Support stable Rust, and reduce dependence on internal Rust features. (#132)

Put all code that depends on nightly-only features behind a new
"nightly" feature, and add support for stable Rust.

And, add implementations of `memcpy` and other functions that LLVM calls so
that origin and its users no longer need to depend on the
compiler_internals crate.

And, introduce new "panic-handler", "panic-handler-abort", "eh-personality",
and "eh-personality-continue" features, so that users no longer need to
use `#[panic_handler]` or `#[lang = "eh_personality"]` in common cases.

And, add `origin::program::abort`, eliminating the need for users to use
`core::intrinsics::abort()`.

Together, these changes mean that origin and most of the example crates no
longer need `#![allow(internal_features)]`, `#![feature(lang_items)]`, or
`#![feature(core_intrinsics)]`, or the associated boilerplate code with
`#[panic_handler]` or `#[lang = "eh_personality"]`, or the explicit
dependency on `compiler_builtins` or the `extern crate
compiler_builtins;`.

Author: sunfishcode

.github/actions/install-rust/README.md

@@ -0,0 +1,18 @@
+# install-rust
+
+A small github action to install `rustup` and a Rust toolchain. This is
+generally expressed inline, but it was repeated enough in this repository it
+seemed worthwhile to extract.
+
+Some gotchas:
+
+* Can't `--self-update` on Windows due to permission errors (a bug in Github
+  Actions)
+* `rustup` isn't installed on macOS (a bug in Github Actions)
+
+When the above are fixed we should delete this action and just use this inline:
+
+```yml
+- run: rustup update $toolchain && rustup default $toolchain
+  shell: bash
+```

.github/actions/install-rust/action.yml

@@ -0,0 +1,12 @@
+name: 'Install Rust toolchain'
+description: 'Install both `rustup` and a Rust toolchain'
+
+inputs:
+  toolchain:
+    description: 'Default toolchan to install'
+    required: false
+    default: 'stable'
+
+runs:
+  using: node20
+  main: 'main.js'

.github/actions/install-rust/main.js

@@ -0,0 +1,38 @@
+const child_process = require('child_process');
+const toolchain = process.env.INPUT_TOOLCHAIN;
+const fs = require('fs');
+
+function set_env(name, val) {
+  fs.appendFileSync(process.env['GITHUB_ENV'], `${name}=${val}\n`)
+}
+
+// Needed for now to get 1.24.2 which fixes a bug in 1.24.1 that causes issues
+// on Windows.
+if (process.platform === 'win32') {
+  child_process.execFileSync('rustup', ['self', 'update']);
+}
+
+child_process.execFileSync('rustup', ['set', 'profile', 'minimal']);
+child_process.execFileSync('rustup', ['update', toolchain, '--no-self-update']);
+child_process.execFileSync('rustup', ['default', toolchain]);
+
+// Deny warnings on CI to keep our code warning-free as it lands in-tree. Don't
+// do this on nightly though since there's a fair amount of warning churn there.
+// RUSTIX: Disable this so that it doesn't overwrite RUSTFLAGS for setting
+// "--cfg rustix_use_libc". We re-add it manually in the workflow.
+//if (!toolchain.startsWith('nightly')) {
+//  set_env("RUSTFLAGS", "-D warnings");
+//}
+
+// Save disk space by avoiding incremental compilation, and also we don't use
+// any caching so incremental wouldn't help anyway.
+set_env("CARGO_INCREMENTAL", "0");
+
+// Turn down debuginfo from 2 to 1 to help save disk space
+set_env("CARGO_PROFILE_DEV_DEBUG", "1");
+set_env("CARGO_PROFILE_TEST_DEBUG", "1");
+
+if (process.platform === 'darwin') {
+  set_env("CARGO_PROFILE_DEV_SPLIT_DEBUGINFO", "unpacked");
+  set_env("CARGO_PROFILE_TEST_SPLIT_DEBUGINFO", "unpacked");
+}

.github/workflows/main.yml

@@ -23,6 +23,7 @@ jobs:
     strategy:
       matrix:
         build: [ubuntu, i686-linux, aarch64-linux, riscv64-linux]
+        rust: [1.78, nightly-2024-10-06]
         include:
           - build: ubuntu
             os: ubuntu-latest
@@ -50,8 +51,14 @@ jobs:
             qemu: qemu-riscv64 -L /usr/riscv64-linux-gnu
             qemu_target: riscv64-linux-user
             host_target: riscv64gc-unknown-linux-gnu
+          - rust: nightly-2024-10-06
+            features: nightly
     steps:
     - uses: actions/checkout@v4
+    - uses: ./.github/actions/install-rust
+      with:
+        toolchain: ${{ matrix.rust }}
+
     - name: Configure Cargo target
       run: |
         echo CARGO_BUILD_TARGET=${{ matrix.target }} >> $GITHUB_ENV
@@ -113,6 +120,6 @@ jobs:
 
