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Document Fn traits implemented for all ABIs #2383

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7 changes: 3 additions & 4 deletions src/types/function-item.md
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Expand Up @@ -37,18 +37,17 @@ let foo_ptr_2 = if want_i32 {
```

r[type.fn-item.traits]
All function items implement [`Copy`], [`Clone`], [`Send`], and [`Sync`].
All function items implement [`Copy`], [`Clone`], and all the [auto traits][lang-types.auto-traits].

[`Fn`], [`FnMut`], and [`FnOnce`] are implemented unless the function has any of the following:

- an [`unsafe`][unsafe.fn] qualifier
- a [`target_feature` attribute][attributes.codegen.target_feature]
- an [ABI][items.fn.extern] other than `"Rust"`
- an [ABI][items.fn.extern] of `"custom"`
- a [C-variadic][items.fn.c-variadic] rest parameter

[`Clone`]: ../special-types-and-traits.md#clone
[`Copy`]: ../special-types-and-traits.md#copy
[`Send`]: ../special-types-and-traits.md#send
[`Sync`]: ../special-types-and-traits.md#sync
[coercion]: ../type-coercions.md
[function pointers]: function-pointer.md
[zero-sized]: glossary.zst
3 changes: 3 additions & 0 deletions src/types/function-pointer.md
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Expand Up @@ -53,6 +53,9 @@ For the function to be variadic, its `extern` ABI must be one of those listed in
r[type.fn-pointer.extern-custom]
An `extern "custom"` function pointer must follow the rules in [items.fn.extern.custom.signature].

r[type.fn-pointer.traits]
A function pointer implements [the same traits][type.fn-item.traits] as a function item with the same signature.

r[type.fn-pointer.attributes]
## Attributes on function pointer parameters

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