libstd/panicking.rs`
+- Allocations
+  - `owned_box`: `liballoc/boxed.rs`
+  - `exchange_malloc`: `liballoc/heap.rs`
+  - `box_free`: `liballoc/heap.rs`
+- Operands
+  - `not`: `libcore/ops/bit.rs`
+  - `bitand`: `libcore/ops/bit.rs`
+  - `bitor`: `libcore/ops/bit.rs`
+  - `bitxor`: `libcore/ops/bit.rs`
+  - `shl`: `libcore/ops/bit.rs`
+  - `shr`: `libcore/ops/bit.rs`
+  - `bitand_assign`: `libcore/ops/bit.rs`
+  - `bitor_assign`: `libcore/ops/bit.rs`
+  - `bitxor_assign`: `libcore/ops/bit.rs`
+  - `shl_assign`: `libcore/ops/bit.rs`
+  - `shr_assign`: `libcore/ops/bit.rs`
+  - `deref`: `libcore/ops/deref.rs`
+  - `deref_mut`: `libcore/ops/deref.rs`
+  - `index`: `libcore/ops/index.rs`
+  - `index_mut`: `libcore/ops/index.rs`
+  - `add`: `libcore/ops/arith.rs`
+  - `sub`: `libcore/ops/arith.rs`
+  - `mul`: `libcore/ops/arith.rs`
+  - `div`: `libcore/ops/arith.rs`
+  - `rem`: `libcore/ops/arith.rs`
+  - `neg`: `libcore/ops/arith.rs`
+  - `add_assign`: `libcore/ops/arith.rs`
+  - `sub_assign`: `libcore/ops/arith.rs`
+  - `mul_assign`: `libcore/ops/arith.rs`
+  - `div_assign`: `libcore/ops/arith.rs`
+  - `rem_assign`: `libcore/ops/arith.rs`
+  - `eq`: `libcore/cmp.rs`
+  - `ord`: `libcore/cmp.rs`
+- Functions
+  - `fn`: `libcore/ops/function.rs`
+  - `fn_mut`: `libcore/ops/function.rs`
+  - `fn_once`: `libcore/ops/function.rs`
+  - `generator_state`: `libcore/ops/generator.rs`
+  - `generator`: `libcore/ops/generator.rs`
+- Other
+  - `coerce_unsized`: `libcore/ops/unsize.rs`
+  - `drop`: `libcore/ops/drop.rs`
+  - `drop_in_place`: `libcore/ptr.rs`
+  - `clone`: `libcore/clone.rs`
+  - `copy`: `libcore/marker.rs`
+  - `send`: `libcore/marker.rs`
+  - `sized`: `libcore/marker.rs`
+  - `unsize`: `libcore/marker.rs`
+  - `sync`: `libcore/marker.rs`
+  - `phantom_data`: `libcore/marker.rs`
+  - `freeze`: `libcore/marker.rs`
+  - `debug_trait`: `libcore/fmt/mod.rs`
+  - `non_zero`: `libcore/nonzero.rs`
\ No newline at end of file
diff --git a/src/doc/unstable-book/src/library-features/alloc-jemalloc.md b/src/doc/unstable-book/src/library-features/alloc-jemalloc.md
index 18ff838dd32..425d4cb79b2 100644
--- a/src/doc/unstable-book/src/library-features/alloc-jemalloc.md
+++ b/src/doc/unstable-book/src/library-features/alloc-jemalloc.md
@@ -8,55 +8,6 @@ See also [`alloc_system`](library-features/alloc-system.html).
 
