Auto merge of #75388 - JohnTitor:rollup-9tgkxnl, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - #74744 (Update RELEASES.md for 1.46.0)
 - #75085 (Transmute big endian `s6_addr` and `[u16; 8]`)
 - #75226 (Miri: Renamed "undef" to "uninit")
 - #75333 (polymorphize: constrain unevaluated const handling)
 - #75338 (move stack size check to const_eval machine)
 - #75347 (Rustdoc: Fix natural ordering to look at all numbers.)
 - #75352 (Tweak conditions for E0026 and E0769)
 - #75353 (Tiny cleanup, remove unnecessary `unwrap`)
 - #75359 (unused_delims: trim expr)
 - #75360 (Add sample fix for E0749)

Failed merges:

r? @ghost

Author: bors

RELEASES.md

@@ -1,3 +1,104 @@
+Version 1.46.0 (2020-08-27)
+==========================
+
+Language
+--------
+- [`if`, `match`, and `loop` expressions can now be used in const functions.][72437]
+- [Additionally you are now also able to coerce and cast to slices (`&[T]`) in
+  const functions.][73862]
+- [The `#[track_caller]` attribute can now be added to functions to use the
+  function's caller's location information for panic messages.][72445]
+- [Recursively indexing into tuples no longer needs parentheses.][71322] E.g.
+  `x.0.0` over `(x.0).0`.
+- [`mem::transmute` can now be used in static and constants.][72920] **Note**
+  You currently can't use `mem::transmute` in constant functions.
+
+Compiler
+--------
+- [You can now use the `cdylib` target on Apple iOS and tvOS platforms.][73516]
+- [Enabled static "Position Independent Executables" by default
+  for `x86_64-unknown-linux-musl`.][70740]
+
+Libraries
+---------
+- [`mem::forget` is now a `const fn`.][73887]
+- [`String` now implements `From<char>`.][73466]
+- [The `leading_ones`, and `trailing_ones` methods have been stabilised for all
+  integer types.][73032]
+- [`vec::IntoIter<T>` now implements `AsRef<[T]>`.][72583]
+- [All non-zero integer types (`NonZeroU8`) now implement `TryFrom` for their
+  zero-able equivalent (e.g. `TryFrom<u8>`).][72717]
+- [`&[T]` and `&mut [T]` now implement `PartialEq<Vec<T>>`.][71660]
+- [`(String, u16)` now implements `ToSocketAddrs`.][73007]
+- [`vec::Drain<'_, T>` now implements `AsRef<[T]>`.][72584]
+
+Stabilized APIs
+---------------
+- [`Option::zip`]
+- [`vec::Drain::as_slice`]
+
+Cargo
+-----
+Added a number of new environment variables that are now available when
+compiling your crate.
+
+- [`CARGO_BIN_NAME` and `CARGO_CRATE_NAME`][cargo/8270] Providing the name of
+  the specific binary being compiled and the name of the crate.
+- [`CARGO_PKG_LICENSE`][cargo/8325] The license from the manifest of the package.
+- [`CARGO_PKG_LICENSE_FILE`][cargo/8387] The path to the license file.
+
+Compatibility Notes
+-------------------
+- [The target configuration option `abi_blacklist` has been renamed
+  to `unsupported_abis`.][74150] The old name will still continue to work.
+- [Rustc will now warn if you have a C-like enum that implements `Drop`.][72331]
+  This was previously accepted but will become a hard error in a future release.
+- [Rustc will fail to compile if you have a struct with
+  `#[repr(i128)]` or `#[repr(u128)]`.][74109] This representation is currently only
+  allowed on `enum`s.
+- [Tokens passed to `macro_rules!` are now always captured.][73293] This helps
+  ensure that spans have the correct information, and may cause breakage if you
+  were relying on receiving spans with dummy information.
+- [The InnoSetup installer for Windows is no longer available.][72569] This was
+  a legacy installer that was replaced by a MSI installer a few years ago but
+  was still being built.
+- [`{f32, f64}::asinh` now returns the correct values for negative numbers.][72486]
+- [Rustc will no longer accept overlapping trait implementations that only
+  differ in how the lifetime was bound.][72493]
+- [Rustc now correctly relates the lifetime of an existential associated
+  type.][71896] This fixes some edge cases where `rustc` would erroneously allow
+  you to pass a shorter lifetime than expected.
+
+[74109]: https://github.com/rust-lang/rust/pull/74109/
+[74150]: https://github.com/rust-lang/rust/pull/74150/
+[73862]: https://github.com/rust-lang/rust/pull/73862/
+[73887]: https://github.com/rust-lang/rust/pull/73887/
+[73466]: https://github.com/rust-lang/rust/pull/73466/
+[73516]: https://github.com/rust-lang/rust/pull/73516/
+[73293]: https://github.com/rust-lang/rust/pull/73293/
+[73007]: https://github.com/rust-lang/rust/pull/73007/
+[73032]: https://github.com/rust-lang/rust/pull/73032/
+[72920]: https://github.com/rust-lang/rust/pull/72920/
+[72569]: https://github.com/rust-lang/rust/pull/72569/
+[72583]: https://github.com/rust-lang/rust/pull/72583/
+[72584]: https://github.com/rust-lang/rust/pull/72584/
+[72717]: https://github.com/rust-lang/rust/pull/72717/
+[72437]: https://github.com/rust-lang/rust/pull/72437/
+[72445]: https://github.com/rust-lang/rust/pull/72445/
+[72486]: https://github.com/rust-lang/rust/pull/72486/
+[72493]: https://github.com/rust-lang/rust/pull/72493/
+[72331]: https://github.com/rust-lang/rust/pull/72331/
+[71896]: https://github.com/rust-lang/rust/pull/71896/
+[71660]: https://github.com/rust-lang/rust/pull/71660/
+[71322]: https://github.com/rust-lang/rust/pull/71322/
+[70740]: https://github.com/rust-lang/rust/pull/70740/
+[cargo/8270]: https://github.com/rust-lang/cargo/pull/8270/
+[cargo/8325]: https://github.com/rust-lang/cargo/pull/8325/
+[cargo/8387]: https://github.com/rust-lang/cargo/pull/8387/
+[`Option::zip`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.zip
+[`vec::Drain::as_slice`]: https://doc.rust-lang.org/stable/std/vec/struct.Drain.html#method.as_slice
+
+
 Version 1.45.2 (2020-08-03)
 ==========================
 
