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Introduce ahash-compile-time-rng feature. #125

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merged 2 commits into from
Oct 31, 2019

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0ndorio
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@0ndorio 0ndorio commented Oct 30, 2019

Content

Disables the default features of ahash and reintroduces them
through a new feature called ahash-compile-time-rng, which is
enabled by default.

The new feature makes it possible for depended crates to rely on
hashbrown with ahash as default hasher and to disable the
compile-time-rng at the same time.

This might be useful for any depended crate targeting no_std,
which contains rand or rand_core somewhere inside the dependency
tree as a bug in cargo accidentally enables the underlying getrandom
feature if compile-time-rng is enabled [1].

... fixes #124

[1] rust-lang/cargo#5760


Warnings

(1) Compiling ahash with disabled compile-time-rng feature is currently broken and requires tkaitchuck/aHash#25 to be merged in advance.

(2) This introduces a hidden behavior change for all dependent crates, using hashbrown with default-features = false and features = 'ahash'. This happens as the ahash feature no longer implicitly enables the compile-time-rng feature of ahash.


Is the naming of the feature okay? Do I need to add any additional changes?

@0ndorio 0ndorio force-pushed the allow_to_disable_ahash_feature branch from 3fe2350 to 2907d9b Compare October 30, 2019 13:10
@Amanieu
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Amanieu commented Oct 30, 2019

Clippy seems to be failing due to a new lint. Could you add clippy::must_use_candidate to the whitelist in lib.rs?

Also, could you document the feature in README.md (there's a feature list near the bottom).

Disables the default features of `ahash` and reintroduces them
through a new feature called `ahash-compile-time-rng`, which is
enabled by default.

The new feature makes it possible for depended crates to rely on
`hashbrown` with `ahash` as default hasher and to disable the
`compile-time-rng` at the same time.

This might be useful for any dependent crate targeting `no_std`,
which contains `rand` or `rand_core` somewhere inside the dependency
tree as a bug in cargo accidentally enables the underlying `getrandom`
feature if `compile-time-rng` is enabled [1].

... fixes rust-lang#124

[1] rust-lang/cargo#5760
@0ndorio 0ndorio force-pushed the allow_to_disable_ahash_feature branch from 2907d9b to 43911e5 Compare October 30, 2019 15:16
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0ndorio commented Oct 30, 2019

Clippy seems to be failing due to a new lint. Could you add clippy::must_use_candidate to the whitelist in lib.rs?

Added new commit to fix this.

Also, could you document the feature in README.md (there's a feature list near the bottom).

Amended the documentation to the original commit.

@0ndorio 0ndorio force-pushed the allow_to_disable_ahash_feature branch from 43911e5 to 388287c Compare October 30, 2019 15:39
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Amanieu commented Oct 30, 2019

You need to run cargo fmt to fix CI.

@0ndorio 0ndorio force-pushed the allow_to_disable_ahash_feature branch from 388287c to 92bc9f8 Compare October 31, 2019 09:18
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Amanieu commented Oct 31, 2019

@bors r+

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bors commented Oct 31, 2019

📌 Commit 92bc9f8 has been approved by Amanieu

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bors commented Oct 31, 2019

⌛ Testing commit 92bc9f8 with merge 592137a...

bors added a commit that referenced this pull request Oct 31, 2019
Introduce `ahash-compile-time-rng` feature.

**Content**

Disables the default features of `ahash` and reintroduces them
through a new feature called `ahash-compile-time-rng`, which is
enabled by default.

The new feature makes it possible for depended crates to rely on
`hashbrown` with `ahash` as default hasher and to disable the
`compile-time-rng` at the same time.

This might be useful for any depended crate targeting `no_std`,
which contains `rand` or `rand_core` somewhere inside the dependency
tree as a bug in cargo accidentally enables the underlying `getrandom`
feature if `compile-time-rng` is enabled [1].

... fixes #124

[1] rust-lang/cargo#5760

---

**Warnings**

 (1) Compiling `ahash` with disabled `compile-time-rng` feature is currently broken and requires tkaitchuck/aHash#25 to be merged in advance.

 (2) This introduces a hidden behavior change for all dependent crates, using hashbrown with `default-features = false` and `features = 'ahash'`. This happens as the `ahash` feature no longer implicitly enables the `compile-time-rng` feature of `ahash`.

---

Is the naming of the feature okay?  Do I need to add any additional  changes?
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bors commented Oct 31, 2019

☀️ Test successful - checks-travis
Approved by: Amanieu
Pushing 592137a to master...

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[Request] Update documentation to mention potential no_std problem.
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