Auto merge of #52616 - kennytm:rollup, r=kennytm

Rollup of 11 pull requests

Successful merges:

 - #51807 (Deprecation of str::slice_unchecked(_mut))
 - #52051 (mem::swap the obvious way for types smaller than the SIMD optimization's block size)
 - #52465 (Add CI test harness for `thumb*` targets. [IRR-2018-embedded])
 - #52507 (Reword when `_` couldn't be inferred)
 - #52508 (Document that Unique::empty() and NonNull::dangling() aren't sentinel values)
 - #52521 (Fix links in rustdoc book.)
 - #52581 (Avoid using `#[macro_export]` for documenting builtin macros)
 - #52582 (Typo)
 - #52587 (Add missing backtick in UniversalRegions doc comment)
 - #52594 (Run the error index tool against the sysroot libdir)
 - #52615 (Added new lines to .gitignore.)

5 files changed, 57 insertions, 47 deletions

diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index c830c22ee5f..83f9dfea8f2 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -543,6 +543,7 @@ macro_rules! unimplemented {
 /// into libsyntax itself.
 ///
 /// For more information, see documentation for `std`'s macros.
+#[cfg(dox)]
 mod builtin {
 
     /// Unconditionally causes compilation to fail with the given error message when encountered.
@@ -551,8 +552,7 @@ mod builtin {
     ///
     /// [`std::compile_error!`]: ../std/macro.compile_error.html
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! compile_error {
         ($msg:expr) => ({ /* compiler built-in */ });
         ($msg:expr,) => ({ /* compiler built-in */ });
@@ -564,8 +564,7 @@ mod builtin {
     ///
     /// [`std::format_args!`]: ../std/macro.format_args.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! format_args {
         ($fmt:expr) => ({ /* compiler built-in */ });
         ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ });
@@ -577,8 +576,7 @@ mod builtin {
     ///
     /// [`std::env!`]: ../std/macro.env.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! env {
         ($name:expr) => ({ /* compiler built-in */ });
         ($name:expr,) => ({ /* compiler built-in */ });
@@ -590,8 +588,7 @@ mod builtin {
     ///
     /// [`std::option_env!`]: ../std/macro.option_env.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! option_env {
         ($name:expr) => ({ /* compiler built-in */ });
         ($name:expr,) => ({ /* compiler built-in */ });
@@ -603,8 +600,7 @@ mod builtin {
     ///
     /// [`std::concat_idents!`]: ../std/macro.concat_idents.html
     #[unstable(feature = "concat_idents_macro", issue = "29599")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! concat_idents {
         ($($e:ident),+) => ({ /* compiler built-in */ });
         ($($e:ident,)+) => ({ /* compiler built-in */ });
@@ -616,8 +612,7 @@ mod builtin {
     ///
     /// [`std::concat!`]: ../std/macro.concat.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! concat {
         ($($e:expr),*) => ({ /* compiler built-in */ });
         ($($e:expr,)*) => ({ /* compiler built-in */ });
@@ -629,8 +624,7 @@ mod builtin {
     ///
     /// [`std::line!`]: ../std/macro.line.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! line { () => ({ /* compiler built-in */ }) }
 
     /// A macro which expands to the column number on which it was invoked.
@@ -639,8 +633,7 @@ mod builtin {
     ///
     /// [`std::column!`]: ../std/macro.column.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! column { () => ({ /* compiler built-in */ }) }
 
     /// A macro which expands to the file name from which it was invoked.
@@ -649,8 +642,7 @@ mod builtin {
     ///
     /// [`std::file!`]: ../std/macro.file.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! file { () => ({ /* compiler built-in */ }) }
 
     /// A macro which stringifies its arguments.
@@ -659,8 +651,7 @@ mod builtin {
     ///
     /// [`std::stringify!`]: ../std/macro.stringify.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! stringify { ($($t:tt)*) => ({ /* compiler built-in */ }) }
 
     /// Includes a utf8-encoded file as a string.
@@ -669,8 +660,7 @@ mod builtin {
     ///
     /// [`std::include_str!`]: ../std/macro.include_str.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! include_str {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -682,8 +672,7 @@ mod builtin {
     ///
     /// [`std::include_bytes!`]: ../std/macro.include_bytes.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! include_bytes {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -695,8 +684,7 @@ mod builtin {
     ///
     /// [`std::module_path!`]: ../std/macro.module_path.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! module_path { () => ({ /* compiler built-in */ }) }
 
