Add replacementSpan for string completions

[mjbvz]

TypeScript Version: 3.3.0-dev.2019010

From microsoft/vscode#53962

Search Terms:

• completions / suggestions
• replacementSpan

Problem

For code such as:

interface TFunction {
    (_: 'login.title', __?: {}): string;
    (_: 'login.description', __?: {}): string;
    (_: 'login.sendEmailAgree', __?: {}): string;
    (_: 'login.termsOfUse', __?: {}): string;
    (_: 'login.privacyPolicy', __?: {}): string;
    (_: 'login.sendEmailButton', __?: {}): string;
    (_: 'login.emailInputPlaceholder', __?: {}): string;
    (_: 'login.errorWrongEmailTitle', __?: {}): string;
    (_: 'login.errorWrongEmailDescription', __?: {}): string;
    (_: 'login.errorGeneralEmailTitle', __?: {}): string;
    (_: 'login.errorGeneralEmailDescription', __?: {}): string;
    (_: 'login.loginErrorTitle', __?: {}): string;
    (_: 'login.loginErrorDescription', __?: {}): string;
    (_: 'login.openEmailAppErrorTitle', __?: {}): string;
    (_: 'login.openEmailAppErrorDescription', __?: {}): string;
    (_: 'login.openEmailAppErrorConfirm', __?: {}): string;
  }

const f: TFunction = (() => {}) as any;

f('login.email|')

Where a completion is being triggered at the | in the f call. VS code currently manually tries to compute the span to replace within the string. This is not very reliable because we are only have the text content of the document.

Proposal:
For strings completions, it would be helpful if TS could return the entire range to be replaced with the replacementSpan property on the completion item. This should be more reliable than having VS code try to compute it.

In the above case, the replacement span would cover the range of login.email

[Kingwl]

I have founded setting editor.suggest.insertMode is already existed in vscode.
And replacementSpan is already existed in completion entry.
Is that mean we just need to fill the replacementSpan in the ts side?
And should we always fill that in all of request even editor.suggest.insertMode is turn on?

[DanielRosenwasser]

Thanks @Kingwl!