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Clarify corner case for parsing `in <place-expr> { <block> }`.

This commit is contained in:
Felix S. Klock II 2015-02-12 02:30:12 +01:00
parent 94109f02ea
commit 6279f55a05
1 changed files with 8 additions and 0 deletions
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text/0809-box-and-in-for-stdlib.md
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@ -110,6 +110,14 @@ tandem with types provided by the stdlib, such as `Box<T>`.
Make `in <place-expr> { <block> }` an overloaded operator that uses
the `<place-expr>` to determine what placement code to run.
Note: when `<place-expr>` is just an identifier,
`<place-expr> { <block> }` is not parsed as a struct literal.
We accomplish this via the same means that is used e.g. for `if` expressions:
we restrict `<place-expr>` to not include struct literals
(see [RFC 92]).
[RFC 92]: https://github.com/rust-lang/rfcs/blob/master/text/0092-struct-grammar.md
* The only stablized implementation for the `box <expr>` operator
proposed by this RFC is `Box<T>`. The question of which other types
should support integration with `box <expr>` is a library design