Add an example to std::thread::Result type
This PR is a part of https://github.com/rust-lang/rust/issues/29378. I submit this PR with the help (mentoring) of @steveklabnik. I'm still not sure my request is good enough but I don't want to spoil the issue with too much questions so I continue here. r? @steveklabnik
Windows historically has problems with threads panicking and the main thread
exiting at the same time, typically causing deadlocks. In the past (#25824)
we've joined on threads but this just prevents running the test for now to avoid
tampering with the example.
Derive Hash for ThreadId + better example
Derive `Hash` for `ThreadId` (see comments in #21507). Useful for making maps based on thread, e.g. `HashMap<ThreadId, ?>`. Also update example code for thread IDs to be more useful.
* Since the switch to pulldown-cmark reference links need a blank line
before the URLs.
* Reference link references are not case sensitive.
* Doc comments need to be indented uniformly otherwise rustdoc gets
confused.
std: remove a workaround for privacy limitations
`std::thread::Thread` implements a non-exported `NewThread` trait to allow for internal-only use of `Thread::new`. Nowadays we have `pub(crate)`, which accomplishes the same thing but much more idiomatically.
Rustdoc handles this correctly (I checked and I didn't see `Thread::new` on the rustdoc entry for `Thread` with this change), and the stage1 `rustc` emits the correct error still (I'm assuming that the stage1 compiler uses my `libstd`?):
```
$ ./build/x86_64-apple-darwin/stage1/bin/rustc test.rs
error: method `new` is private
--> test.rs:4:18
|
4 | let thread = thread::Thread::new(None);
| ^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error
```
Add ThreadId for comparing threads
This adds the capability to store and compare threads with the current calling thread via a new struct, `std::thread::ThreadId`. Addresses the need outlined in issue #21507.
This avoids the need to add any special checks to the existing thread structs and does not rely on the system to provide an identifier for a thread, since it seems that this approach is unreliable and undesirable. Instead, this simply uses a lazily-created, thread-local `usize` whose value is copied from a global atomic counter. The code should be simple enough that it should be as much reliable as the `#[thread_local]` attribute it uses (however much that is).
`ThreadId`s can be compared directly for equality and have copy semantics.
Also see these other attempts:
- rust-lang/rust#29457
- rust-lang/rust#29448
- rust-lang/rust#29447
And this in the RFC repo: rust-lang/rfcs#1435
Working asmjs and wasm targets
This patch set results in a working standard library for the asmjs-unknown-emscripten and wasm32-unknown-emscripten targets. It is based on the work of @badboy and @rschulman.
It does a few things:
- Updates LLVM with the emscripten [fastcomp](https://github.com/rust-lang/llvm/pull/50) patches, which include the pnacl IR legalizer and the asm.js backend. This patch is thought not to have any significant effect on existing targets.
- Teaches rustbuild to correctly link C code with emscripten
- Updates gcc-rs to work correctly with emscripten
- Teaches rustbuild to run crate tests for emscripten with node
- Modifies Thread::new to return an error on emscripten, to facilitate debugging a common failure mode
- Modifies libtest to run in single-threaded mode for emscripten
- Ignores a host of tests that don't work yet, mostly dealing with threads and I/O
- Updates libc with wasm32 definitions (presently the same as asmjs)
- Adds a wasm32-unknown-emscripten target that feeds the output of LLVM's asmjs backend through emcc to generate wasm
Notes and caveats:
- This is only known to work with `--enable-rustbuild`.
- The wasm32 target can't be tested correctly yet because of issues in compiletest and limitations in node https://github.com/kripken/emscripten/issues/4542, but hello.rs does seem to work when run on node via the binaryen interpreter
- This requires an up to date installation of the emscripten sdk from its incoming branch
- Unwinding is very broken
- When enabling the emscripten targets jemalloc is disabled for all targets, which results in test failures for the host
Next steps are to fix the jemalloc issue, start building the two emscripten targets on the auto builders, then start producing nightlies.
https://github.com/rust-lang/rust/issues/36317 tracks work on this.
Fixes https://github.com/rust-lang/rust/issues/36515
Fixes https://github.com/rust-lang/rust/issues/36515
Fixes https://github.com/rust-lang/rust/issues/36356
Felix Raimundo