@@ -7,6 +108,7 @@ Version 1.45.2 (2020-08-03)
 [74954]: https://github.com/rust-lang/rust/issues/74954
 [74784]: https://github.com/rust-lang/rust/issues/74784
 
+
 Version 1.45.1 (2020-07-30)
 ==========================
 
@@ -20,6 +122,7 @@ Version 1.45.1 (2020-07-30)
 [74509]: https://github.com/rust-lang/rust/pull/74509
 [74457]: https://github.com/rust-lang/rust/pull/74457
 
+
 Version 1.45.0 (2020-07-16)
 ==========================
 

library/std/src/lib.rs

@@ -249,6 +249,7 @@
 #![feature(clamp)]
 #![feature(concat_idents)]
 #![feature(const_cstr_unchecked)]
+#![feature(const_fn_transmute)]
 #![feature(const_raw_ptr_deref)]
 #![feature(container_error_extra)]
 #![feature(core_intrinsics)]

library/std/src/net/ip.rs

@@ -10,6 +10,7 @@ use crate::cmp::Ordering;
 use crate::fmt::{self, Write as FmtWrite};
 use crate::hash;
 use crate::io::Write as IoWrite;
+use crate::mem::transmute;
 use crate::sys::net::netc as c;
 use crate::sys_common::{AsInner, FromInner};
 
@@ -1045,27 +1046,23 @@ impl Ipv6Addr {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_ipv6", since = "1.32.0")]
+    #[allow_internal_unstable(const_fn_transmute)]
     pub const fn new(a: u16, b: u16, c: u16, d: u16, e: u16, f: u16, g: u16, h: u16) -> Ipv6Addr {
+        let addr16 = [
+            a.to_be(),
+            b.to_be(),
+            c.to_be(),
+            d.to_be(),
+            e.to_be(),
+            f.to_be(),
+            g.to_be(),
+            h.to_be(),
+        ];
         Ipv6Addr {
             inner: c::in6_addr {
-                s6_addr: [
-                    (a >> 8) as u8,
-                    a as u8,
-                    (b >> 8) as u8,
-                    b as u8,
-                    (c >> 8) as u8,
-                    c as u8,
-                    (d >> 8) as u8,
-                    d as u8,
-                    (e >> 8) as u8,
-                    e as u8,
-                    (f >> 8) as u8,
-                    f as u8,
-                    (g >> 8) as u8,
-                    g as u8,
-                    (h >> 8) as u8,
-                    h as u8,
-                ],
+                // All elements in `addr16` are big endian.
+                // SAFETY: `[u16; 8]` is always safe to transmute to `[u8; 16]`.
+                s6_addr: unsafe { transmute::<_, [u8; 16]>(addr16) },
             },
         }
     }
@@ -1108,16 +1105,19 @@ impl Ipv6Addr {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn segments(&self) -> [u16; 8] {
-        let arr = &self.inner.s6_addr;
+        // All elements in `s6_addr` must be big endian.
+        // SAFETY: `[u8; 16]` is always safe to transmute to `[u16; 8]`.
+        let [a, b, c, d, e, f, g, h] = unsafe { transmute::<_, [u16; 8]>(self.inner.s6_addr) };
+        // We want native endian u16
         [
-            u16::from_be_bytes([arr[0], arr[1]]),
-            u16::from_be_bytes([arr[2], arr[3]]),
-            u16::from_be_bytes([arr[4], arr[5]]),
-            u16::from_be_bytes([arr[6], arr[7]]),
-            u16::from_be_bytes([arr[8], arr[9]]),
-            u16::from_be_bytes([arr[10], arr[11]]),
-            u16::from_be_bytes([arr[12], arr[13]]),
-            u16::from_be_bytes([arr[14], arr[15]]),
+            u16::from_be(a),
+            u16::from_be(b),
+            u16::from_be(c),
+            u16::from_be(d),
+            u16::from_be(e),
+            u16::from_be(f),
+            u16::from_be(g),
+            u16::from_be(h),
         ]
     }
 

