Auto merge of #51214 - kennytm:rollup, r=kennytm

Rollup of 12 pull requests

Successful merges:

 - #51050 (std::fs::DirEntry.metadata(): use fstatat instead of lstat when possible)
 - #51123 (Update build instructions)
 - #51127 (Add doc link from discriminant struct to function.)
 - #51146 (typeck: Do not pass the field check on field error)
 - #51147 (Stabilize SliceIndex trait.)
 - #51151 (Move slice::exact_chunks directly above exact_chunks_mut for more con…)
 - #51152 (Replace `if` with `if and only if` in the definition dox of `Sync`)
 - #51153 (Link panic and compile_error docs)
 - #51158 (Mention spec and indented blocks in doctest docs)
 - #51186 (Remove two redundant .nll.stderr files)
 - #51203 (Two minor `obligation_forest` tweaks.)
 - #51213 (fs: copy: Use File::set_permissions instead of fs::set_permissions)

Failed merges:

README.md

@@ -38,6 +38,7 @@ Read ["Installation"] from [The Book].
 3. Build and install:
 
     ```sh
+    $ git submodule update --init --recursive --progress
     $ ./x.py build && sudo ./x.py install
     ```
 

src/doc/rustdoc/src/documentation-tests.md

@@ -284,3 +284,27 @@ environment that has no network access.
 compiles, then the test will fail. However please note that code failing
 with the current Rust release may work in a future release, as new features
 are added.
+
+## Syntax reference
+
+The *exact* syntax for code blocks, including the edge cases, can be found
+in the [Fenced Code Blocks](https://spec.commonmark.org/0.28/#fenced-code-blocks)
+section of the CommonMark specification.
+
+Rustdoc also accepts *indented* code blocks as an alternative to fenced
+code blocks: instead of surrounding your code with three backticks, you
+can indent each line by four or more spaces.
+
+``````markdown
+    let foo = "foo";
+    assert_eq!(foo, "foo");
+``````
+
+These, too, are documented in the CommonMark specification, in the
+[Indented Code Blocks](https://spec.commonmark.org/0.28/#indented-code-blocks)
+section.
+
+However, it's preferable to use fenced code blocks over indented code blocks.
+Not only are fenced code blocks considered more idiomatic for Rust code,
+but there is no way to use directives such as `ignore` or `should_panic` with
+indented code blocks.

src/liballoc/lib.rs

@@ -104,7 +104,6 @@
 #![feature(ptr_internals)]
 #![feature(ptr_offset_from)]
 #![feature(rustc_attrs)]
-#![feature(slice_get_slice)]
 #![feature(specialization)]
 #![feature(staged_api)]
 #![feature(str_internals)]

src/liballoc/slice.rs

@@ -121,7 +121,7 @@ pub use core::slice::{RSplit, RSplitMut};
 pub use core::slice::{from_raw_parts, from_raw_parts_mut};
 #[stable(feature = "from_ref", since = "1.28.0")]
 pub use core::slice::{from_ref, from_mut};
-#[unstable(feature = "slice_get_slice", issue = "35729")]
+#[stable(feature = "slice_get_slice", since = "1.28.0")]
 pub use core::slice::SliceIndex;
 #[unstable(feature = "exact_chunks", issue = "47115")]
 pub use core::slice::{ExactChunks, ExactChunksMut};

src/libcore/marker.rs

@@ -294,7 +294,7 @@ pub trait Copy : Clone {
 /// This trait is automatically implemented when the compiler determines
 /// it's appropriate.
 ///
-/// The precise definition is: a type `T` is `Sync` if `&T` is
+/// The precise definition is: a type `T` is `Sync` if and only if `&T` is
 /// [`Send`][send]. In other words, if there is no possibility of
 /// [undefined behavior][ub] (including data races) when passing
 /// `&T` references between threads.

