Typescript: Setting noErrorTruncation to false truncates inferred type of variables/functions; which are not errors

[AnyhowStep]

TypeScript Version: 3.0.1

Search Terms: noErrorTruncation

In TS 2.9, if noErrorTruncation is unset, or set to false, hovering the cursor over an identifier for type inference in VS code would bring up a tooltip with the inferred type.

In TS 3.0, if noErrorTruncation is unset, or set to false, the tooltip with the inferred type will be truncated with ellipsis.

Code

TS 2.9, with noErrorTruncation : false

    /*snip*/
    __canAccept: {
        page?: string | number | null | undefined;
        itemsPerPage?: string | number | null | undefined;
    };
}

TS 3.0 with noErrorTruncation : false

    /*snip*/
    __canAccept: {
        ...;
    };
}

Expected behavior:

noErrorTruncation is about truncating errors.

The tooltips displaying inferred types aren't errors, and should not be affected by this flag.

Actual behavior:

noErrorTruncation affects tooltips displaying inferred types.

---

If anyone else is having this problem, just go to your tsconfig.json, add the following line,

"noErrorTruncation": true,

and restart VS code (or your editor of choice)

[AnyhowStep]

Weird. I thought I finally "fixed" it but, even with noErrorTruncation turned on, some long and complicated types still show up with ellipsis.

Is there a noInferredTypeTruncation thing I'm missing?

---

Turning on noErrorTruncation certainly stops some truncations, but it still doesn't prevent others.

[TomaszWaszczyk]

Weird. I thought I finally "fixed" it but, even with noErrorTruncation turned on, some long and complicated types still show up with ellipsis.

The same for me. TypeScript 3.2.2

[AnyhowStep]

I'm pretty sure it has something to do with createElidedInformationPlaceholder

[xbtsw]

The ellipses makes it very hard to debug Pick, Omit, etc, when things went wrong.

[aleclarson]

@xbtsw Using "noErrorTruncation": true works perfectly on my end. (typescript v3.4.3)

edit: Something like noInferredTypeTruncation would be great! 👍

[xbtsw]

@aleclarson maybe I should say “when things not went as intended”. As you probably noticed the problems not always manifest itself as an error. Sometimes debugging is done by hovering on an inferred type.

[AnyhowStep]

I'm still on 3.5.1.

This is kind of blocking my attempts at continuous integration =/

I do a character-by-character comparison of messageText for output errors, for my compile-time tests. I remove the working directory from import("...") types but the type names keep getting truncated at arbitrary places.

So, different working directory name lengths = different ellipsis positions = failing CI

If noErrorTruncation didn't truncate types in errors, I'd be passing CI.
I guess I'll just ignore messageText in CI for now...

[Ciantic]

It's not just CI, it's usability problem. I actually like browsing (and copying) the type from the hover tip in the VSCode, and when it gets truncated it's pretty much useless.

// from https://developer.twitter.com/en/docs/tweets/data-dictionary/overview/intro-to-tweet-json
let foo = {
  "text": "My added comments to this Tweet ---> https:\/\/t.co\/LinkToTweet",
  "user": {
    "screen_name": "TweetQuoter"
  },
  "quoted_status": {
    "text": "original message",
    "user": {
      "screen_name": "OriginalTweeter"
    },
    "place": {      
    },
    "entities": {      
    },
    "extended_entities": {      
    }
  },
  "place": {    
  },
    "entities": {
      "hashtags": [

      ],
      "urls": [
        {
          "url": "https://t.co/W1FqVrsjQk",
          "expanded_url": "https://twittercommunity.com/t/rt-with-comment-aka-quote-tweets-now-may-have-media-attached-across-twitter-apis/125539",
          "display_url": "twittercommunity.com/t/rt-with-comm…",
          "unwound": {
            "url": "https://twittercommunity.com/t/rt-with-comment-aka-quote-tweets-now-may-have-media-attached-across-twitter-apis/125539",
            "status": 200,
            "title": "RT with comment, aka Quote Tweets, now may have media attached across Twitter APIs",
            "description": "Today we’re announcing a new feature that allows userspeople on Twitter to add a GIF, video, or photo to their Retweet with comments, aka Quote Tweets. Developers will start to see additional media metadata included in the payload for Quote Tweets. Quote Tweets with media will be rendered very similarly to Tweets with media across our APIs. This rendering is an addition to the existing media field, so this should not be a breaking change for application owners, if they are already ingesting med..."
          },
          "indices": [
            162,
            185
          ]
        },
        {
          "url": "https://t.co/lXs26mCkIl",
          "expanded_url": "https://twitter.com/TwitterSupport/status/1125479034513645569",
          "display_url": "twitter.com/TwitterSupport…",
          "indices": [
            186,
            209
          ]
        }
      ],
      "user_mentions": [