 ------------------------
 
-The compiler currently ships two default allocators: `alloc_system` and
-`alloc_jemalloc` (some targets don't have jemalloc, however). These allocators
-are normal Rust crates and contain an implementation of the routines to
-allocate and deallocate memory. The standard library is not compiled assuming
-either one, and the compiler will decide which allocator is in use at
-compile-time depending on the type of output artifact being produced.
-
-Binaries generated by the compiler will use `alloc_jemalloc` by default (where
-available). In this situation the compiler "controls the world" in the sense of
-it has power over the final link. Primarily this means that the allocator
-decision can be left up the compiler.
-
-Dynamic and static libraries, however, will use `alloc_system` by default. Here
-Rust is typically a 'guest' in another application or another world where it
-cannot authoritatively decide what allocator is in use. As a result it resorts
-back to the standard APIs (e.g. `malloc` and `free`) for acquiring and releasing
-memory.
-
-# Switching Allocators
-
-Although the compiler's default choices may work most of the time, it's often
-necessary to tweak certain aspects. Overriding the compiler's decision about
-which allocator is in use is done simply by linking to the desired allocator:
-
-```rust,no_run
-#![feature(alloc_system)]
-
-extern crate alloc_system;
-
-fn main() {
-    let a = Box::new(4); // Allocates from the system allocator.
-    println!("{}", a);
-}
-```
-
-In this example the binary generated will not link to jemalloc by default but
-instead use the system allocator. Conversely to generate a dynamic library which
-uses jemalloc by default one would write:
-
-```rust,ignore
-#![feature(alloc_jemalloc)]
-#![crate_type = "dylib"]
-
-extern crate alloc_jemalloc;
-
-pub fn foo() {
-    let a = Box::new(4); // Allocates from jemalloc.
-    println!("{}", a);
-}
-# fn main() {}
-```
+This feature has been replaced by [the `jemallocator` crate on crates.io.][jemallocator].
 
+[jemallocator]: https://crates.io/crates/jemallocator
diff --git a/src/doc/unstable-book/src/library-features/alloc-system.md b/src/doc/unstable-book/src/library-features/alloc-system.md
index 1d261db6ba1..9effab202ca 100644
--- a/src/doc/unstable-book/src/library-features/alloc-system.md
+++ b/src/doc/unstable-book/src/library-features/alloc-system.md
@@ -1,10 +1,10 @@
 # `alloc_system`
 
-The tracking issue for this feature is: [#33082]
+The tracking issue for this feature is: [#32838]
 
-[#33082]: https://github.com/rust-lang/rust/issues/33082
+[#32838]: https://github.com/rust-lang/rust/issues/32838
 
-See also [`alloc_jemalloc`](library-features/alloc-jemalloc.html).
+See also [`global_allocator`](language-features/global-allocator.html).
 
 ------------------------
 
@@ -30,13 +30,18 @@ memory.
 
 Although the compiler's default choices may work most of the time, it's often
 necessary to tweak certain aspects. Overriding the compiler's decision about
-which allocator is in use is done simply by linking to the desired allocator:
+which allocator is in use is done through the `#[global_allocator]` attribute:
 
 ```rust,no_run
-#![feature(alloc_system)]
+#![feature(alloc_system, global_allocator, allocator_api)]
 
 extern crate alloc_system;
 
+use alloc_system::System;
+
+#[global_allocator]
+static A: System = System;
+
 fn main() {
     let a = Box::new(4); // Allocates from the system allocator.
     println!("{}", a);
@@ -47,11 +52,22 @@ In this example the binary generated will not link to jemalloc by default but
 instead use the system allocator. Conversely to generate a dynamic library which
 uses jemalloc by default one would write:
 
+(The `alloc_jemalloc` crate cannot be used to control the global allocator,
+crate.io’s `jemallocator` crate provides equivalent functionality.)
+
+```toml
+# Cargo.toml
+[dependencies]
+jemallocator = "0.1"
+```
 ```rust,ignore
-#![feature(alloc_jemalloc)]
+#![feature(global_allocator)]
 #![crate_type = "dylib"]
 
-extern crate alloc_jemalloc;
+extern crate jemallocator;
+
+#[global_allocator]
+static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
 
