rustc_codegen_ssa: fix range check in codegen_get_discr.
Fixes#61696, see https://github.com/rust-lang/rust/issues/61696#issuecomment-505473018 for more details.
In short, I had wanted to use `x - a <= b - a` to check whether `x` is in `a..=b` (as it's 1 comparison instead of 2 *and* `b - a` is guaranteed to fit in the same data type, while `b` itself might not), but I ended up with `x - a + c <= b - a + c` instead, because `x - a + c` was the final value needed.
That latter comparison is equivalent to checking that `x` is in `(a - c)..=b`, i.e. it also includes `(a - c)..a`, not just `a..=b`, so if `c` is not `0`, it will cause false positives.
This presented itself as the non-niche ("dataful") variant sometimes being treated like a niche variant, in the presence of uninhabited variants (which made `c`, aka the index of the first niche variant, arbitrarily large).
r? @nagisa, @rkruppe or @oli-obk
rustbuild: Improve assert about building tools once
In developing #61557 I noticed that there were two parts of our tools
that were rebuilt twice on CI. One was rustfmt fixed in #61557, but
another was Cargo. The actual fix for Cargo's double compile was
rust-lang/cargo#7010 and took some time to propagate here. In an effort
to continue to assert that Cargo is itself not compiled twice, I updated
the assertion in rustbuild at the time of working on #61557 but couldn't
land it because the fix wouldn't be ready until the next bootstrap.
The next bootstrap is now here, so the fix can now land! This does not
change the behavior of rustbuild but it is intended to catch the
previous iteration of compiling cargo twice. The main update here was to
consider more files than those in `$target/release/deps` but also
consider those in `$target/release`. That's where, for example,
`libcargo.rlib` shows up and it's the file we learn about, and that's
what we want to deduplicate.
Make struct_tail normalize when possible
As noted in commit message: this replaces the existing methods to extract the struct tail(s) with new entry points that make the handling of normalization explicit.
Most of the places that call `struct_tail` are during codegen, post type-checking, and therefore they can get away with using `tcx.normalize_erasing_regions` (this is the entry point `struct_tail_erasing_lifetimes`)
For other cases that may arise, one can use the core method, which is parameterized over the normalization `Ty -> Ty` closure (`struct_tail_with_normalize`).
Or one can use the trivial entry point that does not normalization (`struct_tail_without_normalization`)
----
I spent a little while trying to make a test that exposed the bug via `impl Trait` rather than a projection, but I failed to find something that tripped up the current nightly `rustc`.
* I have *not* spent any time trying to make tests that trip up the other places where `struct_tail` was previously being called. While I do think the task of making such tests could be worthwhile, I am simply running out of time. (Its also possible that the layout code is always the first point called, and thus it may be pointless to try to come up with such tests.)
I also spent a little time discussing with @eddyb where this code should live. They suggested moving `struct_tail` and its sibling `struct_lockstep_tails` to the `LayoutCx`. But in the interest of time, I have left that refactoring (which may be questionable at this point) to a follow-up task.
----
Fix#60431
Fact generation for liveness calculations in Polonius
This PR tracks ongoing work to extend `rustc` with support for generating variable use, definition, and later also drop output for the Polonius solver, the whole of which is being tracked in [Polonius Issue #104](https://github.com/rust-lang/polonius/issues/104).
Add `impl<T> FromIterator<T> for Arc/Rc<[T]>`
Add implementations of `FromIterator<T> for Arc/Rc<[T]>` with symmetrical logic.
This also takes advantage of specialization in the case of iterators with known length (`TrustedLen`) to elide the final allocation/copying from a `Vec<T>` into `Rc<[T]>` because we can allocate the space for the `Rc<[T]>` directly when the size is known. This is the primary motivation and why this is to be preferred over `iter.collect::<Vec<_>>().into(): Rc<[T]>`.
Moreover, this PR does some refactoring in some places.
r? @RalfJung for the code
cc @alexcrichton from T-libs
Rollup of 12 pull requests
Successful merges:
- #61535 (Coherence test when a generic type param has a default value from an associated type)
- #62274 (rustc_mir: follow FalseUnwind's real_target edge in qualify_consts.)