      ],
      "symbols": [

      ],
      "media": [
        {
          "id": 1125490782532657153,
          "id_str": "1125490782532657153",
          "indices": [
            210,
            233
          ],
          "media_url": "http://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "media_url_https": "https://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "url": "https://t.co/T9MBCHZWcD",
          "display_url": "pic.twitter.com/T9MBCHZWcD",
          "expanded_url": "https://twitter.com/TwitterDev/status/1125490788736032770/photo/1",
          "type": "animated_gif",
          "video_info": {
            "aspect_ratio": [
              101,
              165
            ],
            "variants": [
              {
                "bitrate": 0,
                "content_type": "video/mp4",
                "url": "https://video.twimg.com/tweet_video/D56L51LV4AEEC8-.mp4"
              }
            ]
          },
          "sizes": {
            "thumb": {
              "w": 150,
              "h": 150,
              "resize": "crop"
            },
            "small": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "large": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "medium": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            }
          }
        }
      ]
    },
    "extended_entities": {
      "media": [
        {
          "id": 1125490782532657153,
          "id_str": "1125490782532657153",
          "indices": [
            210,
            233
          ],
          "media_url": "http://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "media_url_https": "https://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "url": "https://t.co/T9MBCHZWcD",
          "display_url": "pic.twitter.com/T9MBCHZWcD",
          "expanded_url": "https://twitter.com/TwitterDev/status/1125490788736032770/photo/1",
          "type": "animated_gif",
          "video_info": {
            "aspect_ratio": [
              101,
              165
            ],
            "variants": [
              {
                "bitrate": 0,
                "content_type": "video/mp4",
                "url": "https://video.twimg.com/tweet_video/D56L51LV4AEEC8-.mp4"
              }
            ]
          },
          "sizes": {
            "thumb": {
              "w": 150,
              "h": 150,
              "resize": "crop"
            },
            "small": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "large": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "medium": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            }
          }
        }
      ]
    }
  };

[asanacam]

noErrorTruncation also does not solve this problem for me.

[bradennapier]

Yes agree here, it would be huge to at least have some tool - perhaps even something dedicated that would allow us to see the fully expanded and normalized type that typescript will use. Perhaps a custom "peek" style popup for it so that we can choose to view it only when we need to in the case of large types that would make processing type extreme.

[lake2]

same issue +1
Any way to solve this?

[xbtsw]

The ellipsis makes it especially difficult to debug type issues (not type errors) involving Pick, Omit etc.

For example in a type that involves Omit I made a typo in second parameter of Omit, then in some other place I wondered why a interface property is still accepted. The ellipsis makes it difficult to trace back and find the original typo.

[MattiasMartens]

This is an issue that keeps popping up for me. Any motion on it?

[Hati-]

Having this problem as well. Investigating and debugging this issue led me to find this being introduced in merge https://github.com/microsoft/TypeScript/pull/24258.

Typescript starts truncating the output when it reaches the default hard-limit of 160 * 10 characters to prevent the server from hanging too long, even with "noErrorTruncation": true set. There's currently no option for VS Code to disable it from the looks of it:
https://github.com/microsoft/TypeScript/blob/57e2fe0462bb897e581aa489f1d6040db559d82b/src/services/utilities.ts#L1993

For people using VS Code, a quick fix would be opening
<Microsoft VS Code install folder>/resources/app/extensions/node_modules/typescript/lib/tsserver.js
and change
ts.defaultMaximumTruncationLength = 160 at around line 12797
to something higher like
ts.defaultMaximumTruncationLength = 800.

[MattiasMartens]

Thank you for your efforts sleuthing this out @Hati- !

I would hope to see this value bound as a configurable TS preference. However it is awesome to know that there is a way to hack around the limitation.