Niko Matsakis [Mon, 17 Sep 2018 18:00:33 +0000 (14:00 -0400)]
use approx. bounds to decide whether to add outlives obligations
Before, if we had a projection like `<T as Foo<'0>>::Bar: 'x` and a
where clause like `<T as Foo<'a>>::Bar: 'a`, we considered those to
have nothing to do with one another. Therefore, we would use the
"overconstrained" path of adding `T: 'x` and `'0: 'x` requirements. We
now do a "fuzzy" match where we erase regions first and hence we see
the env bound `'a`.
Niko Matsakis [Wed, 12 Sep 2018 21:48:51 +0000 (17:48 -0400)]
apply `process_registered_region_obligations` at the end of regionck
We used to apply it repeatedly as we went, relying on the current
value of the `region_bound_pairs_accum` vector. But now we save those
values into a map, so we can just process all the registered region
obligations at the end.
Auto merge of #53824 - ljedrz:begone_onevector, r=michaelwoerister
Remove OneVector, increase related SmallVec capacities
Removes the `OneVector` type alias (equivalent to `SmallVec<[T; 1]>`); it is used in scenarios where the capacity of 1 is often exceeded, which might be nullifying the performance wins (due to spilling to the heap) expected when using `SmallVec` instead of `Vec`.
The numbers I used in this PR are very rough estimates - it would probably be a good idea to adjust some/all of them, which is what this proposal is all about.
It might be a good idea to additionally create some local type aliases for the `SmallVec`s in the `Folder` trait, as they are repeated in quite a few spots; I'd be happy to apply this sort of adjustments.
Auto merge of #54575 - pietroalbini:rollup, r=pietroalbini
Rollup of 12 pull requests
Successful merges:
- #53518 (Add doc for impl From in char_convert)
- #54058 (Introduce the partition_dedup/by/by_key methods for slices)
- #54281 (Search box)
- #54368 (Reduce code block sides padding)
- #54498 (The project moved under the Mozilla umbrella)
- #54518 (resolve: Do not block derive helper resolutions on single import resolutions)
- #54522 (Fixed three small typos.)
- #54529 (aarch64-pc-windows-msvc: Don't link libpanic_unwind to libtest.)
- #54537 (Rename slice::exact_chunks() to slice::chunks_exact())
- #54539 (Fix js error)
- #54557 (incr.comp.: Don't automatically enable -Zshare-generics for incr. comp. builds.)
- #54558 (Improvements to finding LLVM's FileCheck)
Pietro Albini [Tue, 25 Sep 2018 20:34:51 +0000 (22:34 +0200)]
Rollup merge of #54558 - tromey:find-filecheck, r=nikomatsakis
Improvements to finding LLVM's FileCheck
This patch adds a few improvements to how the build system finds
LLVM's FileCheck program.
* On Fedora, the system LLVM installs FileCheck in the "llvm"
subdirectory of the LLVM libdir. This patch teaches the build
system to look there.
* This adds a configure option to specify which llvm-config executable
to use. This is handy on systems that can parallel install multiple
versions of LLVM; for example I can now:
./configure --llvm-config=/bin/llvm-config-5.0-64
... to build against LLVM 5, rather than whatever the default
llvm-config might be.
* Finally, this adds a configure- and config.toml- option to set the
path to FileCheck. This is handy when building against an LLVM
where FileCheck was not installed. This happens on compatibility
installs of LLVM on Fedora.
Pietro Albini [Tue, 25 Sep 2018 20:34:50 +0000 (22:34 +0200)]
Rollup merge of #54557 - michaelwoerister:dont-auto-share-generics-for-incr-comp, r=alexcrichton
incr.comp.: Don't automatically enable -Zshare-generics for incr. comp. builds.
So far the compiler would automatically enable sharing of monomorphizations for incremental builds. That was OK because without (Thin)LTO this could have very little impact on the runtime performance of the generated code. However, since https://github.com/rust-lang/rust/pull/53673, ThinLTO and incr. comp. can be combined, so the trade-off is not as clear anymore.
This PR removes the automatic tie between the two options. Whether monomorphizations are shared between crates or not now _only_ depends on the optimization level.
Pietro Albini [Tue, 25 Sep 2018 20:34:46 +0000 (22:34 +0200)]
Rollup merge of #54529 - michaelwoerister:dont-unwind-test, r=alexcrichton
aarch64-pc-windows-msvc: Don't link libpanic_unwind to libtest.
