Cannot instantiate generic type with not nil parameter type

[iacore]

Function echo outputs the wrong string.

Example

{.experimental: "notnil".}
import tables

type FooObject = object
type Foo = ref FooObject not nil
type Bar = object
    table: Table[int, Foo]

proc `=init`(x: var Foo) =
    x = new(Foo)

let bar = Bar()

Current Output

> nim c -r test.nim
Hint: used config file '/home/user/.choosenim/toolchains/nim-#devel/config/nim.cfg' [Conf]
Hint: used config file '/home/user/.choosenim/toolchains/nim-#devel/config/config.nims' [Conf]
...................................................................
/home/user/computing/test/test.nim(12, 14) Error: The Bar type requires the following fields to be initialized: table.

What's wrong

1

There should be some way to specify default value of not nil reference type.

2

The error message doesn't tell why table can't be initialized.

3

let table: Table[int, Foo] = newTable()

yields the compile error

Error: cannot instantiate: 'A'

not

Error: cannot instantiate: 'Foo'

Possible Solution

Use =init hook or some other proc for the default value.

Additional Information

This is related to https://nim-lang.github.io/Nim/manual_experimental_strictnotnil.html This is related to user defined default value.

Nim Compiler Version 1.5.1 [Linux: amd64]
Compiled at 2021-10-15
Copyright (c) 2006-2021 by Andreas Rumpf

git hash: 73330711a3d753d25b073fb1dc24cb16e559724d
active boot switches: -d:release

[iacore]

Trying to instantiate not nil ref type

{.experimental: "notnil".}
import tables

type FooObject = object
type Foo = ref FooObject not nil
type Bar = object
    table: Table[int, Foo]

proc `=init`(x: var Foo) =
    x = new(Foo)

let foo: Foo

Output

Error: 'let' symbol requires an initialization

[Araq]

Use =init hook or some other proc for the default value.

There is no =init hook in today's Nim. The RFC hasn't been implemented.

Error: 'let' symbol requires an initialization

That's not a bug either.