Rollup merge of rust-lang#64203 - alexreg:rush-pr-2, r=centril

A few cosmetic improvements to code & comments in liballoc and libcore

Factored out from hacking on rustc for work on the REPL.

r? @Centril

src/liballoc/collections/linked_list/tests.rs

@@ -102,8 +102,8 @@ fn test_append() {
         assert_eq!(m.pop_front(), Some(elt))
     }
     assert_eq!(n.len(), 0);
-    // let's make sure it's working properly, since we
-    // did some direct changes to private members
+    // Let's make sure it's working properly, since we
+    // did some direct changes to private members.
     n.push_back(3);
     assert_eq!(n.len(), 1);
     assert_eq!(n.pop_front(), Some(3));

src/liballoc/raw_vec/tests.rs

@@ -5,12 +5,12 @@ fn allocator_param() {
     use crate::alloc::AllocErr;
 
     // Writing a test of integration between third-party
-    // allocators and RawVec is a little tricky because the RawVec
+    // allocators and `RawVec` is a little tricky because the `RawVec`
     // API does not expose fallible allocation methods, so we
     // cannot check what happens when allocator is exhausted
     // (beyond detecting a panic).
     //
-    // Instead, this just checks that the RawVec methods do at
+    // Instead, this just checks that the `RawVec` methods do at
     // least go through the Allocator API when it reserves
     // storage.
 
@@ -44,7 +44,7 @@ fn allocator_param() {
 fn reserve_does_not_overallocate() {
     {
         let mut v: RawVec<u32> = RawVec::new();
-        // First `reserve` allocates like `reserve_exact`
+        // First, `reserve` allocates like `reserve_exact`.
         v.reserve(0, 9);
         assert_eq!(9, v.capacity());
     }

src/liballoc/rc.rs

@@ -567,7 +567,7 @@ impl<T: ?Sized> Rc<T> {
     ///     let x = Rc::from_raw(x_ptr);
     ///     assert_eq!(&*x, "hello");
     ///
-    ///     // Further calls to `Rc::from_raw(x_ptr)` would be memory unsafe.
+    ///     // Further calls to `Rc::from_raw(x_ptr)` would be memory-unsafe.
     /// }
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!

src/liballoc/sync.rs

@@ -547,7 +547,7 @@ impl<T: ?Sized> Arc<T> {
     ///     let x = Arc::from_raw(x_ptr);
     ///     assert_eq!(&*x, "hello");
     ///
-    ///     // Further calls to `Arc::from_raw(x_ptr)` would be memory unsafe.
+    ///     // Further calls to `Arc::from_raw(x_ptr)` would be memory-unsafe.
     /// }
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!

src/libcore/any.rs

@@ -153,13 +153,13 @@ impl dyn Any {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is<T: Any>(&self) -> bool {
-        // Get TypeId of the type this function is instantiated with
+        // Get `TypeId` of the type this function is instantiated with.
         let t = TypeId::of::<T>();
 
-        // Get TypeId of the type in the trait object
+        // Get `TypeId` of the type in the trait object.
         let concrete = self.type_id();
 
-        // Compare both TypeIds on equality
+        // Compare both `TypeId`s on equality.
         t == concrete
     }
 

src/libcore/marker.rs

@@ -602,10 +602,10 @@ unsafe impl<T: ?Sized> Freeze for *mut T {}
 unsafe impl<T: ?Sized> Freeze for &T {}
 unsafe impl<T: ?Sized> Freeze for &mut T {}
 
-/// Types which can be safely moved after being pinned.
+/// Types that can be safely moved after being pinned.
 ///
 /// Since Rust itself has no notion of immovable types, and considers moves
-/// (e.g. through assignment or [`mem::replace`]) to always be safe,
+/// (e.g., through assignment or [`mem::replace`]) to always be safe,
 /// this trait cannot prevent types from moving by itself.
 ///
 /// Instead it is used to prevent moves through the type system,

src/libcore/ptr/mod.rs

@@ -1042,7 +1042,7 @@ impl<T: ?Sized> *const T {
         (self as *const u8) == null()
     }
 
-    /// Cast to a pointer to a different type
+    /// Casts to a pointer of another type.
     #[stable(feature = "ptr_cast", since = "1.38.0")]
     #[inline]
     pub const fn cast<U>(self) -> *const U {
@@ -1726,7 +1726,7 @@ impl<T: ?Sized> *mut T {
         (self as *mut u8) == null_mut()
     }
 
-    /// Cast to a pointer to a different type
+    /// Casts to a pointer of another type.
     #[stable(feature = "ptr_cast", since = "1.38.0")]
     #[inline]
     pub const fn cast<U>(self) -> *mut U {

src/libcore/ptr/non_null.rs

@@ -125,7 +125,7 @@ impl<T: ?Sized> NonNull<T> {
         &mut *self.as_ptr()
     }
 
-    /// Cast to a pointer of another type
+    /// Casts to a pointer of another type.
     #[stable(feature = "nonnull_cast", since = "1.27.0")]
     #[inline]
     pub const fn cast<U>(self) -> NonNull<U> {

src/libstd/env.rs

@@ -290,7 +290,7 @@ impl Error for VarError {
 ///
 /// Note that while concurrent access to environment variables is safe in Rust,
 /// some platforms only expose inherently unsafe non-threadsafe APIs for
-/// inspecting the environment. As a result extra care needs to be taken when
+/// inspecting the environment. As a result, extra care needs to be taken when
 /// auditing calls to unsafe external FFI functions to ensure that any external
 /// environment accesses are properly synchronized with accesses in Rust.
 ///

src/libstd/error.rs

@@ -197,10 +197,10 @@ pub trait Error: Debug + Display {
     #[stable(feature = "error_source", since = "1.30.0")]
     fn source(&self) -> Option<&(dyn Error + 'static)> { None }
 
