Add Iterator::advance_by and DoubleEndedIterator::advance_back_by
This PR adds the iterator method
```rust
fn advance_by(&mut self, n: usize) -> Result<(), usize>
```
that advances the iterator by `n` elements, returning `Ok(())` if this succeeds or `Err(len)` if the length of the iterator was less than `n`.
Currently `Iterator::nth` is the method to override for efficiently advancing an iterator by multiple elements at once. `advance_by` is superior for this purpose because
- it's simpler to implement: instead of advancing the iterator and producing the next element you only need to advance the iterator
- it composes better: iterators like `Chain` and `FlatMap` can implement `advance_by` in terms of `advance_by` on their inner iterators, but they cannot implement `nth` in terms of `nth` on their inner iterators (see #60395)
- the default implementation of `nth` can trivially be implemented in terms of `advance_by` and `next`, which this PR also does
This PR also adds `DoubleEndedIterator::advance_back_by` for all the same reasons.
I'll make a tracking issue if it's decided this is worth merging. Also let me know if anything can be improved, this went through several iterations so there might very well still be room for improvement (especially in the doc comments). I've written overrides of these methods for most iterators that already override `nth`/`nth_back`, but those still need tests so I'll add them in a later PR.
cc @cuviper @scottmcm @Amanieu
Rollup of 12 pull requests
Successful merges:
- #77037 (more tiny clippy cleanups)
- #77233 (BTreeMap: keep an eye out on the size of the main components)
- #77280 (Ensure that all LLVM components requested by tests are available on CI)
- #77284 (library: Forward compiler-builtins "mem" feature)
- #77296 (liveness: Use Option::None to represent absent live nodes)
- #77322 (Add unstable book docs for `-Zunsound-mir-opts`)
- #77328 (Use `rtassert!` instead of `assert!` from the child process after fork() in std::sys::unix::process::Command::spawn())
- #77331 (Add test for async/await combined with const-generics.)
- #77338 (Fix typo in alloc vec comment)
- #77340 (Alloc vec use imported path)
- #77345 (Add test for issue #74761)
- #77348 (Update books)
Failed merges:
r? `@ghost`
Update books
## rust-by-example
5 commits in 19f0a0372af497b34369cf182d9d16156cab2969..7d3ff1c12db08a847a57a054be4a7951ce532d2d
2020-08-26 09:38:48 -0300 to 2020-09-28 15:54:25 -0300
- Prevent duplicated error information in "wrapping errors" example (rust-lang/rust-by-example#1375)
- Avoid lifetime annotation in struct example (rust-lang/rust-by-example#1378)
- Clone.md comment and variable name change (rust-lang/rust-by-example#1379)
- Replace panic example with a simpler version (rust-lang/rust-by-example#1380)
- Prefer `const` over `static` (rust-lang/rust-by-example#1381)
## embedded-book
1 commits in 0cd2ca116274b915924c3a7e07c1e046b6f19b77..dd310616308e01f6cf227f46347b744aa56b77d9
2020-08-19 10:33:15 +0000 to 2020-09-26 08:54:08 +0000
- Add instructions for ARM v8 instruction sets (rust-embedded/book#265)
Use `rtassert!` instead of `assert!` from the child process after fork() in std::sys::unix::process::Command::spawn()
As discussed in #73894, `assert!` panics on failure, which is not signal-safe, and `rtassert!` is a suitable replacement.
Fixes#73894.
r? @Amanieu @cuviper @joshtriplett
library: Forward compiler-builtins "mem" feature
This fixes https://github.com/rust-lang/wg-cargo-std-aware/issues/53
Now users will be able to do:
```
cargo build -Zbuild-std=core -Zbuild-std-features=compiler-builtins-mem
```
and correctly get the Rust implemenations for `memcpy` and friends.
Signed-off-by: Joe Richey <joerichey@google.com>
Ensure that all LLVM components requested by tests are available on CI
Addresses https://github.com/rust-lang/rust/pull/75064#issuecomment-667722652
I used an environment variable because passing a command line option all the way from CI to compiletest would be just too much hassle for this task.
