Zack M. Davis [Sat, 2 Jun 2018 23:49:34 +0000 (16:49 -0700)]
add FIXMEs pleading for post-@ edit of commentary on mem_categorization
(The present author fears not being knowledgeable enough to rewrite the
comments unilaterally; merely calling it out is a lazy half-measure, but
at least doesn't actively make things worse the way an ill-informed
rewrite would.)
#50455 pointed out that the unreachable-pub suggestion for brace-grouped `use`s was bogus; #50476 partially ameliorated this by marking the suggestion as `Applicability::MaybeIncorrect`, but this is the actual fix.
Meanwhile, another application of having spans available in `hir::Visibility` is found in the private-no-mangle lints, where we can now issue a suggestion to use `pub` if the item has a more restricted visibility marker (this seems much less likely to come up in practice than not having any visibility keyword at all, but thoroughness is a virtue). While we're there, we can also add a helpful note if the item does have a `pub` (but triggered the lint presumably because enclosing modules were private).
Preventing `const fn` from allowing to work around the ban on reading from statics would cripple `const fn` almost into uselessness.
Additionally, the limitation for reading from statics comes from the old const evaluator(s) and is not shared by `miri`.
This PR loosens the rules around use of statics to allow statics to evaluate other statics by value, allowing all of the above examples to compile and run successfully.
Reads from extern (foreign) statics are however still disallowed by miri, because there is no compile-time value to be read.
```rust
extern static A: u32;
static B: u32 = A; // error
```
This opens up a new avenue of potential issues, as a static can now not just refer to other statics or read from other statics, but even contain references that point into itself.
While it might seem like this could cause subtle bugs like allowing a static to be initialized by its own value, this is inherently impossible in miri.
Reading from a static causes the `const_eval` query for that static to be invoked. Calling the `const_eval` query for a static while already inside the `const_eval` query of said static will cause cycle errors.
It is not possible to accidentally create a bug in miri that would enable initializing a static with itself, because the memory of the static *does not exist* while being initialized.
The memory is not uninitialized, it is not there. Thus any change that would accidentally allow reading from a not yet initialized static would cause ICEs.
Tests have been modified according to the new rules, and new tests have been added for writing to `static mut`s within definitions of statics (which needs to fail), and incremental compilation with complex/interlinking static definitions.
Note that incremental compilation did not need to be adjusted, because all of this was already possible before with workarounds (like intermediate `const fn`s) and the encoding/decoding already supports all the possible cases.
Auto merge of #51969 - pietroalbini:rollup, r=pietroalbini
Rollup of 7 pull requests
Successful merges:
- #51511 (Stabilize Iterator::flatten in 1.29, fixes #48213.)
- #51853 (Fix some doc links)
- #51890 (Fix inconsequential typo in GlobalAlloc doc example)
- #51920 (use literal span for concrete type suggestion)
- #51921 (improve the error message when `#[panic_implementation]` is missing)
- #51922 (rename the llvm-tools component to llvm-tools-preview and tweak its image)
- #51961 (Fix typo in /src/librustc_resolve/lib.rs)
Pietro Albini [Sun, 1 Jul 2018 19:18:43 +0000 (21:18 +0200)]
Rollup merge of #51511 - Centril:feature/stabilize_iterator_flatten, r=SimonSapin
Stabilize Iterator::flatten in 1.29, fixes #48213.
This PR stabilizes [`Iterator::flatten`](https://doc.rust-lang.org/nightly/std/iter/trait.Iterator.html#method.flatten) in *version 1.29* (1.28 goes to beta in 10 days, I don't think there's enough time to land it in that time, but let's see...).
Tracking issue is: #48213.
cc @bluss re. itertools.
r? @SimonSapin
ping @pietroalbini -- let's do a crater run when this passes CI :)
Auto merge of #51833 - wesleywiser:faster_large_constant_arrays, r=oli-obk
Speed up compilation of large constant arrays
This is a different approach to #51672 as suggested by @oli-obk. Rather
than write each repeated value one-by-one, we write the first one and
then copy its value directly into the remaining memory.
With this change, the [toy program](https://github.com/rust-lang/rust/blob/c2f4744d2db4e162df824d0bd0b093ba4b351545/src/test/run-pass/mir_heavy_promoted.rs) goes from 63 seconds to 19 seconds on my machine.
Edit: Inlining `Size::bytes()` saves an additional 6 seconds dropping the total time to 13 seconds on my machine.
Zack M. Davis [Sun, 1 Jul 2018 18:05:10 +0000 (11:05 -0700)]
call it `hir::VisibilityKind` instead of `hir::Visibility_:*`
It was pointed out in review that the glob-exported
underscore-suffixed convention for `Spanned` HIR nodes is no longer
preferred: see February 2016's #31487 for AST's migration away from
this style towards properly namespaced NodeKind enums.
Auto merge of #51536 - davidtwco:nll-dyn-trait-underscore-error-improvements, r=nikomatsakis
NLL: bad error message when converting anonymous lifetime to `'static`
Contributes to #46983. This PR doesn't introduce fantastic errors, but it should hopefully lay some groundwork for diagnostic improvements.
r? @nikomatsakis
Auto merge of #51855 - Eh2406:i51821, r=nikomatsakis
A fix for 51821
This dedupe the vec of `OutlivesConstraint` using a `FxHashSet<(RegionVid, RegionVid)>` it alsow adds a `struct ConstraintSet` to encapsulate/ensure this behavere.
