Do not break long urls in comments.

[malbarbo]

// https://github.com/rust-lang/rfcs/blob/master/text/0195-associated-items.md#encoding-higher-kinded-types

is format to this

// https://github.com/rust-lang/rfcs/blob/master/text/0195-associated-items.
// md#encoding-higher-kinded-types

[marcusklaas]

What should we do with such comments?

[malbarbo]

Leave it as it is. Break a url is bad because we cannot click it anymore...

[nrc]

We could try to break before the URL, if we are into breaking comments, otherwise leave as is.

[chriskrycho]

Note that this also breaks in the case of the (style-guide-recommended) reference-style link, so this:

/// Here's a snippet talking about [higher-kinded types][1]. We might go on...

[1]: https://github.com/rust-lang/rfcs/blob/master/text/0195-associated-items.md#encoding-higher-kinded-types

becomes this:

/// Here's a snippet talking about [higher-kinded types][1]. We might go on...
///
/// [1]: https://github.com/rust-lang/rfcs/blob/master/text/0195-associated-
/// items.md#encoding-higher-kinded-types

I think the best solution is:

• break before inline URLs if line-wrapping in comments of whatever variety
• avoid wrapping at all in reference-style links

[hauleth]

There should be no breakings in reference-style links as this brakes formatting also:

/// Here's a snippet talking about [higher-kinded types][1]. We might go on...
///
/// [1]: https://short.example.link/ "Long description that will appear in hover on the link, this often contain description of page that is linked"

becomes this:

/// Here's a snippet talking about [higher-kinded types][1]. We might go on...
///
/// [1]: https://short.example.link/ "Long description that will appear in hover
/// on the link, this often contain description of page that is linked"

[nrc]

This gets left as is by default, but the bug still exists if we turn on comment formatting

[marcusklaas]

Closed by #911.

[gnzlbg]

When calling rustfmt on a file with:

//! For a quick overview see
//! [wikipedia](https://en.wikipedia.org/wiki/Bit_Manipulation_Instruction_Sets#BMI1_.28Bit_Manipulation_Instruction_Set_1.29).
//! The reference is [Intel 64 and IA-32 Architectures Software Developer's
//! Manual Volume 2: Instruction Set Reference,
//! A-Z](http://www.intel.de/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf).
//!

I get errors of the form:

Rustfmt failed at ...: line exceeded maximum length (sorry)
Rustfmt failed at ...: line exceeded maximum length (sorry)

Is this normal? Seems related to this issue but this issue is closed.

[gnzlbg]

It also seems to fail when an URL is in a list in a comment. For example here:

/// # Intrinsic (when available BMI1)
///
/// - [`BEXTR`](http://www.felixcloutier.com/x86/BEXTR.html): Bit field extract (supports 32/64 bit registers).
///

That could be formatted to something like

/// # Intrinsic (when available BMI1)
///
/// - [`BEXTR`](http://www.felixcloutier.com/x86/BEXTR.html): Bit field 
///   extract (supports 32/64 bit registers).
///