[stdlib] Make StringSlice.split() return List[StringSlice]

[martinvuyk]

Split off from #4016. Part of #3528

[JoeLoser]

!sync

[JoeLoser]

Sadly, this is still crashing parameter inference internally (CC: @zyx-billy):

1.      Crash resolving decl body at loc("open-source/mojo/stdlib/stdlib/collections/string/string.mojo":1460:8)
    >>     fn split(self, sep: StringSlice, maxsplit: Int = -1) raises -> List[String]:
              ^........................................................................
    >>         """Split the string by a separator.
    >>
    >>         Args:
    >>             sep: The string to split on.
2.      Crash parsing statement at loc("open-source/mojo/stdlib/stdlib/collections/string/string.mojo":1486:9)
    >>         return _to_string_list(
               ^......................
    >>             self.as_string_slice().split(sep, maxsplit=maxsplit)
    >>         )

I'm going to mark this as "blocked" label here for my own book-keeping. I've asked the compiler team to take a look at this internally.

A few things:

• We eventually want String.split(...) to return List[StringSlice], but this was blocked by similar issues above with parameter inference. See [stdlib] Make String.split() return List[StringSlice] #4016 that this particular PR was split off from.
• It didn't crash/fail in the open source CI which is strange - I don't know why yet.

[JoeLoser]

Sadly, this is still crashing parameter inference internally (CC: @zyx-billy):

1.      Crash resolving decl body at loc("open-source/mojo/stdlib/stdlib/collections/string/string.mojo":1460:8)
    >>     fn split(self, sep: StringSlice, maxsplit: Int = -1) raises -> List[String]:
              ^........................................................................
    >>         """Split the string by a separator.
    >>
    >>         Args:
    >>             sep: The string to split on.
2.      Crash parsing statement at loc("open-source/mojo/stdlib/stdlib/collections/string/string.mojo":1486:9)
    >>         return _to_string_list(
               ^......................
    >>             self.as_string_slice().split(sep, maxsplit=maxsplit)
    >>         )

I'm going to mark this as "blocked" label here for my own book-keeping. I've asked the compiler team to take a look at this internally.

A few things:

• We eventually want String.split(...) to return List[StringSlice], but this was blocked by similar issues above with parameter inference. See [stdlib] Make split return List[StringSlice] #4016 that this particular PR was split off from.
• It didn't crash/fail in the open source CI which is strange - I don't know why yet.

@martinvuyk update here: @zyx-billy fixed the parameter inference issue and I just rebased this synced PR internally. It's about to pass CI and land. This should unblock #3894 and friends as well in the next nightly. It was hitting similar parameter inference bugs IIRC. So feel free to rebase those when this fix lands and we can get those in. Thank you everyone for chasing this down!

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[modularbot]

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