What problem does this feature solve?

It's good to have warnings in some scenario where pure annotations are not able
to be interpreted due to the position of the comment.

For example, pure annotation in the example down below is not able
to be interpreted due to position and it's ignored by the parser.

/* #__PURE__ */ React.createElement;

whereas, rollup would emit this warning to help people adjust the placement of pure annotation.

Rollup completed with warnings:
main.js (1:0): A comment "/* #__PURE__ */" in "main.js" contains an annotation that Rollup cannot interpret due to the position of the comment. The comment will be removed to avoid issues. [(link)](https://rollupjs.org/configuration-options/#pure)
/main.js (1:0)
1: /* #__PURE__ */ React.createElement;

https://rollupjs.org/repl/?version=4.59.0&shareable=eyJleGFtcGxlIjpudWxsLCJtb2R1bGVzIjpbeyJjb2RlIjoiLyogI19fUFVSRV9fICovIFJlYWN0LmNyZWF0ZUVsZW1lbnQ7IiwiaXNFbnRyeSI6dHJ1ZSwibmFtZSI6Im1haW4uanMifV0sIm9wdGlvbnMiOnt9fQ==

Original issue: oxc-project/oxc#20334

What does the proposed API look like?

No need