 pub fn foo() {
     let a = Box::new(4); // Allocates from jemalloc.
@@ -59,4 +75,3 @@ pub fn foo() {
 }
 # fn main() {}
 ```
-
diff --git a/src/liballoc_system/lib.rs b/src/liballoc_system/lib.rs
index 2eb659699eb..7aa5f8a9186 100644
--- a/src/liballoc_system/lib.rs
+++ b/src/liballoc_system/lib.rs
@@ -14,7 +14,7 @@
 #![unstable(feature = "alloc_system",
             reason = "this library is unlikely to be stabilized in its current \
                       form or name",
-            issue = "27783")]
+            issue = "32838")]
 #![feature(global_allocator)]
 #![feature(allocator_api)]
 #![feature(alloc)]
diff --git a/src/librustc/ich/impls_ty.rs b/src/librustc/ich/impls_ty.rs
index f719ce15092..50f7e4ba176 100644
--- a/src/librustc/ich/impls_ty.rs
+++ b/src/librustc/ich/impls_ty.rs
@@ -518,7 +518,7 @@ impl_stable_hash_for!(enum ty::cast::CastKind {
     FnPtrAddrCast
 });
 
-impl_stable_hash_for!(struct ::middle::region::FirstStatementIndex { idx });
+impl_stable_hash_for!(tuple_struct ::middle::region::FirstStatementIndex { idx });
 impl_stable_hash_for!(struct ::middle::region::Scope { id, code });
 
 impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for region::Scope {
diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs
index 635bcbf7771..fa4ee7c0092 100644
--- a/src/librustc/middle/region.rs
+++ b/src/librustc/middle/region.rs
@@ -156,26 +156,11 @@ pub struct BlockRemainder {
     pub first_statement_index: FirstStatementIndex,
 }
 
-#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, RustcEncodable,
-         RustcDecodable, Copy)]
-pub struct FirstStatementIndex { pub idx: u32 }
-
-impl Idx for FirstStatementIndex {
-    fn new(idx: usize) -> Self {
-        assert!(idx <= SCOPE_DATA_REMAINDER_MAX as usize);
-        FirstStatementIndex { idx: idx as u32 }
-    }
-
-    fn index(self) -> usize {
-        self.idx as usize
-    }
-}
-
-impl fmt::Debug for FirstStatementIndex {
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Debug::fmt(&self.index(), formatter)
-    }
-}
+newtype_index!(FirstStatementIndex
+    {
+        DEBUG_NAME = "",
+        MAX = SCOPE_DATA_REMAINDER_MAX,
+    });
 
 impl From<ScopeData> for Scope {
     #[inline]
@@ -208,7 +193,7 @@ impl Scope {
             SCOPE_DATA_DESTRUCTION => ScopeData::Destruction(self.id),
             idx => ScopeData::Remainder(BlockRemainder {
                 block: self.id,
-                first_statement_index: FirstStatementIndex { idx }
+                first_statement_index: FirstStatementIndex::new(idx as usize)
             })
         }
     }
diff --git a/src/librustc_data_structures/indexed_vec.rs b/src/librustc_data_structures/indexed_vec.rs
index 6c5a37aa1e5..1d1b367de20 100644
--- a/src/librustc_data_structures/indexed_vec.rs
+++ b/src/librustc_data_structures/indexed_vec.rs
@@ -65,7 +65,7 @@ macro_rules! newtype_index {
     (@type[$type:ident] @max[$max:expr] @debug_name[$debug_name:expr]) => (
         #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord,
             RustcEncodable, RustcDecodable)]
-        pub struct $type(u32);
+        pub struct $type(pub u32);
 
