struct fields in enum declarations generate junk types

[jorgeadriano]

A struct inside an enum generates a type identifier (as it does outside when used outside an enum).

enum S { C {a:int, b:int}};  
enum C {};

t.rs:10:4: 10:13 error: duplicate definition of type `C`
t.rs:10     enum C {};
        ^~~~~~~~~
t.rs:9:13: 9:29 note: first definition of type `C` here
t.rs:9     enum S { C {a:int, b:int}};  
                ^~~~~~~~~~~~~~~~

In particular the following declaration doesn't typecheck.

enum S { S {a:int, b:int}}; 

t.rs:6:13: 6:29 error: duplicate definition of type `S`
t.rs:6     enum S { S {a:int, b:int}};  
                    ^~~~~~~~~~~~~~~~
t.rs:6:4: 6:30 note: first definition of type `S` here
t.rs:6     enum S { S {a:int, b:int}};  

This is inconsistent with the general case in which such is allowed. E.g., both declarations below type check, despite type and value constructors having the same identifier:

enum S { S(int, int) }
struct S {a:int, b:int};

As a sidenote, we can't create values of these generated types even if wished to do so for some reason, since the value constructor associated with the struct field is set to create values of the enum type.

enum S { C {a:int, b:int} };  
let k : C = C{a:0, b:0};

t.rs:10:12: 10:13 error: found value name used as a type: DefVariant(syntax::ast::DefId{crate: 0, node: 7}, syntax::ast::DefId{crate: 0, node: 14}, true)
t.rs:10     let k : C = C{a:0, b:0};

My tests were performed on v0.8, but the bug was confirmed to be present in 0.9pre. Using Linux, OpenSUSE 13.1

[huonw]

This is now actually by design, RFC #234 places enum variants into the type namespace as well as the value namespace. (This was not the case when this issue was filed, though, so was definitely worth a bug then; thanks!)

The bad error message you note is still an issue, but this is covered more specifically by #17546, so I'm closing this.