     /// Boolean evaluation of configuration flags, at compile-time.
@@ -705,8 +693,7 @@ mod builtin {
     ///
     /// [`std::cfg!`]: ../std/macro.cfg.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! cfg { ($($cfg:tt)*) => ({ /* compiler built-in */ }) }
 
     /// Parse a file as an expression or an item according to the context.
@@ -715,8 +702,7 @@ mod builtin {
     ///
     /// [`std::include!`]: ../std/macro.include.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! include {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -727,9 +713,8 @@ mod builtin {
     /// For more information, see the documentation for [`std::assert!`].
     ///
     /// [`std::assert!`]: ../std/macro.assert.html
-    #[macro_export]
+    #[rustc_doc_only_macro]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg(dox)]
     macro_rules! assert {
         ($cond:expr) => ({ /* compiler built-in */ });
         ($cond:expr,) => ({ /* compiler built-in */ });
diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 8fb4e0d6a02..a0fe6e98806 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -638,7 +638,7 @@ pub unsafe fn uninitialized<T>() -> T {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn swap<T>(x: &mut T, y: &mut T) {
     unsafe {
-        ptr::swap_nonoverlapping(x, y, 1);
+        ptr::swap_nonoverlapping_one(x, y);
     }
 }
 
diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 0af642258c2..d020e14be4c 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -188,6 +188,19 @@ pub unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
 }
 
 #[inline]
+pub(crate) unsafe fn swap_nonoverlapping_one<T>(x: *mut T, y: *mut T) {
+    // For types smaller than the block optimization below,
+    // just swap directly to avoid pessimizing codegen.
+    if mem::size_of::<T>() < 32 {
+        let z = read(x);
+        copy_nonoverlapping(y, x, 1);
+        write(y, z);
+    } else {
+        swap_nonoverlapping(x, y, 1);
+    }
+}
+
+#[inline]
 unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) {
     // The approach here is to utilize simd to swap x & y efficiently. Testing reveals
     // that swapping either 32 bytes or 64 bytes at a time is most efficient for intel
@@ -2703,6 +2716,11 @@ impl<T: Sized> Unique<T> {
     ///
     /// This is useful for initializing types which lazily allocate, like
     /// `Vec::new` does.
+    ///
+    /// Note that the pointer value may potentially represent a valid pointer to
+    /// a `T`, which means this must not be used as a "not yet initialized"
+    /// sentinel value. Types that lazily allocate must track initialization by
+    /// some other means.
     // FIXME: rename to dangling() to match NonNull?
     pub const fn empty() -> Self {
         unsafe {
@@ -2834,6 +2852,11 @@ impl<T: Sized> NonNull<T> {
     ///
     /// This is useful for initializing types which lazily allocate, like
     /// `Vec::new` does.
+    ///
+    /// Note that the pointer value may potentially represent a valid pointer to
+    /// a `T`, which means this must not be used as a "not yet initialized"
+    /// sentinel value. Types that lazily allocate must track initialization by
+    /// some other means.
     #[stable(feature = "nonnull", since = "1.25.0")]
     pub fn dangling() -> Self {
         unsafe {
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index 255e8a07d75..3e215de58dd 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -1055,7 +1055,7 @@ impl<'a, P: Pattern<'a>> SplitInternal<'a, P> {
         if !self.finished && (self.allow_trailing_empty || self.end - self.start > 0) {
             self.finished = true;
             unsafe {
-                let string = self.matcher.haystack().slice_unchecked(self.start, self.end);
+                let string = self.matcher.haystack().get_unchecked(self.start..self.end);
                 Some(string)
             }
         } else {
@@ -1070,7 +1070,7 @@ impl<'a, P: Pattern<'a>> SplitInternal<'a, P> {
         let haystack = self.matcher.haystack();
         match self.matcher.next_match() {
             Some((a, b)) => unsafe {
-                let elt = haystack.slice_unchecked(self.start, a);
+                let elt = haystack.get_unchecked(self.start..a);
                 self.start = b;
                 Some(elt)
             },
@@ -1095,13 +1095,13 @@ impl<'a, P: Pattern<'a>> SplitInternal<'a, P> {
         let haystack = self.matcher.haystack();
         match self.matcher.next_match_back() {
             Some((a, b)) => unsafe {
-                let elt = haystack.slice_unchecked(b, self.end);
+                let elt = haystack.get_unchecked(b..self.end);
                 self.end = a;
                 Some(elt)
             },
             None => unsafe {
                 self.finished = true;
-                Some(haystack.slice_unchecked(self.start, self.end))
+                Some(haystack.get_unchecked(self.start..self.end))
             },
         }
     }
@@ -1222,7 +1222,7 @@ impl<'a, P: Pattern<'a>> MatchIndicesInternal<'a, P> {
     #[inline]
     fn next(&mut self) -> Option<(usize, &'a str)> {
         self.0.next_match().map(|(start, end)| unsafe {
-            (start, self.0.haystack().slice_unchecked(start, end))
+            (start, self.0.haystack().get_unchecked(start..end))
         })
     }
 
