enum variants aren't considered to be const

[doy]

This compiles:

static i: int = 4;

fn main () {
    let x: [int, ..i] = [1, 2, 3, 4];
    println(fmt!("%?", x));
}

But this doesn't:

enum Foo {
    Bar = 4,
}
static i: int = Bar as int;

fn main () {
    let x: [int, ..i] = [1, 2, 3, 4];
    println(fmt!("%?", x));
}

test2.rs:7:11: 7:21 error: expected constant expr for vector length: Can't cast str to int
test2.rs:7     let x: [int, ..i] = [1, 2, 3, 4];
                      ^~~~~~~~~~

That error message doesn't seem to make sense, but that may be because it's just confused - I also get this error message in other circumstances, and I don't understand what the difference is:

src/info/builtin.rs:79:11: 79:52 error: expected constant expr for vector length: Non-constant path in constant expr
src/info/builtin.rs:79 static db: [[Option<&'static str>, ..ncap], ..nterm] = [
                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[catamorphism]

It seems like the constant checker believes that Bar is a constant, whereas the constant evaluator does not. They should agree. I'm not sure which behavior is right. Also, it seems counter-intuitive that you can't refer to a constant (i) in other constants.

Nominating for milestone 1, welll-defined.

[huonw]

Works now. Fixed by 877bba9 (possibly; at the very least, it includes a testcase).

[tikue]

This doesn't seem to work now.

enum Category {
    A,
    B,
    C,
    NumCategories,
}
static NUM_CATEGORIES: uint = NumCategories as uint;

fn main() {
    let the_categories: [Category, ..NUM_CATEGORIES] = [A, B, C];
    printfln!(the_categories);
}

$ x86_64-apple-darwin/stage2/bin/rust run static_test.rs
static_test.rs:10:24: 10:52 error: expected constant expr for vector length: Non-constant path in constant expr
static_test.rs:10 let the_categories: [Category, ..NUM_CATEGORIES] = [A, B, C];

[jdm]

I'm doubtful that the earlier testcase ever worked; 877bba9 explicitly calls out in the commit message that C style enums don't work in type signatures, only values.

[pnkfelix]

Part of #5551; inherits its maturity milestone implicitly.