src/libcore/mem.rs

@@ -835,7 +835,9 @@ pub unsafe fn transmute_copy<T, U>(src: &T) -> U {
 
 /// Opaque type representing the discriminant of an enum.
 ///
-/// See the `discriminant` function in this module for more information.
+/// See the [`discriminant`] function in this module for more information.
+///
+/// [`discriminant`]: fn.discriminant.html
 #[stable(feature = "discriminant_value", since = "1.21.0")]
 pub struct Discriminant<T>(u64, PhantomData<fn() -> T>);
 

src/libcore/slice/mod.rs

@@ -691,41 +691,6 @@ impl<T> [T] {
         Chunks { v: self, chunk_size: chunk_size }
     }
 
-    /// Returns an iterator over `chunk_size` elements of the slice at a
-    /// time. The chunks are slices and do not overlap. If `chunk_size` does
-    /// not divide the length of the slice, then the last up to `chunk_size-1`
-    /// elements will be omitted.
-    ///
-    /// Due to each chunk having exactly `chunk_size` elements, the compiler
-    /// can often optimize the resulting code better than in the case of
-    /// [`chunks`].
-    ///
-    /// # Panics
-    ///
-    /// Panics if `chunk_size` is 0.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(exact_chunks)]
-    ///
-    /// let slice = ['l', 'o', 'r', 'e', 'm'];
-    /// let mut iter = slice.exact_chunks(2);
-    /// assert_eq!(iter.next().unwrap(), &['l', 'o']);
-    /// assert_eq!(iter.next().unwrap(), &['r', 'e']);
-    /// assert!(iter.next().is_none());
-    /// ```
-    ///
-    /// [`chunks`]: #method.chunks
-    #[unstable(feature = "exact_chunks", issue = "47115")]
-    #[inline]
-    pub fn exact_chunks(&self, chunk_size: usize) -> ExactChunks<T> {
-        assert!(chunk_size != 0);
-        let rem = self.len() % chunk_size;
-        let len = self.len() - rem;
-        ExactChunks { v: &self[..len], chunk_size: chunk_size}
-    }
-
     /// Returns an iterator over `chunk_size` elements of the slice at a time.
     /// The chunks are mutable slices, and do not overlap. If `chunk_size` does
     /// not divide the length of the slice, then the last chunk will not
@@ -761,6 +726,41 @@ impl<T> [T] {
         ChunksMut { v: self, chunk_size: chunk_size }
     }
 
+    /// Returns an iterator over `chunk_size` elements of the slice at a
+    /// time. The chunks are slices and do not overlap. If `chunk_size` does
+    /// not divide the length of the slice, then the last up to `chunk_size-1`
+    /// elements will be omitted.
+    ///
+    /// Due to each chunk having exactly `chunk_size` elements, the compiler
+    /// can often optimize the resulting code better than in the case of
+    /// [`chunks`].
+    ///
+    /// # Panics
+    ///
+    /// Panics if `chunk_size` is 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(exact_chunks)]
+    ///
+    /// let slice = ['l', 'o', 'r', 'e', 'm'];
+    /// let mut iter = slice.exact_chunks(2);
+    /// assert_eq!(iter.next().unwrap(), &['l', 'o']);
+    /// assert_eq!(iter.next().unwrap(), &['r', 'e']);
+    /// assert!(iter.next().is_none());
+    /// ```
+    ///
+    /// [`chunks`]: #method.chunks
+    #[unstable(feature = "exact_chunks", issue = "47115")]
+    #[inline]
+    pub fn exact_chunks(&self, chunk_size: usize) -> ExactChunks<T> {
+        assert!(chunk_size != 0);
+        let rem = self.len() % chunk_size;
+        let len = self.len() - rem;
+        ExactChunks { v: &self[..len], chunk_size: chunk_size}
+    }
+
     /// Returns an iterator over `chunk_size` elements of the slice at a time.
     /// The chunks are mutable slices, and do not overlap. If `chunk_size` does
     /// not divide the length of the slice, then the last up to `chunk_size-1`
@@ -1977,35 +1977,63 @@ fn slice_index_overflow_fail() -> ! {
     panic!("attempted to index slice up to maximum usize");
 }
 