I added a new variable, but any of the already existing ones defined by CI could be used instead.
r? @Mark-Simulacrum
Add support for cmse_nonsecure_entry attribute
This pull request adds the `cmse_nonsecure_entry` attribute under an unstable feature.
I was not sure if it was fine for me to send directly the pull-request or if I should submit a RFC first. I was told on Zulip that it was fine to do so but please close it if I need first submit a RFC or follow another process instead.
The `cmse_nonsecure_entry` attribute is a LLVM attribute that will be available in LLVM 11. I plan to rebase on the [upgrade PR](https://github.com/rust-lang/rust/pull/73526) once merged to make this one compile.
This attribute modifies code generation of the function as explained [here](https://developer.arm.com/documentation/ecm0359818/latest/) to make it work with the TrustZone-M hardware feature. This feature is only available on `thumbv8m` targets so I created an error for that if one tries to use this attribute for another target.
I added this attribute in Rust as any other LLVM attribute are added but since this one is target-dependent I am not sure if it was the best thing to do. Please indicate me if you think of other ways, like isolating target-dependent attributes together.
----------------
Tracking issue: https://github.com/rust-lang/rust/issues/75835
Don't warn if the config file is somewhere other than `config.toml`
Previously, `config.config` was always hardcoded as `"config.toml"`.
I thought that it was being overridden with the actual value later, but
it turns out `flags.config` was being completely discarded. This keeps
`config.config` in sync with `flags.config`.
Fixes https://github.com/rust-lang/rust/issues/77293
r? `@Mark-Simulacrum`
cc `@davidtwco`
This patch adds support for the LLVM cmse_nonsecure_entry attribute.
This is a target-dependent attribute that only has sense for the
thumbv8m Rust targets.
You can find more information about this attribute here:
https://developer.arm.com/documentation/ecm0359818/latest/
Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
Secure entry functions do not support if arguments are passed on the
stack. An "unsupported" diagnostic will be emitted by LLVM if that is
the case.
This commits adds support in Rust for that diagnostic so that an error
will be output if that is the case!
Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
bootstrap: Always build for host, even when target is given
This changes the behavior from *not* building for host whenever an
explicit target is specified. I find this much less confusing.
You can still disable host steps by passing an explicit empty list for
host.
Fixes#76990.
r? `@Mark-Simulacrum`
Liveness refactoring continued
* Move body_owner field from IrMaps to Liveness (the only user of the field).
* Use upvars instead of FnKind to check for closures (avoids FnKind, will be useful when checking all bodies, not just fns).
* Use visit_param to add variables corresponding to params.
* Store upvars_mentioned inside Liveness struct.
* Inline visitor implementation for IrMaps, avoiding unnecessary indirection.
* Test interaction with automatically_derived attribute (not covered by any of existing tests).
No functional changes intended.
Refactor versions detection in build-manifest
This PR refactors how `build-manifest` handles versions, making the following changes:
* `build-manifest` now detects the "package releases" on its own, without relying on rustbuild providing them through CLI arguments. This drastically simplifies calling the tool outside of `x.py`, and will allow to ship the prebuilt tool in a tarball in the future, with the goal of stopping to invoke `x.py` during `promote-release`.
* The `tar` command is not used to extract the version and the git hash from tarballs anymore. The `flate2` and `tar` crates are used instead. This makes detecting those pieces of data way faster, as the archive is decompressed just once and we stop parsing the archive once all the information is retrieved.
* The code to extract the version and the git hash now stores all the collected data dynamically, without requiring to add new fields to the `Builder` struct every time.
I tested the changes locally and it should behave the same as before.
r? `@Mark-Simulacrum`
Resolve `crate` in intra-doc links properly across crates
Closes https://github.com/rust-lang/rust/issues/77193; see https://github.com/rust-lang/rust/issues/77193#issuecomment-699065946 for an explanation of what's going on here.