src/librustc_codegen_llvm/consts.rs

@@ -41,15 +41,15 @@ pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll
             // some arbitrary byte value.
             //
             // FIXME: relay undef bytes to codegen as undef const bytes
-            let bytes = alloc.inspect_with_undef_and_ptr_outside_interpreter(next_offset..offset);
+            let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(next_offset..offset);
             llvals.push(cx.const_bytes(bytes));
         }
         let ptr_offset = read_target_uint(
             dl.endian,
             // This `inspect` is okay since it is within the bounds of the allocation, it doesn't
             // affect interpreter execution (we inspect the result after interpreter execution),
             // and we properly interpret the relocation as a relocation pointer offset.
-            alloc.inspect_with_undef_and_ptr_outside_interpreter(offset..(offset + pointer_size)),
+            alloc.inspect_with_uninit_and_ptr_outside_interpreter(offset..(offset + pointer_size)),
         )
         .expect("const_alloc_to_llvm: could not read relocation pointer")
             as u64;
@@ -74,7 +74,7 @@ pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll
         // arbitrary byte value.
         //
         // FIXME: relay undef bytes to codegen as undef const bytes
-        let bytes = alloc.inspect_with_undef_and_ptr_outside_interpreter(range);
+        let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(range);
         llvals.push(cx.const_bytes(bytes));
     }
 
@@ -452,7 +452,7 @@ impl StaticMethods for CodegenCx<'ll, 'tcx> {
                     // BSS.
                     let all_bytes_are_zero = alloc.relocations().is_empty()
                         && alloc
-                            .inspect_with_undef_and_ptr_outside_interpreter(0..alloc.len())
+                            .inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len())
                             .iter()
                             .all(|&byte| byte == 0);
 
@@ -480,7 +480,7 @@ impl StaticMethods for CodegenCx<'ll, 'tcx> {
                     // because we are doing this access to inspect the final interpreter state (not
                     // as part of the interpreter execution).
                     let bytes =
-                        alloc.inspect_with_undef_and_ptr_outside_interpreter(0..alloc.len());
+                        alloc.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len());
                     let alloc = llvm::LLVMMDStringInContext(
                         self.llcx,
                         bytes.as_ptr().cast(),

src/librustc_error_codes/error_codes/E0749.md

@@ -11,9 +11,19 @@ trait MyTrait {
 impl !MyTrait for u32 {
     type Foo = i32; // error!
 }
-# fn main() {}
 ```
 
 Negative impls are not allowed to have any items. Negative impls declare that a
 trait is **not** implemented (and never will be) and hence there is no need to
 specify the values for trait methods or other items.
+
+One way to fix this is to remove the items in negative impls:
+
+```
+# #![feature(negative_impls)]
+trait MyTrait {
+    type Foo;
+}
+
+impl !MyTrait for u32 {}
+```

src/librustc_lint/unused.rs

@@ -481,25 +481,27 @@ trait UnusedDelimLint {
             let mut err = lint.build(&span_msg);
             let mut ate_left_paren = false;
             let mut ate_right_paren = false;
-            let parens_removed = pattern.trim_matches(|c| match c {
-                '(' | '{' => {
-                    if ate_left_paren {
-                        false
-                    } else {
-                        ate_left_paren = true;
-                        true
+            let parens_removed = pattern
+                .trim_matches(|c| match c {
+                    '(' | '{' => {
+                        if ate_left_paren {
+                            false
+                        } else {
+                            ate_left_paren = true;
+                            true
+                        }
                     }
-                }
-                ')' | '}' => {
-                    if ate_right_paren {
-                        false
-                    } else {
-                        ate_right_paren = true;
-                        true
+                    ')' | '}' => {
+                        if ate_right_paren {
+                            false
+                        } else {
+                            ate_right_paren = true;
+                            true
+                        }
                     }
-                }
-                _ => false,
-            });
+                    _ => false,
+                })
+                .trim();
 
             let replace = {
                 let mut replace = if keep_space.0 {