For unlinked files, add option to add "pub mod" instead of just "mod"

[marcusbuffett]

It seems to be a pretty common pattern to have mod.rs files that are just a bunch of pub mod x, pub mod y etc., so it would be nice when you create an unlinked file and use the code action from rust-analyzer, if in addition to Insert 'mod x;', it would have a Insert 'pub mod x;' option. Super useful feature already, just think this would make it even better :)

Also you guys probably hear this a million times a day but rust-analyzer is amazing; it's totally changed the rust experience for me, and the pace of development is unreal.

[yue4u]

Hi, I would like to work on this and just took a look at some relevant code. The Diagnostic hint seems to be built here.

https://github.com/rust-analyzer/rust-analyzer/blob/2f87ee7f3f9c1efd726774511c9ce02caef73872/crates/ide/src/diagnostics.rs#L161-L171

However, It looks like DiagnosticWithFix is limited to a single fix.

https://github.com/rust-analyzer/rust-analyzer/blob/2f87ee7f3f9c1efd726774511c9ce02caef73872/crates/ide/src/diagnostics.rs#L59-L60

https://github.com/rust-analyzer/rust-analyzer/blob/2f87ee7f3f9c1efd726774511c9ce02caef73872/crates/ide/src/diagnostics/fixes.rs#L25-L30

In this situation I think appending a different Diagnostic is easier to do but does not make much sense, since it's the same problem and the fixes are so similar. It will be better to add / change to DiagnosticWithFixes and accept multiple possible fixes?

In addition, I found the the comment // Override severity and mark as unused. inside of .on::<UnlinkedFile, _>( ... does not match the code below and the item to append is same as the return value of warning_with_fix https://github.com/rust-analyzer/rust-analyzer/blob/2f87ee7f3f9c1efd726774511c9ce02caef73872/crates/ide/src/diagnostics.rs#L230-L234

Anyway I'm new to the rust-analyzer codebase and may read the code wrong, I'd be happy to continue working on this if some instructions are given.