This patch does not itself enable generalized where clauses, but it lays the groundwork. Rather than storing a list of bounds per type parameter, the trait selection and other logic is now driven by a unified list of predicates. All predicate handling is now driven through a common interface. This also fixes a number of bugs where region predicates were being dropped on the floor. As a drive-by, this patch also fixes some bugs in the opt-out-copy feature flag.
That said, this patch does not change the parser or AST in any way, so we still *generate* the list of predicates by walking a list of bounds (and we still *store* the bounds on the `TypeParameterDef` and so on). Those will get patched in a follow-up.
The commits in this case are standalone; the first few are simple refactorings.
r? @nick29581
cc @aturon
in most cases, just the error message changed, but in some cases we
are reporting new errors that OUGHT to have been reported before but
we're overlooked (mostly involving the `'static` bound on `Send`).
These probably happened during the merge of the commit that made `Copy` opt-in.
Also, convert the last occurence of `/**` to `///` in `src/libstd/num/strconv.rs`
This is a first pass at insert on RingBuf. I tried to keep it as simple as possible. I'm not sure of the performance implications of doing one copy vs. copying multiple times but moving a smaller amount of memory. I chose to stick with one copy, even if the amount of memory I have to move is larger.
I believe this is part of #18424
@Gankro mentioned this was missing.
This pull request tries to fix#19340, which states two ICE cases related to enum struct variants.
It is my first attempt to fix the compiler. I found this solution by trial and error, so the method used to fix the issue looks very hacky. Please review it, and direct me to find a better solution.
I'm also to add test cases. Where should I put them? Maybe `src/test/run-pass/issue-19340.rs`?
I am trying to add an implementation of `bitor` for `BTreeSet`. I think I am most of the way there, but I am going to need some guidance to take it all the way.
When I run `make check`, I get:
```
error: cannot move out of dereference of `&`-pointer
self.union(_rhs).map(|&i| i).collect::<BTreeSet<T>>()
^~
```
I'd appreciate any nudges in the right direction. If I can figure this one out, I am sure I will be able to implement `bitand`, `bitxor`, and `sub` as well.
/cc @Gankro
---
**Update**
I have added implementations for `BitOr`, `BitAnd`, `BitXor`, and `Sub` for `BTreeSet`.
Add initial attempt at implementing BitOr for BTreeSet.
Update the implementation of the bitor operator for BTreeSets.
`make check` ran fine through this.
Add implementations for BitAnd, BitXor, and Sub as well.
Remove the FIXME comment and add unstable flags.
Add doctests for the bitop functions.
The current behavior leads to adjustments like `&&*` being applied
instead of just `&` (when the unmodified receiver is a `&T` or an `&mut
T`). This causes both safety errors and unexpected behavior. The safety
errors result from regionck not being prepared for auto-ref-ref-like
adjustments; this is worth fixing on its own, but I think the best way
to do it is to modify regionck to use expr-use-visitor (and fix
expr-use-visitor as well, which I don't think properly invokes `borrow`
for each level of auto-ref), and for now it's simpler to just not
produce the adjustment in question. (I have a separate patch porting
regionck to use exprusevisitor for a different bug, so that is coming.)
Previously, the DeBruijn index for the self type was not being
adjusted to account for the fn binder. This mean that when late-bound
regions were instantiated, you sometimes wind up with two distinct
lifetimes.
Fixes#19537.
This detects (a subset of) the cases when `transmute::<T, U>(x)` can be
lowered to a direct `bitcast T x to U` in LLVM. This assists with
efficiently handling a SIMD vector as multiple different types,
e.g. swapping bytes/words/double words around inside some larger vector
type.
C compilers like GCC and Clang handle integer vector types as `__m128i`
for all widths, and implicitly insert bitcasts as required. This patch
allows Rust to express this, even if it takes a bit of `unsafe`, whereas
previously it was impossible to do at all without inline assembly.
Example:
pub fn reverse_u32s(u: u64x2) -> u64x2 {
unsafe {
let tmp = mem::transmute::<_, u32x4>(u);
let swapped = u32x4(tmp.3, tmp.2, tmp.1, tmp.0);
mem::transmute::<_, u64x2>(swapped)
}
}
Compiling with `--opt-level=3` gives:
Before
define <2 x i64> @_ZN12reverse_u32s20hbdb206aba18a03d8tbaE(<2 x i64>) unnamed_addr #0 {
entry-block:
%1 = bitcast <2 x i64> %0 to i128
%u.0.extract.trunc = trunc i128 %1 to i32
%u.4.extract.shift = lshr i128 %1, 32
%u.4.extract.trunc = trunc i128 %u.4.extract.shift to i32
%u.8.extract.shift = lshr i128 %1, 64
%u.8.extract.trunc = trunc i128 %u.8.extract.shift to i32
%u.12.extract.shift = lshr i128 %1, 96
%u.12.extract.trunc = trunc i128 %u.12.extract.shift to i32
%2 = insertelement <4 x i32> undef, i32 %u.12.extract.trunc, i64 0
%3 = insertelement <4 x i32> %2, i32 %u.8.extract.trunc, i64 1
%4 = insertelement <4 x i32> %3, i32 %u.4.extract.trunc, i64 2
%5 = insertelement <4 x i32> %4, i32 %u.0.extract.trunc, i64 3
%6 = bitcast <4 x i32> %5 to <2 x i64>
ret <2 x i64> %6
}
_ZN12reverse_u32s20hbdb206aba18a03d8tbaE:
.cfi_startproc
movd %xmm0, %rax
punpckhqdq %xmm0, %xmm0
movd %xmm0, %rcx
movq %rcx, %rdx
shrq $32, %rdx
movq %rax, %rsi
shrq $32, %rsi
movd %eax, %xmm0
movd %ecx, %xmm1
punpckldq %xmm0, %xmm1
movd %esi, %xmm2
movd %edx, %xmm0
punpckldq %xmm2, %xmm0
punpckldq %xmm1, %xmm0
retq
After
define <2 x i64> @_ZN12reverse_u32s20hbdb206aba18a03d8tbaE(<2 x i64>) unnamed_addr #0 {
entry-block:
%1 = bitcast <2 x i64> %0 to <4 x i32>
%2 = shufflevector <4 x i32> %1, <4 x i32> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
%3 = bitcast <4 x i32> %2 to <2 x i64>
ret <2 x i64> %3
}
_ZN12reverse_u32s20hbdb206aba18a03d8tbaE:
.cfi_startproc
pshufd $27, %xmm0, %xmm0
retq
