editions support for mdbook test

[vorner]

Hello

I can't find a way to turn on the 2018 edition in mdbook test. I guess this is more of a documentation issue, because after all, there's the 2018 edition of The Book, so it must work somehow. But some kind of option somewhere or explanation how to do that in docs would be nice.

[steveklabnik]

Mdbook calls out to rustdoc, which supports “edition2018” and “edition2015” as a modifier to the triple backtick code blocks.

…

On Nov 3, 2018, at 8:23 PM, vorner ***@***.***> wrote: Hello I can't find a way to turn on the 2018 edition in mdbook test. I guess this is more of a documentation issue, because after all, there's the 2018 edition of The Book, so it must work somehow. But some kind of option somewhere or explanation how to do that in docs would be nice. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[tkaitchuck]

It would be useful to have a config option to set a default. That would avoid having to type it every time, and prevent the loss of syntax highlighting within the IDE.

[kpp]

@steveklabnik Looks like edition2018 is ignored by rustdoc.

src/chapter_1.md:

# Chapter 1

```edition2018
async fn hello() {}
fn main() {
    assert_eq!(1, 2);
}
```

$ rustdoc --test src/chapter_1.md 

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

However with:

```rust
async fn hello() {}
fn main() {
    assert_eq!(1, 2);
}
```

Works as expected:

$ rustdoc --edition 2018 --test src/chapter_1.md 

running 1 test
test src/chapter_1.md - Chapter_1 (line 4) ... FAILED

failures:

---- src/chapter_1.md - Chapter_1 (line 4) stdout ----
Test executable failed (exit code 101).

stderr:
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `1`,
 right: `2`', src/chapter_1.md:4:5

[ehuss]

Yea, this was just recently discovered. There is a PR (rust-lang/rust#66238) to fix that.

[kpp]

How about adding edition=2018 option to mdbook config?

Books will have to replace ```rust with ```edition2018 everywhere to make it work, but it would be useful to change it in config only.

[ehuss]

How about adding edition=2018 option to mdbook config?

There was a recent PR to add that (#1086), but it had a problem so had to be reverted. I'm looking at fixing it, but I wanted to change how the config was defined. It's near the top of my list, so hopefully soon!