     - name: cargo test
       run: |
-        cargo test
+        cargo test --features=${{ matrix.features }}
       env:
         RUST_BACKTRACE: 1

CHANGELOG.md

@@ -1,3 +1,14 @@
+# origin 0.21
+
+## Changes
+
+Origin now supports stable Rust as well as nightly Rust, and nightly-only
+features such as unwinding are now behind a "nightly" feature.
+
+In "take-charge" mode, origin now defines `memcpy`, `memset` and other
+functions needed by rustc and internal Rust libraries, so it's no longer
+necessary to use `compiler_builtins` to provide these.
+
 # origin 0.20
 
 ## Changes

Cargo.toml

@@ -12,6 +12,7 @@ edition = "2021"
 keywords = ["linux"]
 categories = ["no-std"]
 include = ["src", "Cargo.toml", "COPYRIGHT", "LICENSE*", "/*.md"]
+rust-version = "1.78"
 
 [dependencies]
 linux-raw-sys = { version = "0.4.9", default-features = false, features = ["general", "no_std", "elf"] }
@@ -39,13 +40,19 @@ errno = { version = "0.3.3", default-features = false, optional = true }
 # Special dependencies used in rustc-dep-of-std mode.
 core = { version = "1.0.0", optional = true, package = "rustc-std-workspace-core" }
 alloc = { version = "1.0.0", optional = true, package = "rustc-std-workspace-alloc" }
-# Enable "no-f16-f128" for now, to work around lack of support on some targets.
-compiler_builtins = { version = "0.1.112", features = ["no-f16-f128"], optional = true }
 
 [target.'cfg(not(target_arch = "arm"))'.dependencies.unwinding]
 version = "0.2.0"
 default-features = false
 features = ["unwinder"]
+optional = true
+
+# On aarch64, compiler_builtins depends on `getauxval`, so we need rustix with
+# the "param" feature.
+[target.'cfg(target_arch = "aarch64")'.dependencies.rustix]
+version = "0.38.35"
+default-features = false
+features = ["param"]
 
 [dev-dependencies]
 assert_cmd = "2.0.12"
@@ -59,10 +66,9 @@ rustc-dep-of-std = [
     "linux-raw-sys/rustc-dep-of-std",
     "bitflags/rustc-dep-of-std",
     "rustix/rustc-dep-of-std",
-    "unwinding/rustc-dep-of-std",
+    "unwinding?/rustc-dep-of-std",
     "libc?/rustc-dep-of-std",
     "rustix-futex-sync/rustc-dep-of-std",
-    "dep:compiler_builtins",
 ]
 
 # Use origin's implementation of program and thread startup and shutdown as
@@ -121,5 +127,48 @@ experimental-relocate = ["rustix/mm", "rustix/runtime"]
 # until a dynamic linker is written in Rust.
 unstable-errno = ["thread"]
 
+# If you're using nightly Rust, enable this feature to let origin use
+# nightly-only features, which include proper support for unwinding, better
+# safety checks, and better optimizations.
+nightly = ["unwinding"]
+
+# Enable optimizations that reduce code size (at the cost of performance).
+optimize_for_size = []
+
+# Provide a `#[lang = eh_personality]` function suitable for unwinding (for
+# no-std).
+#
+# If you know your program never unwinds and want smaller code size, use
+# "eh-personality-continue" instead.
+#
+# This is only needed in no-std builds, as std provides a personality. See
+# [the "personality" feature of the unwinding crate] for more details.
+#
+# [the "personality" feature of the unwinding crate]: https://crates.io/crates/unwinding#personality-and-other-utilities
+eh-personality = ["unwinding?/personality"]
+
+# Provide a `#[lang = eh_personality]` function that just returns
+# `CONTINUE_UNWIND` (for no-std). Use this if you know your program will never
+# unwind and don't want any extra code.
+eh-personality-continue = ["unwinding?/personality-dummy"]
+
+# Provide a `#[panic_handler]` function suitable for unwinding (for no-std).
+#
+# If you know your program never panics and want smaller code size, use
+# "panic-handler-abort" instead.
+#
+# This is only needed in no-std builds, as std provides a panic handler. See
+# [the "panic-handler" feature of the unwinding crate] for more details.
+#
+# [the "panic-handler" feature of the unwinding crate]: https://crates.io/crates/unwinding#personality-and-other-utilities
+panic-handler = ["unwinding?/panic-handler"]
+
+# Provide a `#[panic_handler]` function that just aborts (for no-std). Use this
+# if you know your program will never panic and don't want any extra code.
+panic-handler-abort = ["unwinding?/panic-handler-dummy"]
+
+# Enable this to define the `getauxval` function.
+getauxval = ["rustix/param"]
+
 [package.metadata.docs.rs]
-features = ["take-charge", "origin-start", "thread", "signal"]
+features = ["take-charge", "origin-start", "thread", "signal", "nightly"]

