Add .gitignore to .ruff_cache (#208)

src/cache.rs

@@ -1,8 +1,10 @@
 use std::collections::hash_map::DefaultHasher;
-use std::fs::Metadata;
+use std::fs::{File, Metadata};
 use std::hash::{Hash, Hasher};
+use std::io::Write;
 use std::path::Path;
 
+use anyhow::Result;
 use cacache::Error::EntryNotFound;
 use filetime::FileTime;
 use log::error;
@@ -83,6 +85,15 @@ fn cache_key(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> String
     )
 }
 
+pub fn init() -> Result<()> {
+    let gitignore_path = Path::new(cache_dir()).join(".gitignore");
+    if gitignore_path.exists() {
+        return Ok(());
+    }
+    let mut file = File::create(gitignore_path)?;
+    file.write_all(b"*").map_err(|e| e.into())
+}
+
 pub fn get(
     path: &Path,
     metadata: &Metadata,

src/lib.rs

@@ -2,7 +2,7 @@ extern crate core;
 
 mod ast;
 mod autofix;
-mod cache;
+pub mod cache;
 pub mod check_ast;
 mod check_lines;
 pub mod checks;

src/main.rs

@@ -12,6 +12,7 @@ use notify::{raw_watcher, RecursiveMode, Watcher};
 use rayon::prelude::*;
 use walkdir::DirEntry;
 
+use ::ruff::cache;
 use ::ruff::checks::CheckCode;
 use ::ruff::checks::CheckKind;
 use ::ruff::fs::iter_python_files;
@@ -168,6 +169,8 @@ fn inner_main() -> Result<ExitCode> {
         settings.extend_exclude = cli.extend_exclude;
     }
 
+    cache::init()?;
+
     if cli.watch {
         if cli.fix {
             println!("Warning: --fix is not enabled in watch mode.");