Document and/or deprecate Node's getFullStart() vs. pos?

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Comment

Coming over from https://github.com/typescript-eslint/typescript-eslint/issues/8227 -> https://discord.com/channels/508357248330760243/640177429775777792/1194002057858916483: it looks like ts.Node objects have both a pos: number property and a getFullStart(): number method that directly returns this.pos:

https://github.com/microsoft/TypeScript/blob/02f9ddf55d27716c0306ec6561baf80d42744fed/src/services/services.ts#L564-L566

Doing some quick Find all references from the interfaces' definitions in VS Code:

• Node's getFullStart() has 25 results
• ReadonlyTextRanges readonly pos has 407 results

I looked through the GitHub repo and code history but couldn't find anything justifying why both exist. My hunch is maybe that #9529 which added getFullStart() predates TS 2.0's readonly (TS 2.0 release notes > readonly)?

Given that getFullStart() incurs an extra function call, is there any reason beyond backwards compatibility to keep it around? If not, would the team be open to marking it as @deprecated in JSDoc to reduce ambiguity?

Start with src/services/services.ts around the referenced getFullStart() implementation, then compare the Node and ReadonlyTextRange interface definitions and the linked history around #9529. Determine whether the two APIs have a documented distinction and whether deprecation is appropriate; done means recording the rationale or deprecation decision in the relevant TypeScript API documentation or JSDoc.