On 23/06/2021 21:15, Mark Wielaard wrote: > On Wed, Jun 23, 2021 at 12:51:34AM +0200, Mark Wielaard wrote: >> 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? > Tom pointed out on irc that it doesn't seem possible to access enum > variant types except through a matching expression. The Rust Reference > also seems to be inconsistent. As mentioned above it mentions you can > use a tuple index to refer to a field of a enum tuple variant. But it > also says "A tuple indexing expression accesses fields of tuples and > tuple structs." So it probably really isn't possible to use a tuple > index on enum tuple variants. > > I did notice the same issue as for unit tuple struct types. The empty > tuple wasn't accepted in the parser. The attached patch, also at > https://code.wildebeest.org/git/user/mjw/gccrs/commit/?h=tuple_enum_variant_unit > fixes this. > > It does include a test case, but most of it is commented out because > actually resolving enum types isn't implemented yet. If you uncomment > the rest of the testcase you get: > > tuple_enum_variants.rs:3:31: error: failed to resolve TypePath: E > 3 | fn f(e0: E, e1: E, e2: E) -> (E,E,E,()) > | ^ > tuple_enum_variants.rs:3:31: error: unresolved type > tuple_enum_variants.rs:3:33: error: failed to resolve TypePath: E > 3 | fn f(e0: E, e1: E, e2: E) -> (E,E,E,()) > | ^ > tuple_enum_variants.rs:3:33: error: unresolved type > tuple_enum_variants.rs:3:35: error: failed to resolve TypePath: E > 3 | fn f(e0: E, e1: E, e2: E) -> (E,E,E,()) > | ^ > tuple_enum_variants.rs:3:35: error: unresolved type > tuple_enum_variants.rs:3:10: error: failed to resolve TypePath: E > 3 | fn f(e0: E, e1: E, e2: E) -> (E,E,E,()) > | ^ > tuple_enum_variants.rs:3:10: error: unresolved type > tuple_enum_variants.rs:3:17: error: failed to resolve TypePath: E > 3 | fn f(e0: E, e1: E, e2: E) -> (E,E,E,()) > | ^ > tuple_enum_variants.rs:3:17: error: unresolved type > tuple_enum_variants.rs:3:24: error: failed to resolve TypePath: E > 3 | fn f(e0: E, e1: E, e2: E) -> (E,E,E,()) > | ^ > tuple_enum_variants.rs:3:24: error: unresolved type > tuple_enum_variants.rs:13:12: error: unknown root segment in path E::T0 > lookup E > 13 | let e0 = E::T0(); > | ^ > tuple_enum_variants.rs:14:12: error: unknown root segment in path E::T1 > lookup E > 14 | let e1 = E::T1(0); > | ^ > tuple_enum_variants.rs:15:12: error: unknown root segment in path E::T2 > lookup E > 15 | let e2 = E::T2(0,1); > | ^ > > Cheers, > > Mark > Hi Mark,
Thanks for the patch, its being merged: https://github.com/Rust-GCC/gccrs/pull/522 I have open issues about enums and unions they will be fixed as part of my work into traits. They are a type of algebraic data type so in theory i can reuse a lot of the existing code to implement them. Thanks --Phil
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