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Rollup merge of #95556 - declanvk:nonnull-provenance, r=dtolnay

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Implement provenance preserving methods on NonNull

### Description
 Add the `addr`, `with_addr`, `map_addr` methods to the `NonNull` type, and map the address type to `NonZeroUsize`.

 ### Motivation
 The `NonNull` type is useful for implementing pointer types which have  the 0-niche. It is currently possible to implement these provenance  preserving functions by calling `NonNull::as_ptr` and `new_unchecked`. The adding these methods makes it more ergonomic.

 ### Testing
 Added a unit test of a non-null tagged pointer type. This is based on some real code I have elsewhere, that currently routes the pointer through a `NonZeroUsize` and back out to produce a usable pointer. I wanted to produce an ideal version of the same tagged pointer struct that preserved pointer provenance.

### Related

Extension of APIs proposed in #95228 . I can also split this out into a separate tracking issue if that is better (though I may need some pointers on how to do that).
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Dylan DPC 2022-04-02 03:34:24 +02:00 • committed by GitHub
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library/core/tests/lib.rs
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@ -86,6 +86,7 @@
#![feature(int_roundings)]
#![feature(slice_group_by)]
#![feature(split_array)]
#![feature(strict_provenance)]
#![feature(trusted_random_access)]
#![feature(unsize)]
#![feature(unzip_option)]