[anneal][v2] Add exocrate toolchain setup and Toolchain resolver

TAG=agy

gherrit-pr-id: Gbbpbt76nsgp2ohpclea46vot5joxx7b5

Author: mdittmer

anneal/v2/src/setup.rs

@@ -0,0 +1,150 @@
+// Copyright 2026 The Fuchsia Authors
+//
+// Licensed under the 2-Clause BSD License <LICENSE-BSD or
+// https://opensource.org/license/bsd-2-clause>, Apache License, Version 2.0
+// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+// This file may not be copied, modified, or distributed except according to
+// those terms.
+
+use anyhow::Context as _;
+
+pub struct SetupArgs {
+    pub local_archive: Option<std::path::PathBuf>,
+}
+
+exocrate::config! {
+    pub const CONFIG: Config = Config {
+        rel_dir_path: [".anneal", "toolchain"],
+        versioned_files: &["../Cargo.toml", "../Cargo.lock"],
+    };
+}
+
+exocrate::parse_remote_archive! {
+    pub const REMOTE: RemoteArchive = "Cargo.toml" [
+        (linux, x86_64),
+        (macos, x86_64),
+        (linux, aarch64),
+        (macos, aarch64),
+    ];
+}
+
+pub enum Tool {
+    Cargo,
+    Charon,
+    Rustc,
+}
+
+impl Tool {
+    pub fn name(&self) -> &'static str {
+        match self {
+            Self::Cargo => "cargo",
+            Self::Charon => "charon",
+            Self::Rustc => "rustc",
+        }
+    }
+
+    pub fn path(&self, toolchain: &Toolchain) -> std::path::PathBuf {
+        match self {
+            Self::Cargo | Self::Rustc => toolchain.rust_bin().join(self.name()),
+            Self::Charon => toolchain.aeneas_bin_dir().join(self.name()),
+        }
+    }
+}
+
+const AENEAS_DIR: &str = "aeneas";
+const RUST_SYSROOT: &str = "rust";
+const AENEAS_BIN_DIR: &str = "bin";
+const RUST_BIN_DIR: &str = "bin";
+const RUST_LIB_DIR: &str = "lib";
+
+pub struct Toolchain {
+    root: std::path::PathBuf,
+}
+
+impl Toolchain {
+    pub fn resolve() -> anyhow::Result<Self> {
+        let location = resolve_location();
+        let root = CONFIG
+            .resolve_installation_dir(location)
+            .context("Toolchain not installed. Please run 'cargo anneal setup' first.")?;
+        Ok(Self { root })
+    }
+
+    pub fn root(&self) -> &std::path::Path {
+        &self.root
+    }
+
+    pub fn aeneas_bin_dir(&self) -> std::path::PathBuf {
+        self.root.join(AENEAS_DIR).join(AENEAS_BIN_DIR)
+    }
+
+    pub fn rust_sysroot(&self) -> std::path::PathBuf {
+        self.root.join(RUST_SYSROOT)
+    }
+
+    pub fn rust_bin(&self) -> std::path::PathBuf {
+        self.rust_sysroot().join(RUST_BIN_DIR)
+    }
+
+    pub fn rust_lib(&self) -> std::path::PathBuf {
+        self.rust_sysroot().join(RUST_LIB_DIR)
+    }
+
+    pub fn command(&self, tool: Tool) -> anyhow::Result<std::process::Command> {
+        let mut cmd = std::process::Command::new(tool.path(self));
+        cmd.env_clear();
+        match tool {
+            Tool::Cargo | Tool::Rustc => {}
+            Tool::Charon => {
+                // The archive supplies Rust tools, but not host build tools
+                // such as the linker. Keep the caller's `PATH` after our Rust
+                // bin directory so Cargo builds use the managed Rust toolchain
+                // while still finding those host tools.
+                cmd.env("CHARON_TOOLCHAIN_IS_IN_PATH", "1")
+                    .env("PATH", prepend_current_path(self.rust_bin())?)
+                    .env(rust_library_path_env_var(), self.rust_lib());
+            }
+        }
+        Ok(cmd)
+    }
+}
+
+fn prepend_current_path(path: std::path::PathBuf) -> anyhow::Result<std::ffi::OsString> {
+    let mut paths = vec![path];
+    if let Some(current_path) = std::env::var_os("PATH") {
+        paths.extend(std::env::split_paths(&current_path));
+    }
+    std::env::join_paths(paths).context("failed to construct PATH for tool command")
+}
+
+/// Returns the platform library search path variable used by Rust tools.
+pub(crate) fn rust_library_path_env_var() -> &'static str {
+    if cfg!(target_os = "macos") { "DYLD_LIBRARY_PATH" } else { "LD_LIBRARY_PATH" }
+}
+
+pub fn run_setup(args: SetupArgs) -> anyhow::Result<()> {
+    let location = resolve_location();
+    let source = match args.local_archive {
+        Some(local_archive) => exocrate::Source::Local(local_archive),
+        None => exocrate::Source::Remote(REMOTE),
+    };
+
+    let (installation_dir, status) = CONFIG
+        .resolve_installation_dir_or_install(location, source)
+        .context("failed to resolve-or-install dependencies")?;
+    if status == exocrate::ResolvedOrInstalled::ResolvedExisting {
+        log::warn!("anneal toolchain was already installed at {:?}", installation_dir);
+    } else {
+        log::info!("anneal toolchain freshly installed at {:?}", installation_dir);
+    }
+    Ok(())
+}
+
+fn resolve_location() -> exocrate::Location {
+    if std::env::var("__ANNEAL_LOCAL_DEV").is_ok() {
+        exocrate::Location::LocalDev
+    } else {
+        exocrate::Location::UserGlobal
+    }
+}

