fix trait objects with a Self-containing projection values
Fixes#56288.
This follows ALT2 in the issue.
beta-nominating since this is a regression.
r? @nikomatsakis
Fix various aspects around `let` bindings inside const functions
* forbid `let` bindings in const contexts that use short circuiting operators
* harden analysis code against derefs of mutable references
Initially this PR was about stabilizing `let` bindings, but too many flaws were exposed that need some more testing on nightly
add coherence future-compat warnings for marker-only trait objects
The future-compat warnings break code that assumes that `dyn Send + Sync !=
dyn Sync + Send`, and are the first step in making them equal. cc #33140.
Note: this lint should be made to default-warn before we merge. It is deny only for the crater run.
r? @nikomatsakis / @scalexm . cc @Centril & @alexreg.
This commit extends previous work to kill borrows from a local after
assignment into that local to kill borrows from a projection after
assignment into a prefix of that place.
Bump minimum required LLVM version to 6.0
Based on the discussion in #55842, while the overall position of Rust wrt LLVM continues to be contentious, there does seem to be a consensus that there is no need for continued support of LLVM 5. This PR bumps our version requirement to LLVM 6.0 and makes Travis run against that.
I hope that this is going to unblock #52694. If I understand correctly, while this issue still exists in LLVM 6, Ubuntu has backported the relevant patch.
r? @alexcrichton
This PR causes unsized coercions to not be disabled by `$0: Unsize<dyn
Object>` coercion obligations when we have an `$0: Sized` obligation
somewhere.
Note that `X: Unsize<dyn Object>` obligations can't fail *as
obligations* if `X: Sized` holds, so this still maintains some version
of monotonicity (I think that an unsized coercion can't be converted to
no coercion by unifying type variables).
Fixes#49593 (unblocking never_type).
Make RValue::Discriminant a normal Shallow read
Enum layout optimizations mean that the discriminant of an enum may not be stored in a tag disjoint from the rest of the fields of the enum. Stop borrow checking as though they are.
Run with MIRI to see why this is needed: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=09a3236685a06b6096e2e2e3968b852c.
This issue exists with the lexical borrow checker as well (see #45045) so migrate mode should prevent this from being immediately breaking.
r? @nikomatsakis
Fixes#56797
rustc: Add an unstable `simd_select_bitmask` intrinsic
This is going to be required for binding a number of AVX-512 intrinsics
in the `stdsimd` repository, and this intrinsic is the same as
`simd_select` except that it takes a bitmask as the first argument
instead of a SIMD vector. This bitmask is then transmuted into a `<NN x
i8>` argument, depending on how many bits it is.
cc rust-lang-nursery/stdsimd#310
Clearer error message for dead assign
I'm not that this is the right place for this (if it needs an RFC or not).
I had the problem where I misunderstood the compiler lint message https://github.com/rust-lang/rust/issues/56436 and other people seem to have had the same problem https://www.reddit.com/r/rust/comments/8cy9p4/value_assigned_to_is_never_read/.
I think this new wording might be slightly clearer (and help out beginners like me). I'm very new though, so there might be some nuance I'm missing that would make this more confusing or a bad idea for other reasons.
I thought I would create a PR to make it easy to change the code if the consensus was that it would make sense to make a change.
If this is the wrong place for this sort of thing I'll happily delete/move it.
overhaul external doc attribute diagnostics
This PR improves the error handling and spans for the external doc attribute. Many cases that silently failed before now emit errors, spans are tightened, and the errors have help and suggestions.
I tried to address all the cases that users ran into in the tracking issue.
cc #44732
r? @QuietMisdreavus
Add test of current behavior (infer free region within closure body)
This behavior was previously not encoded in our test suite.
it is pretty important that we test this behavior. In particular, in #56537 I had proposed expanding the lifetime elision rules so that they would apply to some of the cases encoded in this test, which would cause them to start failing to compile successfully (because the lifetime attached to the return type would start being treated as connected to the lifetime on the input parameter to the lambda expression, which is explicitly *not* what the code wants in this particular case).
In other words, I am trying to ensure that anyone who tries such experiments with lifetime elision in the future quickly finds out why we don't support lifetime elision on lambda expressions (at least not in the naive manner described on #56537).
Fix private_no_mangle_fns message grammar
Simply changes "an warning" to "a warning" in the `private_no_mangle_fns` warning. I started getting this in some code after upgrading to 1.31.0.
2018 edition - confusing error message when declaring unnamed parameters
Fixes#53990.
This PR adds a note providing context for the change to argument
names being required in the 2018 edition for trait methods and a
suggestion for the fix.
Contexually dependent error message for E0424 when value is assigned to "self"
This is an improvement for pull request #54495 referencing issue #54369. If the "self" keyword is assigned a value as though it were a valid identifier, it will now report:
```
let self = "self";
^^^^ `self` value is a keyword and may not be bound to variables or shadowed
```
instead of
```
let self = "self";
^^^^ `self` value is a keyword only available in methods with `self` parameter
```
If anyone has a better idea for what the error should be I'd be happy to modify it appropriately.
This is going to be required for binding a number of AVX-512 intrinsics
in the `stdsimd` repository, and this intrinsic is the same as
`simd_select` except that it takes a bitmask as the first argument
instead of a SIMD vector. This bitmask is then transmuted into a `<NN x
i8>` argument, depending on how many bits it is.
cc rust-lang-nursery/stdsimd#310
The future-compat warnings break code that assumes that `dyn Send + Sync !=
dyn Sync + Send`, and are the first step in making them equal. cc #33140.
It should be possible to revert this commit when we're done with the
warnings.
rustc: Add an unstable `simd_select_bitmask` intrinsic
This is going to be required for binding a number of AVX-512 intrinsics
in the `stdsimd` repository, and this intrinsic is the same as
`simd_select` except that it takes a bitmask as the first argument
instead of a SIMD vector. This bitmask is then transmuted into a `<NN x
i8>` argument, depending on how many bits it is.
cc rust-lang-nursery/stdsimd#310
