Object lifetime defaults (RFC 599) #22230
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r? @pnkfelix (rust_highfive has picked a reviewer for you, use r? to override) |
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@nikomatsakis okay, r=me . I had a couple absurdly minor nits, but really, you could probably just land this. |
…ol closures are gone and type parameters can now have multiple region bounds (and hence use a different path). Should have no effect on the external behavior of the compiler.
complete set of regions are available when converting types.
…o be mostly improved, to my eye. Nonetheless, as this commit demonstrates, the previous commits was a [breaking-change]. In practice, breakage is focused on functions of this form: ```rust fn foo(..., object: Box<FnMut()>) ```` where `FnMut()` could be any trait object type. The older scheme defaulted objects in argument position so that they were bounded by a fresh lifetime: ```rust fn foo<'a>(..., object: Box<FnMut()+'a>) ``` This meant that the object could contain borrowed data. The newer scheme defaults to a lifetime bound of `'static`: ```rust fn foo(..., object: Box<FnMut()+'static>) ``` This means that the object cannot contain borrowed data. In some cases, the best fix is to stop using `Box`: ```rust fn foo(..., object: &mut FnMut()) ``` but another option is to write an explicit annotation for the `'a` lifetime that used to be implicit. Both fixes are demonstrated in this commit.
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Feb 16, 2015
…felix Implement rules described in rust-lang/rfcs#599. Fixes #22211. ~~Based atop PR #22182, so the first few commits (up to and including "Pacify the mercilous nrc") have already been reviewed.~~
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Implement rules described in rust-lang/rfcs#599.
Fixes #22211.
Based atop PR #22182, so the first few commits (up to and including "Pacify the mercilous nrc") have already been reviewed.