Many of the iterator adaptors will perform faster folds if they forward
to their inner iterator's folds, especially for inner types like `Chain`
which are optimized too. The following types are newly specialized:
| Type | `fold` | `rfold` |
| ----------- | ------ | ------- |
| `Enumerate` | ✓ | ✓ |
| `Filter` | ✓ | ✓ |
| `FilterMap` | ✓ | ✓ |
| `FlatMap` | exists | ✓ |
| `Fuse` | ✓ | ✓ |
| `Inspect` | ✓ | ✓ |
| `Peekable` | ✓ | N/A¹ |
| `Skip` | ✓ | N/A² |
| `SkipWhile` | ✓ | N/A¹ |
¹ not a `DoubleEndedIterator`
² `Skip::next_back` doesn't pull skipped items at all, but this couldn't
be avoided if `Skip::rfold` were to call its inner iterator's `rfold`.
Benchmarks
----------
In the following results, plain `_sum` computes the sum of a million
integers -- note that `sum()` is implemented with `fold()`. The
`_ref_sum` variants do the same on a `by_ref()` iterator, which is
limited to calling `next()` one by one, without specialized `fold`.
The `chain` variants perform the same tests on two iterators chained
together, to show a greater benefit of forwarding `fold` internally.
test iter::bench_enumerate_chain_ref_sum ... bench: 2,216,264 ns/iter (+/- 29,228)
test iter::bench_enumerate_chain_sum ... bench: 922,380 ns/iter (+/- 2,676)
test iter::bench_enumerate_ref_sum ... bench: 476,094 ns/iter (+/- 7,110)
test iter::bench_enumerate_sum ... bench: 476,438 ns/iter (+/- 3,334)
test iter::bench_filter_chain_ref_sum ... bench: 2,266,095 ns/iter (+/- 6,051)
test iter::bench_filter_chain_sum ... bench: 745,594 ns/iter (+/- 2,013)
test iter::bench_filter_ref_sum ... bench: 889,696 ns/iter (+/- 1,188)
test iter::bench_filter_sum ... bench: 667,325 ns/iter (+/- 1,894)
test iter::bench_filter_map_chain_ref_sum ... bench: 2,259,195 ns/iter (+/- 353,440)
test iter::bench_filter_map_chain_sum ... bench: 1,223,280 ns/iter (+/- 1,972)
test iter::bench_filter_map_ref_sum ... bench: 611,607 ns/iter (+/- 2,507)
test iter::bench_filter_map_sum ... bench: 611,610 ns/iter (+/- 472)
test iter::bench_fuse_chain_ref_sum ... bench: 2,246,106 ns/iter (+/- 22,395)
test iter::bench_fuse_chain_sum ... bench: 634,887 ns/iter (+/- 1,341)
test iter::bench_fuse_ref_sum ... bench: 444,816 ns/iter (+/- 1,748)
test iter::bench_fuse_sum ... bench: 316,954 ns/iter (+/- 2,616)
test iter::bench_inspect_chain_ref_sum ... bench: 2,245,431 ns/iter (+/- 21,371)
test iter::bench_inspect_chain_sum ... bench: 631,645 ns/iter (+/- 4,928)
test iter::bench_inspect_ref_sum ... bench: 317,437 ns/iter (+/- 702)
test iter::bench_inspect_sum ... bench: 315,942 ns/iter (+/- 4,320)
test iter::bench_peekable_chain_ref_sum ... bench: 2,243,585 ns/iter (+/- 12,186)
test iter::bench_peekable_chain_sum ... bench: 634,848 ns/iter (+/- 1,712)
test iter::bench_peekable_ref_sum ... bench: 444,808 ns/iter (+/- 480)
test iter::bench_peekable_sum ... bench: 317,133 ns/iter (+/- 3,309)
test iter::bench_skip_chain_ref_sum ... bench: 1,778,734 ns/iter (+/- 2,198)
test iter::bench_skip_chain_sum ... bench: 761,850 ns/iter (+/- 1,645)
test iter::bench_skip_ref_sum ... bench: 478,207 ns/iter (+/- 119,252)
test iter::bench_skip_sum ... bench: 315,614 ns/iter (+/- 3,054)
test iter::bench_skip_while_chain_ref_sum ... bench: 2,486,370 ns/iter (+/- 4,845)
test iter::bench_skip_while_chain_sum ... bench: 633,915 ns/iter (+/- 5,892)
test iter::bench_skip_while_ref_sum ... bench: 666,926 ns/iter (+/- 804)
test iter::bench_skip_while_sum ... bench: 444,405 ns/iter (+/- 571)
Add suggestions for misspelled method names
Use the syntax::util::lev_distance module to provide suggestions when a
named method cannot be found.
