Static + Method: Hangs nim compilation (and zombifies nim process)

[mratsim]

The following snippet will hang nim compilation.
Nim processes will consume a lot of Cpu and must be killed manually.

The strange thing is that to compile, I can uncomment:

• either the method
• or the tensor object creation (with static generic)

type
  Backend* = enum
    Cpu

  Tensor*[B: static[Backend]; T] = object
    data: seq[T]


proc toTensor*[T](s:openarray[T], B: static[Backend]): Tensor[B,T] =
  result.data = @s


####
type Autograd = ref object of RootObj

method forward[B,T](self: Autograd, list_tensors: varargs[Tensor[B,T]]): T {.base.}=
  raise newException(ValueError, "Forward is not implemented for this function")

type AddFn = ref object of Autograd


## Commenting either the following will make the program compiles
method forward[B,T](self: AddFn, a, b: Tensor[B,T]): T =
  return 1 + 1

## Or commenting the following will make the program compiles
let a = [0,1,2,3,4,5].toTensor(Cpu)

Without static at all, everything compiles.

type
  Backend* = enum
    Cpu

  Tensor*[T] = object
    data: seq[T]


proc toTensor*[T](s:openarray[T]): Tensor[T] =
  result.data = @s


####
type Autograd = ref object of RootObj

method forward[T](self: Autograd, list_tensors: varargs[Tensor[T]]): T {.base.}=
  raise newException(ValueError, "Forward is not implemented for this function")

type AddFn = ref object of Autograd


## No issue
method forward[T](self: AddFn, a, b: Tensor[T]): T =
  return 1 + 1

## No issue
let a = [0,1,2,3,4,5].toTensor()

I'm using Nim 0.17 on MacOS (install by choosenim stable)

[subsetpark]

Reproduced on Linux with:

Nim Compiler Version 0.17.1 (2017-07-08) [Linux: amd64]
Copyright (c) 2006-2017 by Andreas Rumpf

active boot switches: -d:release

[narimiran]

Nim processes will consume a lot of Cpu and must be killed manually.

Nim v0.19.0, Linux, raises: "Error: generic instantiation too nested"

[andreaferretti]

Compiles fine on MacOS devel da4215a

[narimiran]

Compiles fine on MacOS devel

Confirmed on Linux with the latest devel — compilation is successful.