An error occurs when calling generic and overloaded proc with declare operator ()

[ishowta]

Nim Compiler Version 0.17.3 [Linux: amd64]
Copyright (c) 2006-2017 by Andreas Rumpf

git hash: 7e6dc3679aaf463a957af7ff6bb34317c7656d4c
active boot switches: -d:release

{.experimental: "callOperator".}

proc noGenericProc(n:int)                    = discard

proc noGenericWithOverloadingProc(n:int)     = discard
proc noGenericWithOverloadingProc(n:string)  = discard

proc genericProc[T](n:int)                   = discard

proc genericWithOverloadingProc[T](n:int)    = discard
proc genericWithOverloadingProc[T](n:string) = discard

block:
  noGenericProc(1)                    # ok
  noGenericWithOverloadingProc(1)     # ok
  genericProc[int](1)                 # ok
  genericWithOverloadingProc[int](1)  # ok

block:
  type A = object
  type B = object
  proc `()`(a:A, b:B) = discard

  noGenericProc(1)                    # ok
  noGenericWithOverloadingProc(1)     # ok
  genericProc[int](1)                 # ok
  genericWithOverloadingProc[int](1)  # error

  discard newSeq[int](1)              # this also error

test.nim(29, 34) Error: type mismatch: got (proc (n: int){.noSideEffect, gcsafe, locks: 0.} | proc (n: string){.noSideEffect, gcsafe, locks: 0.}, int literal(1))
but expected one of:
proc `()`(a: A; b: B)

expression: ()(genericWithOverloadingProc, 1)

[ghost]

@kinironote do you think this code should work or not?

[ishowta]

I think this code should work.
As far as I've tried, it seems that an error occurs regardless of what operator () is declared.

{.experimental.}

var s = newSeq[int](3)

echo s  # ok

{.experimental.}

proc `()`(a:string, b:string):string = a & b

var s = newSeq[int](3)

echo s  # error

I may be misunderstanding something. I'm sorry.

[shirleyquirk]

Reduced:

{.experimental: "callOperator".}

type Foo = object
proc `()`(foo: Foo) = discard

proc mewSeq[T](a,b:int)=discard
proc mewSeq[T](c:int)= discard
mewSeq[int]()

Obviously the above shouldn't compile, but mewSeq[int](5) also doesn't compile and the error message is the point:

/usercode/in.nim(8, 12) Error: type mismatch: got <proc (a: int, b: int){.noSideEffect, gcsafe, locks: 0.} | proc (c: int){.noSideEffect, gcsafe, locks: 0.}>
but expected one of: 
proc `()`(foo: Foo)
  first type mismatch at position: 1
  required type for foo: Foo
  but expression 'mewSeq' is of type: void

expression: ()(mewSeq)