Make Vec::new a const fn
#50233
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Make Vec::new a const fn
#50233
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r? @kennytm (rust_highfive has picked a reviewer for you, use r? to override) |
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
oli-obk
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Apr 26, 2018
src/liballoc/vec.rs
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| @@ -324,7 +324,7 @@ impl<T> Vec<T> { | |||
| #[stable(feature = "rust1", since = "1.0.0")] | |||
| pub fn new() -> Vec<T> { | |||
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You forgot the actual change of this PR 😆
kennytm
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Apr 26, 2018
src/liballoc/vec.rs
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| @@ -322,9 +322,9 @@ impl<T> Vec<T> { | |||
| /// ``` | |||
| #[inline] | |||
| #[stable(feature = "rust1", since = "1.0.0")] | |||
| pub fn new() -> Vec<T> { | |||
| pub const fn new() -> Vec<T> { | |||
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Please mark this with #[rustc_const_unstable(feature = "const_vec_new")] so we don't need to insta-stable this.
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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The test needs |
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This changes the behavior for zero-sized types. Before this change, If we want to preserve the current optimization for zero-sized types, then instead of getting rid of the |
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@alexreg would it be possible to get an ETA on that? What does "very soon" mean exactly? If it will be in the next few weeks or so, then I think it would be worth it to wait for that. Otherwise, we could use the |
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@mbrubeck That approach doesn't quite work: |
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If you don't use an intermediate const, then the trick should work. Const if is still ways off. So use the array trick |
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Still. the trick works now. No need to block this PR |
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Yeah, I don't dispute that. ;-) |
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Hmm... tidy is segfaulting on my machine, so I can't run tests at the moment... |
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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Oh 🤦♂️ |
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@kennytm I think this is ready for another review |
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@bors r+ |
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📌 Commit f9f9923 has been approved by |
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Apr 30, 2018
Make `Vec::new` a `const fn`
`RawVec::empty/_in` are a hack. They're there because `if size_of::<T> == 0 { !0 } else { 0 }` is not allowed in `const` yet. However, because `RawVec` is unstable, the `empty/empty_in` constructors can be removed when rust-lang#49146 is done...
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Apr 30, 2018
Rollup of 7 pull requests Successful merges: - #50233 (Make `Vec::new` a `const fn`) - #50312 (Add more links in panic docs) - #50316 (Fix some broken links in docs.) - #50325 (Add a few more tests for proc macro feature gating) - #50327 (Display correct unused field suggestion for nested struct patterns) - #50330 (check that #[used] is used only on statics) - #50344 (Update Cargo to 2018-04-28 122fd5be5201913d42e219e132d6569493583bca) Failed merges:
impl String {
pub fn new() -> String {
String { vec: Vec::new() }
}
}Given that |
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Good idea! |
kennytm
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May 9, 2018
Make `String::new()` const Following the steps of rust-lang#50233 , make `String::new()` a `const fn`.
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Dec 11, 2018
Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
pietroalbini
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Dec 12, 2018
Test capacity of ZST vector Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
pietroalbini
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Dec 13, 2018
Test capacity of ZST vector Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
kennytm
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Dec 13, 2018
Test capacity of ZST vector Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
kennytm
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Dec 14, 2018
Test capacity of ZST vector Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
kennytm
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Dec 14, 2018
Test capacity of ZST vector Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
pietroalbini
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Dec 14, 2018
Test capacity of ZST vector Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
pietroalbini
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Dec 15, 2018
Test capacity of ZST vector Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.
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RawVec::empty/_inare a hack. They're there becauseif size_of::<T> == 0 { !0 } else { 0 }is not allowed inconstyet. However, becauseRawVecis unstable, theempty/empty_inconstructors can be removed when #49146 is done...