         impl Idx for $type {
             fn new(value: usize) -> Self {
@@ -99,7 +99,7 @@ macro_rules! newtype_index {
     // Replace existing default for max
     (@type[$type:ident] @max[$_max:expr] @debug_name[$debug_name:expr]
             MAX = $max:expr, $($tokens:tt)*) => (
-        newtype_index!(@type[$type] @max[$max] @debug_name[$debug_name] $(tokens)*);
+        newtype_index!(@type[$type] @max[$max] @debug_name[$debug_name] $($tokens)*);
     );
 
     // Replace existing default for debug_name
diff --git a/src/librustc_mir/diagnostics.rs b/src/librustc_mir/diagnostics.rs
index 98c5345c69d..0f67f7bf6de 100644
--- a/src/librustc_mir/diagnostics.rs
+++ b/src/librustc_mir/diagnostics.rs
@@ -320,20 +320,68 @@ Since `MyStruct` is a type that is not marked `Copy`, the data gets moved out
 of `x` when we set `y`. This is fundamental to Rust's ownership system: outside
 of workarounds like `Rc`, a value cannot be owned by more than one variable.
 
-If we own the type, the easiest way to address this problem is to implement
-`Copy` and `Clone` on it, as shown below. This allows `y` to copy the
-information in `x`, while leaving the original version owned by `x`. Subsequent
-changes to `x` will not be reflected when accessing `y`.
+Sometimes we don't need to move the value. Using a reference, we can let another
+function borrow the value without changing its ownership. In the example below,
+we don't actually have to move our string to `calculate_length`, we can give it
+a reference to it with `&` instead.
+
+```
+fn main() {
+    let s1 = String::from("hello");
+
+    let len = calculate_length(&s1);
+
+    println!("The length of '{}' is {}.", s1, len);
+}
+
+fn calculate_length(s: &String) -> usize {
+    s.len()
+}
+```
+
+A mutable reference can be created with `&mut`.
+
+Sometimes we don't want a reference, but a duplicate. All types marked `Clone`
+can be duplicated by calling `.clone()`. Subsequent changes to a clone do not
+affect the original variable.
+
+Most types in the standard library are marked `Clone`. The example below
+demonstrates using `clone()` on a string. `s1` is first set to "many", and then
+copied to `s2`. Then the first character of `s1` is removed, without affecting
+`s2`. "any many" is printed to the console.
+
+```
+fn main() {
+    let mut s1 = String::from("many");
+    let s2 = s1.clone();
+    s1.remove(0);
+    println!("{} {}", s1, s2);
+}
+```
+
+If we control the definition of a type, we can implement `Clone` on it ourselves
+with `#[derive(Clone)]`.
+
+Some types have no ownership semantics at all and are trivial to duplicate. An
+example is `i32` and the other number types. We don't have to call `.clone()` to
+clone them, because they are marked `Copy` in addition to `Clone`.  Implicit
+cloning is more convienient in this case. We can mark our own types `Copy` if
+all their members also are marked `Copy`.
+
+In the example below, we implement a `Point` type. Because it only stores two
+integers, we opt-out of ownership semantics with `Copy`. Then we can
+`let p2 = p1` without `p1` being moved.
 
