rustdoc: Update pulldown-cmark to 0.8

[camelid]

Thanks to @marcusklaas's great work, pulldown-cmark now supports smart punctuation! This means that rustdoc can now have smart apostrophes, dashes, etc.

---

@rustbot modify labels: T-rustdoc C-enhancement

[camelid]

It looks like there are a few breaking changes in the API:

$ ./x.py build --stage 1
error[E0308]: mismatched types
   --> src/librustdoc/html/markdown.rs:942:72
    |
934 |           let replacer = |_: &str, s: &str| {
    |  ________________________-
935 | |             if let Some(link) = links.iter().find(|link| &*link.original_text == s) {
936 | |                 Some((link.href.clone(), link.new_text.clone()))
937 | |             } else {
938 | |                 None
939 | |             }
940 | |         };
    | |_________- the found closure
941 | 
942 |           let p = Parser::new_with_broken_link_callback(md, opts(), Some(&replacer));
    |                                                                          ^^^^^^^^^ types differ in mutability
    |
    = note: expected mutable reference `&mut dyn for<'r> std::ops::FnMut(pulldown_cmark::BrokenLink<'r>) -> std::option::Option<(pulldown_cmark::CowStr<'_>, pulldown_cmark::CowStr<'_>)>`
                       found reference `&[closure@src/librustdoc/html/markdown.rs:934:24: 940:10 links:_]`

error[E0308]: mismatched types
    --> src/librustdoc/html/markdown.rs:1023:18
     |
1012 |           let replacer = |_: &str, s: &str| {
     |  ________________________-
1013 | |             if let Some(link) = links.iter().find(|link| &*link.original_text == s) {
1014 | |                 Some((link.href.clone(), link.new_text.clone()))
1015 | |             } else {
1016 | |                 None
1017 | |             }
1018 | |         };
     | |_________- the found closure
...
1023 |               Some(&replacer),
     |                    ^^^^^^^^^ types differ in mutability
     |
     = note: expected mutable reference `&mut dyn for<'r> std::ops::FnMut(pulldown_cmark::BrokenLink<'r>) -> std::option::Option<(pulldown_cmark::CowStr<'_>, pulldown_cmark::CowStr<'_>)>`
                        found reference `&[closure@src/librustdoc/html/markdown.rs:1012:24: 1018:10 links:_]`

error[E0308]: mismatched types
    --> src/librustdoc/html/markdown.rs:1091:72
     |
1087 |           let push = |_: &str, s: &str| {
     |  ____________________-
1088 | |             shortcut_links.borrow_mut().push((s.to_owned(), locate(s)));
1089 | |             None
1090 | |         };
     | |_________- the found closure
1091 |           let p = Parser::new_with_broken_link_callback(md, opts(), Some(&push));
     |                                                                          ^^^^^ types differ in mutability
     |
     = note: expected mutable reference `&mut dyn for<'r> std::ops::FnMut(pulldown_cmark::BrokenLink<'r>) -> std::option::Option<(pulldown_cmark::CowStr<'_>, pulldown_cmark::CowStr<'_>)>`
                        found reference `&[closure@src/librustdoc/html/markdown.rs:1087:20: 1090:10 shortcut_links:_, locate:_]`

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0308`.
error: could not compile `rustdoc`.

[marcusklaas]

Yup, the broken link callback type changed. Instead of two strings, you are now passed a BrokenLink, which contains the reference that was previously passed, amongst other things. It also expects you to return CowStrs, which can be created by calling Into::into on chars, &strs or Strings. Finally, we now accept FnMuts, which means that we need a mutable reference to the callback instead of a regular reference.

Fundamentally, it works the same way as before. It should be relatively straightforward to make the changes. Hope the above helps!

[camelid]

Okay, thanks!

[camelid]

@rustbot claim

[camelid]

Hmm, I fixed the breaking changes, but it doesn't seem to be working:

That was generated by build/x86_64-apple-darwin/stage1/bin/rustdoc after I built it from this Markdown:

# Test of "smart punctuation"

Hello there -- this is "smart punctuation"!

[marcusklaas]

I can't see the PR, but did you remember to enable the smart punctuation option? It's not enabled by default.

[camelid]

I haven't pushed it up yet, so that's why :)

Ah, I didn't realize it was a parser option, I thought it was enabled by default or a crate-level feature. Thanks!

[camelid]

That worked, but it looks like smart punctuation doesn't work in headers, is that intentional?

[marcusklaas]

Erm, not that I know. I will investigate for a bit.

[marcusklaas]

I cannot reproduce this on pulldown itself -- seems to be working in titles there. Maybe rustdoc is doing something to titles? (I know nothing of rustdoc)

[camelid]

Okay, thanks for looking into it! Maybe rustdoc has some kind of custom header renderer.

[Dylan-DPC-zz]

cc @GuillaumeGomez