Support for stable host toolchain (risc0#817)

* Switch to `stable` channel in `rust-toolchain.toml`
* Adjust `risc0-build` to support any host-side rustc version.
* Download LLVM source for build-toolchain
* `risc0-build` uses env vars to make debugging toolchains easier

bonsai/ethereum-relay/Cargo.toml

@@ -18,7 +18,7 @@ bincode = "1.3"
 bonsai-ethereum-contracts = { workspace = true }
 bonsai-rest-api-mock = { workspace = true }
 bonsai-sdk = { workspace = true, features = ["async"] }
-clap = { version = "4.0, <4.4.0", features = ["derive", "env"] }
+clap = { version = "4.4", features = ["derive", "env"] }
 displaydoc = "0.2"
 ethers = { version = "2.0", features = ["rustls", "ws", "ethers-solc"] }
 ethers-signers = { version = "2.0", features = ["aws"] }

bonsai/examples/governance/rust-toolchain.toml

@@ -1,4 +1,4 @@
 [toolchain]
-channel = "nightly-2023-03-06"
-components = [ "rustfmt", "rust-src" ]
+channel = "stable"
+components = ["rustfmt", "rust-src"]
 profile = "minimal"

examples/ecdsa/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2021"
 default-run = "ecdsa-example"
 
 [dependencies]
-clap = "4.0, <4.4.0"
+clap = "4.4"
 ecdsa-methods = { path = "methods" }
 k256 = { version = "0.13", features = ["serde"] }
 rand_core = "0.6.4"

risc0/build/src/lib.rs

@@ -172,11 +172,16 @@ fn guest_packages(pkg: &Package) -> Vec<Package> {
         .collect()
 }
 
+fn is_debug() -> bool {
+    get_env_var("RISC0_BUILD_DEBUG") == "1"
+}
+
 /// Returns all methods associated with the given riscv guest package.
 fn guest_methods<P>(pkg: &Package, target_dir: P) -> Vec<Risc0Method>
 where
     P: AsRef<Path>,
 {
+    let profile = if is_debug() { "debug" } else { "release" };
     pkg.targets
         .iter()
         .filter(|target| target.kind.iter().any(|kind| kind == "bin"))
@@ -185,21 +190,32 @@ where
             elf_path: target_dir
                 .as_ref()
                 .join("riscv32im-risc0-zkvm-elf")
-                .join("release")
+                .join(profile)
                 .join(&target.name),
         })
         .collect()
 }
 
+fn get_env_var(name: &str) -> String {
+    println!("cargo:rerun-if-env-changed={name}");
+    env::var(name).unwrap_or_default()
+}
+
+fn sanitized_cmd(tool: &str) -> Command {
+    let mut cmd = Command::new(tool);
+    for (key, _) in env::vars().filter(|x| x.0.starts_with("CARGO") || x.0.starts_with("RUSTUP")) {
+        cmd.env_remove(key);
+    }
+    cmd
+}
+
 // Builds a package that targets the riscv guest into the specified target
 // directory.
 fn build_guest_package<P>(pkg: &Package, target_dir: P, features: Vec<String>)
 where
     P: AsRef<Path>,
 {
-    let skip_var_name = "RISC0_SKIP_BUILD";
-    println!("cargo:rerun-if-env-changed={}", skip_var_name);
-    if env::var(skip_var_name).is_ok() {
+    if !get_env_var("RISC0_SKIP_BUILD").is_empty() {
         return;
     }
 
@@ -208,27 +224,47 @@ where
     let mut args = vec![
         "+risc0",
         "build",
-        "--release",
         "--target",
         "riscv32im-risc0-zkvm-elf",
         "--manifest-path",
         pkg.manifest_path.as_str(),
         "--target-dir",
         target_dir.as_ref().to_str().unwrap(),
     ];
+
+    if !is_debug() {
+        args.push("--release");
+    }
+
     let features_str = features.join(",");
     if !features.is_empty() {
         args.push("--features");
         args.push(&features_str);
     }
-    println!("Building guest package: cargo {}", args.join(" "));
 
-    let mut cmd = Command::new("cargo");
-    for (key, _) in env::vars().filter(|x| x.0.starts_with("CARGO") || x.0.starts_with("RUSTUP")) {
-        cmd.env_remove(key);
+    let rustc = sanitized_cmd("rustup")
+        .args(["+risc0", "which", "rustc"])
+        .output()
+        .unwrap()
+        .stdout;
+    let rustc = String::from_utf8(rustc).unwrap();
+    let rustc = rustc.trim();
+
+    let mut cmd = sanitized_cmd("cargo");
+
+    let rust_src = get_env_var("RISC0_RUST_SRC");
+    if !rust_src.is_empty() {
+        args.push("-Z");
+        args.push("build-std=alloc,core,proc_macro,panic_abort,std");
+        args.push("-Z");
+        args.push("build-std-features=compiler-builtins-mem");
+        cmd.env("__CARGO_TESTS_ONLY_SRC_ROOT", rust_src);
     }
 
+    println!("Building guest package: cargo {}", args.join(" "));
+
     let mut child = cmd
+        .env("RUSTC", rustc)
         .env(
             "CARGO_ENCODED_RUSTFLAGS",
             [

risc0/cargo-risczero/Cargo.toml

@@ -17,7 +17,7 @@ name = "cargo-risczero"
 anyhow = { version = "1.0", features = ["backtrace"] }
 cargo-generate = "0.18"
 cargo_metadata = "0.17"
-clap = { version = "4.0, <4.4.0", features = ["derive"] }
+clap = { version = "4", features = ["derive"] }
 const_format = "0.2"
 dirs = "5.0"
 docker-generate = "0.1"

risc0/cargo-risczero/src/commands/config.toml

@@ -9,3 +9,6 @@ configure-args = []
 [rust]
 lld = true
 llvm-tools = true
+
+[llvm]
+download-ci-llvm = false