Lifetime elision #187
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Lifetime elision #187
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Havvy
reviewed
Jan 6, 2018
| @@ -59,50 +59,6 @@ unsafe fn bump_levels_unsafe2() -> u32 { | |||
| Mutable statics have the same restrictions as normal statics, except that the | |||
| type does not have to implement the `Sync` trait. | |||
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| ## `'static` lifetime elision | |||
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Not sure how, but it'd be nice for this page to say it's possible and link to the rules for it.
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There is at least a mention of this on the constant items page with a link.
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aturon
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Feb 13, 2018
src/lifetime-elision.md
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| _default object lifetime bound_. These were defined in [RFC 599] and amended in | ||
| [RFC 1156]. | ||
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| If the trait object is used as for a type argument of a generic type then the |
src/lifetime-elision.md
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| * If there is more than one bound from the containing type then an explicit | ||
| bound must be specified | ||
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| Then the bounds on the trait are used: |
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The text doesn't make clear the relationship between these bullets and the previous ones.
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alercah
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Feb 13, 2018
src/lifetime-elision.md
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| In order to make common patterns more ergonomic, Rust allows lifetimes to be | ||
| *elided* in [function item], [function pointer] and [closure trait] signatures. | ||
| The following rules are used to infer lifetime parameters for elided lifetimes. | ||
| It is an error to elide lifetime parameters that cannot be infered. |
alercah
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Feb 13, 2018
src/lifetime-elision.md
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| type FunTrait = for<'a> Fn(&'a str) -> &'a str; // expanded | ||
| ``` | ||
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| ## Defaults trait object lifetimes |
* Don't talk about a future feature * Add examples of elision in function pointers/traits * A rule for 'static bounds on trait objects * Static lifetime elision doesn't happen in function pointers/traits
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Thanks, fixed now. |
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cc @alercah |
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I don't see anything that looks off to me, but I also don't have the time for a detailed read. |
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Second PR to add documentation for lifetimes (next will probably moving the relevant parts of the NLL RFC text into the reference when it gets stabilised).
This is mostly existing documentation from the nomicon/reference. Significant changes from that documentation:
implheaders)'staticis the preferred bound in trait objects with multiple bounds:const RESOLVED_STATIC: &Fn(&Foo, &Bar) -> &Bazis invalid, not inferred with'staticlifetimes. (This matches: http://rust-lang.github.io/rfcs/1623-static.html, so I'm guessing that it's just a docs issue)cc #9 (rust-lang/rfcs#141)