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Update the unstable book regarding [e; dyn n].
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@ -127,13 +127,13 @@ One of the objectives of this feature is to allow `Box<dyn FnOnce>`, instead of
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## Variable length arrays
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The RFC also describes an extension to the array literal syntax `[e; n]`: you'll be able to specify non-const `n` to allocate variable length arrays on the stack.
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The RFC also describes an extension to the array literal syntax: `[e; dyn n]`. In the syntax, `n` isn't necessarily a constant expression. The array is dynamically allocated on the stack and has the type of `[T]`, instead of `[T; n]`.
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```rust,ignore
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#![feature(unsized_locals)]
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fn mergesort<T: Ord>(a: &mut [T]) {
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let mut tmp = [T; a.len()];
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let mut tmp = [T; dyn a.len()];
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// ...
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}
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@ -144,7 +144,7 @@ fn main() {
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}
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```
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VLAs are not implemented yet.
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VLAs are not implemented yet. The syntax isn't final, either. We may need an alternative syntax for Rust 2015 because, in Rust 2015, expressions like `[e; dyn(1)]` would be ambiguous. One possible alternative proposed in the RFC is `[e; n]`: if `n` captures one or more local variables, then it is considered as `[e; dyn n]`.
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## Advisory on stack usage
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