Auto merge of #42856 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 8 pull requests

- Successful merges: #42777, #42783, #42787, #42821, #42822, #42825, #42829, #42833
- Failed merges:

src/bootstrap/check.rs

@@ -265,7 +265,7 @@ pub fn compiletest(build: &Build,
         let llvm_components = output(Command::new(&llvm_config).arg("--components"));
         let llvm_cxxflags = output(Command::new(&llvm_config).arg("--cxxflags"));
         cmd.arg("--cc").arg(build.cc(target))
-           .arg("--cxx").arg(build.cxx(target))
+           .arg("--cxx").arg(build.cxx(target).unwrap())
            .arg("--cflags").arg(build.cflags(target).join(" "))
            .arg("--llvm-components").arg(llvm_components.trim())
            .arg("--llvm-cxxflags").arg(llvm_cxxflags.trim());

src/bootstrap/compile.rs

@@ -291,7 +291,7 @@ pub fn rustc(build: &Build, target: &str, compiler: &Compiler) {
        !target.contains("windows") &&
        !target.contains("apple") {
         cargo.env("LLVM_STATIC_STDCPP",
-                  compiler_file(build.cxx(target), "libstdc++.a"));
+                  compiler_file(build.cxx(target).unwrap(), "libstdc++.a"));
     }
     if build.config.llvm_link_shared {
         cargo.env("LLVM_LINK_SHARED", "1");

src/bootstrap/lib.rs

@@ -452,6 +452,10 @@ impl Build {
             cargo.env(format!("CC_{}", target), self.cc(target))
                  .env(format!("AR_{}", target), self.ar(target).unwrap()) // only msvc is None
                  .env(format!("CFLAGS_{}", target), self.cflags(target).join(" "));
+
+            if let Ok(cxx) = self.cxx(target) {
+                 cargo.env(format!("CXX_{}", target), cxx);
+            }
         }
 
         if self.config.extended && compiler.is_final_stage(self) {
@@ -838,13 +842,13 @@ impl Build {
         self.cc[target].1.as_ref().map(|p| &**p)
     }
 
-    /// Returns the path to the C++ compiler for the target specified, may panic
-    /// if no C++ compiler was configured for the target.
-    fn cxx(&self, target: &str) -> &Path {
+    /// Returns the path to the C++ compiler for the target specified.
+    fn cxx(&self, target: &str) -> Result<&Path, String> {
         match self.cxx.get(target) {
-            Some(p) => p.path(),
-            None => panic!("\n\ntarget `{}` is not configured as a host,
-                            only as a target\n\n", target),
+            Some(p) => Ok(p.path()),
+            None => Err(format!(
+                    "target `{}` is not configured as a host, only as a target",
+                    target))
         }
     }
 

src/bootstrap/native.rs

@@ -155,7 +155,7 @@ pub fn llvm(build: &Build, target: &str) {
         }
 
         let cc = build.cc(target);
-        let cxx = build.cxx(target);
+        let cxx = build.cxx(target).unwrap();
 
         // Handle msvc + ninja + ccache specially (this is what the bots use)
         if target.contains("msvc") &&

src/bootstrap/sanity.rs

@@ -139,7 +139,7 @@ pub fn check(build: &mut Build) {
         }
     }
     for host in build.config.host.iter() {
-        need_cmd(build.cxx(host).as_ref());
+        need_cmd(build.cxx(host).unwrap().as_ref());
     }
 
     // The msvc hosts don't use jemalloc, turn it off globally to

src/liballoc/boxed.rs

@@ -42,8 +42,10 @@
 //! Recursive structures must be boxed, because if the definition of `Cons`
 //! looked like this:
 //!
-//! ```rust,ignore
+//! ```compile_fail,E0072
+//! # enum List<T> {
 //! Cons(T, List<T>),
+//! # }
 //! ```
 //!
 //! It wouldn't work. This is because the size of a `List` depends on how many

