Impl UUID macro

[QnnOkabayashi]

I'm submitting a feature

Description

Implementing the uuid! macro for parsing string literals at compile time.

Motivation

Very convenient for config files

Tests

I duplicated the valid str parsing tests for uuid!(), and they all compiled. For testing for failure, I checked that invalid inputs don't work:

1. non literal: uuid!(struct) fails properly.
2. non string literal: uuid!(44) fails properly.
3. invalid string: uuid!("hello world") fails properly

I didn't bother to test more extensively then that, do we care?

Also, can someone verify that tokenizing to ::uuid::Uuid::from_bytes([#tokens]) is hygienic?

Related Issue(s)

#422

[QnnOkabayashi]

Required to stop shared/error.rs and shared/parser.rs from complaining. I just copy-pasted it from uuid.

[KodrAus]

Thanks for working on this @QnnOkabayashi!

I think we might need to wrap this up in a macro_rules macro in uuid that can pass the fully-qualified path to the Uuid type using the $crate metavariable. We could then move the docs to this public macro and make the proc-macro a private implementation detail.

It would also be great to test this using trybuild so we can look at diagnostics for invalid inputs, and test that renaming uuid or defining a root module called uuid doesn’t cause the macro to break.

Is this something you’d be interested in exploring further? If not I’m happy to merge and fill those bits in.

Thanks again! 🙇

[QnnOkabayashi]

I think we might need to wrap this up in a macro_rules macro in uuid that can pass the fully-qualified path to the Uuid type using the $crate metavariable. We could then move the docs to this public macro and make the proc-macro a private implementation detail.

Done 👍

It would also be great to test this using trybuild so we can look at diagnostics for invalid inputs, and test that renaming uuid or defining a root module called uuid doesn’t cause the macro to break.

Done 👍

Also since the macro is integrated with the crate now, I was able to use the internal diagnostic information in the ErrorKind type to improve the diagnostics. For example, if there's an invalid character, it only points to that character

error: invalid character: expected an optional prefix of `urn:uuid:` followed by 0123456789abcdefABCDEF-, found G at 20
  --> benches/macros/invalid_parse.rs:25:44
   |
25 | const _: Uuid = uuid!("F9168C5E-CEB2-4faa-BGBF-329BF39FA1E4");
   |                                            ^

If there's an invalid group length, it points to that group

error: invalid group length: expected 12, found 8 in group 4
  --> benches/macros/invalid_parse.rs:26:48
   |
26 | const _: Uuid = uuid!("01020304-1112-2122-3132-41424344");
   |                                                ^^^^^^^^

[KodrAus]

This looks great, thanks @QnnOkabayashi!

I should've merged this one ahead of my changes to our benches. I just renamed some of the files. We probably don't really need benches for the uuid! macro, since it should be "free" 🙂

[KodrAus]

Besides the merge conflict this should be ready to go now.

[QnnOkabayashi]

Besides the merge conflict this should be ready to go now.

Should be good to go now!