Part of #30197
Require rlibs for dependent crates when linking static executables
This handles the case for `CrateTypeExecutable` and `+crt_static`. I reworked the match block to avoid duplicating the `attempt_static` and error checking code again (this case would have been a copy of the `CrateTypeCdylib`/`CrateTypeStaticlib` case).
On `linux-musl` targets where `std` was built with `crt_static = false` in `config.toml`, this change brings the test suite from entirely failing to mostly passing.
This change should not affect behavior for other crate types, or for targets which do not respect `+crt_static`.
Allow writing metadata without llvm
# Todo:
* [x] Rebase
* [x] Fix eventual errors
* [x] <strike>Find some crate to write elf files</strike> (will do it later)
Cc #43842
encode region::Scope using fewer bytes
Now that region::Scope is no longer interned, its size is more important. This PR encodes region::Scope in 8 bytes instead of 12, which should speed up region inference somewhat (perf testing needed) and should improve the margins on #36799 by 64MB (that's not a lot, I did this PR mostly to speed up region inference).
This is a perf-sensitive PR. Please don't roll me up.
r? @eddyb
This is based on #44743 so I could get more accurate measurements on #36799.
In particular:
* introduce the shallow/deep distinction for read/write accesses
* use the notions of prefixes, shallow prefixes, and supporting prefixes
rather than trying to recreate the restricted sets from ast-borrowck.
* Add shallow reads of Discriminant and ArrayLength, and treat them
as artificial fields when doing prefix traversals.
This is a partial revert of #42588. There is a usability concern
reported in #44294 that was not considered in the discussion of the PR,
so I would like to back this out of 1.21. As is, I think users would
have a worse and more confusing experience with this lint enabled by
default. We can re-enabled once there are better diagnostics or the case
in #44294 does not trigger the lint.
* Adjust bootstrap to provide useful output on failure
* Add missing package dependencies in the build environment
* Fix permission bits on prebuilt toolchain files
Move effect-checking to MIR
This allows emitting lints from MIR and moves the effect-checking pass to work on it.
I'll make `repr(packed)` misuse unsafe in a separate PR.
r? @eddyb
put empty generic lists behind a pointer
This reduces the size of hir::Expr from 128 to 88 bytes (!) and shaves
200MB out of #36799.
This is a performance-sensitive PR so please don't roll it up.
r? @eddyb
On "the parameter type `T` may not live long enough" error, point to the
parameter type suggesting lifetime bindings:
```
error[E0310]: the parameter type `T` may not live long enough
--> $DIR/lifetime-doesnt-live-long-enough.rs:28:5
|
27 | struct Foo<T> {
| - help: consider adding an explicit lifetime bound `T: 'static`...
28 | foo: &'static T
| ^^^^^^^^^^^^^^^
|
note: ...so that the reference type `&'static T` does not outlive the data it points at
--> $DIR/lifetime-doesnt-live-long-enough.rs:28:5
|
28 | foo: &'static T
| ^^^^^^^^^^^^^^^
```
The convention for suggesting close matches is to provide at most one match (the
closest one). Change the suggestions for misspelt method names to obey that.
typeck::check::coercion - roll back failed unsizing type vars
This wraps unsizing coercions within an additional level of
`commit_if_ok`, which rolls back type variables if the unsizing coercion
fails. This prevents a large amount of type-variables from accumulating
while type-checking a large function, e.g. shaving 2GB off one of the
4GB peaks in #36799.
This is a performance-sensitive PR so please don't roll it up.
r? @eddyb
cc @nikomatsakis
Now that region::Scope is no longer interned, its size is more
important. This PR encodes region::Scope in 8 bytes instead of 12, which
should speed up region inference somewhat (perf testing needed) and
should improve the margins on #36799 by 64MB (that's not a lot, I did
this PR mostly to speed up region inference).
add comparison operators to must-use lint (under `fn_must_use` feature)
Although RFC 1940 is about annotating functions with `#[must_use]`, a
key part of the motivation was linting unused equality operators.
(See
https://github.com/rust-lang/rfcs/pull/1812#issuecomment-265695898—it
seems to have not been clear to discussants at the time that marking the
comparison methods as `must_use` would not give us the lints on
comparison operators, at least in (what the present author understood
as) the most straightforward implementation, as landed in #43728
(3645b062).)
To rectify the situation, we here lint unused comparison operators as
part of the unused-must-use lint (feature gated by the `fn_must_use`
feature flag, which now arguably becomes a slight (tolerable in the
opinion of the present author) misnomer).
This is in the matter of #43302.
cc @crumblingstatue
