Doctests don't work in bin targets

[kornelski]

It's surprising that doctests don't work binary targets:

cargo new foo --bin

/// ```rust
/// assert!(false);
/// ```
fn main() {
    println!("Hello, world!");
}

cargo test --all

I'd expect the above to fail, but it looks like the doc-comment code is never ran. Even if I explicitly enable doctests for the binary:

[[bin]]
name = "foo"
path = "src/main.rs"
doctest = true

they still aren't run.

[alexcrichton]

This is a limitation of rustdoc, it can't run doctests over binaries.

[huxi]

Could this limitation be addressed? I elaborated a bit why I consider this important over in the users forum.

[alexcrichton]

Heh everything can be addressed with enough elbow grease! It's a matter of design and problem solving now moreso than "let's fix the accidental omission"

[huxi]

I wasn't sure if your comment was meant in a "works as intended" or "it has to be like that" way so I wanted to add a bit more background info.

The issue description isn't 100% on point.

/// ```rust
/// assert!(false);
/// ```
fn foo() {
    println!("Hello, world!");
}

In the code above rustdoc won't execute the doctest, neither in case of lib nor bin, because it is not pub. This is also problematic.

In case of bin even pub doctests are ignored.

[alexcrichton]

Indeed that is correct! It may be best to discuss this at rust-lang/rust rather than Cargo, as this is all mostly remnants of rustdoc itself

[vi]

If it is tricky to get

/// ```

to execute always, maybe it can warn about it instead? Like "This doctest is not expected to be executed because of {it is a non-library crate, not a public item}".

[kornelski]

Moved issue to: rust-lang/rust#50784

[jyn514]

@kornelski this is now supported in rustdoc: rust-lang/rust#50784 (comment)
Can you reopen the issue?

[kriomant]

Is this issue blocked by anything or there's just no spare hands to fix it? Will you accept PR?