src/liballoc/fmt.rs

@@ -230,7 +230,7 @@
 //! There are a number of related macros in the `format!` family. The ones that
 //! are currently implemented are:
 //!
-//! ```ignore
+//! ```ignore (only-for-syntax-highlight)
 //! format!      // described above
 //! write!       // first argument is a &mut io::Write, the destination
 //! writeln!     // same as write but appends a newline

src/liballoc/raw_vec.rs

@@ -244,7 +244,11 @@ impl<T, A: Alloc> RawVec<T, A> {
     ///
     /// # Examples
     ///
-    /// ```ignore
+    /// ```
+    /// # #![feature(alloc)]
+    /// # extern crate alloc;
+    /// # use std::ptr;
+    /// # use alloc::raw_vec::RawVec;
     /// struct MyVec<T> {
     ///     buf: RawVec<T>,
     ///     len: usize,
@@ -261,6 +265,10 @@ impl<T, A: Alloc> RawVec<T, A> {
     ///         self.len += 1;
     ///     }
     /// }
+    /// # fn main() {
+    /// #   let mut vec = MyVec { buf: RawVec::new(), len: 0 };
+    /// #   vec.push(1);
+    /// # }
     /// ```
     #[inline(never)]
     #[cold]
@@ -440,13 +448,17 @@ impl<T, A: Alloc> RawVec<T, A> {
     ///
     /// # Examples
     ///
-    /// ```ignore
+    /// ```
+    /// # #![feature(alloc)]
+    /// # extern crate alloc;
+    /// # use std::ptr;
+    /// # use alloc::raw_vec::RawVec;
     /// struct MyVec<T> {
     ///     buf: RawVec<T>,
     ///     len: usize,
     /// }
     ///
-    /// impl<T> MyVec<T> {
+    /// impl<T: Clone> MyVec<T> {
     ///     pub fn push_all(&mut self, elems: &[T]) {
     ///         self.buf.reserve(self.len, elems.len());
     ///         // reserve would have aborted or panicked if the len exceeded
@@ -459,6 +471,10 @@ impl<T, A: Alloc> RawVec<T, A> {
     ///         }
     ///     }
     /// }
+    /// # fn main() {
+    /// #   let mut vector = MyVec { buf: RawVec::new(), len: 0 };
+    /// #   vector.push_all(&[1, 3, 5, 7, 9]);
+    /// # }
     /// ```
     pub fn reserve(&mut self, used_cap: usize, needed_extra_cap: usize) {
         unsafe {

src/liballoc/rc.rs

@@ -273,7 +273,7 @@ struct RcBox<T: ?Sized> {
 /// See the [module-level documentation](./index.html) for more details.
 ///
 /// The inherent methods of `Rc` are all associated functions, which means
-/// that you have to call them as e.g. [`Rc::get_mut(&value)`][get_mut] instead of
+/// that you have to call them as e.g. [`Rc::get_mut(&mut value)`][get_mut] instead of
 /// `value.get_mut()`. This avoids conflicts with methods of the inner
 /// type `T`.
 ///

src/liballoc/string.rs

@@ -124,7 +124,7 @@ use boxed::Box;
 /// similar, but without the UTF-8 constraint. The second implication is that
 /// you cannot index into a `String`:
 ///
-/// ```ignore
+/// ```compile_fail,E0277
 /// let s = "hello";
 ///
 /// println!("The first letter of s is {}", s[0]); // ERROR!!!

src/liballoc/vec.rs

@@ -156,7 +156,7 @@ use Bound::{Excluded, Included, Unbounded};
 /// However be careful: if you try to access an index which isn't in the `Vec`,
 /// your software will panic! You cannot do this:
 ///
-/// ```ignore
+/// ```should_panic
 /// let v = vec![0, 2, 4, 6];
 /// println!("{}", v[6]); // it will panic!
 /// ```

src/libcore/cell.rs

@@ -942,6 +942,13 @@ impl<'b, T: ?Sized> Ref<'b, T> {
 #[unstable(feature = "coerce_unsized", issue = "27732")]
 impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> {}
 
