tsconfig inheritance requires saving child tsconfig before changes in parent are applied to applicable files.

[ozyman42]

• VSCode Version: 1.30.2
• OS Version: Windows 10

Steps to Reproduce:

1. Create a new folder then open it in VSCode
2. Create the project:

example_folder/
├── src
│   ├── example.ts
│   └── tsconfig.json
└── tsconfig-base.json

example_folder/tsconfig-base.json

{
    "compilerOptions": {
        "lib": [],
        "types": []
    }
}

example_folder/src/tsconfig.json

{
    "extends": "../tsconfig-base",
    "compilerOptions": {
        "noImplicitAny": true
    }
}

example_folder/src/example.ts

new Promise(()=>{});
console.log("hello world");

3. Open example_folder/src/example.ts

You should see vscode complain about 2 errors in the file: the names Promise and console cannot be found. This is expected.

4. Change example_folder/tsconfig-base.json from its original form to this:

{
    "compilerOptions": {
        "lib": ["esnext"],
        "types": []
    }
}

Expected behavior: the error about the Promise not being found should go away.
Actual behavior: the error is still there.

4. Go to example_folder/src/tsconfig.json and hit the save key.

Only after this does the error go away. The save of the inherited tsconfig should trigger the errors to disappear, but it seems that these changes only get reflected in the inheriting tsconfig when it is saved again (even if the inheriting tsconfig file does not change).

Does this issue occur when all extensions are disabled?: Yes

[mjbvz]

Moving upstream as I can repo this with tsc --watch as well. Steps:

tsconfig.json

{
    "extends": "./tsconfig.base.json"
}

tsconfig.base.json

{
  "compilerOptions": {
  }
}

x.ts

const a: string = undefined;

1. Run tsc --watch -p tsconfig.json
2. See no errors
3. Now open tsconfig.base.json and add "strict": true
4. Save tsconfig.base.json

Bug
Nothing happens. Only after the tsconfig.json is saved do you see the error about strict null checks

[sheetalkamat]

This is duplicate and same root cause as known issue: #17753

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.