README.md

@@ -28,6 +28,11 @@ This is used by [Mustang] and [Eyra] in their libc implementations, and in the
 [Origin Studio] project in its std implementation, which are three different
 ways to support building Rust programs written entirely in Rust.
 
+It works with both stable (currently Rust >= 1.78) and nightly Rust. If you're
+using nightly Rust, enable the feature "nightly" to let origin use nightly-only
+features, which include proper support for unwinding, better safety checks, and
+better optimizations.
+
 ## Example crates
 
 Origin can also be used on its own, in several different configurations:

example-crates/external-start/Cargo.toml

@@ -7,15 +7,14 @@ publish = false
 [dependencies]
 # Origin can be depended on just like any other crate. For no_std, disable
 # the default features, and the desired features.
-origin = { path = "../..", default-features = false, features = ["take-charge", "external-start", "thread", "alloc"] }
+origin = { path = "../..", default-features = false, features = ["take-charge", "external-start", "thread", "alloc", "eh-personality-continue", "panic-handler-abort", "nightly"] }
 
 # Ensure that libc gets linked.
 libc = { version = "0.2", default-features = false }
 
 # Crates to help writing no_std code.
 atomic-dbg = { version = "0.1.8", default-features = false }
 rustix-dlmalloc = { version = "0.1.0", features = ["global"] }
-compiler_builtins = { version = "0.1.112", features = ["mem", "no-f16-f128"] }
 
 # This is just an example crate, and not part of the origin workspace.
 [workspace]

example-crates/external-start/src/main.rs

@@ -2,28 +2,15 @@
 
 #![no_std]
 #![no_main]
-#![allow(internal_features)]
-#![feature(lang_items)]
-#![feature(core_intrinsics)]
 
 extern crate alloc;
-extern crate compiler_builtins;
 extern crate libc;
 
 use alloc::boxed::Box;
-use atomic_dbg::{dbg, eprintln};
+use atomic_dbg::eprintln;
 use core::sync::atomic::{AtomicBool, Ordering};
 use origin::{program, thread};
 
-#[panic_handler]
-fn panic(panic: &core::panic::PanicInfo<'_>) -> ! {
-    dbg!(panic);
-    core::intrinsics::abort();
-}
-
-#[lang = "eh_personality"]
-extern "C" fn eh_personality() {}
-
 #[global_allocator]
 static GLOBAL_ALLOCATOR: rustix_dlmalloc::GlobalDlmalloc = rustix_dlmalloc::GlobalDlmalloc;
 
@@ -90,5 +77,5 @@ unsafe fn origin_main(_argc: usize, _argv: *mut *mut u8, _envp: *mut *mut u8) ->
 #[no_mangle]
 unsafe fn main(_argc: i32, _argv: *mut *mut u8, _envp: *mut *mut u8) -> i32 {
     eprintln!("Main was not supposed to be called!");
-    core::intrinsics::abort();
+    program::abort();
 }

example-crates/no-std/Cargo.toml

@@ -7,7 +7,7 @@ publish = false
 [dependencies]
 # Origin can be depended on just like any other crate. For no_std, disable
 # the default features. And enable "libc" to enable the libc implementations.
-origin = { path = "../..", default-features = false, features = ["libc", "thread", "alloc"] }
+origin = { path = "../..", default-features = false, features = ["libc", "thread", "alloc", "eh-personality-continue", "panic-handler-abort", "nightly"] }
 
 # Crates to help writing no_std code.
 atomic-dbg = { version = "0.1.8", default-features = false }