Declaring structs/enums in function scope

[54k1]

I tried to perform the following:

fn f () {
    enum E {}
}

enum E {}

And, I got the following error message:
Error E: Name "E" is already in use at [5:5].

Should this be the behavior?
struct/enum declarations in a scope must become inaccessible when out of scope. (In this case, they are inaccessible, however, it won't let us declare another enum/struct with the same name)
The check for previously declared enum/struct is being done in Parser::check_if_declared. We should probably move it to the interpreter where the name resolution by scope is handled.

@tuqqu what do you think about this? What should be the behavior?

[tuqqu]

Ideally, it should not be the behaviour, indeed.

Good catch actually.
The parser should not be handling enum/struct collisions. And it can't do it properly anyways.

Other name collisions are resolved on declaration in interpreter::env as they ought to be (constants, functions).
And it works as expected and this is allowed:

fn f() {
    const x = 10;
    fn y() {}
}
const x = 10;
fn y() {}

If I am not missing anything we need to add a similar check to define_struct and define_enum and remove the check_if_declared from the parser altogether.

While we are at it we can also fix the current confusing error messages of define_function and define_constant

const x = 10;
fn x() {}  //Error x: Trying to redefine function "x" at [2:3]. 

It really should be just Name "x" is already in use at [..].

[tuqqu]

implemented in #7