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Explicitly mention in the docs that grow, grow_zeroed, and shrink have to handle changes in alignment #97

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autumnontape opened this issue Mar 30, 2022 · 4 comments
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Explicitly mention in the docs that grow, grow_zeroed, and shrink have to handle changes in alignment #97

autumnontape opened this issue Mar 30, 2022 · 4 comments

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@autumnontape
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The docs currently imply that the alignment of new_layout may be different from that of old_layout by not stating otherwise. Reallocations with altered alignments are extremely uncommon; I had to track down #5 in this repository to convince myself this wasn't a mistake. This could be a pitfall for implementors of Allocator if it's not made more explicit.
@Amanieu
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Amanieu commented Mar 31, 2022

Sounds good, would you be willing to make a PR to rust-lang/rust to update the documentation?

@autumnontape
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Sure! I can probably do that a few hours from now.

@autumnontape autumnontape mentioned this issue Mar 31, 2022
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@autumnontape
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I've opened rust-lang/rust#95546.

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Apr 1, 2022
@matthiaskrgr
Rollup merge of rust-lang#95546 - autumnontape:allocator-realloc-alig…
2c6c5af 
…n-docs, r=Amanieu

add notes about alignment-altering reallocations to Allocator docs

As I said in rust-lang/wg-allocators#97, the fact that calls to `grow`, `grow_zeroed`, and `shrink` may request altered alignments is surprising and may be a pitfall for implementors of `Allocator` if it's left implicit. This pull request adds a note to the "Safety" section of each function's docs making it explicit.
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Apr 1, 2022
@matthiaskrgr
Rollup merge of rust-lang#95546 - autumnontape:allocator-realloc-alig…
a92286f 
…n-docs, r=Amanieu

add notes about alignment-altering reallocations to Allocator docs

As I said in rust-lang/wg-allocators#97, the fact that calls to `grow`, `grow_zeroed`, and `shrink` may request altered alignments is surprising and may be a pitfall for implementors of `Allocator` if it's left implicit. This pull request adds a note to the "Safety" section of each function's docs making it explicit.
@autumnontape
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rust-lang/rust#95546 was merged!

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@Amanieu @autumnontape