Re: tuple indexes

[Philip Herron <philip.herron@embecosm.com>]

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On 22/06/2021 23:51, Mark Wielaard wrote:
> Hi,
>
> I was looking into https://github.com/Rust-GCC/gccrs/issues/511 "rust
> has two kinds of integer literal" Which explains that integer literals
> used for a tuple index are not general integer literals.
>
> First I wanted to write some tests, and started with some constructs
> that should pass. But some don't. In particular the empty tuple struct
> isn't recognized, and the struct name path lookup doesn't work when
> initializing the tuple struct.
>
> tuple_index.rs:16:12: error: unrecognised token ‘)’ in type
>    16 |   struct E();
>       |            ^
> tuple_index.rs:16:12: error: could not parse type in tuple struct field
>
> tuple_index.rs:20:12: error: unknown root segment in path O lookup O
>    20 |   let so = O(0);
>       |            ^
> tuple_index.rs:24:12: error: unknown root segment in path T lookup T
>    24 |   let st = T(0,1);
>       |            ^
> tuple_index.rs:28:12: error: unknown root segment in path M lookup M
>    28 |   let sm = M(0,1,2,3,4,5,6,7,8,9,10);
>       |            ^
>
> I haven't had time to try to resolve these issues, but wanted to
> report them.
>
> Finally, the The Rust Reference says "A tuple index is used to refer
> to the fields of tuples, tuple structs, and tuple variants." I don't
> understand how this would work for tuple variants. Does anybody have
> an example of how to refer to a tuple variant so a tuple index can be
> used on it?
>
> Cheers,
>
> Mark
>
Hi Mark,

Good find, I have raised https://github.com/Rust-GCC/gccrs/issues/519.
From the top of my head I think there are a few issues going on.

1. The parser is not able to parse the structure definitions within a
block properly.

2. The knock on is that the name resolution and type resolution will
need updated to handle this.

I think I might take a quick look into this one today I want to double
check a few things as it may have a knock on as to what I am working on.
If i make any progress I will update the ticket and let you know here.

Thanks,

--Phil



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