[Coding Guideline]: Do Not Depend on Function Pointer Identity #256
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| - Comparing function pointers for equality (``fn1 == fn2``) | ||
| - Assuming a unique function address | ||
| - Using function pointers as identity keys (e.g., in maps, registries, matchers) |
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you can still use function pointers as keys, they just don't have a one-to-one relationship to function items, so you can't rely on a function item giving the same function pointer or different items giving different pointers. (ignoring #[no_mangle]). so e.g. you can have a HashSet<fn()> and it works just fine as long as you don't assume inserting any particular function item does anything other than guaranteeing calling one or more of the entries is equivalent to calling that function item.
rcseacord
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@rcseacord you'll want to consider this discussion before the guideline is ready for merge rust-lang/unsafe-code-guidelines#589, since it addresses the same topic |
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FYI @rcseacord @manhatsu -- I got this building again, aside from the code examples, see: #287 Feel free to just yoink the commit from there and replace the commits on this feature branch (i.e. cherry-pick that commit I linked above onto your local updated That way we keep all the comment history from on here. (The coding examples also need to be updated to compile) |
manhatsu
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Clarify function pointer stability issues and provide examples of potential problems and compliant solutions.
Added a non-compliant example demonstrating issues with function address stability and uninitialized memory in Rust.
Updated references and clarified text regarding function pointer stability and the implications of using `#[no_mangle]` functions. Added citations for better context and understanding.
Refactor handler registration to pass mutable vector.
Clarify guideline on function pointer comparison and provide examples of indirect comparisons.
PLeVasseur
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Coding guidelines based on #255