Add ruff version with long version display (#8034)

Adds a new `ruff version` sub-command which displays long version
information in the style of `cargo` and `rustc`. We include the number
of commits since the last release tag if its a development build, in the
style of Python's versioneer.

```
❯ ruff version
ruff 0.1.0+14 (947940e91 2023-10-18)
```

```
❯ ruff version --output-format json
{
  "version": "0.1.0",
  "commit_info": {
    "short_commit_hash": "947940e91",
    "commit_hash": "947940e91269f20f6b3f8f8c7c63f8e914680e80",
    "commit_date": "2023-10-18",
    "last_tag": "v0.1.0",
    "commits_since_last_tag": 14
  }
}%
```

```
❯ cargo version
cargo 1.72.1 (103a7ff2e 2023-08-15)
```
## Test plan

I've tested this manually locally, but want to at least add unit tests
for the message formatting. We'd also want to check the next release to
ensure the information is correct.

I checked build behavior with a detached head and branches.

## Future work

We could include rustc and cargo versions from the build, the current
Python version, and other diagnostic information for bug reports.

The `--version` and `-V` output is unchanged. However, we could update
it to display the long ruff version without the rust and cargo versions
(this is what cargo does). We'll need to be careful to ensure this does
not break downstream packages which parse our version string.

```
❯ ruff --version
ruff 0.1.0
```

The LSP should be updated to use `ruff version --output-format json`
instead of parsing `ruff --version`.

crates/ruff_cli/Cargo.toml

@@ -66,7 +66,7 @@ wild = { version = "2" }
 assert_cmd = { version = "2.0.8" }
 # Avoid writing colored snapshots when running tests from the terminal
 colored = { workspace = true, features = ["no-color"]}
-insta = { workspace = true, features = ["filters"] }
+insta = { workspace = true, features = ["filters", "json"] }
 insta-cmd = { version = "0.4.0" }
 tempfile = "3.6.0"
 test-case = { workspace = true }

crates/ruff_cli/build.rs

@@ -0,0 +1,80 @@
+use std::{fs, path::Path, process::Command};
+
+fn main() {
+    // The workspace root directory is not available without walking up the tree
+    // https://github.com/rust-lang/cargo/issues/3946
+    let workspace_root = Path::new(&std::env::var("CARGO_MANIFEST_DIR").unwrap())
+        .join("..")
+        .join("..");
+
+    commit_info(&workspace_root);
+
+    #[allow(clippy::disallowed_methods)]
+    let target = std::env::var("TARGET").unwrap();
+    println!("cargo:rustc-env=RUST_HOST_TARGET={target}");
+}
+
+fn commit_info(workspace_root: &Path) {
+    // If not in a git repository, do not attempt to retrieve commit information
+    let git_dir = workspace_root.join(".git");
+    if !git_dir.exists() {
+        return;
+    }
+
+    let git_head_path = git_dir.join("HEAD");
+    println!(
+        "cargo:rerun-if-changed={}",
+        git_head_path.as_path().display()
+    );
+
+    let git_head_contents = fs::read_to_string(git_head_path);
+    if let Ok(git_head_contents) = git_head_contents {
+        // The contents are either a commit or a reference in the following formats
+        // - "<commit>" when the head is detached
+        // - "ref <ref>" when working on a branch
+        // If a commit, checking if the HEAD file has changed is sufficient
+        // If a ref, we need to add the head file for that ref to rebuild on commit
+        let mut git_ref_parts = git_head_contents.split_whitespace();
+        git_ref_parts.next();
+        if let Some(git_ref) = git_ref_parts.next() {
+            let git_ref_path = git_dir.join(git_ref);
+            println!(
+                "cargo:rerun-if-changed={}",
+                git_ref_path.as_path().display()
+            );
+        }
+    }
+
+    let output = match Command::new("git")
+        .arg("log")
+        .arg("-1")
+        .arg("--date=short")
+        .arg("--abbrev=9")
+        .arg("--format=%H %h %cd %(describe)")
+        .output()
+    {
+        Ok(output) if output.status.success() => output,
+        _ => return,
+    };
+    let stdout = String::from_utf8(output.stdout).unwrap();
+    let mut parts = stdout.split_whitespace();
+    let mut next = || parts.next().unwrap();
+    println!("cargo:rustc-env=RUFF_COMMIT_HASH={}", next());
+    println!("cargo:rustc-env=RUFF_COMMIT_SHORT_HASH={}", next());
+    println!("cargo:rustc-env=RUFF_COMMIT_DATE={}", next());
+
+    // Describe can fail for some commits
+    // https://git-scm.com/docs/pretty-formats#Documentation/pretty-formats.txt-emdescribeoptionsem
+    if let Some(describe) = parts.next() {
+        let mut describe_parts = describe.split('-');
+        println!(
+            "cargo:rustc-env=RUFF_LAST_TAG={}",
+            describe_parts.next().unwrap()
+        );
+        // If this is the tagged commit, this component will be missing
+        println!(
+            "cargo:rustc-env=RUFF_LAST_TAG_DISTANCE={}",
+            describe_parts.next().unwrap_or("0")
+        );
+    }
+}

