kennytm [Mon, 20 Nov 2017 19:14:42 +0000 (03:14 +0800)]
Rollup merge of #46088 - vitiral:read_doc, r=steveklabnik
add doc for doing `Read` from `&str`
This information can be found on [stackoverflow](https://stackoverflow.com/questions/32674905/pass-string-to-function-taking-read-trait) but I think it would be beneficial if it was documented in the `Read` trait itself.
I had an *extremely* hard time finding this information, and "mocking" a reader with a string is an EXTREMELY common thing (I believe).
kennytm [Mon, 20 Nov 2017 19:14:41 +0000 (03:14 +0800)]
Rollup merge of #46082 - Enet4:mutex_from, r=sfackler
impl From for Mutex and RwLock
I felt that these implementations were missing, because doing `x.into()` works for other smart containers (such as `RefCell`), and in general I would say that the conversion makes sense.
bors [Mon, 20 Nov 2017 12:10:14 +0000 (12:10 +0000)]
Auto merge of #45998 - ollie27:doc_book_css, r=steveklabnik
Fix broken CSS for book redirect pages
rust.css has to be next to the font files so we shouldn't copy it for
only the book redirect pages, instead just use the version that is
already there.
This also removes the duplicate code creating version_info.html.
bors [Mon, 20 Nov 2017 08:29:46 +0000 (08:29 +0000)]
Auto merge of #45905 - alexcrichton:add-wasm-target, r=aturon
std: Add a new wasm32-unknown-unknown target
This commit adds a new target to the compiler: wasm32-unknown-unknown. This target is a reimagining of what it looks like to generate WebAssembly code from Rust. Instead of using Emscripten which can bring with it a weighty runtime this instead is a target which uses only the LLVM backend for WebAssembly and a "custom linker" for now which will hopefully one day be direct calls to lld.
Notable features of this target include:
* There is zero runtime footprint. The target assumes nothing exists other than the wasm32 instruction set.
* There is zero toolchain footprint beyond adding the target. No custom linker is needed, rustc contains everything.
* Very small wasm modules can be generated directly from Rust code using this target.
* Most of the standard library is stubbed out to return an error, but anything related to allocation works (aka `HashMap`, `Vec`, etc).
* Naturally, any `#[no_std]` crate should be 100% compatible with this new target.
This target is currently somewhat janky due to how linking works. The "linking" is currently unconditional whole program LTO (aka LLVM is being used as a linker). Naturally that means compiling programs is pretty slow! Eventually though this target should have a linker.
This target is also intended to be quite experimental. I'm hoping that this can act as a catalyst for further experimentation in Rust with WebAssembly. Breaking changes are very likely to land to this target, so it's not recommended to rely on it in any critical capacity yet. We'll let you know when it's "production ready".
### Building yourself
First you'll need to configure the build of LLVM and enable this target
Next you'll want to remove any previously compiled LLVM as it needs to be rebuilt with WebAssembly support. You can do that with:
```
$ rm -rf build
```
And then you're good to go! A `./x.py build` should give you a rustc with the appropriate libstd target.
### Test support
Currently testing-wise this target is looking pretty good but isn't complete. I've got almost the entire `run-pass` test suite working with this target (lots of tests ignored, but many passing as well). The `core` test suite is [still getting LLVM bugs fixed](https://reviews.llvm.org/D39866) to get that working and will take some time. Relatively simple programs all seem to work though!
In general I've only tested this with a local fork that makes use of LLVM 5 rather than our current LLVM 4 on master. The LLVM 4 WebAssembly backend AFAIK isn't broken per se but is likely missing bug fixes available on LLVM 5. I'm hoping though that we can decouple the LLVM 5 upgrade and adding this wasm target!
### But the modules generated are huge!
It's worth nothing that you may not immediately see the "smallest possible wasm module" for the input you feed to rustc. For various reasons it's very difficult to get rid of the final "bloat" in vanilla rustc (again, a real linker should fix all this). For now what you'll have to do is:
bors [Mon, 20 Nov 2017 05:58:23 +0000 (05:58 +0000)]
Auto merge of #45819 - Havvy:cell, r=aturon
Add RefCell<T>::replace_with
I also moved the `Panic` sections to before examples in the other two functions also under this feature gate, and changed the variable names in `replace` to be more readable.
Alex Crichton [Mon, 23 Oct 2017 03:01:00 +0000 (20:01 -0700)]
std: Add a new wasm32-unknown-unknown target
This commit adds a new target to the compiler: wasm32-unknown-unknown. This
target is a reimagining of what it looks like to generate WebAssembly code from
Rust. Instead of using Emscripten which can bring with it a weighty runtime this
instead is a target which uses only the LLVM backend for WebAssembly and a
"custom linker" for now which will hopefully one day be direct calls to lld.
Notable features of this target include:
* There is zero runtime footprint. The target assumes nothing exists other than
the wasm32 instruction set.
* There is zero toolchain footprint beyond adding the target. No custom linker
is needed, rustc contains everything.
