Update books
## reference
3 commits in fa5dfb832ef8a7568e17dabf612f486d641ff4ac..320d232b206edecb67489316f71a14e31dbc6c08
2019-09-16 20:42:56 +0200 to 2019-10-01 17:05:35 +0200
- Update async/await keywords to real keywords. (rust-lang-nursery/reference#687)
- Remove the warning that appears on every page. (rust-lang-nursery/reference#685)
- Eschew fp lit pattern (rust-lang-nursery/reference#683)
## book
9 commits in 871416b85c1a73717d65d6f4a9ea29e5aef3db0e..04806c80be0f54b1290287e3f85e84bdfc0b6ec7
2019-09-16 09:46:20 -0400 to 2019-10-01 20:20:22 -0400
- Fix tidy error. (rust-lang/book#2104)
- Fancy quotes
- Commit autogenerated cargo content
- Move all scripts into tools
- We can start lines with numbers without creating ordered lists
- ci: validate that all used references are defined (rust-lang/book#2032)
- Remove the check for unstable features
- Specify the rustc version we're using in a rust-toolchain file
- Fix broken link to Chapter 13-01 in Chapter 12-04 (rust-lang/book#2025)
## rust-by-example
9 commits in 67cfbf31df880728dcf7cb35b15b028ec92caf31..a6288e7407a6c4c19ea29de6d43f40c803883f21
2019-09-18 09:36:40 -0300 to 2019-10-01 10:09:14 -0300
- Add reference to lifetime in structs (rust-lang/rust-by-example#1274)
- Rectangle ambiguity (rust-lang/rust-by-example#1270)
- Make Parsing a String code editable (rust-lang/rust-by-example#1268)
- Fix match range pattern usage (rust-lang/rust-by-example#1269)
- Added type alias enum variant rfc (rust-lang/rust-by-example#1267)
- Chapter 9.2.5: impl FnOnce() works in 1.35 (rust-lang/rust-by-example#1266)
- Move chapters from folder "traits" to "trait" (rust-lang/rust-by-example#1263)
- Capturing changes (rust-lang/rust-by-example#1265)
- Fixrust-lang/rust-by-example#1261: document Iterator::position (rust-lang/rust-by-example#1262)
r? @ghost
Fully clear `HandlerInner` in `Handler::reset_err_count`
Address [`FIXME`](702b45e409/src/librustc_errors/lib.rs (L472)) for `Handler::reset_err_count` in the way suggested by @Mark-Simulacrum, i. e. clear all the fields of `HandlerInner`.
cc @estebank
Fix zebra-striping in generic dataflow visualization
A small formatting improvement to #64828.
Prior to this, the background color of the first row of the table for each basic block changed seemingly at random. You can see this in [basic block #5](https://github.com/rust-lang/rust/pull/64828#issuecomment-536690047) under "New table". Now it is always light.
This also updates the example table to match the current output.
use try_fold instead of try_for_each to reduce compile time
as it was stated in #64572 that the biggest gain was due to less code was generated I tried to reduce the number of functions to inline by using try_fold direct instead of calling try_for_each that calls try_fold.
as there is some gains with using the try_fold function this is maybe a way forward.
when I tried to compile the clap-rs benchmark I get times gains only some % from #64572
there is more function that use eg. fold that calls try_fold that also can be changed but the question is how mush "duplication" that is tolerated in std to give faster compile times
can someone start a perf run?
cc @nnethercote @scottmcm @bluss
r? @ghost
SelfProfiler API refactoring and part one of event review
This PR refactors the `SelfProfiler` a little bit so that most profiling methods are RAII-based. The codegen backend code already had something similar, this refactoring pulls this functionality up into `SelfProfiler` itself, for general use.
The second commit of this PR is a review and update of the existing events we are already recording. Names have been made more consistent. CGU names have been removed from event names. They will be added back in when function parameter recording is implemented.
There is still some work to be done for adding new events, especially around trait resolution and the incremental system.
r? @wesleywiser
Avoid `chain()` in `find_constraint_paths_between_regions()`.
This iterator can be hot, and chained iterators are slow. The second
half of the chain is almost always empty, so this commit specializes the
code to avoid the chained iteration.
This change reduces instruction counts for the `wg-grammar` benchmark by
up to 1.5%.
Make all alt builders produce parallel-enabled compilers
We're not quite ready to ship parallel compilers by default, but the alt
builders are not used too much (in theory), so we believe that shipping
a possibly-broken compiler there is not too problematic.
r? @nikomatsakis
This works just as you might expect - an 'extern const fn' is a 'const
fn' that is callable from foreign code.
Currently, panicking is not allowed in consts. When RFC 2345 is
stabilized, then panicking in an 'extern const fn' will produce a
compile-time error when invoked at compile time, and an abort when
invoked at runtime.
Since this is extending the language (we're allowing the `const` keyword
in a new context), I believe that this will need an FCP. However, it's a
very minor change, so I didn't think that filing an RFC was necessary.
