9e78bc5d4f
Remove confusing comment about ideally using `!` for `c_void`
Using `!` for `c_void` would have the problem that pointers and
potentially references to an uninhabited type would be created, and at
least for references this is UB.
In addition document that newtype wrappers around `c_void` can be used
safely in place of `extern type` until the latter is stabilized.
----
I'm not 100% sure about the usage for opaque types as the [nomicon](https://doc.rust-lang.org/nomicon/ffi.html#representing-opaque-structs) still recommends using `#[repr(C)] pub struct Foo { _private: [u8; 0] }` but it seems like these two should be equivalent in the end? Also the `#[repr(C)]` (in both cases) should be unneeded because such types never being passed by value, never being dereferenced but only passed around as pointer or reference, so the representation of (*values* of) the type itself should not matter at all?
Also in context of `c_void` and `!` the second unresolved question in the [`extern type`](https://github.com/rust-lang/rust/issues/43467) stabilization ticket seems relevant
> In [std's](
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|---|---|---|
| .. | ||
| bootstrap | ||
| build_helper | ||
| ci | ||
| doc | ||
| etc | ||
| grammar | ||
| liballoc | ||
| libarena | ||
| libcore | ||
| libfmt_macros | ||
| libgraphviz | ||
| libpanic_abort | ||
| libpanic_unwind | ||
| libproc_macro | ||
| libprofiler_builtins | ||
| librustc | ||
| librustc_allocator | ||
| librustc_apfloat | ||
| librustc_asan | ||
| librustc_borrowck | ||
| librustc_codegen_llvm | ||
| librustc_codegen_ssa | ||
| librustc_codegen_utils | ||
| librustc_cratesio_shim | ||
| librustc_data_structures | ||
| librustc_driver | ||
| librustc_errors | ||
| librustc_fs_util | ||
| librustc_incremental | ||
| librustc_lint | ||
| librustc_llvm | ||
| librustc_lsan | ||
| librustc_metadata | ||
| librustc_mir | ||
| librustc_msan | ||
| librustc_passes | ||
| librustc_plugin | ||
| librustc_privacy | ||
| librustc_resolve | ||
| librustc_save_analysis | ||
| librustc_target | ||
| librustc_traits | ||
| librustc_tsan | ||
| librustc_typeck | ||
| librustdoc | ||
| libserialize | ||
| libstd | ||
| libsyntax | ||
| libsyntax_ext | ||
| libsyntax_pos | ||
| libterm | ||
| libtest | ||
| libunwind | ||
| llvm@f4728ed8fa | ||
| llvm-emscripten@7f23313edf | ||
| rtstartup | ||
| rustc | ||
| rustllvm | ||
| stdsimd@269d0ba959 | ||
| test | ||
| tools | ||
| .gitignore | ||
| README.md | ||
| stage0.txt | ||
This directory contains the source code of the rust project, including:
rustcand its testslibstd- Various submodules for tools, like rustdoc, rls, etc.
For more information on how various parts of the compiler work, see the rustc guide.
There is also useful content in the following READMEs, which are gradually being moved over to the guide:
- https://github.com/rust-lang/rust/tree/master/src/librustc/ty/query
- https://github.com/rust-lang/rust/tree/master/src/librustc/dep_graph
- https://github.com/rust-lang/rust/blob/master/src/librustc/infer/region_constraints
- https://github.com/rust-lang/rust/tree/master/src/librustc/infer/higher_ranked
- https://github.com/rust-lang/rust/tree/master/src/librustc/infer/lexical_region_resolve