Builtin macro pattern separator

[Undin]

Since #62243 builtin macros use , as a separator between different patterns. Although, all other macros use ; instead.
Is it intended change?
This change breaks parser in IntelliJ Rust plugin. Should we adjust our parser or it should be fixed from stdlib side?

[Undin]

@petrochenkov

[petrochenkov]

The comma is not specific to built-in macros, but rather to unstable macro macros in general (which are currently used to define built-in macros).

So, it's reasonable for IntelliJ to adjust its parser if it wants to support unstable code.

[petrochenkov]

(Note that the comma itself is pretty questionable, so it's likely that it will be changed into something else, for example no separator at all, once macro macros are closer to stabilization.)

[Undin]

@petrochenkov Thanks for quick reply!
Then we will adjust our parser