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Add Default to std::alloc::System #59451

Merged
merged 1 commit into from
Mar 28, 2019
Merged

Add Default to std::alloc::System #59451

merged 1 commit into from
Mar 28, 2019

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TimDiekmann
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@TimDiekmann TimDiekmann commented Mar 26, 2019 •
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System is a unit struct, thus, it can be constructed without any additional information. Therefore Default is a noop. However, in generic code, a T: Default may happen as in

#[derive(Default)]
struct Foo<A> {
    allocator: A
}

Does this need a feature gate?
Should I also add PartialEq/Eq/PartialOrd/Ord/Hash?

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r? @rkruppe

(rust_highfive has picked a reviewer for you, use r? to override)

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 26, 2019
@Centril Centril added the relnotes Marks issues that should be documented in the release notes of the next release. label Mar 27, 2019
@Centril Centril added this to the 1.35 milestone Mar 27, 2019
@Centril Centril added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. needs-fcp This change is insta-stable, so needs a completed FCP to proceed. labels Mar 27, 2019
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Centril commented Mar 27, 2019

Randomly reassigning to T-libs member, r? @sfackler

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Trait impls are automatically stable, so no need for a feature gate here.

Let's not add Hash/Eq/etc yet - they're a bit silly since this type's a unit struct after all.

@bors r+ rollup

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bors commented Mar 27, 2019

📌 Commit 8733b2a has been approved by sfackler

@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 Mar 27, 2019
@Centril Centril removed the needs-fcp This change is insta-stable, so needs a completed FCP to proceed. label Mar 27, 2019
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TimDiekmann commented Mar 27, 2019 •
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Let's not add Hash/Eq/etc yet - they're a bit silly since this type's a unit struct after all.

I think this was the exact reason, why Default wasn't implemented. IMO a trait should be implemented regardless of its structure as generic code does not care if it's a unit struct or not.

Centril added a commit to Centril/rust that referenced this pull request Mar 27, 2019
@Centril
Rollup merge of rust-lang#59451 - TimDiekmann:patch-1, r=sfackler
2fefc07 
Add `Default` to `std::alloc::System`

`System` is a unit struct, thus, it can be constructed without any additional information. Therefore `Default` is a noop. However, in generic code, a `T: Default` may happen as in

```rust
#[derive(Default)]
struct Foo<A> {
    allocator: A
}
```

Does this need a feature gate?
Should I also add `PartialEq/Eq/PartialOrd/Ord/Hash`?
@Centril Centril mentioned this pull request Mar 27, 2019
Closed
Centril added a commit to Centril/rust that referenced this pull request Mar 27, 2019
@Centril
Rollup merge of rust-lang#59451 - TimDiekmann:patch-1, r=sfackler
a077493 
Add `Default` to `std::alloc::System`

`System` is a unit struct, thus, it can be constructed without any additional information. Therefore `Default` is a noop. However, in generic code, a `T: Default` may happen as in

```rust
#[derive(Default)]
struct Foo<A> {
    allocator: A
}
```

Does this need a feature gate?
Should I also add `PartialEq/Eq/PartialOrd/Ord/Hash`?
@Centril Centril mentioned this pull request Mar 27, 2019
Closed
Centril added a commit to Centril/rust that referenced this pull request Mar 27, 2019
@Centril
Rollup merge of rust-lang#59451 - TimDiekmann:patch-1, r=sfackler
d04b1ec 
Add `Default` to `std::alloc::System`

`System` is a unit struct, thus, it can be constructed without any additional information. Therefore `Default` is a noop. However, in generic code, a `T: Default` may happen as in

```rust
#[derive(Default)]
struct Foo<A> {
    allocator: A
}
```

Does this need a feature gate?
Should I also add `PartialEq/Eq/PartialOrd/Ord/Hash`?
@Centril Centril mentioned this pull request Mar 27, 2019
Closed
cuviper added a commit to cuviper/rust that referenced this pull request Mar 28, 2019
@cuviper
Rollup merge of rust-lang#59451 - TimDiekmann:patch-1, r=sfackler
44c411e 
Add `Default` to `std::alloc::System`

`System` is a unit struct, thus, it can be constructed without any additional information. Therefore `Default` is a noop. However, in generic code, a `T: Default` may happen as in

```rust
#[derive(Default)]
struct Foo<A> {
    allocator: A
}
```

Does this need a feature gate?
Should I also add `PartialEq/Eq/PartialOrd/Ord/Hash`?
@cuviper cuviper mentioned this pull request Mar 28, 2019
Merged
bors added a commit that referenced this pull request Mar 28, 2019
@bors
Auto merge of #59471 - cuviper:rollup, r=cuviper
d20e000 
Rollup of 18 pull requests

Successful merges:

 - #57293 (Make some lints incremental)
 - #57565 (syntax: Remove warning for unnecessary path disambiguators)
 - #58253 (librustc_driver => 2018)
 - #58837 (librustc_interface => 2018)
 - #59268 (Add suggestion to use `&*var` when `&str: From<String>` is expected)
 - #59283 (Make ASCII case conversions more than 4× faster)
 - #59284 (adjust MaybeUninit API to discussions)
 - #59372 (add rustfix-able suggestions to trim_{left,right} deprecations)
 - #59390 (Make `ptr::eq` documentation mention fat-pointer behavior)
 - #59393 (Refactor tuple comparison tests)
 - #59420 ([CI] record docker image info for reuse)
 - #59421 (Reject integer suffix when tuple indexing)
 - #59430 (Renames `EvalContext` to `InterpretCx`)
 - #59439 (Generalize diagnostic for `x = y` where `bool` is the expected type)
 - #59449 (fix: Make incremental artifact deletion more robust)
 - #59451 (Add `Default` to `std::alloc::System`)
 - #59459 (Add some tests)
 - #59460 (Include id in Thread's Debug implementation)

Failed merges:

r? @ghost
@bors bors merged commit 8733b2a into rust-lang:master Mar 28, 2019
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request May 31, 2019
@jperkin
rust: Update to 1.35.0.
6e0b39c 
Version 1.35.0 (2019-05-23)
==========================

Language
--------
- [`FnOnce`, `FnMut`, and the `Fn` traits are now implemented for `Box<FnOnce>`,
  `Box<FnMut>`, and `Box<Fn>` respectively.][59500]
- [You can now coerce closures into unsafe function pointers.][59580] e.g.
  ```rust
  unsafe fn call_unsafe(func: unsafe fn()) {
      func()
  }

  pub fn main() {
      unsafe { call_unsafe(|| {}); }
  }
  ```


Compiler
--------
- [Added the `armv6-unknown-freebsd-gnueabihf` and
  `armv7-unknown-freebsd-gnueabihf` targets.][58080]
- [Added the `wasm32-unknown-wasi` target.][59464]


Libraries
---------
- [`Thread` will now show its ID in `Debug` output.][59460]
- [`StdinLock`, `StdoutLock`, and `StderrLock` now implement `AsRawFd`.][59512]
- [`alloc::System` now implements `Default`.][59451]
- [Expanded `Debug` output (`{:#?}`) for structs now has a trailing comma on the
  last field.][59076]
- [`char::{ToLowercase, ToUppercase}` now
  implement `ExactSizeIterator`.][58778]
- [All `NonZero` numeric types now implement `FromStr`.][58717]
- [Removed the `Read` trait bounds
  on the `BufReader::{get_ref, get_mut, into_inner}` methods.][58423]
- [You can now call the `dbg!` macro without any parameters to print the file
  and line where it is called.][57847]
- [In place ASCII case conversions are now up to 4× faster.][59283]
  e.g. `str::make_ascii_lowercase`
- [`hash_map::{OccupiedEntry, VacantEntry}` now implement `Sync`
  and `Send`.][58369]

Stabilized APIs
---------------
- [`f32::copysign`]
- [`f64::copysign`]
- [`RefCell::replace_with`]
- [`RefCell::map_split`]
- [`ptr::hash`]
- [`Range::contains`]
- [`RangeFrom::contains`]
- [`RangeTo::contains`]
- [`RangeInclusive::contains`]
- [`RangeToInclusive::contains`]
- [`Option::copied`]

Cargo
-----
- [You can now set `cargo:rustc-cdylib-link-arg` at build time to pass custom
  linker arguments when building a `cdylib`.][cargo/6298] Its usage is highly
  platform specific.

Misc
----
- [The Rust toolchain is now available natively for musl based distros.][58575]

[59460]: rust-lang/rust#59460
[59464]: rust-lang/rust#59464
[59500]: rust-lang/rust#59500
[59512]: rust-lang/rust#59512
[59580]: rust-lang/rust#59580
[59283]: rust-lang/rust#59283
[59451]: rust-lang/rust#59451
[59076]: rust-lang/rust#59076
[58778]: rust-lang/rust#58778
[58717]: rust-lang/rust#58717
[58369]: rust-lang/rust#58369
[58423]: rust-lang/rust#58423
[58080]: rust-lang/rust#58080
[57847]: rust-lang/rust#57847
[58575]: rust-lang/rust#58575
[cargo/6298]: rust-lang/cargo#6298
[`f32::copysign`]: https://doc.rust-lang.org/stable/std/primitive.f32.html#method.copysign
[`f64::copysign`]: https://doc.rust-lang.org/stable/std/primitive.f64.html#method.copysign
[`RefCell::replace_with`]: https://doc.rust-lang.org/stable/std/cell/struct.RefCell.html#method.replace_with
[`RefCell::map_split`]: https://doc.rust-lang.org/stable/std/cell/struct.RefCell.html#method.map_split
[`ptr::hash`]: https://doc.rust-lang.org/stable/std/ptr/fn.hash.html
[`Range::contains`]: https://doc.rust-lang.org/std/ops/struct.Range.html#method.contains
[`RangeFrom::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeFrom.html#method.contains
[`RangeTo::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeTo.html#method.contains
[`RangeInclusive::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html#method.contains
[`RangeToInclusive::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeToInclusive.html#method.contains
[`Option::copied`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.copied
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