There are a few exceptions to the rule that Arc/Rc are immutable. Rather
than dig into the details, add "generally" to hint at this difference,
as it's kind of a distraction at this point in the docs.
Additionally, Arc's docs were slightly different here generally, so add
in both the existing language and the exception.
Fixes#44105
`EndRegion` do not always correspond to borrow-data entries
Remove assertion that the argument to every `EndRegion` correspond to some dataflow-tracked borrow-data entry.
Fix#44828
(The comment thread on the aforementioned issue discusses why its best to just remove this assertion.)
fix ItemKind::DefaultImpl doc comment
Upgrade comment to doc comment.
...Is this actually used? If so, why does the `Impl` variant right below have a `Defaultness`?
Add links to headers in README and CONTRIBUTING
this also adds dependencies to CONTRIBUTING
I'm just getting started building the rust compiler and noticed this information/ability was missing.
It was also missing the gdb dependency for running tests. I pulled the information out of `appveyor.yml` and recommended later than 7.1 because that is what [apt ships](https://packages.ubuntu.com/search?suite=trusty&keywords=gdb). Feel free to tell me something different!
Don't unwrap work item results as the panic trace is useless
Fixes#43402 now there's no multithreaded panic printouts
Also update a comment
--------
Likely regressed in #43506, where the code was changed to panic in worker threads on error.
Unwrapping gives zero extra information since the stack trace is so short, so we may as well just surface that there was an error and exit the thread properly. Because there are then no multithreaded printouts, I think it should mean the output of the test for #26199 is deterministic and not interleaved (thanks to @philipc https://github.com/rust-lang/rust/issues/43402#issuecomment-333835271 for a hint).
Sadly the output is now:
```
thread '<unnamed>' panicked at 'aborting due to worker thread panic', src/librustc_trans/back/write.rs:1643:20
note: Run with `RUST_BACKTRACE=1` for a backtrace.
error: could not write output to : No such file or directory
error: aborting due to previous error
```
but it's an improvement over the multi-panic situation before.
r? @alexcrichton
Extend `dump_mir` and functions it calls in order to allow callers to
add custom information. We do this by adding an enum `PassWhere` and
an extra argument of type `FnMut(PassWhere, &mut Write) ->
io::Result<()>`. This callback is responsible for printing the extra
information when MIR is dumped at various stages.
For the "nll" pass, use the new mechanism to dump the `Region`
information after the header, but before the control flow graph for
every function.
In the interest of keeping the output somewhat concise, implement
a custom Debug impl for `Region`
Open Questions:
* What should we call what has been called `PassWhere` so far?
* Use size_t where size_t is used, while it's not critical on our
specifically supported architectures, this is more accurate.
* Update HND_SPECIAL_COUNT to the correct value, and give it the size
that enum is likely to be.
incr.comp.: Switch to red/green change tracking, remove legacy system.
This PR finally switches incremental compilation to [red/green tracking](https://github.com/rust-lang/rust/issues/42293) and completely removes the legacy dependency graph implementation -- which includes a few quite costly passes that are simply not needed with the new system anymore.
There's still some documentation to be done and there's certainly still lots of optimizing and tuning ahead -- but the foundation for red/green is in place with this PR. This has been in the making for a long time `:)`
r? @nikomatsakis
cc @alexcrichton, @rust-lang/compiler
