Add errata print01-ch07-lst2-open-paren

[nmarley]

No description provided.

[jonhoo]

Good catch! I'd actually like the fix to be the the other way though — we should change the closing paren to a brace }. Macros can be called with either, and this is less like an argument list than a block, so {} feels more appropriate.

[nmarley]

Thanks, I had no idea! I will push a commit to use a brace instead.

[jonhoo]

I believe the ; is still needed. I think you need one to terminate all function-like macro invocations 🤔

Also, would you mind updating the file name?

[nmarley]

No problem updating the filename.

Regarding the semicolon, I got an error when trying it with a brace + semicolon during my own testing. Would you be able to double-check? If you insist I can remove it.

Here is the error I got:

error: expected item, found `;`
  --> test2.rs:21:53
   |
21 | test_battery! {u8 as u8_tests3, u128 as u128_tests3};
   |                                                     ^ help: remove this semicolon

error: aborting due to previous error

Here is my code if it helps:

https://gist.github.com/nmarley/0831cf27ca12ce7e6b1234af8162e94e

[nmarley]

It seems like println! works with braces both with and without the ;, so I'll just assume there's some magic that I don't yet understand and add the semicolon here.

[jonhoo]

Huh, no, looks like you're spot on. From the reference, macro invocations with a {} are not ;-terminated:

MacroInvocationSemi :
      SimplePath ! ( TokenTree* ) ;
   | SimplePath ! [ TokenTree* ] ;
   | SimplePath ! { TokenTree* }

This is also supported by rust-lang/rust#34418.

So let's get rid of the ; again then!

[nmarley]

Oh nice! Thanks for letting me know where to find this information.

[jonhoo]

Thanks!