TypeScript Version: 3.3.3333

If you configure in the tsconfig.json a rootDirs section like

{
    "compilerOptions": {
        "baseUrl": "src",
        "rootDirs": [
            "src",
            "src_gen"
        ]
    }
}

When you try autocomplete an import the subjections ignore what is available in the rootDirs, only show the options available in the same folder of the editing file.

Example

File src/example/example.tsx

import { exampleImport } from './[autocomplete here]'
import { exampleImport2 } from '../[autocomplete here]'

Try to autocomplete after ./, ../, or any subfolder, the displayed options are only the options available in the src folder, but not the options available in the src_gen folder.

Note: No matter the folder's order in the rootDirs sections, the result is the same. The value of the baseUrl option is not important for reproduce this behaviour.

Maybe related to: #28550 and #30147