Auto merge of #53433 - kennytm:rollup, r=kennytm

Rollup of 10 pull requests

Successful merges:

 - #52946 (Documented impl From on line 367 of libserialize/json.rs)
 - #53234 (Remove Travis shutdown debug scripts, and remove CI-specific DNS settings)
 - #53313 (Two small improvements)
 - #53360 (Addressed #51602)
 - #53364 (Warn if the user tries to use GATs)
 - #53373 (Tweak unclosed delimiter parser error)
 - #53377 (std: Use target_pointer_width for BACKTRACE_ELF_SIZE)
 - #53395 (Use #[non_exhaustive] on internal enums)
 - #53399 (Tidy: ignore non-Markdown files when linting for the Unstable Book)
 - #53412 (syntax_ext: remove leftover span_err_if_not_stage0 macro.)

4 files changed, 13 insertions, 20 deletions

diff --git a/src/libstd/build.rs b/src/libstd/build.rs
index 26d93f97e69..016e7adb4c9 100644
--- a/src/libstd/build.rs
+++ b/src/libstd/build.rs
@@ -104,7 +104,8 @@ fn build_libbacktrace(target: &str) -> Result<(), ()> {
     } else {
         build.file("../libbacktrace/elf.c");
 
-        if target.contains("64") {
+        let pointer_width = env::var("CARGO_CFG_TARGET_POINTER_WIDTH").unwrap();
+        if pointer_width == "64" {
             build.define("BACKTRACE_ELF_SIZE", "64");
         } else {
             build.define("BACKTRACE_ELF_SIZE", "32");
diff --git a/src/libstd/io/error.rs b/src/libstd/io/error.rs
index 02a3ce8b9c4..3e50988a68b 100644
--- a/src/libstd/io/error.rs
+++ b/src/libstd/io/error.rs
@@ -97,6 +97,7 @@ struct Custom {
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow(deprecated)]
+#[non_exhaustive]
 pub enum ErrorKind {
     /// An entity was not found, often a file.
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -180,15 +181,6 @@ pub enum ErrorKind {
     /// read.
     #[stable(feature = "read_exact", since = "1.6.0")]
     UnexpectedEof,
-
-    /// A marker variant that tells the compiler that users of this enum cannot
-    /// match it exhaustively.
-    #[unstable(feature = "io_error_internals",
-               reason = "better expressed through extensible enums that this \
-                         enum cannot be exhaustively matched against",
-               issue = "0")]
-    #[doc(hidden)]
-    __Nonexhaustive,
 }
 
 impl ErrorKind {
@@ -212,7 +204,6 @@ impl ErrorKind {
             ErrorKind::Interrupted => "operation interrupted",
             ErrorKind::Other => "other os error",
             ErrorKind::UnexpectedEof => "unexpected end of file",
-            ErrorKind::__Nonexhaustive => unreachable!()
         }
     }
 }
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index 5d463225ae9..60ad330bb9b 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -311,6 +311,7 @@
 #![feature(doc_keyword)]
 #![feature(panic_info_message)]
 #![feature(panic_implementation)]
+#![feature(non_exhaustive)]
 
 #![default_lib_allocator]
 
diff --git a/src/libstd/sys/cloudabi/abi/cloudabi.rs b/src/libstd/sys/cloudabi/abi/cloudabi.rs
index 2909db5098e..cd9a5ad448f 100644
--- a/src/libstd/sys/cloudabi/abi/cloudabi.rs
+++ b/src/libstd/sys/cloudabi/abi/cloudabi.rs
@@ -121,6 +121,7 @@ include!("bitflags.rs");
 /// File or memory access pattern advisory information.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum advice {
   /// The application expects that it will not access the
   /// specified data in the near future.
@@ -140,12 +141,12 @@ pub enum advice {
   /// The application expects to access the specified data
   /// in the near future.
   WILLNEED   = 6,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u8,
 }
 
 /// Enumeration describing the kind of value stored in [`auxv`](struct.auxv.html).
 #[repr(u32)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum auxtype {
   /// Base address of the binary argument data provided to
   /// [`proc_exec()`](fn.proc_exec.html).
@@ -210,12 +211,12 @@ pub enum auxtype {
   SYSINFO_EHDR = 262,
   /// Thread ID of the initial thread of the process.
   TID          = 261,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u32,
 }
 
 /// Identifiers for clocks.
 #[repr(u32)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum clockid {
   /// The system-wide monotonic clock, which is defined as a
   /// clock measuring real time, whose value cannot be
@@ -232,7 +233,6 @@ pub enum clockid {
   REALTIME           = 3,
   /// The CPU-time clock associated with the current thread.
   THREAD_CPUTIME_ID  = 4,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u32,
 }
 
 /// A userspace condition variable.
@@ -267,6 +267,7 @@ pub const DIRCOOKIE_START: dircookie = dircookie(0);
 /// exclusively or merely provided for alignment with POSIX.
 #[repr(u16)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum errno {
   /// No error occurred. System call completed successfully.
   SUCCESS        =  0,
@@ -422,7 +423,6 @@ pub enum errno {
   XDEV           = 75,
   /// Extension: Capabilities insufficient.
   NOTCAPABLE     = 76,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u16,
 }
 
 bitflags! {
@@ -438,6 +438,7 @@ bitflags! {
 /// Type of a subscription to an event or its occurrence.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum eventtype {
   /// The time value of clock [`subscription.union.clock.clock_id`](struct.subscription_clock.html#structfield.clock_id)
   /// has reached timestamp [`subscription.union.clock.timeout`](struct.subscription_clock.html#structfield.timeout).
@@ -463,7 +464,6 @@ pub enum eventtype {
   /// The process associated with process descriptor
   /// [`subscription.union.proc_terminate.fd`](struct.subscription_proc_terminate.html#structfield.fd) has terminated.
   PROC_TERMINATE = 7,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u8,
 }
 
 /// Exit code generated by a process when exiting.
@@ -530,6 +530,7 @@ pub type filesize = u64;
 /// The type of a file descriptor or file.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum filetype {
   /// The type of the file descriptor or file is unknown or
   /// is different from any of the other types specified.
@@ -558,7 +559,6 @@ pub enum filetype {
   SOCKET_STREAM    = 130,
   /// The file refers to a symbolic link inode.
   SYMBOLIC_LINK    = 144,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u8,
 }
 
 bitflags! {
@@ -847,12 +847,12 @@ bitflags! {
 /// memory.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum scope {
   /// The object is stored in private memory.
   PRIVATE = 4,
   /// The object is stored in shared memory.
   SHARED  = 8,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u8,
 }
 
 bitflags! {
@@ -878,6 +878,7 @@ bitflags! {
 /// Signal condition.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum signal {
   /// Process abort signal.
   ///
@@ -983,7 +984,6 @@ pub enum signal {
   ///
   /// Action: Terminates the process.
   XFSZ   = 26,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u8,
 }
 
 bitflags! {
@@ -1049,6 +1049,7 @@ pub type userdata = u64;
 /// should be set.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+#[non_exhaustive]
 pub enum whence {
   /// Seek relative to current position.
   CUR = 1,
@@ -1056,7 +1057,6 @@ pub enum whence {
   END = 2,
   /// Seek relative to start-of-file.
   SET = 3,
-  #[doc(hidden)] _NonExhaustive = -1 as isize as u8,
 }
 
 /// Auxiliary vector entry.