compile_rustfmt rewrite

check_diff/Cargo.toml

@@ -9,5 +9,4 @@ edition = "2021"
 clap = { version = "4.4.2", features = ["derive"] }
 tracing = "0.1.37"
 tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
-[dev-dependencies]
 tempfile = "3"

check_diff/src/lib.rs

@@ -1,11 +1,49 @@
 use std::env;
 use std::io;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::process::Command;
+use std::str::Utf8Error;
 use tracing::info;
 
+pub enum CheckDiffError {
+    /// Git related errors
+    FailedGit(GitError),
+    /// Error for generic commands
+    FailedCommand(&'static str),
+    /// UTF8 related errors
+    FailedUtf8(Utf8Error),
+    /// Error for building rustfmt from source
+    FailedSourceBuild(&'static str),
+    /// Error when obtaining binary version
+    FailedBinaryVersioning(PathBuf),
+    /// Error when obtaining cargo version
+    FailedCargoVersion(&'static str),
+    IO(std::io::Error),
+}
+
+impl From<io::Error> for CheckDiffError {
+    fn from(error: io::Error) -> Self {
+        CheckDiffError::IO(error)
+    }
+}
+
+impl From<GitError> for CheckDiffError {
+    fn from(error: GitError) -> Self {
+        CheckDiffError::FailedGit(error)
+    }
+}
+
+impl From<Utf8Error> for CheckDiffError {
+    fn from(error: Utf8Error) -> Self {
+        CheckDiffError::FailedUtf8(error)
+    }
+}
+
 pub enum GitError {
     FailedClone { stdout: Vec<u8>, stderr: Vec<u8> },
+    FailedRemoteAdd { stdout: Vec<u8>, stderr: Vec<u8> },
+    FailedFetch { stdout: Vec<u8>, stderr: Vec<u8> },
+    FailedSwitch { stdout: Vec<u8>, stderr: Vec<u8> },
     IO(std::io::Error),
 }
 
@@ -15,6 +53,35 @@ impl From<io::Error> for GitError {
     }
 }
 
+// will be used in future PRs, just added to make the compiler happy
+#[allow(dead_code)]
+pub struct CheckDiffRunners {
+    feature_runner: RustfmtRunner,
+    src_runner: RustfmtRunner,
+}
+
+pub struct RustfmtRunner {
+    ld_library_path: String,
+    binary_path: PathBuf,
+}
+
+impl RustfmtRunner {
+    fn get_binary_version(&self) -> Result<String, CheckDiffError> {
+        let Ok(command) = Command::new(&self.binary_path)
+            .env("LD_LIBRARY_PATH", &self.ld_library_path)
+            .args(["--version"])
+            .output()
+        else {
+            return Err(CheckDiffError::FailedBinaryVersioning(
+                self.binary_path.clone(),
+            ));
+        };
+
+        let binary_version = std::str::from_utf8(&command.stdout)?.trim();
+        return Ok(binary_version.to_string());
+    }
+}
+
 /// Clone a git repository
 ///
 /// Parameters:
@@ -47,6 +114,62 @@ pub fn clone_git_repo(url: &str, dest: &Path) -> Result<(), GitError> {
     return Ok(());
 }
 
