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by devit
1887 days ago
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1. You mean Cow<'a, str>? It's an enum of either String or &'a str, typically used with 'static so you can either store an heap-allocated string or a static string without copying it to the heap 2. Given you mention "maps of option", probably you are doing something like opt.map(|x| &x.field) or equivalent which is obviously invalid (since you are returning a reference to a subobject of a function argument). Instead, you need to do opt.as_ref().map(|x| &x.field) (or as_mut() if it's mutable). |
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