+#[stable(feature = "std_guard_impls", since = "1.20")]
+impl<'a, T: ?Sized + fmt::Display> fmt::Display for Ref<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.value.fmt(f)
+    }
+}
+
 impl<'b, T: ?Sized> RefMut<'b, T> {
     /// Make a new `RefMut` for a component of the borrowed data, e.g. an enum
     /// variant.
@@ -1034,6 +1041,13 @@ impl<'b, T: ?Sized> DerefMut for RefMut<'b, T> {
 #[unstable(feature = "coerce_unsized", issue = "27732")]
 impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<RefMut<'b, U>> for RefMut<'b, T> {}
 
+#[stable(feature = "std_guard_impls", since = "1.20")]
+impl<'a, T: ?Sized + fmt::Display> fmt::Display for RefMut<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.value.fmt(f)
+    }
+}
+
 /// The core primitive for interior mutability in Rust.
 ///
 /// `UnsafeCell<T>` is a type that wraps some `T` and indicates unsafe interior operations on the

src/libcore/iter/mod.rs

@@ -211,7 +211,7 @@
 //! There's one more subtle bit here: the standard library contains an
 //! interesting implementation of [`IntoIterator`]:
 //!
-//! ```ignore
+//! ```ignore (only-for-syntax-highlight)
 //! impl<I: Iterator> IntoIterator for I
 //! ```
 //!

src/libcore/marker.rs

@@ -434,7 +434,7 @@ macro_rules! impls{
 /// example, here is a struct `Slice` that has two pointers of type `*const T`,
 /// presumably pointing into an array somewhere:
 ///
-/// ```ignore
+/// ```compile_fail,E0392
 /// struct Slice<'a, T> {
 ///     start: *const T,
 ///     end: *const T,

src/libcore/mem.rs

@@ -328,11 +328,18 @@ pub fn align_of_val<T: ?Sized>(val: &T) -> usize {
 ///
 /// Here's an example of how a collection might make use of needs_drop:
 ///
-/// ```ignore
+/// ```
 /// #![feature(needs_drop)]
 /// use std::{mem, ptr};
 ///
-/// pub struct MyCollection<T> { /* ... */ }
+/// pub struct MyCollection<T> {
+/// #   data: [T; 1],
+///     /* ... */
+/// }
+/// # impl<T> MyCollection<T> {
+/// #   fn iter_mut(&mut self) -> &mut [T] { &mut self.data }
+/// #   fn free_buffer(&mut self) {}
+/// # }
 ///
 /// impl<T> Drop for MyCollection<T> {
 ///     fn drop(&mut self) {
@@ -575,7 +582,7 @@ pub fn swap<T>(x: &mut T, y: &mut T) {
 /// `replace` allows consumption of a struct field by replacing it with another value.
 /// Without `replace` you can run into issues like these:
 ///
-/// ```ignore
+/// ```compile_fail,E0507
 /// struct Buffer<T> { buf: Vec<T> }
 ///
 /// impl<T> Buffer<T> {
@@ -645,7 +652,7 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
 ///
 /// Borrows are based on lexical scope, so this produces an error:
 ///
-/// ```ignore
+/// ```compile_fail,E0502
 /// let mut v = vec![1, 2, 3];
 /// let x = &v[0];
 ///

