Error: generic instantiation too nested

[gabbhack]

During some work on new version of deser and deser_json I found that the code below doesn't compile

Code below

import options

import deser, deser_json

let jsonString = readFile("twitter.json")

type
  Object = object
    statuses: seq[Status]
    search_metadata: SearchMetadata

  Status = object
    metadata: Metadata
    created_at: string
    id: int64
    id_str: string
    text: string
    source: string
    truncated: bool
    in_reply_to_status_id: Option[float]
    in_reply_to_status_id_str: Option[string]
    in_reply_to_user_id: Option[int]
    in_reply_to_user_id_str: Option[string]
    in_reply_to_screen_name: Option[string]
    user: User
    retweet_count: int64
    favorite_count: int64
    entities: StatusEntities
    favorited: bool
    retweeted: bool
    lang: string

  Metadata = object
    result_type: string
    iso_language_code: string

  User = object
    id: int
    id_str: string
    name: string
    screen_name: string
    location: string
    description: string
    url: Option[string]
    entities: UserEntities
    protected: bool
    followers_count: int64
    friends_count: int64
    listed_count: int64
    created_at: string
    favourites_count: int64
    utc_offset: Option[int]
    time_zone: Option[string]
    geo_enabled: bool
    verified: bool
    statuses_count: int64
    lang: string
    contributors_enabled: bool
    is_translator: bool
    is_translation_enabled: bool
    profile_background_color: string
    profile_background_image_url: string
    profile_background_image_url_https: string
    profile_background_tile: bool
    profile_image_url: string
    profile_image_url_https: string
    profile_banner_url: Option[string]
    profile_link_color: string
    profile_sidebar_border_color: string
    profile_sidebar_fill_color: string
    profile_text_color: string
    profile_use_background_image: bool
    default_profile: bool
    default_profile_image: bool
    following: bool
    follow_request_sent: bool
    notifications: bool

  UserEntities = object
    description: Description
    url: Option[Description]

  Description = object
    urls: seq[Url]

  Url = object
    url: string
    expanded_url: string
    display_url: string
    indices: seq[int64]

  StatusEntities = object
    hashtags: seq[Hashtag]
    urls: seq[Url]
    user_mentions: seq[UserMentions]
    media: Option[seq[Media]]
  
  Hashtag = object
    text: string
    indices: seq[int]
  
  Media = object
    id: int64
    id_str: string
    indices: seq[int64]
    media_url: string
    media_url_https: string
    url: string
    display_url: string
    expanded_url: string
    `type`: string
    sizes: Sizes
    source_status_id: Option[float]
    source_status_id_str: Option[string]
  
  Sizes = object
    thumb: Size
    large: Size
    medium: Size
    small: Size
  
  Size = object
    w: int64
    h: int64
    resize: string

  UserMentions = object
    screen_name: string
    name: string
    id: int64
    id_str: string
    indices: seq[int64]

  SearchMetadata = object
    completed_in: float64
    max_id: int64
    max_id_str: string
    next_results: string
    query: string
    refresh_url: string
    count: int64
    since_id: int64
    since_id_str: string

makeDeserializable([
  Object,
  Status,
  Metadata,
  User,
  UserEntities,
  Description,
  Url,
  StatusEntities,
  Hashtag,
  Media,
  Sizes,
  Size,
  UserMentions,
  SearchMetadata
])

for i in 0..1000000:
  var obj = fromJson(Object, jsonString)