This implements the suggestion from https://github.com/rust-lang/rust/issues/54190#issuecomment-422904437 in order to unbreak bootstrapping for the `aarch64-pc-windows-msvc` target. With this applied and using MSVC 15.8.3 for linking the bootstrap actually works and I can cross-compile a hello-world program.
Pietro Albini [Tue, 25 Sep 2018 20:34:38 +0000 (22:34 +0200)]
Rollup merge of #54058 - Kerollmops:slice-dedup, r=shepmaster
Introduce the partition_dedup/by/by_key methods for slices
This PR propose to add three methods to the slice type, the `partition_dedup`, `partition_dedup_by` and `partition_dedup_by_key`. The two other methods are based on `slice::partition_dedup_by`.
These methods take a mutable slice, deduplicates it and moves all duplicates to the end of it, returning two mutable slices, the first containing the deduplicated elements and the second all the duplicates unordered.
```rust
let mut slice = [1, 2, 2, 3, 3, 2];
let (dedup, duplicates) = slice.partition_dedup();
The benefits of adding these methods is that it is now possible to:
- deduplicate a slice without having to allocate and possibly clone elements on the heap, really useful for embedded stuff that can't allocate for example.
- not loose duplicate elements, because, when using `Vec::dedup`, duplicates elements are dropped. These methods add more flexibillity to the user.
Note that this is near a copy/paste of the `Vec::dedup_by` function, once this method is stable the goal is to replace the algorithm in `Vec` by the following.
```rust
pub fn Vec::dedup_by<F>(&mut self, same_bucket: F)
where F: FnMut(&mut T, &mut T) -> bool
{
let (dedup, _) = self.as_mut_slice().partition_dedup_by(same_bucket);
let len = dedup.len();
self.truncate(len);
}
```
This is part of [RFC 2071](https://github.com/rust-lang/rfcs/blob/master/text/2071-impl-trait-existential-types.md) ([tracking issue](https://github.com/rust-lang/rust/issues/34511)), but exists behind the separate feature gate `impl_trait_in_bindings`.
resolve: Do not block derive helper resolutions on single import resolutions
Derive helpers conflict currently conflict with anything else, so if some resolution from a single import appears later, it will result in error anyway
Auto merge of #54411 - cramertj:await-keyword-error, r=nikomatsakis
Make "await" a pseudo-edition keyword
This change makes "await" ident an error in 2018 edition without async_await
feature and adds "await" to the 2018 edition keyword lint group that
suggest migration on the 2015 edition.
Tom Tromey [Tue, 25 Sep 2018 15:13:02 +0000 (09:13 -0600)]
Improvements to finding LLVM's FileCheck
This patch adds a few improvements to how the build system finds
LLVM's FileCheck program.
* On Fedora, the system LLVM installs FileCheck in the "llvm"
subdirectory of the LLVM libdir. This patch teaches the build
system to look there.
* This adds a configure option to specify which llvm-config executable
to use. This is handy on systems that can parallel install multiple
versions of LLVM; for example I can now:
./configure --llvm-config=/bin/llvm-config-5.0-64
... to build against LLVM 5, rather than whatever the default
llvm-config might be.
* Finally, this adds a configure- and config.toml- option to set the
path to FileCheck. This is handy when building against an LLVM
where FileCheck was not installed. This happens on compatibility
installs of LLVM on Fedora.
Auto merge of #53693 - scottmcm:marker-trait-attribute, r=nikomatsakis
Support an explicit annotation for marker traits
From the tracking issue for rust-lang/rfcs#1268:
> It seems obvious that we should make a `#[marker]` annotation. ~ https://github.com/rust-lang/rust/issues/29864#issuecomment-368959441
This PR allows you to put `#[marker]` on a trait, at which point:
- [x] The trait must not have any items ~~All of the trait's items must have defaults~~
- [x] Any impl of the trait must be empty (not override any items)
- [x] But impls of the trait are allowed to overlap
Auto merge of #53438 - matthewjasper:permissive-match-access, r=pnkfelix
[NLL] Be more permissive when checking access due to Match
Partially addresses #53114. notably, we should now have parity with AST borrowck. Matching on uninitialized values is still forbidden.
