This resolves issue #908.
Notable changes:
- On Windows, LLVM integrated assembler emits bad stack unwind tables when segmented stacks are enabled. However, unwind info directives in the assembly output are correct, so we generate assembly first and then run it through an external assembler, just like it is already done for Android builds.
- Linker is invoked via "g++" command instead of "gcc": g++ passes the appropriate magic parameters to the linker, which ensure correct registration of stack unwind tables in dynamic libraries.
This PR includes the addition of the essential CRUD functionality exposed as a part of the `uv_fs_*` api. There's a lot more to be done, but the essential abstractions are in place and can be easily expanded.
A summary:
* `rt::io::file::FileStream` is fleshed out and behaves as a *non-positional* file stream (that is, it has a cursor that can be viewed/changed via `tell` and `seek`
* The underlying abstraction in `RtioFileStream` exposes pairs of `read(), write()` and `pread(), pwrite()`. The latter two take explicit `offset` params and don't respect the current cursor location in a file afaik. They both use the same underlying libuv impl
* Because libuv explicitly does *not* support `seek`/`tell` operations, these are impl'd in `UvFileStream` by using `lseek(2)` on the raw file descriptor.
* I did my best to flesh out and adhere to the stubbing that was already present in `rt::io::file` and the tests should back that up. There may be things missing.
* All of the work to test `seek`/`tell` is done in `rt::io::file`, even though the actual impl is down in `rt::uv::uvio`.
* We have the ability to spin up an `~RtioFileStream` from a raw file descriptor. This would be useful for interacting with stdin and stdout via newrt.
* The lowest level abstractions (in `rt::uv::file`) support fully synchronous/blocking interactions with the uv API and there is a CRUD test using it. This may also be useful for blocking printf, if desired (the default would be non-blocking and uses libuv's io threadpool)
There are a few polish things I need to do still (the foremost that I know of is undefined behavior when seek'ing beyond the file's boundary).
After this lands, I want to move on to mapping more of the `uv_fs_*` API (especially `uv_fs_stat`). Also a few people have mentioned interest in `uv_pipe_t` support. I'm open to suggestions.
- change all uses of Path in fn args to &P
- FileStream.read assumptions were wrong (libuv file io is non-positional)
- the above will mean that we "own" Seek impl info .. should probably
push it in UvFileDescriptor..
- needs more tests
This commit removes the "super_*" functions from
typeck::infer::combine, and adds them as default methods on the
Combine trait instead, making it possible to remove a lot of
boilerplate from the various impls of Combine.
I've been wanting to do this for over a year. In fact, it was my
original motivation for default methods!
It might be possible to tighten things up even more, but this is the
bulk of it.
Implement CharIterator as a separate struct, so that it can be .clone()'d. Fix `.char_range_at_reverse` so that it performs better, closer to the forwards version. This makes the reverse iterators and users like `.rfind()` perform better.
Before
test str::bench::char_iterator ... bench: 146 ns/iter (+/- 0)
test str::bench::char_iterator_ascii ... bench: 397 ns/iter (+/- 49)
test str::bench::char_iterator_rev ... bench: 576 ns/iter (+/- 8)
test str::bench::char_offset_iterator ... bench: 128 ns/iter (+/- 2)
test str::bench::char_offset_iterator_rev ... bench: 425 ns/iter (+/- 59)
After
test str::bench::char_iterator ... bench: 130 ns/iter (+/- 1)
test str::bench::char_iterator_ascii ... bench: 307 ns/iter (+/- 5)
test str::bench::char_iterator_rev ... bench: 185 ns/iter (+/- 8)
test str::bench::char_offset_iterator ... bench: 131 ns/iter (+/- 13)
test str::bench::char_offset_iterator_rev ... bench: 183 ns/iter (+/- 2)
To be able to use a string slice to represent the CharIterator, a function `slice_unchecked` is added, that does the same as `slice_bytes` but without any boundary checks.
It would be possible to implement CharIterator with pointer arithmetic to make it *much more efficient*, but since vec iterator is still improving, it's too early to attempt to re-implement it in other places. Hopefully CharIterator can be implemented on top of vec iterator without any unsafe code later.
Additional changes fix the documentation about null termination.