This will allow libc (and other FFI crates) to make many functions
`const`, without having to give up on making them `extern` as well.
We now use `DataflowResultsCursor` to get the dataflow state before
calls to `rustc_peek`. The original version used a custom implementation
that only looked at assignment statements. This also extends
`rustc_peek` to take arguments by-value as well as by-reference, and
allows *all* dataflow analyses, not just those dependent on `MoveData`,
to be inspected.
As described in #57374, NLL currently produces unhelpful higher-ranked
trait bound (HRTB) errors when '-Zno-leak-check' is enabled.
This PR tackles one half of this issue - making the error message point
at the proper span. The error message itself is still the very generic
"higher-ranked subtype error", but this can be improved in a follow-up
PR.
The root cause of the bad spans lies in how NLL attempts to compute the
'blamed' region, for which it will retrieve a span for.
Consider the following code, which (correctly) does not compile:
```rust
let my_val: u8 = 25;
let a: &u8 = &my_val;
let b = a;
let c = b;
let d: &'static u8 = c;
```
This will cause NLL to generate the following subtype constraints:
d :< c
c :< b
b <: a
Since normal Rust lifetimes are covariant, this results in the following
region constraints (I'm using 'd to denote the lifetime of 'd',
'c to denote the lifetime of 'c, etc.):
'c: 'd
'b: 'c
'a: 'b
From this, we can derive that 'a: 'd holds, which implies that 'a: 'static
must hold. However, this is not the case, since 'a refers to 'my_val',
which does not outlive the current function.
When NLL attempts to infer regions for this code, it will see that the
region 'a has grown 'too large' - it will be inferred to outlive
'static, despite the fact that is not declared as outliving 'static
We can find the region responsible, 'd, by starting at the *end* of
the 'constraint chain' we generated above. This works because for normal
(non-higher-ranked) lifetimes, we generally build up a 'chain' of
lifetime constraints *away* from the original variable/lifetime.
That is, our original lifetime 'a is required to outlive progressively
more regions. If it ends up living for too long, we can look at the
'end' of this chain to determine the 'most recent' usage that caused
the lifetime to grow too large.
However, this logic does not work correctly when higher-ranked trait
bounds (HRTBs) come into play. This is because HRTBs have
*contravariance* with respect to their bound regions. For example,
this code snippet compiles:
```rust
let a: for<'a> fn(&'a ()) = |_| {};
let b: fn(&'static ()) = a;
```
Here, we require that 'a' is a subtype of 'b'. Because of
contravariance, we end up with the region constraint 'static: 'a,
*not* 'a: 'static
This means that our 'constraint chains' grow in the opposite direction
of 'normal lifetime' constraint chains. As we introduce subtypes, our
lifetime ends up being outlived by other lifetimes, rather than
outliving other lifetimes. Therefore, starting at the end of the
'constraint chain' will cause us to 'blame' a lifetime close to the original
definition of a variable, instead of close to where the bad lifetime
constraint is introduced.
This PR improves how we select the region to blame for 'too large'
universal lifetimes, when bound lifetimes are involved. If the region
we're checking is a 'placeholder' region (e.g. the region 'a' in
for<'a>, or the implicit region in fn(&())), we start traversing the
constraint chain from the beginning, rather than the end.
There are two (maybe more) different ways we generate region constraints for NLL:
requirements generated from trait queries, and requirements generated
from MIR subtype constraints. While the former always use explicit
placeholder regions, the latter is more tricky. In order to implement
contravariance for HRTBs, TypeRelating replaces placeholder regions with
existential regions. This requires us to keep track of whether or not an
existential region was originally a placeholder region. When we look for
a region to blame, we check if our starting region is either a
placeholder region or is an existential region created from a
placeholder region. If so, we start iterating from the beginning of the
constraint chain, rather than the end.
syntax: cleanup param, method, and misc parsing
Do some misc cleanup of the parser:
- Method and parameter parsing is refactored.
- A parser for `const | mut` is introduced that https://github.com/rust-lang/rust/pull/64588 can reuse.
- Some other misc parsing.
Next up in a different PR:
- ~Implementing https://github.com/rust-lang/rust/issues/64252.~ -- maybe some other time...
- Heavily restructuring up `item.rs` which is a mess (hopefully, no promises ^^).
r? @petrochenkov
BTreeSet intersection, is_subset & difference optimizations
...based on the range of values contained; in particular, a massive improvement when these ranges are disjoint (or merely touching), like in the neg-vs-pos benchmarks already in liballoc. Inspired by #64383 but none of the ideas there worked out.
I introduced another variant in IntersectionInner and in DifferenceInner, because I couldn't find a way to initialize these iterators as empty if there's no empty set around.
Also, reduced the size of "large" sets in test cases - if Miri can't handle it, it was needlessly slowing down everyone.
