Fix rust-lldb wrapper scripts.
Currently the `rust-lldb` wrapper provided by Rust project is broken. The error messages it produces on launch are as follows:
```
warning: ignoring unknown option: --one-line-before-file=command script import "/Users/kon/.rustup/toolchains/nightly-2019-05-02-x86_64-apple-darwin/lib/rustlib/etc/lldb_rust_formatters.py"
warning: ignoring unknown option: --one-line-before-file=type summary add --no-value --python-function lldb_rust_formatters.print_val -x ".*" --category Rust
warning: ignoring unknown option: --one-line-before-file=type category enable Rust
(lldb) target create "target/debug/nagare"
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/Users/kon/.rustup/toolchains/nightly-2019-05-02-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/python2.7/site-packages/lldb/__init__.py", line 1481, in <module>
class SBAddress(object):
File "/Users/kon/.rustup/toolchains/nightly-2019-05-02-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/python2.7/site-packages/lldb/__init__.py", line 1647, in SBAddress
__swig_getmethods__["module"] = GetModule
NameError: name '__swig_getmethods__' is not defined
Traceback (most recent call last):
File "<string>", line 1, in <module>
NameError: name 'run_one_line' is not defined
Traceback (most recent call last):
File "<string>", line 1, in <module>
NameError: name 'run_one_line' is not defined
Traceback (most recent call last):
File "<string>", line 1, in <module>
NameError: name 'run_one_line' is not defined
...etc.
```
The errors stem from two regressions: one caused by an LLVM upgrade and one caused by unintended upgrade to SWIG 4.0 (SWIG is a wrapper generator that is used to generate Python bindings for LLVM and LLDB.)
(Edit: found the exact dates) The SWIG breakage happened because of a Homebrew version upgrade on `nightly-2019-05-01-x86_64-apple-darwin` and the LLVM breakage happened on `nightly-2019-01-27-x86_64-apple-darwin` (likely to have been caused by https://github.com/rust-lang/rust/pull/57675 ).
The fix is to update the LLVM parameter syntax and to "downgrade" to SWIG 3.0.x. SWIG 3.0.x is not going to be supported by Homebrew forever, but should be good for now, until LLDB upgrades to support SWIG 4.0.0. Here's some more info about Homebrew support: https://github.com/Homebrew/homebrew-core/pull/39929 & https://github.com/Homebrew/homebrew-core/pull/40882 I'm going to send a bug & fix to LLDB about SWIG 4.0.0 to get the situation fixed in the future.
It would be good to also backport this to beta, since it's such a small change, and will fix an obvious regression.
Previously we would only generate a list of synthetic implementations
for two well known traits – Send and Sync. With this patch all the auto
traits known to rustc are considered. This includes such traits like
Unpin and user’s own traits.
Sadly the implementation still iterates through the list of crate items
and checks them against the traits, which for non-std crates containing
their own auto-traits will still not include types defined in std/core.
It is an improvement nontheless.
rustc: disallow cloning HIR nodes.
Besides being inefficient, cloning also risks creating broken HIR (without properly recreating all the IDs and whatnot, in which case you might as well reconstruct the entire node without ever `Clone`-ing anything).
We detect *some* detrimental situations (based on the occurrence of `HirId`s, I believe?), but it's better to statically disallow it, IMO.
One of the examples that is fixed by this PR is `tcx.hir().fn_decl{,_by_hir_id}`, which was cloning an entire `hir::FnDecl` *every single time it was called*.
r? @petrochenkov cc @rust-lang/compiler
Implement nth_back for slice::{Iter, IterMut}
Part of #54054.
I implemented `nth_back` as straightforwardly as I could, and then slightly changed `nth` to match `nth_back`. I believe I did so correctly, but please double-check 🙂
I also added the helper methods `zst_shrink`, `next_unchecked`, and `next_back_unchecked` to get rid of some duplicated code. These changes hopefully make this code easier to understand for new contributors like me.
I noticed the `is_empty!` and `len!` macros which sole purpose seems to be inlining, according to the comment right above them, but the `is_empty` and `len` methods are already marked with `#[inline(always)]`. Does that mean we could replace these macros with method calls, without affecting anything? I'd love to get rid of them.
macos tlv workaround
fixes: #60141
Includes:
* remove dead code: `requires_move_before_drop`. This hasn't been needed for a while now (oops I should have removed it in #57655)
* redox had a copy of `fast::Key` (not sure why?). That has been removed.
* Perform a `read_volatile` on OSX to reduce `tlv_get_addr` calls per `__getit` from (4-2 depending on context) to 1.
`tlv_get_addr` is relatively expensive (~1.5ns on my machine).
Previously, in contexts where `__getit` was inlined, 4 calls to `tlv_get_addr` were performed per lookup. For some reason when `__getit` is not inlined this is reduced to 2x - and performance improves to match.
After this PR, I have only ever seen 1x call to `tlv_get_addr` per `__getit`, and macos now benefits from situations where `__getit` is inlined.
I'm not sure if the `read_volatile(&&__KEY)` trick is working around an LLVM bug, or a rustc bug, or neither.
r? @alexcrichton