Error

C:\Users\Noname\Desktop\main.nim(163, 21) template/generic instantiation of `fromJson` from here
E:\Dev\nim\deser_json\src\deser_json\des.nim(22, 7) template/generic instantiation of `deserialize` from here
C:\Users\Noname\Desktop\main.nim(146, 3) template/generic instantiation of `deserializeMap` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(201, 19) template/generic instantiation of `visitMap` from here
C:\Users\Noname\Desktop\main.nim(146, 3) template/generic instantiation of `nextValue` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(399, 11) template/generic instantiation of `nextValueSeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(251, 7) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(41, 13) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(275, 15) template/generic instantiation of `deserializeSeq` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(193, 19) template/generic instantiation of `visitSeq` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(268, 23) template/generic instantiation of `items` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(353, 45) template/generic instantiation of `nextElement` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(348, 11) template/generic instantiation of `nextElementSeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(231, 14) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(41, 13) template/generic instantiation of `deserialize` from here
C:\Users\Noname\Desktop\main.nim(147, 3) template/generic instantiation of `deserializeMap` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(201, 19) template/generic instantiation of `visitMap` from here
C:\Users\Noname\Desktop\main.nim(147, 3) template/generic instantiation of `nextValue` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(399, 11) template/generic instantiation of `nextValueSeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(251, 7) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(41, 13) template/generic instantiation of `deserialize` from here
C:\Users\Noname\Desktop\main.nim(149, 3) template/generic instantiation of `deserializeMap` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(201, 19) template/generic instantiation of `visitMap` from here
C:\Users\Noname\Desktop\main.nim(149, 3) template/generic instantiation of `nextValue` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(399, 11) template/generic instantiation of `nextValueSeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(251, 7) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(41, 13) template/generic instantiation of `deserialize` from here
C:\Users\Noname\Desktop\main.nim(150, 3) template/generic instantiation of `deserializeMap` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(201, 19) template/generic instantiation of `visitMap` from here
C:\Users\Noname\Desktop\main.nim(150, 3) template/generic instantiation of `nextValue` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(399, 11) template/generic instantiation of `nextValueSeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(251, 7) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(41, 13) template/generic instantiation of `deserialize` from here
C:\Users\Noname\Desktop\main.nim(151, 3) template/generic instantiation of `deserializeMap` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(201, 19) template/generic instantiation of `visitMap` from here
C:\Users\Noname\Desktop\main.nim(151, 3) template/generic instantiation of `nextValue` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(399, 11) template/generic instantiation of `nextValueSeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(251, 7) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(41, 13) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(275, 15) template/generic instantiation of `deserializeSeq` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(193, 19) template/generic instantiation of `visitSeq` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(268, 23) template/generic instantiation of `items` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(353, 45) template/generic instantiation of `nextElement` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(348, 11) template/generic instantiation of `nextElementSeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(231, 14) template/generic instantiation of `deserialize` from here
E:\Dev\nim\deser\src\deser\des\impls.nim(41, 13) template/generic instantiation of `deserialize` from here
C:\Users\Noname\Desktop\main.nim(152, 3) template/generic instantiation of `deserializeMap` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(201, 19) template/generic instantiation of `visitMap` from here
C:\Users\Noname\Desktop\main.nim(152, 3) template/generic instantiation of `keys` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(408, 35) template/generic instantiation of `nextKey` from here
E:\Dev\nim\deser\src\deser\des\helpers.nim(396, 11) template/generic instantiation of `nextKeySeed` from here
E:\Dev\nim\deser_json\src\deser_json\des\des.nim(236, 22) template/generic instantiation of `eatSpace` from here
E:\Dev\nim\deser_json\src\deser_json\jsony.nim(52, 10) Error: generic instantiation too nested

After recompile compiler with higher c.instCounter value error was fixed

[gabbhack]

Maybe related nim-lang/Nim#16389

[gabbhack]

More readable example:

import deser, deser_json

type
  One = object
    two: Two
  
  Two = object
    three: Three

  Three = object
    four: Four

  Four = object 
    five: Five
  
  Five = object
    six: Six
  
  Six = object
    seven: Seven
  
  Seven = object

makeDeserializable([
  One,
  Two,
  Three,
  Four,
  Five,
  Six,
  Seven,
])

echo One.fromJson("")

[gabbhack]

import deser, deser_json

type
  One = object
    two: Two
  
  Two = object
    three: Three

  Three = object
    four: Four

  Four = object 
    five: Five
  
  Five = object
    six: Six
  
  Six = object
    seven: Seven
  
  Seven = object

makeDeserializable([
  One,
  Two,
  Three,
  Four,
  Five,
  Six,
  Seven,
])

# echo Seven.fromJson("{}")

echo One.fromJson("""{"two": {"three": {"four": {"five": {"six": {"seven": {}}}}}}}""")

If uncomment line this code will work

[gabbhack]

import deser, deser_json

type
  One = object
    two: Two
  
  Two = object
    three: Three

  Three = object
    four: Four

  Four = object 
    five: Five
  
  Five = object
    six: Six
  
  Six = object
    seven: Seven
  
  Seven = object

makeDeserializable([
  One,
  Two,
  Three,
  Four,
  Five,
  Six,
  Seven,
])

template hack(a: typed) = discard

hack(Two.fromJson(""))

echo One.fromJson("""{"two": {"three": {"four": {"five": {"six": {"seven": {}}}}}}}""")

hackaround