For cases where there are references in the parameters and in the the
outputs that do not match, and where no closures are involved, this
commit introduces an improved error that mentions (or synthesizes)
a name for the regions involved to better illustrate why the borrow
does not live long enough.
Previously, region naming would always highlight the source of the
region name it found. Now, region naming returns the name as part
of a larger structure that encodes the source of the region naming
such that a region name can be optionally added to the diagnostic.
Previously, explain_borrow would emit an error with the explanation of
the a borrow. Now, it returns a enum with what the explanation for the
borrow is and any relevant spans or information such that the calling
code can choose to emit the same note/suggestion as before by calling
the emit method on the new enum.
incr.comp.: Allow for more fine-grained testing of CGU reuse and use it to test incremental ThinLTO.
This adds some tests specifically targeted at incremental ThinLTO, plus the infrastructure for tracking the kind of cache hit/miss we had for a given CGU. @alexcrichton, let me know if you can think of any more tests to add. ThinLTO works rather reliably for small functions, so we should be able to test it in a robust way.
I think after this lands it might time for a "Help us test incremental ThinLTO" post on irlo.
r? @alexcrichton
Report when borrow could cause `&mut` aliasing during Drop
We were already issuing an error for the cases where this cropped up, so this is not fixing any soundness holes. The previous diagnostic just wasn't accurately describing the problem in the user's code.
Fix#52059
[NLL] Record more infomation on free region constraints in typeck
Changes:
* Makes the span of the MIR return place point to the return type
* Don't try to use a path to a type alias as a path to the adt it aliases (fixes an ICE)
* Don't claim that `self` is declared outside of the function. [see this test](f2995d5b1a (diff-0c9e6b1b204f42129b481df9ce459d44))
* Remove boring/interesting distinction and instead add a `ConstraintCategory` to the constraint.
* Add categories for implicit `Sized` and `Copy` requirements, for closure bounds, for user type annotations and `impl Trait`.
* Don't use the span of the first statement for Locations::All bounds (even if it happens to work on the tests we have)
Future work:
* Fine tuning the heuristic used to choose the place the report the error.
* Reporting multiple places (behind a flag)
* Better closure bounds reporting. This probably requires some discussion.
r? @nikomatsakis
Implement `MaybeUninit`
This PR:
- Adds `MaybeUninit` (see #53491) to `{core,std}::mem`.
- Makes `mem::{uninitialized,zeroed}` panic when they are used to instantiate an uninhabited type.
- Does *not* deprecate `mem::{uninitialized,zeroed}` just yet. As per https://github.com/rust-lang/rust/issues/53491#issuecomment-414147666, we should not deprecate them until `MaybeUninit` is stabilized.
- It replaces uses of `mem::{uninitialized,zeroed}` in core and alloc with `MaybeUninit`.
There are still several instances of `mem::{uninitialized,zeroed}` in `std` that *this* PR doesn't address.
r? @RalfJung
cc @eddyb you may want to look at the new panicking logic
NLL: disallow creation of immediately unusable variables
Fix#53695
Original description follows
----
This WIP PR is for discussing the impact of fixing #53695 by injecting a fake read in let patterns.
(Travis will fail, at least the `mir-opt` suite is failing in its current state)
During metadata loading, the AdtDefs for every ADT in the universe need
to be loaded (for example, for coherence of builtin traits). For that,
the attributes of the AdtDef need to be loaded too.
The attributes of a struct are duplicated between 2 def ids - the
constructor def-id, and the "type" def id. Loading attributes for both
def-ids, which was done in #53721, slowed the compilation of small
crates by 2-3%. This PR makes sure we only load the attributes for the
"type" def-id, avoiding the slowdown.
Rollup of 16 pull requests
Successful merges:
- #53652 (define copy_within on slices)
- #54261 (Make `dyn` a keyword in the 2018 edition)
- #54280 (remove (more) CAS API from Atomic* types where not natively supported)
- #54323 (rustbuild: drop color handling)
- #54350 (Support specifying edition in doc test)
- #54370 (Improve handling of type bounds in `bit_set.rs`.)
- #54371 (add -Zui-testing to rustdoc)
- #54374 (Make 'proc_macro::MultiSpan' public.)
- #54402 (Use no_default_libraries for all NetBSD flavors)
- #54409 (Detect `for _ in in bar {}` typo)
- #54412 (add applicability to span_suggestion call)
- #54413 (Add UI test for deref recursion limit printing twice)
- #54415 (parser: Tweak function parameter parsing to avoid rollback on succesfull path)
- #54420 (Compress `Liveness` data some more.)
- #54422 (Simplify slice's first(_mut) and last(_mut) with get)
- #54446 (Unify christianpoveda's emails)
Failed merges:
- #54058 (Introduce the partition_dedup/by/by_key methods for slices)
r? @ghost
avoid leaking host details in proc macro metadata decoding
proc macro crates are essentially implemented as dynamic libraries using
a dlopen-based ABI. They are also Rust crates, so they have 2 worlds -
the "host" world in which they are defined, and the "target" world in
which they are used.
For all the "target" world knows, the proc macro crate might not even
be implemented in Rust, so leaks of details from the host to the target
must be avoided for correctness.
Because the "host" DefId space is different from the "target" DefId
space, any leak involving a DefId will have a nonsensical or
out-of-bounds DefKey, and will cause all sorts of crashes.
This PR fixes all leaks I have found in `decoder`. In particular, #54059
was caused by host native libraries leaking into the target, which feels
like it might even be a correctness issue if it doesn't cause an ICE.
Fixes#54059
Simplify slice's first(_mut) and last(_mut) with get
This change makes these functions easier to read and interpret. I haven't detected any difference in performance locally.
r? @Mark-Simulacrum
Compress `Liveness` data some more.
Profiling shows that the `(reader, writer, used)` triples used by
liveness analysis almost always have invalid `reader` and `writer`
fields. We can take advantage of this knowledge to use a compressed
representation for them, falling back to a secondary table for the
uncommon cases.
This change reduces instruction counts on numerous benchmarks, the best
by 16%. It also reduces max-rss on numerous benchmarks, the best by 38%.
The patch also renames these triples from `Users` to `RWU`, because it's
confusing having a type whose name is plural and then used within
vectors whose names are also plural.
r? @nikomatsakis
parser: Tweak function parameter parsing to avoid rollback on succesfull path
Since rollback is not perfect and may e.g. leave non-fatal errors after it, we need to make sure compilation fails if it happens.
So in particular case of `fn parse_arg_general` we need to parse the "good" `TYPE` first and only then rollback and recover erroneous `PAT: TYPE` if necessary.
Found when working on https://github.com/rust-lang/rfcs/pull/2544#issuecomment-423293222.
r? @ghost
