The original description suggests that the original `Rc<T>` itself is downgraded, which doesn't seem to be what the code does. At the same time, `Rc` is one of those types that can do weird things with only a shared reference, so I thought it would be good to be clear.
linkchecker: Treat directory links as errors
Directory links don't work well offline so they should be treated as errors.
All examples of this I know of are fixed in #34021.
[MIR] Implement overflow checking
The initial set of changes is from @Aatch's #33255 PR, rebased on master, plus:
Added an `Assert` terminator to MIR, to simplify working with overflow and bounds checks.
With this terminator, error cases can be accounted for directly, instead of looking for lang item calls.
It also keeps the MIR slimmer, with no extra explicit blocks for the actual panic calls.
Warnings can be produced when the `Assert` is known to always panic at runtime, e.g.:
```rust
warning: index out of bounds: the len is 1 but the index is 3
--> <anon>:1:14
1 |> fn main() { &[std::io::stdout()][3]; }
|> ^^^^^^^^^^^^^^^^^^^^^^
```
Generalized the `OperandValue::FatPtr` optimization to any aggregate pair of immediates.
This allows us to generate the same IR for overflow checks as old trans, not something worse.
For example, addition on `i16` calls `llvm.sadd.with.overflow.i16`, which returns `{i16, i1}`.
However, the Rust type `(i16, bool)`, has to be `{i16, i8}`, only an immediate `bool` is `i1`.
But if we split the pair into an `i16` and an `i1`, we can pass them around as such for free.
The latest addition is a rebase of #34054, updated to work for pairs too. Closes#34054, fixes#33873.
Last but not least, the `#[rustc_inherit_overflow_checks]` attribute was introduced to control the
overflow checking behavior of generic or `#[inline]` functions, when translated in another crate.
It is **not** intended to be used by crates other than `libcore`, which is in the unusual position of
being distributed as only an optimized build with no checks, even when used from debug mode.
Before MIR-based translation, this worked out fine, as the decision for overflow was made at
translation time, in the crate being compiled, but MIR stored in `rlib` has to contain the checks.
To avoid always generating the checks and slowing everything down, a decision was made to
use an attribute in the few spots of `libcore` that need it (see #33255 for previous discussion):
* `core::ops::{Add, Sub, Mul, Neg, Shl, Shr}` implementations for integers, which have `#[inline]` methods and can be used in generic abstractions from other crates
* `core::ops::{Add, Sub, Mul, Neg, Shl, Shr}Assign` same as above, for augmented assignment
* `pow` and `abs` methods on integers, which intentionally piggy-back on built-in multiplication and negation, respectively, to get overflow checks
* `core::iter::{Iterator, Chain, Peek}::count` and `core::iter::Enumerate::{next, nth}`, also documented as panicking on overflow, from addition, counting elements of an iterator in an `usize`
generate fewer basic blocks for variant switches
CC #33567
Adds a new field to TestKind::Switch that tracks the variants that are actually matched against. The other candidates target a common "otherwise" block.
This commit attempts to bring our prepends to PATH on Windows when loading
plugins because we've been seeing quite a few issues with failing to spawn a
process on Windows, the leading theory of which is that PATH is too large as a
result of this. Currently this is mostly a stab in the dark as it's not
confirmed to actually fix the problem, but it's probably not a bad change to
have anyway!
cc #33844Closes#17360
Fix a regression in the configuration folder
This fixes#34028, a regression caused by #33706 in which unconfigured impl items generated by a macro in an impl item position are not removed.
r? @nrc
Projection cache and better warnings for #32330
This PR does three things:
- it lays the groundwork for the more precise subtyping rules discussed in #32330, but does not enable them;
- it issues warnings when the result of a leak-check or subtyping check relies on a late-bound region which will late become early-bound when #32330 is fixed;
- it introduces a cache for projection in the inference context.
I'm not 100% happy with the approach taken by the cache here, but it seems like a step in the right direction. It results in big wins on some test cases, but not as big as previous versions -- I think because it is caching the `Vec<Obligation>` (whereas before I just returned the normalized type with an empty vector). However, that change was needed to fix an ICE in @alexcrichton's future-rs module (I haven't fully tracked the cause of that ICE yet). Also, because trans/the collector use a fresh inference context for every call to `fulfill_obligation`, they don't profit nearly as much from this cache as they ought to.
Still, here are the results from the future-rs `retry.rs`:
```
06:26 <nmatsakis> time: 6.246; rss: 44MB item-bodies checking
06:26 <nmatsakis> time: 54.783; rss: 63MB translation item collection
06:26 <nmatsakis> time: 140.086; rss: 86MB translation
06:26 <nmatsakis> time: 0.361; rss: 46MB item-bodies checking
06:26 <nmatsakis> time: 5.299; rss: 63MB translation item collection
06:26 <nmatsakis> time: 12.140; rss: 86MB translation
```
~~Another example is the example from #31849. For that, I get 34s to run item-bodies without any cache. The version of the cache included here takes 2s to run item-bodies type-checking. An alternative version which doesn't track nested obligations takes 0.2s, but that version ICEs on @alexcrichton's future-rs (and may well be incorrect, I've not fully convinced myself of that). So, a definite win, but I think there's definitely room for further progress.~~
Pushed a modified version which improves performance of the case from #31849:
```
lunch-box. time rustc --stage0 ~/tmp/issue-31849.rs -Z no-trans
real 0m33.539s
user 0m32.932s
sys 0m0.570s
lunch-box. time rustc --stage2 ~/tmp/issue-31849.rs -Z no-trans
real 0m0.195s
user 0m0.154s
sys 0m0.042s
```
Some sort of cache is also needed for unblocking further work on lazy normalization, since that will lean even more heavily on the cache, and will also require cycle detection.
r? @arielb1
Incr. comp. dep-node for traits, tests
Introduce new tests and also make dep-node for trait selection a bit more selective.
Fixes#33850
r? @michaelwoerister
MSVC requires unwinding code to be split to a tree of *funclets*, where each funclet
can only branch to itself or to to its parent.
Luckily, the code we generates matches this pattern. Recover that structure in
an analyze pass and translate according to that.
rustbuild: Clean more on `make clean`
Be sure to not use the old build cache for the bootstrap build system nor the
old caches of the compiler/cargo extractions (in case something went wrong).
Closes#33986
Support 16-bit pointers as well as i/usize
I'm opening this pull request to get some feedback from the community.
Although Rust doesn't support any platforms with a native 16-bit pointer at the moment, the [AVR-Rust][ar] fork is working towards that goal. Keeping this forked logic up-to-date with the changes in master has been onerous so I'd like to merge these changes so that they get carried along when refactoring happens. I do not believe this should increase the maintenance burden.
This is based on the original work of Dylan McKay (@dylanmckay).
[ar]: https://github.com/avr-rust/rust
Rename main thread from "<main>" to "main".
Fix issue #33789
We may need to discuss whether this counts as a breaking change since code may check the main thread name against "\<main\>". Discussion is in #33789
