{
  "$type": "site.standard.document",
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  "path": "/t/pre-rfc-make-some-feature-detected-function-to-fn-pointer-casts-safe-through-zst-token-types/24353#post_5",
  "publishedAt": "2026-05-24T15:09:55.000Z",
  "site": "https://internals.rust-lang.org",
  "textContent": "At least some context outside the target feature attributes needs to have the ability to create that first entry point. I was not aware you could do that cast inside the context already (so soundness of this is already promised). This does change the perspective on struct-target-feature/3525 a bit: an entry point might have a target token type in its signature but it can still be used to construct many other safe function pointers with a simple signature—so those tokens already provide a useful base case. I suppose I would still prefer another (macro) way that avoids the whole function layer for ergonomics reasons.\n\nMaybe that should be discussed at the RFC directly though instead of as a competing one.",
  "title": "[Pre-RFC] Make some feature-detected function-to-fn-pointer casts safe through ZST token types"
}