src/libcore/ops/place.rs

@@ -38,7 +38,13 @@ pub trait Place<Data: ?Sized> {
 ///
 /// `PLACE <- EXPR` effectively desugars into:
 ///
-/// ```rust,ignore
+/// ```
+/// # #![feature(placement_new_protocol, box_heap)]
+/// # use std::ops::{Placer, Place, InPlace};
+/// # #[allow(non_snake_case)]
+/// # fn main() {
+/// # let PLACE = std::boxed::HEAP;
+/// # let EXPR = 1;
 /// let p = PLACE;
 /// let mut place = Placer::make_place(p);
 /// let raw_place = Place::pointer(&mut place);
@@ -47,6 +53,7 @@ pub trait Place<Data: ?Sized> {
 ///     std::ptr::write(raw_place, value);
 ///     InPlace::finalize(place)
 /// }
+/// # ; }
 /// ```
 ///
 /// The type of `PLACE <- EXPR` is derived from the type of `PLACE`;
@@ -89,14 +96,21 @@ pub trait InPlace<Data: ?Sized>: Place<Data> {
 ///
 /// `box EXPR` effectively desugars into:
 ///
-/// ```rust,ignore
+/// ```
+/// # #![feature(placement_new_protocol)]
+/// # use std::ops::{BoxPlace, Place, Boxed};
+/// # #[allow(non_snake_case)]
+/// # fn main() {
+/// # let EXPR = 1;
 /// let mut place = BoxPlace::make_place();
 /// let raw_place = Place::pointer(&mut place);
 /// let value = EXPR;
+/// # let _: Box<_> =
 /// unsafe {
 ///     ::std::ptr::write(raw_place, value);
 ///     Boxed::finalize(place)
 /// }
+/// # ; }
 /// ```
 ///
 /// The type of `box EXPR` is supplied from its surrounding

src/libcore/ops/range.rs

@@ -26,7 +26,7 @@ use fmt;
 /// It does not have an `IntoIterator` implementation, so you can't use it in a
 /// `for` loop directly. This won't compile:
 ///
-/// ```ignore
+/// ```compile_fail,E0277
 /// for i in .. {
 ///    // ...
 /// }
@@ -184,7 +184,7 @@ impl<Idx: PartialOrd<Idx>> RangeFrom<Idx> {
 /// It does not have an `IntoIterator` implementation, so you can't use it in a
 /// `for` loop directly. This won't compile:
 ///
-/// ```ignore
+/// ```compile_fail,E0277
 /// for i in ..5 {
 ///     // ...
 /// }
@@ -313,7 +313,8 @@ impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
 /// It does not have an `IntoIterator` implementation, so you can't use it in a
 /// `for` loop directly. This won't compile:
 ///
-/// ```ignore
+/// ```compile_fail,E0277
+/// #![feature(inclusive_range_syntax)]
 /// for i in ...5 {
 ///     // ...
 /// }

src/libcore/panicking.rs

@@ -15,8 +15,10 @@
 //! useful an upstream crate must define panicking for libcore to use. The current
 //! interface for panicking is:
 //!
-//! ```ignore
-//! fn panic_impl(fmt: fmt::Arguments, &(&'static str, u32)) -> !;
+//! ```
+//! # use std::fmt;
+//! fn panic_impl(fmt: fmt::Arguments, file_line: &(&'static str, u32)) -> !
+//! # { loop {} }
 //! ```
 //!
 //! This definition allows for panicking with any general message, but it does not

src/libcore/ptr.rs

@@ -408,11 +408,11 @@ impl<T: ?Sized> *const T {
     ///
     /// Basic usage:
     ///
-    /// ```ignore
-    /// let val: *const u8 = &10u8 as *const u8;
+    /// ```
+    /// let ptr: *const u8 = &10u8 as *const u8;
     ///
     /// unsafe {
-    ///     if let Some(val_back) = val.as_ref() {
+    ///     if let Some(val_back) = ptr.as_ref() {
     ///         println!("We got back the value: {}!", val_back);
     ///     }
     /// }
@@ -570,11 +570,11 @@ impl<T: ?Sized> *mut T {
     ///
     /// Basic usage:
     ///
-    /// ```ignore
-    /// let val: *mut u8 = &mut 10u8 as *mut u8;
+    /// ```
+    /// let ptr: *mut u8 = &mut 10u8 as *mut u8;
     ///
     /// unsafe {
-    ///     if let Some(val_back) = val.as_ref() {
+    ///     if let Some(val_back) = ptr.as_ref() {
     ///         println!("We got back the value: {}!", val_back);
     ///     }
     /// }

src/libgraphviz/lib.rs

@@ -111,7 +111,7 @@
 //!
 //! Output from first example (in `example1.dot`):
 //!
-//! ```ignore
+//! ```dot
 //! digraph example1 {
 //!     N0[label="N0"];
 //!     N1[label="N1"];