Auto merge of #51882 - varkor:check-type_dependent_defs, r=estebank
Always check type_dependent_defs
Directly indexing into `type_dependent_defs` has caused multiple ICEs in the past (https://github.com/rust-lang/rust/issues/46771, https://github.com/rust-lang/rust/issues/49241, etc.) and is almost certainly responsible for #51798 too. This PR ensures we always check `type_dependent_defs` first, which should prevent any more of these (or at least make them easier to track down).
Zack M. Davis [Sun, 1 Jul 2018 05:08:27 +0000 (22:08 -0700)]
in which the private/restricted-in-public error messaging gets specific
April 2016's Issue #33174 called out the E0446 diagnostics as
confusing. While adding the name of the restricted type to the message
(548e681f) clarified matters somewhat, Esteban Küber pointed out that we
could stand to place a secondary span on the restricted type.
Here, we differentiate between crate-visible, truly private, and
otherwise restricted types, and place a secondary span specifically on
the visibility modifier of the restricted type's declaration (which we
can do now that HIR visibilities have spans!).
Zack M. Davis [Thu, 28 Jun 2018 05:50:24 +0000 (22:50 -0700)]
private no-mangle lints: help hint note if visibility modifier is `pub`
If the item is `pub`, one imagines users being confused as to why it's
not reachable/exported; a code suggestion is beyond our local knowledge
here, but we can at least offer a prose hint. (Thanks to Vadim
Petrochenkov for shooting down the present author's original bad idea
for the note text.)
While we're here, use proper HELP expectations instead of ad hoc
comments to communicate (and now, enforce) the expected suggestions in
test/ui/lint/suggestions.rs.
Zack M. Davis [Thu, 28 Jun 2018 05:30:23 +0000 (22:30 -0700)]
private no-mangle lints: issue suggestion for restricted visibility
This is probably quite a lot less likely to come up in practice than the
"inherited" (no visibility keyword) case, but now that we have
visibility spans in the HIR, we can do this, and it presumably doesn't
hurt to be exhaustive. (Who can say but that the attention to detail
just might knock someone's socks off, someday, somewhere?)
Zack M. Davis [Sun, 1 Jul 2018 03:34:18 +0000 (20:34 -0700)]
in which hir::Visibility recalls whence it came (i.e., becomes Spanned)
There are at least a couple (and plausibly even three) diagnostics that
could use the spans of visibility modifiers in order to be reliably
correct (rather than hacking and munging surrounding spans to try to
infer where the visibility keyword must have been).
We follow the naming convention established by the other `Spanned` HIR
nodes: the "outer" type alias gets the "prime" node-type name, the
"inner" enum gets the name suffixed with an underscore, and the variant
names are prefixed with the prime name and `pub use` exported from here
(from HIR).
Thanks to veteran reviewer Vadim Petrochenkov for suggesting this
uniform approach. (A previous draft, based on the reasoning that
`Visibility::Inherited` should not have a span, tried to hack in a named
`span` field on `Visibility::Restricted` and a positional field on
`Public` and `Crate`. This was ... not so uniform.)
Zack M. Davis [Sun, 1 Jul 2018 03:22:19 +0000 (20:22 -0700)]
choose a less arbitrary span when parsing the empty visibility modifier
Visibility spans were added to the AST in #47799 (d6bdf296) as a
`Spanned<_>`—which means that we need to choose a span even in the case
of inherited visibility (what you get when there's no `pub` &c. keyword
at all). That initial implementation's choice is pretty
counterintuitive, which could matter if we want to use it as a site to
suggest inserting a visibility modifier, &c.
(The phrase "Schelling span" in the comment is meant in analogy to the
game-theoretic concept of a "Schelling point", a value that is chosen
simply because it's what one can expect to agree upon with other agents
in the absence of explicit coördination.)
Mark Simulacrum [Thu, 28 Jun 2018 16:06:42 +0000 (10:06 -0600)]
Notice non-toplevel dll dependencies in rustbuild
Previously Cargo would hardlink all the dependencies into the "root" as
foo.dll and the `toplevel` array would get populated with these, but
that's no longer the case. Instead, cargo will only do this for the
final artifacts/final libraries.
Rustbuild is updated to continue looping through the artifacts mentioned
instead of early-returning. This should fix the bug.
@alexcrichton found the cause of this and suggested this fix.
Zack M. Davis [Sat, 30 Jun 2018 05:02:52 +0000 (22:02 -0700)]
in which we plug the crack where `?`-desugaring leaked into errors
Most of the time, it's not a problem that the types of the arm bodies in
a desugared-from-`?` match are different (that is, specifically: in `x?`
where x is a `Result<A, B>`, the `Ok` arm body is an `A`, whereas the
`Err` arm diverges to return a `Result<A, B>`), because they're being
assigned to different places. But in tail position, the types do need to
match, and our error message was explicitly referring to "match arms",
which is confusing when there's no `match` in the sweetly sugared
source.
It is not without some misgivings that we pollute the clarity-of-purpose
of `note_error_origin` with the suggestion to wrap with `Ok` (the other
branches are pointing out the odd-arm-out in the HIR that is the origin
of the error; the new branch that issues the `Ok` suggestion is serving
a different purpose), but it's the natural place to do it given that
we're already matching on `ObligationCauseCode::MatchExpressionArm {
arm_span, source }` there.
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