* ~~Give fake borrows for match their own `BorrowKind`~~
* ~~Allow borrows with this kind to happen on values that are already mutably borrowed.~~
* ~~Track borrows with this type even behind shared reference dereferences and consider all accesses to be deep when checking for conflicts with this borrow type. See [src/test/ui/issues/issue-27282-mutate-before-diverging-arm-3.rs](https://github.com/rust-lang/rust/commit/cb5c989598178af505fb215dd97afca8cc2b659f#diff-a2126cd3263a1f5342e2ecd5e699fbc6) for an example soundness issue this fixes (a case of #27282 that wasn't handled correctly).~~
* Create a new `BorrowKind`: `Shallow` (name can be bike-shed)
* `Shallow` borrows differ from shared borrows in that
* When we check for access we treat them as a `Shallow(Some(_))` read
* When we check for conflicts with them, if the borrow place is a strict prefix of the access place then we don't consider that a conflict.
* For example, a `Shallow` borrow of `x` does not conflict with any access or borrow of `x.0` or `*x`
* Remove the current fake borrow in matches.
* When building matches, we take a `Shallow` borrow of any `Place` that we switch on or bind in a match, and any prefix of those places. (There are some optimizations where we do fewer borrows, but this shouldn't change semantics)
* `match x { &Some(1) => (), _ => (), }` would `Shallow` borrow `x`, `*x` and `(*x as Some).0` (the `*x` borrow is unnecessary, but I'm not sure how easy it would be to remove.)
* Replace the fake discriminant read with a `ReadForMatch`.
* Change ReadForMatch to only check for initializedness (to prevent `let x: !; match x {}`), but not conflicting borrows. It is still considered a use for liveness and `unsafe` checking.
* Give special cased error messages for this kind of borrow.
Taylor Cramer [Fri, 21 Sep 2018 00:36:31 +0000 (17:36 -0700)]
Make "await" a pseudo-edition keyword
This change makes "await" ident an error in 2018 edition without async_await
feature and adds "await" to the 2018 edition keyword lint group that
suggest migration on the 2015 edition.
Auto merge of #53783 - RalfJung:ptr-docs, r=alexcrichton
Rewrite docs for pointer methods
This takes over https://github.com/rust-lang/rust/pull/51016 by @ecstatic-morse. They did most of the work, I just did some editing.
However, I realized one problem: This updates the docs for the "free functions" in `core::ptr`, but it does not update the copies of these docs for the inherent methods of the `*const T` and `*mut T` types. These getting out-of-sync is certainly bad, but I also don't feel like copying all this stuff around. Instead, we should remove this redundancy. Any good ideas?
Auto merge of #54509 - matthewjasper:better-drop-access, r=pnkfelix
[NLL] Rework checking for borrows conflicting with drops
Previously, we would split the drop access into multiple checks for each
field of a struct/tuple/closure and through `Box` dereferences. This
changes this to check if the borrow is accessed by the drop in
`places_conflict`.
Auto merge of #54485 - arielb1:avoid-ctor-attrs, r=eddyb
avoid loading constructor attributes in AdtDef decoding
During metadata loading, the AdtDefs for every ADT in the universe need
to be loaded (for example, for coherence of builtin traits). For that,
the attributes of the AdtDef need to be loaded too.
The attributes of a struct are duplicated between 2 def ids - the
constructor def-id, and the "type" def id. Loading attributes for both
def-ids, which was done in #53721, slowed the compilation of small
crates by 2-3%. This PR makes sure we only load the attributes for the
"type" def-id, avoiding the slowdown.
Matthew Jasper [Sun, 23 Sep 2018 15:07:45 +0000 (16:07 +0100)]
Rework checking for borrows conflicting with drops
Previously, we would split the drop access into multiple checks for each
field of a struct/tuple/closure and through `Box` dereferences. This
changes this to check if the borrow is accessed by the drop in
places_conflict.
This also allows us to handle enums in a simpler way, since we don't
have to construct any new places.
Matthew Jasper [Sun, 23 Sep 2018 14:56:14 +0000 (15:56 +0100)]
Remove irrelevant message about drop order
When dropping a self-borrowing struct we shouldn't add a "values in a
scope are dropped in the opposite order they are defined" message,
since there is only one value being dropped.
David Wood [Wed, 19 Sep 2018 00:48:47 +0000 (02:48 +0200)]
Only annotate if borrow is returned.
Error now correctly checks whether the borrow that does not live
long enough is being returned before annotating the error with the
arguments and return type from the signature - as this would not be
relevant if the borrow was not being returned.
David Wood [Mon, 17 Sep 2018 18:49:21 +0000 (20:49 +0200)]
Added note about dangling references.
This error can only occur within a function when a borrow of data owned
within the function is returned; and when there are arguments that could
have been returned instead. Therefore, it is always applicable to add a
specific note that links to the relevant rust documentation about
dangling references.
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