* Very small wasm modules can be generated directly from Rust code using this
target.
* Most of the standard library is stubbed out to return an error, but anything
related to allocation works (aka `HashMap`, `Vec`, etc).
* Naturally, any `#[no_std]` crate should be 100% compatible with this new
target.
This target is currently somewhat janky due to how linking works. The "linking"
is currently unconditional whole program LTO (aka LLVM is being used as a
linker). Naturally that means compiling programs is pretty slow! Eventually
though this target should have a linker.
This target is also intended to be quite experimental. I'm hoping that this can
act as a catalyst for further experimentation in Rust with WebAssembly. Breaking
changes are very likely to land to this target, so it's not recommended to rely
on it in any critical capacity yet. We'll let you know when it's "production
ready".
---
Currently testing-wise this target is looking pretty good but isn't complete.
I've got almost the entire `run-pass` test suite working with this target (lots
of tests ignored, but many passing as well). The `core` test suite is still
getting LLVM bugs fixed to get that working and will take some time. Relatively
simple programs all seem to work though!
---
It's worth nothing that you may not immediately see the "smallest possible wasm
module" for the input you feed to rustc. For various reasons it's very difficult
to get rid of the final "bloat" in vanilla rustc (again, a real linker should
fix all this). For now what you'll have to do is:
bors [Sun, 19 Nov 2017 22:12:22 +0000 (22:12 +0000)]
Auto merge of #45225 - eddyb:trans-abi, r=arielb1
Refactor type memory layouts and ABIs, to be more general and easier to optimize.
To combat combinatorial explosion, type layouts are now described through 3 orthogonal properties:
* `Variants` describes the plurality of sum types (where applicable)
* `Single` is for one inhabited/active variant, including all C `struct`s and `union`s
* `Tagged` has its variants discriminated by an integer tag, including C `enum`s
* `NicheFilling` uses otherwise-invalid values ("niches") for all but one of its inhabited variants
* `FieldPlacement` describes the number and memory offsets of fields (if any)
* `Union` has all its fields at offset `0`
* `Array` has offsets that are a multiple of its `stride`; guarantees all fields have one type
* `Arbitrary` records all the field offsets, which can be out-of-order
* `Abi` describes how values of the type should be passed around, including for FFI
* `Uninhabited` corresponds to no values, associated with unreachable control-flow
* `Scalar` is ABI-identical to its only integer/floating-point/pointer "scalar component"
* `ScalarPair` has two "scalar components", but only applies to the Rust ABI
* `Vector` is for SIMD vectors, typically `#[repr(simd)]` `struct`s in Rust
* `Aggregate` has arbitrary contents, including all non-transparent C `struct`s and `union`s
Size optimizations implemented so far:
* ignoring uninhabited variants (i.e. containing uninhabited fields), e.g.:
* `Option<!>` is 0 bytes
* `Result<T, !>` has the same size as `T`
* using arbitrary niches, not just `0`, to represent a data-less variant, e.g.:
* `Option<bool>`, `Option<Option<bool>>`, `Option<Ordering>` are all 1 byte
* `Option<char>` is 4 bytes
* using a range of niches to represent *multiple* data-less variants, e.g.:
* `enum E { A(bool), B, C, D }` is 1 byte
Code generation now takes advantage of `Scalar` and `ScalarPair` to, in more cases, pass around scalar components as immediates instead of indirectly, through pointers into temporary memory, while avoiding LLVM's "first-class aggregates", and there's more untapped potential here.
bors [Sun, 19 Nov 2017 12:20:14 +0000 (12:20 +0000)]
Auto merge of #46074 - scottmcm:unspecialize-nth, r=bluss
Undo the Sized specialization from Iterator::nth
I just added this as part of https://github.com/rust-lang/rust/pull/45595, but I'm now afraid there's a specialization issue with it, since I tried to add [another similar specialization](https://github.com/rust-lang/rust/compare/master...scottmcm:faster-iter-by-ref?expand=1#diff-1398f322bc563592215b583e9b0ba936R2390), and ended up getting really disturbing test failures like
```
thread 'iter::test_by_ref_folds' panicked at 'assertion failed: `(left == right)`
left: `15`,
right: `15`', src\libcore\../libcore/tests\iter.rs:1720:4
```
So since this wasn't the most critical part of the change and a new beta is branching within a week, I think putting this part back to what it was before is the best option.
bors [Sat, 18 Nov 2017 15:00:13 +0000 (15:00 +0000)]
Auto merge of #46009 - kennytm:fix-38878-again, r=alexcrichton
Fix #38878 again — restart linker when seeing SIGBUS in additional to SIGSEGV.
In https://github.com/rust-lang/rust/pull/45985#issuecomment-344586645 we see a linker crashed due to Bus Error (signal 10) on macOS. The error was not caught by #40422 since the PR only handles Segmentation Fault (signal 11). The crash log indicates the problem is the same as #38878, so we just amend #40422 to include SIGBUS as well.
(Additionally, modified how the crash logs are printed so that irrelevant logs are truly filtered out.)
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