- #62431 (Add messages to `Option`'s and `Result`'s `must_use` annotation for `is_*`)
- #62453 (in which we suggest anonymizing single-use lifetimes in paths )
- #62568 (Replace unsafe_destructor_blind_to_params with may_dangle)
- #62578 (Add test for #49919)
- #62595 (Document that the crate keyword refers to the project root)
- #62599 (move mem::uninitialized deprecation back by 1 release, to 1.39)
- #62605 (Emit dropped unemitted errors to aid in ICE debugging)
- #62607 (Correctly break out of recovery loop)
- #62608 (`async unsafe fn` tests)
- #62623 (downgrade indirect_structural_match lint to allow)
Failed merges:
r? @ghost
In developing #61557 I noticed that there were two parts of our tools
that were rebuilt twice on CI. One was rustfmt fixed in #61557, but
another was Cargo. The actual fix for Cargo's double compile was
rust-lang/cargo#7010 and took some time to propagate here. In an effort
to continue to assert that Cargo is itself not compiled twice, I updated
the assertion in rustbuild at the time of working on #61557 but couldn't
land it because the fix wouldn't be ready until the next bootstrap.
The next bootstrap is now here, so the fix can now land! This does not
change the behavior of rustbuild but it is intended to catch the
previous iteration of compiling cargo twice. The main update here was to
consider more files than those in `$target/release/deps` but also
consider those in `$target/release`. That's where, for example,
`libcargo.rlib` shows up and it's the file we learn about, and that's
what we want to deduplicate.
move mem::uninitialized deprecation back by 1 release, to 1.39
As per discussion at https://github.com/rust-lang/rust/issues/53491#issuecomment-509271182. Three releases also agrees with the precedent from `trim_left/right`. Three releases means that even nightly users (including rustc itself) get a full cycle from when the announcement is made in the stable release to when nightly starts to warn.
Document that the crate keyword refers to the project root
👋 this is my first rust contribution so I hope I'm doing everything correctly. Help very much appreciated if I'm not.
As far as I can tell this use of `crate` is only documented [in the edition guide for rust 2018](https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-clarity.html#the-crate-keyword-refers-to-the-current-crate). However it should probably be in the documentation for the `crate` keyword itself. This adds that documentation.
Replace unsafe_destructor_blind_to_params with may_dangle
This PR will completely remove support for `#[unsafe_destructor_blind_to_params]` attribute,
which is deprecated in #38970 by `[may_dangle]` unsafe attribute.
Closes#34761
rustc_mir: follow FalseUnwind's real_target edge in qualify_consts.
As far as I can tell, this was accidentally omitted from #47802.
Fixes#62272.
r? @matthewjasper or @nikomatsakis
Coherence test when a generic type param has a default value from an associated type
A followup on #61400.
Before `re_rebalance_coherence`, this fails to compile (even though it should be accepted).
`re_rebalance_coherence` had no direct test for this, and I wanted to (a) make sure it doesn't regress in the future and (b) get it on record that this is actually the intended behavior.
This is a way to address the regression aspect of rust-lang/rust#62614 in the
short term without actually fixing the bug. (My thinking is that the bug that
this lint detects has gone undetected for this long, it can wait a bit longer
until I or someone else has a chance to put in a proper fix that accounts for
rust-lang/rust#62614.)
[rustdoc] Fix storage usage when disabled
Fixes#61239.
@starblue: Can you give a try to this change please? I tried on chrome and firefox and both worked so if you're using another web browser, that might be useful. :)
r? @Manishearth
The old struct tail functions did not deal with `<T as Trait>::A` and `impl
Trait`, at least not explicitly. (We didn't notice this bug before because it
is only exposed when the tail (post deep normalization) is not `Sized`, so it
was a rare case to deal with.)
For post type-checking (i.e. during codegen), there is now
`struct_tail_erasing_lifetimes` and `struct_lockstep_tails_erasing_lifetimes`,
which each take an additional `ParamEnv` argument to drive normalization.
For pre type-checking cases where normalization is not needed, there is
`struct_tail_without_normalization`. (Currently, the only instance of this is
`Expectation::rvalue_hint`.)
All of these new entrypoints work by calling out to common helper routines.
The helpers are parameterized over a closure that handles the normalization.