~~This also fixes the BTreeMap docs that have been broken for a while; see the description on the second commit for why and how.~~ Nope, see the second commit for why the link had to be changed.
r? `@Manishearth`
cc `@dylni`
`@dylni` note that this doesn't solve your original problem - now _both_ `with_code` and `crate::with_code` will be broken links. However this will fix a lot of other broken links (in particular I think https://docs.rs/sqlx/0.4.0-beta.1/sqlx/query/struct.Query.html is because of this bug). I'll open another issue for resolving additional docs in the new scope.
expand: Stop normalizing `NtIdent`s before passing them to built-in macros
Built-in macros should be able to deal with `NtIdents` in the input by themselves like any other parser code.
You can't imagine how bad mutable AST visitors are, *especially* if they are modifying tokens.
This is one step towards removing token visiting from the visitor infrastructure (https://github.com/rust-lang/rust/pull/77271 also works in this direction.)
Optimize `IntRange::from_pat`, then shrink `ParamEnv`
Resolves#77058.
r? `@Mark-Simulacrum`
cc `@vandenheuvel`
Looking at the output of `perf report` for #76244, the hot instructions seemed to be around the call to `pat_constructor` in `IntRange::from_pat`. I carried out an obvious optimization, but it actually made the instruction count higher (see #77075). However, it seems to have mitigated whatever was causing the pipeline stalls, so when combined with #76244, it's a net win.
As you can see below, the regression in #76244 seems to have originated from something measured by `stalled-cycles-backend`. I'll try to collect some finer-grained stats to see if I can isolate it. I wish I had a better idea of what was going on here. I'd like to prevent the regression from reappearing in the future due to small changes in unrelated code.
<details>
<summary>Current `master`:</summary>
```
Performance counter stats for 'cargo +baseline-stage1 check':
2,275.67 msec task-clock:u # 0.998 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
49,826 page-faults:u # 0.022 M/sec
5,117,221,678 cycles:u # 2.249 GHz
299,655,943 stalled-cycles-frontend:u # 5.86% frontend cycles idle
2,284,213,395 stalled-cycles-backend:u # 44.64% backend cycles idle
8,051,871,959 instructions:u # 1.57 insn per cycle
# 0.28 stalled cycles per insn
1,359,589,402 branches:u # 597.447 M/sec
7,359,347 branch-misses:u # 0.54% of all branches
2.281030026 seconds time elapsed
2.108197000 seconds user
0.164183000 seconds sys
```
</details>
<details>
<summary>Shrink `ParamEnv` without changing `IntRange::from_pat`:</summary>
```
Performance counter stats for 'cargo +perf-stage1 check':
2,751.79 msec task-clock:u # 0.996 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
50,103 page-faults:u # 0.018 M/sec
6,260,590,019 cycles:u # 2.275 GHz
317,355,920 stalled-cycles-frontend:u # 5.07% frontend cycles idle
3,397,743,582 stalled-cycles-backend:u # 54.27% backend cycles idle
8,276,224,367 instructions:u # 1.32 insn per cycle
# 0.41 stalled cycles per insn
1,370,453,386 branches:u # 498.023 M/sec
7,281,031 branch-misses:u # 0.53% of all branches
2.763265838 seconds time elapsed
2.544578000 seconds user
0.204548000 seconds sys
```
</details>
<details>
<summary>Shrink `ParamEnv` and change `IntRange::from_pat`: </summary>
```
Performance counter stats for 'cargo +perf-stage1 check':
2,295.57 msec task-clock:u # 0.996 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
49,959 page-faults:u # 0.022 M/sec
5,151,407,066 cycles:u # 2.244 GHz
324,517,829 stalled-cycles-frontend:u # 6.30% frontend cycles idle
2,301,671,001 stalled-cycles-backend:u # 44.68% backend cycles idle
8,130,868,329 instructions:u # 1.58 insn per cycle
# 0.28 stalled cycles per insn
1,356,618,512 branches:u # 590.972 M/sec
7,323,800 branch-misses:u # 0.54% of all branches
2.304509653 seconds time elapsed
2.128090000 seconds user
0.163909000 seconds sys
```
</details>
Dylan DPC
bors
Jonas Schievink
Hugues de Valon
Ralf Jung
samlich
Tomasz Miąsko
Tyler Mandry
Eric Huss
Ivan Tham
Hameer Abbasi
Vadim Petrochenkov
hyd-dev
Wesley Wiser