 ```
 #[derive(Copy, Clone)]
-struct MyStruct { s: u32 }
+struct Point { x: i32, y: i32 }
 
 fn main() {
-    let mut x = MyStruct{ s: 5u32 };
-    let y = x;
-    x.s = 6;
-    println!("{}", x.s);
+    let mut p1 = Point{ x: -1, y: 2 };
+    let p2 = p1;
+    p1.x = 1;
+    println!("p1: {}, {}", p1.x, p1.y);
+    println!("p2: {}, {}", p2.x, p2.y);
 }
 ```
 
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index e217978648e..ad171c4babb 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -238,6 +238,7 @@ impl Clean<ExternalCrate> for CrateNum {
                             if prim.is_some() {
                                 break;
                             }
+                            // FIXME: should warn on unknown primitives?
                         }
                     }
                 }
@@ -1627,6 +1628,7 @@ pub enum PrimitiveType {
     Slice,
     Array,
     Tuple,
+    Unit,
     RawPointer,
     Reference,
     Fn,
@@ -1662,7 +1664,11 @@ impl Type {
             Primitive(p) | BorrowedRef { type_: box Primitive(p), ..} => Some(p),
             Slice(..) | BorrowedRef { type_: box Slice(..), .. } => Some(PrimitiveType::Slice),
             Array(..) | BorrowedRef { type_: box Array(..), .. } => Some(PrimitiveType::Array),
-            Tuple(..) => Some(PrimitiveType::Tuple),
+            Tuple(ref tys) => if tys.is_empty() {
+                Some(PrimitiveType::Unit)
+            } else {
+                Some(PrimitiveType::Tuple)
+            },
             RawPointer(..) => Some(PrimitiveType::RawPointer),
             BorrowedRef { type_: box Generic(..), .. } => Some(PrimitiveType::Reference),
             BareFunction(..) => Some(PrimitiveType::Fn),
@@ -1708,7 +1714,11 @@ impl GetDefId for Type {
             BorrowedRef { type_: box Generic(..), .. } =>
                 Primitive(PrimitiveType::Reference).def_id(),
             BorrowedRef { ref type_, .. } => type_.def_id(),
-            Tuple(..) => Primitive(PrimitiveType::Tuple).def_id(),
+            Tuple(ref tys) => if tys.is_empty() {
+                Primitive(PrimitiveType::Unit).def_id()
+            } else {
+                Primitive(PrimitiveType::Tuple).def_id()
+            },
             BareFunction(..) => Primitive(PrimitiveType::Fn).def_id(),
             Slice(..) => Primitive(PrimitiveType::Slice).def_id(),
             Array(..) => Primitive(PrimitiveType::Array).def_id(),
@@ -1742,6 +1752,7 @@ impl PrimitiveType {
             "array" => Some(PrimitiveType::Array),
             "slice" => Some(PrimitiveType::Slice),
             "tuple" => Some(PrimitiveType::Tuple),
+            "unit" => Some(PrimitiveType::Unit),
             "pointer" => Some(PrimitiveType::RawPointer),
             "reference" => Some(PrimitiveType::Reference),
             "fn" => Some(PrimitiveType::Fn),
@@ -1772,6 +1783,7 @@ impl PrimitiveType {
             Array => "array",
             Slice => "slice",
             Tuple => "tuple",
+            Unit => "unit",
             RawPointer => "pointer",
             Reference => "reference",
             Fn => "fn",
@@ -2693,6 +2705,7 @@ fn build_deref_target_impls(cx: &DocContext,
             Slice => tcx.lang_items().slice_impl(),
             Array => tcx.lang_items().slice_impl(),
             Tuple => None,
+            Unit => None,
             RawPointer => tcx.lang_items().const_ptr_impl(),
             Reference => None,
             Fn => None,
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 6303fd662bf..18d6b1cc1e0 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -614,7 +614,7 @@ fn fmt_type(t: &clean::Type, f: &mut fmt::Formatter, use_absolute: bool) -> fmt:
         }
         clean::Tuple(ref typs) => {
             match &typs[..] {
-                &[] => primitive_link(f, PrimitiveType::Tuple, "()"),
+                &[] => primitive_link(f, PrimitiveType::Unit, "()"),
                 &[ref one] => {
                     primitive_link(f, PrimitiveType::Tuple, "(")?;
                     //carry f.alternate() into this display w/o branching manually
diff --git a/src/librustdoc/html/static/main.js b/src/librustdoc/html/static/main.js
index 8f7cd244c2f..e9a3cfd908e 100644
--- a/src/librustdoc/html/static/main.js
+++ b/src/librustdoc/html/static/main.js
@@ -39,6 +39,13 @@
                      "associatedconstant",
                      "union"];
 
+    // On the search screen, so you remain on the last tab you opened.
+    //
+    // 0 for "Types/modules"
+    // 1 for "As parameters"
+    // 2 for "As return value"
+    var currentTab = 0;
+
     function hasClass(elem, className) {
         if (elem && className && elem.className) {
