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Add #[must_use] to alloc constructors #89726

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merged 2 commits into from
Oct 11, 2021

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jkugelman
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@jkugelman jkugelman commented Oct 10, 2021

Added #[must_use]. to the various forms of new, pin, and with_capacity in the alloc crate. No extra explanations given as I couldn't think of anything useful to add.

I figure this deserves extra scrutiny compared to the other PRs I've done so far. In particular:

  • The 4 pin/pin_in methods I touched. Are there legitimate use cases for pinning and not using the result? Pinning's a difficult concept I'm not very comfortable with.
  • Box's constructors. Do people ever create boxes just for the side effects... allocating or zeroing out memory?

Parent issue: #89692

r? @joshtriplett

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 10, 2021
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@jkugelman jkugelman force-pushed the must-use-alloc-constructors branch from 26ee38e to 58cc18c Compare October 10, 2021 06:19
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I don't think any of these would make sense to call for a side effect. Theoretically they could have a side effect in the allocator, but I don't see any issue with requiring a let _ = or similar in that case.

@bors r+

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bors commented Oct 11, 2021

📌 Commit ecd7ea8 has been approved by joshtriplett

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 11, 2021
@joshtriplett joshtriplett added the relnotes Marks issues that should be documented in the release notes of the next release. label Oct 11, 2021
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Oct 11, 2021
…rs, r=joshtriplett

Add #[must_use] to alloc constructors

Added `#[must_use]`. to the various forms of `new`, `pin`, and `with_capacity` in the `alloc` crate. No extra explanations given as I couldn't think of anything useful to add.

I figure this deserves extra scrutiny compared to the other PRs I've done so far. In particular:

* The 4 `pin`/`pin_in` methods I touched. Are there legitimate use cases for pinning and not using the result? Pinning's a difficult concept I'm not very comfortable with.
* `Box`'s constructors. Do people ever create boxes just for the side effects... allocating or zeroing out memory?

Parent issue: rust-lang#89692

r? `@joshtriplett`
bors added a commit to rust-lang-ci/rust that referenced this pull request Oct 11, 2021
…laumeGomez

Rollup of 7 pull requests

Successful merges:

 - rust-lang#89655 (bootstrap: don't use `--merges` to look for commit hashes for downloading artifacts)
 - rust-lang#89726 (Add #[must_use] to alloc constructors)
 - rust-lang#89729 (Add #[must_use] to core and std constructors)
 - rust-lang#89743 (Fix RUSTC_LOG handling)
 - rust-lang#89753 (Add #[must_use] to from_value conversions)
 - rust-lang#89754 (Cleanup .item-table CSS)
 - rust-lang#89761 (:arrow_up: rust-analyzer)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit d7c9693 into rust-lang:master Oct 11, 2021
@rustbot rustbot added this to the 1.57.0 milestone Oct 11, 2021
@jkugelman jkugelman deleted the must-use-alloc-constructors branch October 11, 2021 17:55
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6 participants