crates/ruff_cli/src/args.rs

@@ -69,6 +69,11 @@ pub enum Command {
     #[doc(hidden)]
     #[clap(hide = true)]
     Format(FormatCommand),
+    /// Display Ruff's version
+    Version {
+        #[arg(long, value_enum, default_value = "text")]
+        output_format: HelpFormat,
+    },
 }
 
 // The `Parser` derive is for ruff_dev, for ruff_cli `Args` would be sufficient

crates/ruff_cli/src/commands/mod.rs

@@ -9,3 +9,4 @@ pub(crate) mod linter;
 pub(crate) mod rule;
 pub(crate) mod show_files;
 pub(crate) mod show_settings;
+pub(crate) mod version;

crates/ruff_cli/src/commands/version.rs

@@ -0,0 +1,21 @@
+use std::io::{self, BufWriter, Write};
+
+use anyhow::Result;
+
+use crate::args::HelpFormat;
+
+/// Display version information
+pub(crate) fn version(output_format: HelpFormat) -> Result<()> {
+    let mut stdout = BufWriter::new(io::stdout().lock());
+    let version_info = crate::version::version();
+
+    match output_format {
+        HelpFormat::Text => {
+            writeln!(stdout, "ruff {}", &version_info)?;
+        }
+        HelpFormat::Json => {
+            serde_json::to_writer_pretty(stdout, &version_info)?;
+        }
+    };
+    Ok(())
+}

crates/ruff_cli/src/lib.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::print_stdout)]
+
 use std::fs::File;
 use std::io::{self, stdout, BufWriter, Write};
 use std::path::{Path, PathBuf};
@@ -27,6 +29,7 @@ mod panic;
 mod printer;
 pub mod resolve;
 mod stdin;
+mod version;
 
 #[derive(Copy, Clone)]
 pub enum ExitStatus {
@@ -134,6 +137,10 @@ pub fn run(
     set_up_logging(&log_level)?;
 
     match command {
+        Command::Version { output_format } => {
+            commands::version::version(output_format)?;
+            Ok(ExitStatus::Success)
+        }
         Command::Rule { rule, all, format } => {
             if all {
                 commands::rule::rules(format)?;

crates/ruff_cli/src/snapshots/ruff_cli__version__tests__version_formatting.snap

@@ -0,0 +1,5 @@
+---
+source: crates/ruff_cli/src/version.rs
+expression: version
+---
+0.0.0

crates/ruff_cli/src/snapshots/ruff_cli__version__tests__version_formatting_with_commit_info.snap

@@ -0,0 +1,5 @@
+---
+source: crates/ruff_cli/src/version.rs
+expression: version
+---
+0.0.0 (53b0f5d92 2023-10-19)

crates/ruff_cli/src/snapshots/ruff_cli__version__tests__version_formatting_with_commits_since_last_tag.snap

@@ -0,0 +1,5 @@
+---
+source: crates/ruff_cli/src/version.rs
+expression: version
+---
+0.0.0+24 (53b0f5d92 2023-10-19)

crates/ruff_cli/src/snapshots/ruff_cli__version__tests__version_serializable.snap