-    /// Gets the `TypeId` of `self`
+    /// Gets the `TypeId` of `self`.
     #[doc(hidden)]
     #[unstable(feature = "error_type_id",
-               reason = "this is memory unsafe to override in user code",
+               reason = "this is memory-unsafe to override in user code",
                issue = "60784")]
     fn type_id(&self, _: private::Internal) -> TypeId where Self: 'static {
         TypeId::of::<Self>()
@@ -616,19 +616,19 @@ impl Error for char::ParseCharError {
     }
 }
 
-// copied from any.rs
+// Copied from `any.rs`.
 impl dyn Error + 'static {
     /// Returns `true` if the boxed type is the same as `T`
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn is<T: Error + 'static>(&self) -> bool {
-        // Get TypeId of the type this function is instantiated with
+        // Get `TypeId` of the type this function is instantiated with.
         let t = TypeId::of::<T>();
 
-        // Get TypeId of the type in the trait object
+        // Get `TypeId` of the type in the trait object.
         let boxed = self.type_id(private::Internal);
 
-        // Compare both TypeIds on equality
+        // Compare both `TypeId`s on equality.
         t == boxed
     }
 
@@ -662,21 +662,21 @@ impl dyn Error + 'static {
 }
 
 impl dyn Error + 'static + Send {
-    /// Forwards to the method defined on the type `Any`.
+    /// Forwards to the method defined on the type `dyn Error`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn is<T: Error + 'static>(&self) -> bool {
         <dyn Error + 'static>::is::<T>(self)
     }
 
-    /// Forwards to the method defined on the type `Any`.
+    /// Forwards to the method defined on the type `dyn Error`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
         <dyn Error + 'static>::downcast_ref::<T>(self)
     }
 
-    /// Forwards to the method defined on the type `Any`.
+    /// Forwards to the method defined on the type `dyn Error`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_mut<T: Error + 'static>(&mut self) -> Option<&mut T> {
@@ -685,21 +685,21 @@ impl dyn Error + 'static + Send {
 }
 
 impl dyn Error + 'static + Send + Sync {
-    /// Forwards to the method defined on the type `Any`.
+    /// Forwards to the method defined on the type `dyn Error`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn is<T: Error + 'static>(&self) -> bool {
         <dyn Error + 'static>::is::<T>(self)
     }
 
-    /// Forwards to the method defined on the type `Any`.
+    /// Forwards to the method defined on the type `dyn Error`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
         <dyn Error + 'static>::downcast_ref::<T>(self)
     }
 
-    /// Forwards to the method defined on the type `Any`.
+    /// Forwards to the method defined on the type `dyn Error`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_mut<T: Error + 'static>(&mut self) -> Option<&mut T> {
@@ -710,7 +710,7 @@ impl dyn Error + 'static + Send + Sync {
 impl dyn Error {
     #[inline]
     #[stable(feature = "error_downcast", since = "1.3.0")]
-    /// Attempt to downcast the box to a concrete type.
+    /// Attempts to downcast the box to a concrete type.
     pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error>> {
         if self.is::<T>() {
             unsafe {
@@ -878,12 +878,12 @@ impl<'a> Iterator for ErrorIter<'a> {
 impl dyn Error + Send {
     #[inline]
     #[stable(feature = "error_downcast", since = "1.3.0")]
-    /// Attempt to downcast the box to a concrete type.
+    /// Attempts to downcast the box to a concrete type.
     pub fn downcast<T: Error + 'static>(self: Box<Self>)
                                         -> Result<Box<T>, Box<dyn Error + Send>> {
         let err: Box<dyn Error> = self;
         <dyn Error>::downcast(err).map_err(|s| unsafe {
-            // reapply the Send marker
+            // Reapply the `Send` marker.
             transmute::<Box<dyn Error>, Box<dyn Error + Send>>(s)
         })
     }
@@ -892,12 +892,12 @@ impl dyn Error + Send {
 impl dyn Error + Send + Sync {
     #[inline]
     #[stable(feature = "error_downcast", since = "1.3.0")]
-    /// Attempt to downcast the box to a concrete type.
+    /// Attempts to downcast the box to a concrete type.
     pub fn downcast<T: Error + 'static>(self: Box<Self>)
                                         -> Result<Box<T>, Box<Self>> {
         let err: Box<dyn Error> = self;
         <dyn Error>::downcast(err).map_err(|s| unsafe {
-            // reapply the Send+Sync marker
+            // Reapply the `Send + Sync` marker.
             transmute::<Box<dyn Error>, Box<dyn Error + Send + Sync>>(s)
         })
     }

src/libstd/ffi/c_str.rs

@@ -615,7 +615,7 @@ impl CString {
 }
 
 // Turns this `CString` into an empty string to prevent
-// memory unsafe code from working by accident. Inline
+// memory-unsafe code from working by accident. Inline
 // to prevent LLVM from optimizing it away in debug builds.
 #[stable(feature = "cstring_drop", since = "1.13.0")]
 impl Drop for CString {

src/libstd/process.rs

@@ -1595,7 +1595,7 @@ pub fn id() -> u32 {
 
 /// A trait for implementing arbitrary return types in the `main` function.
 ///
-/// The c-main function only supports to return integers as return type.
+/// The C-main function only supports to return integers as return type.
 /// So, every type implementing the `Termination` trait has to be converted
 /// to an integer.
 ///