             var elemClass = elem.className;
@@ -758,7 +765,7 @@
 
             var output = '';
             if (array.length > 0) {
-                output = `<table class="search-results"${extraStyle}>`;
+                output = '<table class="search-results"' + extraStyle + '>';
                 var shown = [];
 
                 array.forEach(function(item) {
@@ -812,7 +819,7 @@
                 });
                 output += '</table>';
             } else {
-                output = `<div class="search-failed"${extraStyle}>No results :(<br/>` +
+                output = '<div class="search-failed"' + extraStyle + '>No results :(<br/>' +
                     'Try on <a href="https://duckduckgo.com/?q=' +
                     encodeURIComponent('rust ' + query.query) +
                     '">DuckDuckGo</a>?</div>';
@@ -820,6 +827,13 @@
             return output;
         }
 
+        function makeTabHeader(tabNb, text) {
+            if (currentTab === tabNb) {
+                return '<div class="selected">' + text + '</div>';
+            }
+            return '<div>' + text + '</div>';
+        }
+
         function showResults(results) {
             var output, query = getQuery();
 
@@ -827,9 +841,10 @@
             output = '<h1>Results for ' + escape(query.query) +
                 (query.type ? ' (type: ' + escape(query.type) + ')' : '') + '</h1>' +
                 '<div id="titles">' +
-                '<div class="selected">Types/modules</div>' +
-                '<div>As parameters</div>' +
-                '<div>As return value</div></div><div id="results">';
+                makeTabHeader(0, "Types/modules") +
+                makeTabHeader(1, "As parameters") +
+                makeTabHeader(2, "As return value") +
+                '</div><div id="results">';
 
             output += addTab(results['others'], query);
             output += addTab(results['in_args'], query, false);
@@ -1405,6 +1420,9 @@
 
     // In the search display, allows to switch between tabs.
     function printTab(nb) {
+        if (nb === 0 || nb === 1 || nb === 2) {
+            currentTab = nb;
+        }
         var nb_copy = nb;
         onEach(document.getElementById('titles').childNodes, function(elem) {
             if (nb_copy === 0) {
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 890e1169c05..20da99a6b13 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -170,6 +170,9 @@ pub fn opts() -> Vec<RustcOptGroup> {
         stable("no-default", |o| {
             o.optflag("", "no-defaults", "don't run the default passes")
         }),
+        stable("document-private-items", |o| {
+            o.optflag("", "document-private-items", "document private items")
+        }),
         stable("test", |o| o.optflag("", "test", "run code examples as tests")),
         stable("test-args", |o| {
             o.optmulti("", "test-args", "arguments to pass to the test runner",
@@ -275,6 +278,9 @@ pub fn main_args(args: &[String]) -> isize {
     // Check for unstable options.
     nightly_options::check_nightly_options(&matches, &opts());
 
+    // check for deprecated options
+    check_deprecated_options(&matches);
+
     if matches.opt_present("h") || matches.opt_present("help") {
         usage("rustdoc");
         return 0;
@@ -458,6 +464,18 @@ where R: 'static + Send, F: 'static + Send + FnOnce(Output) -> R {
     let mut passes = matches.opt_strs("passes");
     let mut plugins = matches.opt_strs("plugins");
 
+    // We hardcode in the passes here, as this is a new flag and we
+    // are generally deprecating passes.
+    if matches.opt_present("document-private-items") {
+        default_passes = false;
+
+        passes = vec![
+            String::from("strip-hidden"),
+            String::from("collapse-docs"),
+            String::from("unindent-comments"),
+        ];
+    }
+
     // First, parse the crate and extract all relevant information.
     let mut paths = SearchPaths::new();
     for s in &matches.opt_strs("L") {
@@ -550,3 +568,26 @@ where R: 'static + Send, F: 'static + Send + FnOnce(Output) -> R {
     });
     rx.recv().unwrap()
 }
+
+/// Prints deprecation warnings for deprecated options
+fn check_deprecated_options(matches: &getopts::Matches) {
+    let deprecated_flags = [
+       "input-format",
+       "output-format",
+       "plugin-path",
+       "plugins",
+       "no-defaults",
+       "passes",
+    ];
+
+    for flag in deprecated_flags.into_iter() {
+        if matches.opt_present(flag) {
+            eprintln!("WARNING: the '{}' flag is considered deprecated", flag);
+            eprintln!("WARNING: please see https://github.com/rust-lang/rust/issues/44136");
