feat(anvil): add shell completions subcommand

anvil/Cargo.toml

@@ -63,6 +63,7 @@ clap = { version = "3.0.10", features = [
     "env",
     "wrap_help",
 ], optional = true }
+clap_complete =  { version = "3.0.4", optional = true }
 async-trait = "0.1.53"
 chrono = "0.4.19"
 auto_impl = "0.5.0"
@@ -77,5 +78,5 @@ tokio = { version = "1", features = ["full"] }
 
 [features]
 default = ["cli"]
-cmd = ["foundry-common", "forge", "clap", "ctrlc", "anvil-server/clap"]
+cmd = ["foundry-common", "forge", "clap", "clap_complete", "ctrlc", "anvil-server/clap"]
 cli = ["tokio/full", "cmd", "fdlimit"]

anvil/src/anvil.rs

@@ -1,18 +1,45 @@
 //! The `anvil` cli
 use anvil::cmd::NodeArgs;
-use clap::Parser;
+use clap::{CommandFactory, Parser, Subcommand};
 
 /// A fast local Ethereum development node.
 #[derive(Debug, Parser)]
 #[clap(name = "anvil", version = anvil::VERSION_MESSAGE)]
 pub struct App {
     #[clap(flatten)]
     pub node: NodeArgs,
+
+    #[clap(subcommand)]
+    pub cmd: Option<Commands>,
+}
+
+#[derive(Clone, Debug, Subcommand)]
+pub enum Commands {
+    #[clap(visible_alias = "com", about = "Generate shell completions script.")]
+    Completions {
+        #[clap(arg_enum)]
+        shell: clap_complete::Shell,
+    },
 }
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let app = App::parse();
+
+    if let Some(ref cmd) = app.cmd {
+        match cmd {
+            Commands::Completions { shell } => {
+                clap_complete::generate(
+                    *shell,
+                    &mut App::command(),
+                    "anvil",
+                    &mut std::io::stdout(),
+                );
+            }
+        }
+        return Ok(())
+    }
+
     let _ = fdlimit::raise_fd_limit();
     app.node.run().await?;