Using a generic type in 'raises' pragma's argument

[thenjip]

Hello everyone,

I am trying to wrap the `raise` operator in a procedure like so: 
    
    
    proc raiseException* [E: CatchableError](e: ref E; R: typedesc): R 
{.raises: [E].} =
      raise e
    
    when isMainModule:
      try:
        newException(IOError, "").raiseException(void)
      except IOError:
        echo "exception caught"
    
    
    Run

I tried to compile that program with Nim 0.20.2 and I had the following error:

`prog.nim(1, 79) Error: invalid type for raises/tags list`

I think the compiler verifies what raiseException can raise before the 
procedure can be used, but I could be wrong.

So, is what I am trying to do possible ? And if yes, how ?