Static - type subset of generic type - clang compiler error on multiple arguments

[mratsim]

I'm refactoring https://github.com/unicredit/linear-algebra/ and creating a generic Matrix[M, N, T] of which Matrix32[M, N] and Matrix64[M, N] will be subset to maintain backward compatibility.

I got a strange error on clang with the following test case

type
  Matrix*[M, N: static[int], T: SomeReal] = object
    data: ref array[N * M, T]
  Matrix64*[M, N: static[int]] = Matrix[M, N, float64]

proc zeros64(M,N: static[int]): Matrix64[M,N] =
  new result.data
  for i in 0 .. < (M * N):
    result.data[i] = 0'f64

proc `$`*[M, N: static[int]](m: Matrix64[M, N]): string =
  result = "64"

proc foo*[M,N: static[int], T](a: Matrix[M,N,T]) =
  echo a

proc bar*[M,N: static[int], T](a: Matrix[M,N,T], b: Matrix[M,N,T]) =
  echo a


let a = zeros64(2,2)
foo(a) #works
bar(a,a) #fails

Error is

Hint: used config file '/usr/local/Cellar/nim/HEAD-7e351fc/nim/config/nim.cfg' [Conf]
Hint: system [Processing]
Hint: playground2 [Processing]
CC: linalg_playground2
Error: execution of an external compiler program 'clang -c  -w  -I/usr/local/Cellar/nim/HEAD-7e351fc/nim/lib -o nimcache/linalg_playground2.o nimcache/linalg_playground2.c' failed with exit code: 1

nimcache/linalg_playground2.c:260:57: error: passing 'Matrix_Nb9aIVumBEh1lQnIqrfOM9ag' (aka 'struct Matrix_Nb9aIVumBEh1lQnIqrfOM9ag') to parameter of incompatible type 'Matrix_t9aff0BJYnei5m71SWTA5Wg' (aka 'struct Matrix_t9aff0BJYnei5m71SWTA5Wg')
        bar_dxw2HPX6uLOVcW9bsla0gNA(a_UlQDd4uj9bxnRSukXNrxCBQ, a_UlQDd4uj9bxnRSukXNrxCBQ);
                                                               ^~~~~~~~~~~~~~~~~~~~~~~~~
nimcache/linalg_playground2.c:200:112: note: passing argument to parameter 'b' here
N_NIMCALL(void, bar_dxw2HPX6uLOVcW9bsla0gNA)(Matrix_Nb9aIVumBEh1lQnIqrfOM9ag a, Matrix_t9aff0BJYnei5m71SWTA5Wg b) {
                                                                                                               ^
1 error generated.