+        }
+    }
+
+    if matches.opt_present("no-defaults") {
+        eprintln!("WARNING: (you may want to use --document-private-items)");
+    }
+}
diff --git a/src/libstd/thread/local.rs b/src/libstd/thread/local.rs
index a53c76a333a..cb18eed8ee5 100644
--- a/src/libstd/thread/local.rs
+++ b/src/libstd/thread/local.rs
@@ -325,7 +325,10 @@ impl<T: 'static> LocalKey<T> {
     ///
     /// Once the initialization expression succeeds, the key transitions to the
     /// `Valid` state which will guarantee that future calls to [`with`] will
-    /// succeed within the thread.
+    /// succeed within the thread. Some keys might skip the `Uninitialized`
+    /// state altogether and start in the `Valid` state as an optimization
+    /// (e.g. keys initialized with a constant expression), but no guarantees
+    /// are made.
     ///
     /// When a thread exits, each key will be destroyed in turn, and as keys are
     /// destroyed they will enter the `Destroyed` state just before the
diff --git a/src/test/codegen/abi-x86-interrupt.rs b/src/test/codegen/abi-x86-interrupt.rs
index 838cd4bf6d7..e0b37cb2f32 100644
--- a/src/test/codegen/abi-x86-interrupt.rs
+++ b/src/test/codegen/abi-x86-interrupt.rs
@@ -14,7 +14,6 @@
 
 // ignore-arm
 // ignore-aarch64
-// min-llvm-version 3.8
 
 // compile-flags: -C no-prepopulate-passes
 
diff --git a/src/test/codegen/mainsubprogram.rs b/src/test/codegen/mainsubprogram.rs
index 657f4b662f7..f0508bc90f2 100644
--- a/src/test/codegen/mainsubprogram.rs
+++ b/src/test/codegen/mainsubprogram.rs
@@ -8,14 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// The minimum LLVM version is set to 3.8, but really this test
-// depends on a patch that is was committed to upstream LLVM before
-// 4.0; and also backported to the Rust LLVM fork.
+// This test depends on a patch that was committed to upstream LLVM
+// before 4.0, formerly backported to the Rust LLVM fork.
 
 // ignore-tidy-linelength
 // ignore-windows
 // ignore-macos
-// min-llvm-version 3.8
+// min-llvm-version 4.0
 
 // compile-flags: -g -C no-prepopulate-passes
 
diff --git a/src/test/codegen/mainsubprogramstart.rs b/src/test/codegen/mainsubprogramstart.rs
index cd34a1670dc..8325318f9af 100644
--- a/src/test/codegen/mainsubprogramstart.rs
+++ b/src/test/codegen/mainsubprogramstart.rs
@@ -8,14 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// The minimum LLVM version is set to 3.8, but really this test
-// depends on a patch that is was committed to upstream LLVM before
-// 4.0; and also backported to the Rust LLVM fork.
+// This test depends on a patch that was committed to upstream LLVM
+// before 4.0, formerly backported to the Rust LLVM fork.
 
 // ignore-tidy-linelength
 // ignore-windows
 // ignore-macos
-// min-llvm-version 3.8
+// min-llvm-version 4.0
 
 // compile-flags: -g -C no-prepopulate-passes
 
diff --git a/src/test/run-pass/issue-36023.rs b/src/test/run-pass/issue-36023.rs
index 53a8a403b64..f6c03b384f2 100644
--- a/src/test/run-pass/issue-36023.rs
+++ b/src/test/run-pass/issue-36023.rs
@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// min-llvm-version 3.9
-
 use std::ops::Deref;
 
 fn main() {
diff --git a/src/test/rustdoc/empty-mod-private.rs b/src/test/rustdoc/empty-mod-private.rs
index 6b86af62a66..6c6af19be88 100644
--- a/src/test/rustdoc/empty-mod-private.rs
+++ b/src/test/rustdoc/empty-mod-private.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 // ignore-tidy-linelength
-// compile-flags: --no-defaults --passes collapse-docs --passes unindent-comments --passes strip-priv-imports
+// compile-flags: --document-private-items
 
 // @has 'empty_mod_private/index.html' '//a[@href="foo/index.html"]' 'foo'
 // @has 'empty_mod_private/sidebar-items.js' 'foo'
diff --git a/src/test/rustdoc/issue-15347.rs b/src/test/rustdoc/issue-15347.rs
index 266a3089194..c50df6edd48 100644
--- a/src/test/rustdoc/issue-15347.rs
+++ b/src/test/rustdoc/issue-15347.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags:--no-defaults --passes collapse-docs --passes unindent-comments
+// compile-flags: --no-defaults --passes collapse-docs --passes unindent-comments
 
 // @has issue_15347/fn.foo.html
 #[doc(hidden)]
diff --git a/src/test/rustdoc/pub-method.rs b/src/test/rustdoc/pub-method.rs
index 5998734e4a2..24d566e082e 100644
--- a/src/test/rustdoc/pub-method.rs
+++ b/src/test/rustdoc/pub-method.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 // ignore-tidy-linelength
-// compile-flags: --no-defaults --passes collapse-docs --passes unindent-comments --passes strip-priv-imports
+// compile-flags: --document-private-items
 
 #![crate_name = "foo"]