@@ -1231,7 +1231,7 @@ impl<'a, P: Pattern<'a>> MatchIndicesInternal<'a, P> {
         where P::Searcher: ReverseSearcher<'a>
     {
         self.0.next_match_back().map(|(start, end)| unsafe {
-            (start, self.0.haystack().slice_unchecked(start, end))
+            (start, self.0.haystack().get_unchecked(start..end))
         })
     }
 }
@@ -1274,7 +1274,7 @@ impl<'a, P: Pattern<'a>> MatchesInternal<'a, P> {
     fn next(&mut self) -> Option<&'a str> {
         self.0.next_match().map(|(a, b)| unsafe {
             // Indices are known to be on utf8 boundaries
-            self.0.haystack().slice_unchecked(a, b)
+            self.0.haystack().get_unchecked(a..b)
         })
     }
 
@@ -1284,7 +1284,7 @@ impl<'a, P: Pattern<'a>> MatchesInternal<'a, P> {
     {
         self.0.next_match_back().map(|(a, b)| unsafe {
             // Indices are known to be on utf8 boundaries
-            self.0.haystack().slice_unchecked(a, b)
+            self.0.haystack().get_unchecked(a..b)
         })
     }
 }
@@ -2453,6 +2453,7 @@ impl str {
     /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_deprecated(since = "1.29.0", reason = "use `get_unchecked(begin..end)` instead")]
     #[inline]
     pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str {
         (begin..end).get_unchecked(self)
@@ -2483,6 +2484,7 @@ impl str {
     /// * `begin` and `end` must be byte positions within the string slice.
     /// * `begin` and `end` must lie on UTF-8 sequence boundaries.
     #[stable(feature = "str_slice_mut", since = "1.5.0")]
+    #[rustc_deprecated(since = "1.29.0", reason = "use `get_unchecked_mut(begin..end)` instead")]
     #[inline]
     pub unsafe fn slice_mut_unchecked(&mut self, begin: usize, end: usize) -> &mut str {
         (begin..end).get_unchecked_mut(self)
@@ -2524,8 +2526,8 @@ impl str {
         // is_char_boundary checks that the index is in [0, .len()]
         if self.is_char_boundary(mid) {
             unsafe {
-                (self.slice_unchecked(0, mid),
-                 self.slice_unchecked(mid, self.len()))
+                (self.get_unchecked(0..mid),
+                 self.get_unchecked(mid..self.len()))
             }
         } else {
             slice_error_fail(self, 0, mid)
@@ -3702,7 +3704,7 @@ impl str {
         }
         unsafe {
             // Searcher is known to return valid indices
-            self.slice_unchecked(i, j)
+            self.get_unchecked(i..j)
         }
     }
 
@@ -3741,7 +3743,7 @@ impl str {
         }
         unsafe {
             // Searcher is known to return valid indices
-            self.slice_unchecked(i, self.len())
+            self.get_unchecked(i..self.len())
         }
     }
 
@@ -3788,7 +3790,7 @@ impl str {
         }
         unsafe {
             // Searcher is known to return valid indices
-            self.slice_unchecked(0, j)
+            self.get_unchecked(0..j)
         }
     }
 
diff --git a/src/libcore/str/pattern.rs b/src/libcore/str/pattern.rs
index 464d57a2702..5e63fa9ff35 100644
--- a/src/libcore/str/pattern.rs
+++ b/src/libcore/str/pattern.rs
@@ -354,7 +354,7 @@ unsafe impl<'a> ReverseSearcher<'a> for CharSearcher<'a> {
     #[inline]
     fn next_back(&mut self) -> SearchStep {
         let old_finger = self.finger_back;
-        let slice = unsafe { self.haystack.slice_unchecked(self.finger, old_finger) };
+        let slice = unsafe { self.haystack.get_unchecked(self.finger..old_finger) };
         let mut iter = slice.chars();
         let old_len = iter.iter.len();
         if let Some(ch) = iter.next_back() {