+mod private_slice_index {
+    use super::ops;
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    pub trait Sealed {}
+
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    impl Sealed for usize {}
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    impl Sealed for ops::Range<usize> {}
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    impl Sealed for ops::RangeTo<usize> {}
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    impl Sealed for ops::RangeFrom<usize> {}
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    impl Sealed for ops::RangeFull {}
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    impl Sealed for ops::RangeInclusive<usize> {}
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
+    impl Sealed for ops::RangeToInclusive<usize> {}
+}
+
 /// A helper trait used for indexing operations.
-#[unstable(feature = "slice_get_slice", issue = "35729")]
+#[stable(feature = "slice_get_slice", since = "1.28.0")]
 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
-pub trait SliceIndex<T: ?Sized> {
+pub trait SliceIndex<T: ?Sized>: private_slice_index::Sealed {
     /// The output type returned by methods.
+    #[stable(feature = "slice_get_slice", since = "1.28.0")]
     type Output: ?Sized;
 
     /// Returns a shared reference to the output at this location, if in
     /// bounds.
+    #[unstable(feature = "slice_index_methods", issue = "0")]
     fn get(self, slice: &T) -> Option<&Self::Output>;
 
     /// Returns a mutable reference to the output at this location, if in
     /// bounds.
+    #[unstable(feature = "slice_index_methods", issue = "0")]
     fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>;
 
     /// Returns a shared reference to the output at this location, without
     /// performing any bounds checking.
+    #[unstable(feature = "slice_index_methods", issue = "0")]
     unsafe fn get_unchecked(self, slice: &T) -> &Self::Output;
 
     /// Returns a mutable reference to the output at this location, without
     /// performing any bounds checking.
+    #[unstable(feature = "slice_index_methods", issue = "0")]
     unsafe fn get_unchecked_mut(self, slice: &mut T) -> &mut Self::Output;
 
     /// Returns a shared reference to the output at this location, panicking
     /// if out of bounds.
+    #[unstable(feature = "slice_index_methods", issue = "0")]
     fn index(self, slice: &T) -> &Self::Output;
 
     /// Returns a mutable reference to the output at this location, panicking
     /// if out of bounds.
+    #[unstable(feature = "slice_index_methods", issue = "0")]
     fn index_mut(self, slice: &mut T) -> &mut Self::Output;
 }
 

src/librustc_data_structures/obligation_forest/mod.rs

@@ -75,9 +75,6 @@ pub struct ObligationForest<O: ForestObligation> {
     done_cache: FxHashSet<O::Predicate>,
     /// An cache of the nodes in `nodes`, indexed by predicate.
     waiting_cache: FxHashMap<O::Predicate, NodeIndex>,
-    /// A list of the obligations added in snapshots, to allow
-    /// for their removal.
-    cache_list: Vec<O::Predicate>,
     scratch: Option<Vec<usize>>,
 }
 
@@ -158,7 +155,6 @@ impl<O: ForestObligation> ObligationForest<O> {
             nodes: vec![],
             done_cache: FxHashSet(),
             waiting_cache: FxHashMap(),
-            cache_list: vec![],
             scratch: Some(vec![]),
         }
     }
@@ -207,7 +203,6 @@ impl<O: ForestObligation> ObligationForest<O> {
                 debug!("register_obligation_at({:?}, {:?}) - ok, new index is {}",
                        obligation, parent, self.nodes.len());
                 v.insert(NodeIndex::new(self.nodes.len()));
-                self.cache_list.push(obligation.as_predicate().clone());
                 self.nodes.push(Node::new(parent, obligation));
                 Ok(())
             }

src/librustc_data_structures/obligation_forest/node_index.rs

@@ -17,11 +17,13 @@ pub struct NodeIndex {
 }
 
 impl NodeIndex {
+    #[inline]
     pub fn new(value: usize) -> NodeIndex {
         assert!(value < (u32::MAX as usize));
         NodeIndex { index: NonZeroU32::new((value as u32) + 1).unwrap() }
     }
 
