Remove a gotcha from book/error-handling.md
The book's "Error handling with `Box<Error>`" section talks about `Box<Error>`. In the actual example `Box<Error + Send + Sync>` is used instead so that the corresponding From impls could be used to convert a plain string to an error type. Rust 1.7 added support for conversion from `&str`/`String` to
`Box<Error>`, so this gotcha and later references to it can now be removed.
r? @steveklabnik
Rewrote "How Safe and Unsafe Interact" Nomicon chapter.
The previous version of the chapter covered a lot of ground, but was a little meandering and hard to follow at times. This draft is intended to be clearer and more direct, while still providing the same information as the previous version.
r? @steveklabnik
Have included an example of a Cargo.toml file containing the libc dependency.
The file has been reformatted to use sections. The note on the default features warning is part of the _Using libc_ section but is in bold.
Minor changes to variable bindings chapter
* In "*... name as another binding, that's currently in scope, will ...*", *"
that's currently in scope"* is not a parenthetical element, and the commas
can be omitted.
* Other minor changes.
* In "... name as another binding, that's currently in scope, will ...", ",
that's currently in scope, " is not a parenthetical element, and the commas
can be omitted.
* Other minor changes.
The book's "Error handling with Box<Error>" section talks about Box<Error>.
In the actual example Box<Error + Send + Sync> is used instead so that the
corresponding From impls could be used to convert a plain string to an error
type. Rust 1.7 added support for conversion from &str/String to
Box<Error>, so this gotcha and later references to it can now be removed.
Rename main thread from "<main>" to "main".
Fix issue #33789
We may need to discuss whether this counts as a breaking change since code may check the main thread name against "\<main\>". Discussion is in #33789
Fix a few links in the book
Links to directories and direct links to doc.rust-lang.org don't work properly
when viewing the docs offline so fix them.
r? @steveklabnik
The previous version of the chapter covered a lot of ground, but was a little
meandering and hard to follow at times. This draft is intended to be clearer
and more direct, while still providing the same information as the previous
version.
Clarify the English translation of `?Sized`
* It wasn't clear whether `?Sized` meant "not `Sized`" or "`Sized` or not `Sized`". According to #rust IRC, it does indeed mean "`Sized` or not `Sized`".
* Use the same language as [Trait std::marker::Sized](https://doc.rust-lang.org/std/marker/trait.Sized.html) about how `Sized` is implicitly bound.
* Refer to the syntax as `?Sized`, since it's currently the only allowed trait that can follow `?`.
Book: small improvement to a table to make it clearer
This table is used as an example of four heap values where two of them got deallocated leaving a gap.
It also has stack variables.
Instead of four stack variables I propose three, that way there's no misleading connection between the number of stack variables and heap variables.
But more importantly: three of the four stack variables had the same name (**y**) which could be confusing to a beginner, I changed this as well.
* Use "special bound syntax" instead of "special syntax". `?Sized` is technically a "bound", but `?Sized` is specialized syntax that _only_ works with `Sized`, and no other Trait.
* Replace "constant size" with "sized".