+pub fn git_remote_add(url: &str) -> Result<(), GitError> {
+    let git_cmd = Command::new("git")
+        .args(["remote", "add", "feature", url])
+        .output()?;
+
+    // if the git command does not return successfully,
+    // any command on the repo will fail. So fail fast.
+    if !git_cmd.status.success() {
+        let error = GitError::FailedRemoteAdd {
+            stdout: git_cmd.stdout,
+            stderr: git_cmd.stderr,
+        };
+        return Err(error);
+    }
+
+    info!("Successfully added remote: {url}");
+    return Ok(());
+}
+
+pub fn git_fetch(branch_name: &str) -> Result<(), GitError> {
+    let git_cmd = Command::new("git")
+        .args(["fetch", "feature", branch_name])
+        .output()?;
+
+    // if the git command does not return successfully,
+    // any command on the repo will fail. So fail fast.
+    if !git_cmd.status.success() {
+        let error = GitError::FailedFetch {
+            stdout: git_cmd.stdout,
+            stderr: git_cmd.stderr,
+        };
+        return Err(error);
+    }
+
+    info!("Successfully fetched: {branch_name}");
+    return Ok(());
+}
+
+pub fn git_switch(git_ref: &str, should_detach: bool) -> Result<(), GitError> {
+    let detach_arg = if should_detach { "--detach" } else { "" };
+    let args = ["switch", git_ref, detach_arg];
+    let output = Command::new("git")
+        .args(args.iter().filter(|arg| !arg.is_empty()))
+        .output()?;
+    if !output.status.success() {
+        tracing::error!("Git switch failed: {output:?}");
+        let error = GitError::FailedSwitch {
+            stdout: output.stdout,
+            stderr: output.stderr,
+        };
+        return Err(error);
+    }
+    info!("Successfully switched to {git_ref}");
+    return Ok(());
+}
+
 pub fn change_directory_to_path(dest: &Path) -> io::Result<()> {
     let dest_path = Path::new(&dest);
     env::set_current_dir(&dest_path)?;
@@ -56,3 +179,94 @@ pub fn change_directory_to_path(dest: &Path) -> io::Result<()> {
     );
     return Ok(());
 }
+
+pub fn get_ld_library_path() -> Result<String, CheckDiffError> {
+    let Ok(command) = Command::new("rustc").args(["--print", "sysroot"]).output() else {
+        return Err(CheckDiffError::FailedCommand("Error getting sysroot"));
+    };
+    let sysroot = std::str::from_utf8(&command.stdout)?.trim_end();
+    let ld_lib_path = format!("{}/lib", sysroot);
+    return Ok(ld_lib_path);
+}
+
+pub fn get_cargo_version() -> Result<String, CheckDiffError> {
+    let Ok(command) = Command::new("cargo").args(["--version"]).output() else {
+        return Err(CheckDiffError::FailedCargoVersion(
+            "Failed to obtain cargo version",
+        ));
+    };
+
+    let cargo_version = std::str::from_utf8(&command.stdout)?.trim_end();
+    return Ok(cargo_version.to_string());
+}
+
+/// Obtains the ld_lib path and then builds rustfmt from source
+/// If that operation succeeds, the source is then copied to the output path specified
+pub fn build_rustfmt_from_src(binary_path: PathBuf) -> Result<RustfmtRunner, CheckDiffError> {
+    //Because we're building standalone binaries we need to set `LD_LIBRARY_PATH` so each
+    // binary can find it's runtime dependencies.
+    // See https://github.com/rust-lang/rustfmt/issues/5675
+    // This will prepend the `LD_LIBRARY_PATH` for the master rustfmt binary
+    let ld_lib_path = get_ld_library_path()?;
+
+    info!("Building rustfmt from source");
+    let Ok(_) = Command::new("cargo")
+        .args(["build", "-q", "--release", "--bin", "rustfmt"])
+        .output()
+    else {
+        return Err(CheckDiffError::FailedSourceBuild(
+            "Error building rustfmt from source",
+        ));
+    };
+
+    std::fs::copy("target/release/rustfmt", &binary_path)?;
+
+    return Ok(RustfmtRunner {
+        ld_library_path: ld_lib_path,
+        binary_path,
+    });
+}
+
+// Compiles and produces two rustfmt binaries.
+// One for the current master, and another for the feature branch
+// Parameters:
+// dest: Directory where rustfmt will be cloned
+pub fn compile_rustfmt(
+    dest: &Path,
+    remote_repo_url: String,
+    feature_branch: String,
+    commit_hash: Option<String>,
+) -> Result<CheckDiffRunners, CheckDiffError> {
+    const RUSTFMT_REPO: &str = "https://github.com/rust-lang/rustfmt.git";
+
+    clone_git_repo(RUSTFMT_REPO, dest)?;
+    change_directory_to_path(dest)?;
+    git_remote_add(remote_repo_url.as_str())?;
+    git_fetch(feature_branch.as_str())?;
+
+    let cargo_version = get_cargo_version()?;
+    info!("Compiling with {}", cargo_version);
+    let src_runner = build_rustfmt_from_src(dest.join("src_rustfmt"))?;
+    let should_detach = commit_hash.is_some();
+    git_switch(
+        commit_hash.unwrap_or(feature_branch).as_str(),
+        should_detach,
+    )?;
+
+    let feature_runner = build_rustfmt_from_src(dest.join("feature_rustfmt"))?;
+    info!("RUSFMT_BIN {}", src_runner.get_binary_version()?);
+    info!(
+        "Runtime dependencies for (src) rustfmt -- LD_LIBRARY_PATH: {}",
+        src_runner.ld_library_path
+    );
+    info!("FEATURE_BIN {}", feature_runner.get_binary_version()?);
+    info!(
+        "Runtime dependencies for (feature) rustfmt -- LD_LIBRARY_PATH: {}",
+        feature_runner.ld_library_path
+    );
+
+    return Ok(CheckDiffRunners {
+        src_runner,
+        feature_runner,
+    });
+}

check_diff/src/main.rs

@@ -1,4 +1,7 @@
+use check_diff::compile_rustfmt;
 use clap::Parser;
+use tempfile::Builder;
+use tracing::info;
 
 /// Inputs for the check_diff script
 #[derive(Parser)]
@@ -17,5 +20,16 @@ struct CliInputs {
 }
 
 fn main() {
-    let _args = CliInputs::parse();
+    tracing_subscriber::fmt()
+        .with_env_filter(tracing_subscriber::EnvFilter::from_env("CHECK_DIFF_LOG"))
+        .init();
+    let args = CliInputs::parse();
+    let tmp_dir = Builder::new().tempdir_in("").unwrap();
+    info!("Created tmp_dir {:?}", tmp_dir);
+    let _ = compile_rustfmt(
+        tmp_dir.path(),
+        args.remote_repo_url,
+        args.feature_branch,
+        args.commit_hash,
+    );
 }