Errata

Chapter 13 "Utility Traits" has following sentence:
"Vec<T> and [T: N] implement Borrow<[T]>."

I believe it should be `[T; N]` (semicolon instead of colon).

Note from the Author or Editor:
On page 320, in "Borrow and BorrowMut", we claim that "Vec<T> and [T: N] implement Borrow<[T]>."

The punctuation in "[T: N]" is incorrect. It should be "[T; N]", with a semicolon, not a colon.

let strings: Vec<String> = error_messages();

is not declared mutable. Later used as:

for rs in &mut strings { ......

the point at hand was clearly demonstrated. But minor error nevertheless

Note from the Author or Editor:
Naaol is correct. The last code block in the section should have an extra line, showing the vector declared as mut:

let mut strings = error_messages();
for rs in &mut strings { // the type of rs is &mut String
rs.push('\n'); // add a newline to each string
}

The book says to add "-Z unstable-options --pretty expanded" to the rustc command line.

This used to work, but it doesn't anymore. The option is now spelled "-Z unstable-options -Z unpretty=expanded".

Alternatively, "cargo install cargo-expand" installs a new cargo subcommand that does this for you: "cargo expand".

Near the end of the section on doc-tests, the book says:

> If the code isn't even expected to compile, use `ignore` instead of `no_run`.

This is a mistake because "ignored" tests are only ignored by default. If you do `cargo test --ignored`, Cargo runs them all. The non-compiling code will then fail.

Probably the best thing to do is mark fake Rust code that isn't expected to compile as "text".

The paragraph describes the remaining chapters of the book but omits chapter 20 on asynchronous programming.

Note from the Author or Editor:
This has been fixed.

The crossbeam dependency is added with version constraint = "0.2", this leads to a compilation error, because the closure to spawner.spawn has 0 arguments in crossbeam 0.2, but the code is written for crossbeam 0.8 which expects 1 argument.

Note from the Author or Editor:
Fixed in current text.

“401 BAD REQUEST” => “400 BAD REQUEST”

In the write_image fn, there's a call of encoder.encode with &pixels als the 1st param. pixels is already a slice, so no need to borrow (clippy::needless_borrow).

Note from the Author or Editor:
On page 33, in "Writing Image Files", in the code of `fn write_image`, we originally wrote `encoder.encode(&pixels, ...)`. The `&` is superfluous because `pixels` is already a reference.

The first argument should be simply `pixels`, not `&pixels`.

When attempting to write the output, if an error occurs the message contains args.filename, which is the input file, not the output file.

match fs::write(&args.output, &data) {
Ok(_) => {},
Err(e) => {
eprintln!("{} failed to write to file '{}': {:?}", "Error:".red().bold(), args.filename, e);
std::process::exit(1);
}
};

should instead be

match fs::write(&args.output, &data) {
Ok(_) => {},
Err(e) => {
eprintln!("{} failed to write to file '{}': {:?}", "Error:".red().bold(), args.output, e);
std::process::exit(1);
}
};

Note from the Author or Editor:
On page 45, in the large code block showing `fn main`, there are two similar `eprintln!()` statements that report errors. Each one includes a filename in the error message, but the second prints the wrong filename.

The use of `args.filename` that appears after the call to `fs::write(&args.output, &data)` is incorrect. It should be `args.output` instead. We regret the error.

When attempting to write the output, if an error occurs the message contains args.filename, which is the input file, not the output file.

eprintln!("{} failed to write to file '{}': {:?}", "Error:".red().bold(), args.filename, e);

should instead be

eprintln!("{} failed to write to file '{}': {:?}", "Error:".red().bold(), args.output, e);

Note from the Author or Editor:
On page 47, the first line of the page mentions `args.filename`. This is the wrong filename. It should be `args.output` instead.

Instead of
`cargo test -- --no-capture`
it should be
`cargo test -- --nocapture`

See `cargo test -- --help`

Note from the Author or Editor:
On page 196, the command-line option that causes Cargo not to capture test output is incorrect. We wrote "--no-capture". The correct option is "--nocapture". There is no hyphen between "no" and "capture".

The sentence says that `Creature` is a subtrait and supertrait of `Visible`, while the latter is the supertrait.

Note from the Author or Editor:
On page 270, in "Subtraits", we wrote: "...we say that `Creature` is a subtrait of `Visible`, and that `Creature` is `Visible`’s supertrait."

The second half of the sentence should say, "...and that `Visible` is `Creature`'s supertrait." We got it backwards.

While not a compile error, this line has an unnecessary ‘&’ reference:

Ok(sum + u64::from_str(&line?.trim())?)

This probably should be:

Ok(sum + u64::from_str(line?.trim())?)

Note from the Author or Editor:
Yes, the `&` in that line of code is superfluous and should be removed:

Ok(sum + u64::from_str(line?.trim())?)

On page 606, in Table 21-1, the last three rows of the table are incorrect.

We listed `$( ... ),?` and `$( ... );?` as matching "0 or 1 times, separated by commas" or semicolons. Clearly that doesn't make sense. There is no such syntax in Rust. The last two rows of the table should be deleted.

The last remaining row, `$( ... )?`, should be labeled "Match 0 or 1 times" (deleting the words "with no separator").

Thanks to Sofiane Akermoun for reporting this issue.