In accordance with the requesting issue (#10750):
- `zig test` skips any tests that it cannot spawn, returning success
- `zig run` and `zig build` exit with failure, reporting the command the cannot be run
- `zig clang`, `zig ar`, etc. already punt directly to the appropriate clang/lld main(), even before this change
- Native `libc` Detection is not supported
Additionally, `exec()` and related Builder functions error at run-time, reporting the command that cannot be run
This is a breaking change. Before, usage looked like this:
```zig
const held = mutex.acquire();
defer held.release();
```
Now it looks like this:
```zig
mutex.lock();
defer mutex.unlock();
```
The `Held` type was an idea to make mutexes slightly safer by making it
more difficult to forget to release an aquired lock. However, this
ultimately caused more problems than it solved, when any data structures
needed to store a held mutex. Simplify everything by reducing the API
down to the primitives: lock() and unlock().
Closes#8051Closes#8246Closes#10105
Beside the new order being consistent with the ThreadPool API and making
more sense, this shuffling allows to write the context argument type in
terms of the startFn arguments, reducing the use of anytype (eg. less
explicit casts when using comptime_int parameters, yay).
Sorry for the breakage.
Closes#8082
* move concurrency primitives that always operate on kernel threads to
the std.Thread namespace
* remove std.SpinLock. Nobody should use this in a non-freestanding
environment; the other primitives are always preferable. In
freestanding, it will be necessary to put custom spin logic in there,
so there are no use cases for a std lib version.
* move some std lib files to the top level fields convention
* add std.Thread.spinLoopHint
* add std.Thread.Condition
* add std.Thread.Semaphore
* new implementation of std.Thread.Mutex for Windows and non-pthreads Linux
* add std.Thread.RwLock
Implementations provided by @kprotty
* split std.ResetEvent into:
- ResetEvent - requires init() at runtime and it can fail. Also
requires deinit().
- StaticResetEvent - can be statically initialized and requires no
deinitialization. Initialization cannot fail.
* the POSIX sem_t implementation can in fact fail on initialization
because it is allowed to be implemented as a file descriptor.
* Completely define, clarify, and explain in detail the semantics of
these APIs. Remove the `isSet` function.
* `ResetEvent.timedWait` returns an enum instead of a possible error.
* `ResetEvent.init` takes a pointer to the ResetEvent instead of
returning a copy.
* On Darwin, `ResetEvent` is implemented using Grand Central Dispatch,
which is exposed by libSystem.
stage2 changes:
* ThreadPool: use a single, pre-initialized `ResetEvent` per worker.
* WaitGroup: now requires init() and deinit() and init() can fail.
- Add a `reset` function.
- Compilation initializes one for the work queue in creation and
re-uses it for every update.
- Rename `stop` to `finish`.
- Simplify the implementation based on the usage pattern.