+    #[inline]
     pub fn get(self) -> usize {
         (self.index.get() - 1) as usize
     }

src/librustc_typeck/check/_match.rs

@@ -720,8 +720,11 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
         self.demand_eqtype(pat.span, expected, pat_ty);
 
         // Type check subpatterns.
-        self.check_struct_pat_fields(pat_ty, pat.id, pat.span, variant, fields, etc, def_bm);
-        pat_ty
+        if self.check_struct_pat_fields(pat_ty, pat.id, pat.span, variant, fields, etc, def_bm) {
+            pat_ty
+        } else {
+            self.tcx.types.err
+        }
     }
 
     fn check_pat_path(&self,
@@ -846,7 +849,7 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
                                variant: &'tcx ty::VariantDef,
                                fields: &'gcx [Spanned<hir::FieldPat>],
                                etc: bool,
-                               def_bm: ty::BindingMode) {
+                               def_bm: ty::BindingMode) -> bool {
         let tcx = self.tcx;
 
         let (substs, adt) = match adt_ty.sty {
@@ -864,6 +867,7 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
 
         // Keep track of which fields have already appeared in the pattern.
         let mut used_fields = FxHashMap();
+        let mut no_field_errors = true;
 
         let mut inexistent_fields = vec![];
         // Typecheck each field.
@@ -879,6 +883,7 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
                                     format!("multiple uses of `{}` in pattern", field.ident))
                         .span_label(*occupied.get(), format!("first use of `{}`", field.ident))
                         .emit();
+                    no_field_errors = false;
                     tcx.types.err
                 }
                 Vacant(vacant) => {
@@ -891,6 +896,7 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
                         })
                         .unwrap_or_else(|| {
                             inexistent_fields.push((span, field.ident));
+                            no_field_errors = false;
                             tcx.types.err
                         })
                 }
@@ -989,5 +995,6 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
                 diag.emit();
             }
         }
+        no_field_errors
     }
 }

src/libstd/macros.rs

@@ -38,10 +38,13 @@
 /// The multi-argument form of this macro panics with a string and has the
 /// [`format!`] syntax for building a string.
 ///
+/// See also the macro [`compile_error!`], for raising errors during compilation.
+///
 /// [runwrap]: ../std/result/enum.Result.html#method.unwrap
 /// [`Option`]: ../std/option/enum.Option.html#method.unwrap
 /// [`Result`]: ../std/result/enum.Result.html
 /// [`format!`]: ../std/macro.format.html
+/// [`compile_error!`]: ../std/macro.compile_error.html
 /// [book]: ../book/second-edition/ch09-01-unrecoverable-errors-with-panic.html
 ///
 /// # Current implementation
@@ -286,13 +289,16 @@ pub mod builtin {
     /// Unconditionally causes compilation to fail with the given error message when encountered.
     ///
     /// This macro should be used when a crate uses a conditional compilation strategy to provide
-    /// better error messages for erroneous conditions.
+    /// better error messages for erroneous conditions. It's the compiler-level form of [`panic!`],
+    /// which emits an error at *runtime*, rather than during compilation.
     ///
     /// # Examples
     ///
     /// Two such examples are macros and `#[cfg]` environments.
     ///
-    /// Emit better compiler error if a macro is passed invalid values.
+    /// Emit better compiler error if a macro is passed invalid values. Without the final branch,
+    /// the compiler would still emit an error, but the error's message would not mention the two
+    /// valid values.
     ///
     /// ```compile_fail
     /// macro_rules! give_me_foo_or_bar {
@@ -313,6 +319,8 @@ pub mod builtin {
     /// #[cfg(not(any(feature = "foo", feature = "bar")))]
     /// compile_error!("Either feature \"foo\" or \"bar\" must be enabled for this crate.")
     /// ```
+    ///
+    /// [`panic!`]: ../std/macro.panic.html
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
     #[macro_export]
     macro_rules! compile_error {