Generic code can cause attempts to use constructors for unrelated types to fail

[barcharcraz]

the code

type TMatrix[N,M: static[int], T] = object
  data: array[0..M*N-1, T]
type TMat4f = TMatrix[4,4,float32]
type TVec3f = TMatrix[1,3,float32]
type TVec4f = TMatrix[1,4,float32]
type TVec[N: static[int]; T] = TMatrix[N,1,T]
proc dot*(a, b: TVec): TVec.T =
  #assert(a.data.len == b.data.len)
  for i in 1..a.data.len:
    result += a.data[i-1] * b.data[i-1]
proc row*(a: TMatrix; i: int): auto =
  result = TVec[TMatrix.M, TMatrix.T]()
  for idx in 1..TMatrix.M:
    result.data[idx-1] = a.data[(TMatrix.N * (idx-1)) + (i-1)]
proc col*(a: TMatrix; j: int): auto =
  result = TVec[TMatrix.N, TMatrix.T]()
  for idx in 1..TMatrix.N:
    result.data[idx] = a.data[(TMatrix.N * (j-1)) + (idx-1)]
proc mul*(a: TMat4f; b: TMat4f): TMat4f =
  for i in 1..4:
    for j in 1..4:
      result.data[(4 * (j-1)) + (i-1)] = dot(row(a,i), col(b,j))

var test = TVec4f(data: [1.0'f32, 1.0'f32, 1.0'f32, 1.0'f32])

fails with the error

tconstruct.nim(24, 17) Error: internal error: genObjConstr
No stack traceback available

if test is changed to be a TVec3f then the code works, but it fails again if a mul proc is defined for TMat3f

[gmpreussner]

Workaround:

type TMatrix[N,M: static[int], T] = object
  data: array[0..M*N-1, T]
type TMat4f = TMatrix[4,4,float32]
type TVec3f = TMatrix[1,3,float32]
type TVec4f = TMatrix[1,4,float32]
type TVec[N: static[int]; T] = TMatrix[N,1,T]
proc dot*(a, b: TVec): TVec.T =
  #assert(a.data.len == b.data.len)
  for i in 1..a.data.len:
    result += a.data[i-1] * b.data[i-1]
proc row*[N, M, T](a: TMatrix[N, M, T]; i: int): TVec[M, T] =
  for idx in 1..M:
    result.data[idx-1] = a.data[(N * (idx-1)) + (i-1)]
proc col*[N, M, T](a: TMatrix[N, M, T]; j: int): TVec[N, T] =
  for idx in 1..N:
    result.data[idx] = a.data[(N * (j-1)) + (idx-1)]
proc mul*(a: TMat4f; b: TMat4f): TMat4f =
  for i in 1..4:
    for j in 1..4:
      result.data[(4 * (j-1)) + (i-1)] = dot(row(a,i), col(b,j))

var test = TVec4f(data: [1.0'f32, 1.0'f32, 1.0'f32, 1.0'f32])