Auto merge of #74543 - Manishearth:rollup-m5w6hyg, r=Manishearth

Rollup of 9 pull requests

Successful merges:

 - #73618 (Documentation for the false keyword)
 - #74486 (Improve Read::read_exact documentation)
 - #74514 (Do not clobber RUSTDOCFLAGS)
 - #74516 (do not try fetching the ancestors of errored trait impls)
 - #74520 (include backtrace folder in rust-src component)
 - #74523 (Improve documentation for `core::fmt` internals)
 - #74527 (Add myself to toolstate change notifications for rustfmt)
 - #74534 (Only skip impls of foreign unstable traits)
 - #74536 (fix documentation surrounding the `in` and `for` keywords)

Failed merges:

r? @ghost

2 files changed, 12 insertions, 8 deletions

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 823ce30febe..797318d95b7 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -722,7 +722,9 @@ pub trait Read {
     /// No guarantees are provided about the contents of `buf` when this
     /// function is called, implementations cannot rely on any property of the
     /// contents of `buf` being true. It is recommended that implementations
-    /// only write data to `buf` instead of reading its contents.
+    /// only write data to `buf` instead of reading its contents. The
+    /// documentation on [`read`] has a more detailed explanation on this
+    /// subject.
     ///
     /// # Errors
     ///
@@ -745,6 +747,7 @@ pub trait Read {
     ///
     /// [`File`]s implement `Read`:
     ///
+    /// [`read`]: Read::read
     /// [`File`]: crate::fs::File
     ///
     /// ```no_run
diff --git a/src/libstd/keyword_docs.rs b/src/libstd/keyword_docs.rs
index d985f10ccb4..a62987891b9 100644
--- a/src/libstd/keyword_docs.rs
+++ b/src/libstd/keyword_docs.rs
@@ -387,10 +387,11 @@ mod extern_keyword {}
 //
 /// A value of type [`bool`] representing logical **false**.
 ///
-/// The documentation for this keyword is [not yet complete]. Pull requests welcome!
+/// `false` is the logical opposite of [`true`].
 ///
-/// [`bool`]: primitive.bool.html
-/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601
+/// See the documentation for [`true`] for more information.
+///
+/// [`true`]: keyword.true.html
 mod false_keyword {}
 
 #[doc(keyword = "fn")]
@@ -473,8 +474,8 @@ mod fn_keyword {}
 /// * `for` is also used for [higher-ranked trait bounds] as in `for<'a> &'a T: PartialEq<i32>`.
 ///
 /// for-in-loops, or to be more precise, iterator loops, are a simple syntactic sugar over a common
-/// practice within Rust, which is to loop over an iterator until that iterator returns `None` (or
-/// `break` is called).
+/// practice within Rust, which is to loop over anything that implements [`IntoIterator`] until the
+/// iterator returned by `.into_iter()` returns `None` (or the loop body uses `break`).
 ///
 /// ```rust
 /// for i in 0..5 {
@@ -680,7 +681,7 @@ mod impl_keyword {}
 //
 /// Iterate over a series of values with [`for`].
 ///
-/// The expression immediately following `in` must implement the [`Iterator`] trait.
+/// The expression immediately following `in` must implement the [`IntoIterator`] trait.
 ///
 /// ## Literal Examples:
 ///
@@ -689,7 +690,7 @@ mod impl_keyword {}
 ///
 /// (Read more about [range patterns])
 ///
-/// [`Iterator`]: ../book/ch13-04-performance.html
+/// [`IntoIterator`]: ../book/ch13-04-performance.html
 /// [range patterns]: ../reference/patterns.html?highlight=range#range-patterns
 /// [`for`]: keyword.for.html
 mod in_keyword {}