Allow documentation on fields.

[ticki]

    /// A page management error.
    enum Error {
        /// No clusters left in the freelist.
        ///
        /// This is the equivalent to OOM, but with disk space.
        OutOfClusters {
            description("Out of free clusters.")
        }
        /// A page checksum did not match.
        ///
        /// The checksum of the data and the checksum stored in the page pointer did not match.
        ///
        /// This indicates some form of data corruption in the sector storing the page.
        PageChecksumMismatch {
            /// The page with the mismatching checksum.
            page: page::Pointer,
            /// The actual checksum of the page.
            found: u32,
        } {
            display("Mismatching checksums in {} - expected {:x}, found {:x}.",
                    page, page.checksum, found)
            description("Mismatching checksum in page.")
        }
    }

gives error

error: expected ident, found #
  --> /home/andy/code/tfs/src/io/alloc.rs:22:13
   |
22 |             /// The page with the mismatching checksum.
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[ticki]

The issue seems to be that it doesn't respond to metadata attributes on fields, which has the consequence that #[doc = "blah"] doesn't work.

[ticki]

I've tried to implement it here, but the code is really messy, and I am having a hard time following it, so it ends up in an error currently, however I suspect it is almost in goal.

[tailhook]

I think implementation should be similar to #30, except we don't need these attributes in match statements. Your one looks fine, but I haven't tested it yet.

By the way, this feature and #30 may conflict somehow (both work on attributes on variants but the attributes should be propagated in different ways). This is also the reason why I haven't applied #30. Hadn't checked if the conflict is real, though.

[ticki]

I like #30.

[ticki]

Oh. It's not a replacement, but a related pr. nvm

[tailhook]

Okay, I've merged in #30, but can't easily figure out how to fix this one :(