{
  "$type": "site.standard.document",
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  "path": "/t/interiorassign-trait-a-b/24291#post_12",
  "publishedAt": "2026-05-10T19:49:23.000Z",
  "site": "https://internals.rust-lang.org",
  "tags": [
    "@steffahn"
  ],
  "textContent": "`RefCell` is a good motivating example, but I don't think this needs to be limited to types with interior mutability:\n\n\n    pub trait InteriorAssignMut { /*...*/ }\n    pub trait InteriorAssign: InteriorAssignMut { /*...*/ }\n\n\nContainers like `Option` could implement only `InteriorAssignMut`:\n\n\n    let mut num = Some(12);\n    num := 13;\n\n\nWould this resolve your concern, @steffahn?",
  "title": "InteriorAssign trait { a := b }"
}