auto-import favors import from target instead of source

[chengB12]

TypeScript Version: 4.0.0-dev.20200529
Verify no issue with vs code version 1.45.1 + typescript vsrion: 3.8
Verify issue with vs code + typescript 3.9.3
still have issue with vs code + typescript 4.0.0-dev20200529

Search Terms:
import / auto import
Code
we have project configure as

|
|-- sharedlib
       | -- src
       | -- dist
|-- package1
       | -- src
       | -- dist
|-- package2
       | -- src
       | -- dist

where src is *.ts source code, dist is where compiled *.js files

sharedlib/tsconfig.json

{"compilerOptions": {
    "rootDir": "./",
    "baseUrl": ".",
    "outDir": "dist",
    "paths": {
      "*": [
        "types/*"
      ]
    },
    "composite": true
  },
  "include": [
    "src/**/*.ts",
  ]
}

package1/tsconfig.json

{"compilerOptions": {
    "baseUrl": ".",
    "outDir": "dist",
    "rootDir": "./",
    "paths": {
      "*": [
        "../sharedlib/types/*"
      ],
      "sharedlib": [
        "../sharedlib"
      ]
    },
  },
}

sharedlib/src/foo.ts

export const foo = 1

package1/src/bar.ts

console.log(foo)

Expected behavior:
When in visual studio code + typescript 3.8
auto import will prompt me to import as

import foo from 'sharedlib/src/foo'

console.log(foo)

Actual behavior:
On typescript 3.9.3+
first, before compile sharedlib, it can't recognize foo, thus no auto import
after compile, it auto import the js from

import foo from 'sharedlib/dist/src/foo'

console.log(foo)

the problem are

1. now when I add new exportable in sharedlib, I have to compile the package first before I am write reference code from other packages
2. Because code write before/after ts 3.9 are import from different path even for same module, javascript will treat they as different modules, thus breaks states/singleton, if I didn't manually remove /dist from import

Playground Link:

Related Issues:

[andrewbranch]

@chengB12 can you provide a repository with this problem? I think some important information got lost or mangled when you were distilling it down to a simple case. E.g., I think you’d need in your paths "sharedlib/*": ["../sharedlib/*"], not just the starless version, for any of this to compile under any TypeScript version.

[chengB12]

Hi, I changed in paths, still same issue

I have created a sample project,
sample.zip

[andrewbranch]

@chengB12 thanks! This is helpful. I do see that an auto-import isn’t offered for foo, but I still can’t reproduce it offering to import from sharedlib/dist/src/foo after compiling. Can you provide exact steps on how to reproduce that?

Also, in the non-example version of this, are you using Lerna, yarn workspaces, or any other method of symlinking the packages together within node_modules?

[chengB12]

Here is something interesting, I can't reproduce it with bare minimal

our original project having tons of export on ts-sharedlib, and our package1 has tons of import from ts-sharedlib. in this case vs code with ts 3.8 can infer from 'ts-sharedlib/src' and ts 3.9 can infer from 'ts-sharedlib/dist/src'

however, when I trying to strip all other files from package1, leaving only one example, and suddenly, neither ts 3.8 nor ts 3.9 can infer import anymore.

It sounds like vs code can be trained to auto import cross packages given enough success imports

either way, it sounds like a bug to me if bare minimal can't infer imports

[chengB12]

Sorry I can't provide whole 'issue-reproducible' repo, if needed, I may be able to provide a few screenshots

[andrewbranch]

When you remove all existing references from package1 to sharedlib, the lack of auto imports is currently expected behavior, tracked in #37812. The paths case is a good test case for #38923. But that’s a really well-understood problem, so the dist thing is much more concerning to me, but I can’t know whether or not it’s really a bug without seeing the whole project. For example, if you currently import sharedlib/dist/src/foo anywhere in package1, you’ll get that as a suggestion:

But I don’t think that’s a bug.

[chengB12]

I can share a screenshot,
You can see, I have existing import from 'ts-sharedlib/src...'
and after I comment correct import line,
the auto-import I got is from 'ts-sharedlib/dist/src'

[andrewbranch]

It’s not just the file that matters, though; it’s every file in the project and every file’s dependencies, those dependencies’ dependencies, and so on 😕. Would you be able to share TS Server logs?

[chengB12]

We have lint to ensure no code use import xx from 'ts-sharedlib/dist/src...'
it shouldn't comes from existing imports

tsserver.log