We want to avoid exporting any symbols from Rust's version of libunwind,
and to do so we need to disable visibility annotations to make sure that
the -fvisibility=hidden has effect, and also hide global new/delete.
This matches the CMake build of libunwind.
We don't want to export any symbols from Rust's version of libunwind
as these may collide with other copies of libunwind e.g. when linking
Rust staticlib together C/C++ libraries that have their own version.
Standard library support for riscv64gc-unknown-linux-gnu
Add std support for RISC-V 64-bit GNU/Linux and update libc for RISC-V support.
r? @alexcrichton
- the old interface between HermitCore and the Rust Standard Library
based on a small C library (newlib)
- remove this interface and call directly the unikernel
- remove the dependency to the HermitCore linker
- use rust-lld as linker
add sparc64-unknown-openbsd target
on OpenBSD, some architectures relies on libc++ (from LLVM) and some
others on libestdc++ (particular version of libstdc++ from GCC).
sparc64-unknown-openbsd needs libestdc++ and libgcc (as x86_64 some
years ago). Reintroduce the support of them for openbsd, only for
sparc64 arch. Some others architectures on OpenBSD could use them too.
on OpenBSD, some architectures relies on libc++ (from LLVM) and some
others on libestdc++ (particular version of libstdc++ from GCC).
sparc64-unknown-openbsd needs libestdc++ and libgcc (as x86_64 some
years ago). Reintroduce the support of them for openbsd, only for
sparc64 arch. Some others architectures on OpenBSD could use them too.
This was removed in 8a7dded, but since #62286 hasn't yet made it into
beta, this is breaking the build with llvm-libunwind feature enabled.
Furthemore, restrict the link attribute to Fuchsia and Linux, matching
the logic in build.rs since llvm-libunwind feature isn't yet supported
on other systems.
When llvm-libunwind feature is enabled, we need to use link attribute on
extern "C" blocks to make sure that symbols provided by LLVM's libunwind
that's built as part of Rust's libunwind crate are re-exported.
This addresses issue #62088.
This is duplicated in a few locations throughout the sysroot to work
around issues with not exporting a macro in libstd but still wanting it
available to sysroot crates to define blocks. Nowadays though we can
simply depend on the `cfg-if` crate on crates.io, allowing us to use it
from there!
These are required otherwise libunwind will end up with undefined
references to __gxx_personality_v0 which is provided by C++ ABI
library and that's undesirable.
Ever since we added a Cargo-based build system for the compiler the
standard library has always been a little special, it's never been able
to depend on crates.io crates for runtime dependencies. This has been a
result of various limitations, namely that Cargo doesn't understand that
crates from crates.io depend on libcore, so Cargo tries to build crates
before libcore is finished.
I had an idea this afternoon, however, which lifts the strategy
from #52919 to directly depend on crates.io crates from the standard
library. After all is said and done this removes a whopping three
submodules that we need to manage!
The basic idea here is that for any crate `std` depends on it adds an
*optional* dependency on an empty crate on crates.io, in this case named
`rustc-std-workspace-core`. This crate is overridden via `[patch]` in
this repository to point to a local crate we write, and *that* has a
`path` dependency on libcore.
Note that all `no_std` crates also depend on `compiler_builtins`, but if
we're not using submodules we can publish `compiler_builtins` to
crates.io and all crates can depend on it anyway! The basic strategy
then looks like:
* The standard library (or some transitive dep) decides to depend on a
crate `foo`.
* The standard library adds
```toml
[dependencies]
foo = { version = "0.1", features = ['rustc-dep-of-std'] }
```
* The crate `foo` has an optional dependency on `rustc-std-workspace-core`
* The crate `foo` has an optional dependency on `compiler_builtins`
* The crate `foo` has a feature `rustc-dep-of-std` which activates these
crates and any other necessary infrastructure in the crate.
A sample commit for `dlmalloc` [turns out to be quite simple][commit].
After that all `no_std` crates should largely build "as is" and still be
publishable on crates.io! Notably they should be able to continue to use
stable Rust if necessary, since the `rename-dependency` feature of Cargo
is soon stabilizing.
As a proof of concept, this commit removes the `dlmalloc`,
`libcompiler_builtins`, and `libc` submodules from this repository. Long
thorns in our side these are now gone for good and we can directly
depend on crates.io! It's hoped that in the long term we can bring in
other crates as necessary, but for now this is largely intended to
simply make it easier to manage these crates and remove submodules.
This should be a transparent non-breaking change for all users, but one
possible stickler is that this almost for sure breaks out-of-tree
`std`-building tools like `xargo` and `cargo-xbuild`. I think it should
be relatively easy to get them working, however, as all that's needed is
an entry in the `[patch]` section used to build the standard library.
Hopefully we can work with these tools to solve this problem!
[commit]: 28ee12db81
