typedesc as array members are still allowed

[dawkot]

Example

var xs = [int, float, string]

Error

Error: internal error: symbol has no generated name: int

Example

const xs = [int, float, string]

echo xs[0]
echo xs[1]
echo xs[2]

Output

None
None
None

Expected output

Neither should compile (?)

[krux02]

This is strage, because I have memories implementing a compiler check to prevent exactly this. False memories? Anyway, these issue are related.

#8654
#8610

This PR is related:
#11959

[ghost]

Shows a proper error on latest devel:

~/P/ircord ❯❯❯ nim c -r "/home/dian/Projects/ircord/a.nim"
Hint: used config file '/home/dian/Things/Nim/config/nim.cfg' [Conf]
Hint: used config file '/home/dian/Things/Nim/config/config.nims' [Conf]
Hint: used config file '/home/dian/nim.cfg' [Conf]
....
/home/dian/Projects/ircord/a.nim(1, 5) Error: invalid type: 'typedesc' in this context: 'array[0..2, typedesc]' for var

Do we have a test case for that?

[timotheecour]

• dup of Error: internal error: expr(skType); unknown symbol #9932 which was fixed in disallow typedesc in arrays & move existing checks to types.typeAllowedAux #13261 however I don't see a test case for that in that PR /cc @nc-x so I'd simply add a test case (for both [int] and @[int]) in some tests/errmsgs/t12398.nim test as done in disallow typedesc in arrays & move existing checks to types.typeAllowedAux #13261 (or better, use a doAssert not compiles ... test, which can be megatest-joined)

[timotheecour]

closed by #14795

[kamilchm]

Is there a way to have some sort of list of typedescs in a static block?

[Araq]

You can do type introspection via Nim's macro system.

[timotheecour]

Is there a way to have some sort of list of typedescs in a static block?

type A = (int, float) ?

[kamilchm]

I was looking for something to use a list of types in a loop, eg.:

macro x(t: typedesc) =
  ...

static:
  for t in [MyType1, MyType2, ....]: # <- I want to use it here
    x(t)

[tsoj]

I was looking for something to use a list of types in a loop, eg.:

macro x(t: typedesc) =
  ...

static:
  for t in [MyType1, MyType2, ....]: # <- I want to use it here
    x(t)

In this specific example, you could probably use a macro xMany(args: varargs[untyped]), where each args[i] is a type. But something like openArray[T1, T2, T3] would still be really helpful in cases, where one wouldn't want to use a macro (or a template), but a proper function.
Though I currently can't think of an example other than an entity component system, if I'm honest.