exocrate/src/lib.rs

@@ -73,7 +73,7 @@
 //! };
 //!
 //! // Check whether `source` archive is already installed at `location`, and if not, install it.
-//! let installed_exocrate_dir = CONFIG.resolve_installation_dir_or_install(location, source)
+//! let (installed_exocrate_dir, _) = CONFIG.resolve_installation_dir_or_install(location, source)
 //!     .expect("failed to resolve or install my-tool's exocrate");
 //!
 //! // Invoke tool installed from `tests/my-tool-deps.tar.zst` extracted to versioned exocrate
@@ -186,6 +186,15 @@ pub enum Source {
     Local(PathBuf),
 }
 
+/// Whether an installation was resolved or newly installed.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum ResolvedOrInstalled {
+    /// An existing installation was resolved.
+    ResolvedExisting,
+    /// A new installation was installed.
+    NewlyInstalled,
+}
+
 impl Config {
     /// Resolves the dependency directory, failing if it doesn't exist.
     pub fn resolve_installation_dir(&self, location: Location) -> IoResult<PathBuf> {
@@ -199,14 +208,14 @@ impl Config {
         &self,
         location: Location,
         source: Source,
-    ) -> IoResult<PathBuf> {
+    ) -> IoResult<(PathBuf, ResolvedOrInstalled)> {
         let dir_path = self.dir_path(location);
         if ManagedDirName::new(&dir_path).check_exists().is_ok() {
-            return Ok(dir_path);
+            return Ok((dir_path, ResolvedOrInstalled::ResolvedExisting));
         }
         let (reader, expected_sha) = self.open_source(source)?;
         install(reader, &dir_path, expected_sha)?;
-        Ok(dir_path)
+        Ok((dir_path, ResolvedOrInstalled::NewlyInstalled))
     }
 
     /// Opens the given source.
@@ -763,19 +772,21 @@ mod tests {
         let dev_path = config.dir_path(Location::LocalDev);
         let _ = fs::remove_dir_all(&dev_path);
 
-        let resolved = config
+        let (resolved, status) = config
             .resolve_installation_dir_or_install(Location::LocalDev, Source::Local(archive_path))
             .unwrap();
         assert_eq!(resolved, dev_path);
+        assert_eq!(status, ResolvedOrInstalled::NewlyInstalled);
         assert!(dev_path.join("bin/compiler").exists());
 
-        let resolved2 = config
+        let (resolved2, status2) = config
             .resolve_installation_dir_or_install(
                 Location::LocalDev,
                 Source::Local(PathBuf::from("/nonexistent/path/should/not/be/accessed")),
             )
             .unwrap();
         assert_eq!(resolved2, dev_path);
+        assert_eq!(status2, ResolvedOrInstalled::ResolvedExisting);
 
         fs::remove_dir_all(&dev_path).unwrap();
     }