@@ -0,0 +1,14 @@
+---
+source: crates/ruff_cli/src/version.rs
+expression: version
+---
+{
+  "version": "0.0.0",
+  "commit_info": {
+    "short_commit_hash": "53b0f5d92",
+    "commit_hash": "53b0f5d924110e5b26fbf09f6fd3a03d67b475b7",
+    "commit_date": "2023-10-19",
+    "last_tag": "v0.0.1",
+    "commits_since_last_tag": 0
+  }
+}

crates/ruff_cli/src/version.rs

@@ -0,0 +1,130 @@
+//! Code for representing Ruff's release version number.
+use serde::Serialize;
+use std::fmt;
+
+/// Information about the git repository where Ruff was built from.
+#[derive(Serialize)]
+pub(crate) struct CommitInfo {
+    short_commit_hash: String,
+    commit_hash: String,
+    commit_date: String,
+    last_tag: Option<String>,
+    commits_since_last_tag: u32,
+}
+
+/// Ruff's version.
+#[derive(Serialize)]
+pub(crate) struct VersionInfo {
+    /// Ruff's version, such as "0.5.1"
+    version: String,
+    /// Information about the git commit we may have been built from.
+    ///
+    /// `None` if not built from a git repo or if retrieval failed.
+    commit_info: Option<CommitInfo>,
+}
+
+impl fmt::Display for VersionInfo {
+    /// Formatted version information: "<version>[+<commits>] (<commit> <date>)"
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.version)?;
+
+        if let Some(ref ci) = self.commit_info {
+            if ci.commits_since_last_tag > 0 {
+                write!(f, "+{}", ci.commits_since_last_tag)?;
+            }
+            write!(f, " ({} {})", ci.short_commit_hash, ci.commit_date)?;
+        }
+
+        Ok(())
+    }
+}
+
+/// Returns information about Ruff's version.
+pub(crate) fn version() -> VersionInfo {
+    // Environment variables are only read at compile-time
+    macro_rules! option_env_str {
+        ($name:expr) => {
+            option_env!($name).map(|s| s.to_string())
+        };
+    }
+
+    // This version is pulled from Cargo.toml and set by Cargo
+    let version = option_env_str!("CARGO_PKG_VERSION").unwrap();
+
+    // Commit info is pulled from git and set by `build.rs`
+    let commit_info = option_env_str!("RUFF_COMMIT_HASH").map(|commit_hash| CommitInfo {
+        short_commit_hash: option_env_str!("RUFF_COMMIT_SHORT_HASH").unwrap(),
+        commit_hash,
+        commit_date: option_env_str!("RUFF_COMMIT_DATE").unwrap(),
+        last_tag: option_env_str!("RUFF_LAST_TAG"),
+        commits_since_last_tag: option_env_str!("RUFF_LAST_TAG_DISTANCE")
+            .as_deref()
+            .map_or(0, |value| value.parse::<u32>().unwrap_or(0)),
+    });
+
+    VersionInfo {
+        version,
+        commit_info,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use insta::{assert_display_snapshot, assert_json_snapshot};
+
+    use super::{CommitInfo, VersionInfo};
+
+    #[test]
+    fn version_formatting() {
+        let version = VersionInfo {
+            version: "0.0.0".to_string(),
+            commit_info: None,
+        };
+        assert_display_snapshot!(version);
+    }
+
+    #[test]
+    fn version_formatting_with_commit_info() {
+        let version = VersionInfo {
+            version: "0.0.0".to_string(),
+            commit_info: Some(CommitInfo {
+                short_commit_hash: "53b0f5d92".to_string(),
+                commit_hash: "53b0f5d924110e5b26fbf09f6fd3a03d67b475b7".to_string(),
+                last_tag: Some("v0.0.1".to_string()),
+                commit_date: "2023-10-19".to_string(),
+                commits_since_last_tag: 0,
+            }),
+        };
+        assert_display_snapshot!(version);
+    }
+
+    #[test]
+    fn version_formatting_with_commits_since_last_tag() {
+        let version = VersionInfo {
+            version: "0.0.0".to_string(),
+            commit_info: Some(CommitInfo {
+                short_commit_hash: "53b0f5d92".to_string(),
+                commit_hash: "53b0f5d924110e5b26fbf09f6fd3a03d67b475b7".to_string(),
+                last_tag: Some("v0.0.1".to_string()),
+                commit_date: "2023-10-19".to_string(),
+                commits_since_last_tag: 24,
+            }),
+        };
+        assert_display_snapshot!(version);
+    }
+
+    #[test]
+    fn version_serializable() {
+        let version = VersionInfo {
+            version: "0.0.0".to_string(),
+            commit_info: Some(CommitInfo {
+                short_commit_hash: "53b0f5d92".to_string(),
+                commit_hash: "53b0f5d924110e5b26fbf09f6fd3a03d67b475b7".to_string(),
+                last_tag: Some("v0.0.1".to_string()),
+                commit_date: "2023-10-19".to_string(),
+                commits_since_last_tag: 0,
+            }),
+        };
+        assert_json_snapshot!(version);
+    }
+}