Add a wasmtime completion subcommand

This commit adds a new subcommand to the `wasmtime` CLI which can be
used to generate shell completions for the `wasmtime` version that is
installed. This is relatively easy to do with the `clap_complete` crate
which is also used with various other clap-based CLIs in Rust to
generate completions.

Cargo.toml

@@ -58,6 +58,7 @@ wasmtime-wasi-keyvalue = { workspace = true, optional = true }
 wasmtime-wasi-threads = { workspace = true, optional = true }
 wasmtime-wasi-http = { workspace = true, optional = true }
 clap = { workspace = true }
+clap_complete = { workspace = true, optional = true }
 anyhow = { workspace = true, features = ['std'] }
 target-lexicon = { workspace = true }
 once_cell = { workspace = true }
@@ -288,6 +289,7 @@ windows-sys = "0.59.0"
 env_logger = "0.11.5"
 log = { version = "0.4.8", default-features = false }
 clap = { version = "4.5.17", default-features = false, features = ["std", "derive"] }
+clap_complete = "4.4.7"
 hashbrown = { version = "0.14", default-features = false }
 capstone = "0.12.0"
 once_cell = { version = "1.12.0", default-features = false }
@@ -360,6 +362,7 @@ default = [
  "serve",
  "wast",
  "config",
+ "completion",
 
  # On-by-default WASI features
  "wasi-nn",
@@ -456,6 +459,7 @@ run = [
  "dep:tokio",
  "wasmtime-cli-flags/async",
 ]
+completion = ["dep:clap_complete"]
 
 [[test]]
 name = "host_segfault"

src/bin/wasmtime.rs

@@ -4,10 +4,10 @@
 //! See `wasmtime --help` for usage.
 
 use anyhow::Result;
-use clap::Parser;
+use clap::{CommandFactory, Parser};
 
 /// Wasmtime WebAssembly Runtime
-#[derive(Parser, PartialEq)]
+#[derive(Parser)]
 #[command(
  name = "wasmtime",
  version = version(),
@@ -52,7 +52,7 @@ fn version() -> &'static str {
  option_env!("WASMTIME_VERSION_INFO").unwrap_or(env!("CARGO_PKG_VERSION"))
 }
 
-#[derive(Parser, PartialEq)]
+#[derive(Parser)]
 enum Subcommand {
  /// Runs a WebAssembly module
  #[cfg(feature = "run")]
@@ -81,6 +81,10 @@ enum Subcommand {
  /// Runs a WebAssembly test script file
  #[cfg(feature = "wast")]
  Wast(wasmtime_cli::commands::WastCommand),
+
+ /// Generate shell completions for the `wasmtime` CLI
+ #[cfg(feature = "completion")]
+ Completion(CompletionCommand),
 }
 
 impl Wasmtime {
@@ -112,10 +116,42 @@ impl Wasmtime {
 
  #[cfg(feature = "wast")]
  Subcommand::Wast(c) => c.execute(),
+
+ #[cfg(feature = "completion")]
+ Subcommand::Completion(c) => c.execute(),
  }
  }
 }
 
+/// Generate shell completion scripts for this CLI.
+///
+/// Shells have different paths for their completion scripts. Please refer to
+/// their documentation. For example, to generate completions for the fish
+/// shell, run the following command below:
+///
+/// wasmtime completion fish > ~/.config/fish/completions/wasmtime.fish
+///
+/// For a shell like zsh you can add this to your .zshrc or startup scripts:
+///
+/// eval "$(wasmtime completion zsh)"
+#[derive(Parser)]
+#[cfg(feature = "completion")]
+pub struct CompletionCommand {
+ /// The shell to generate completions for.
+ shell: clap_complete::Shell,
+}
+
+#[cfg(feature = "completion")]
+impl CompletionCommand {
+ pub fn execute(&self) -> Result<()> {
+ let mut cmd = Wasmtime::command();
+ let cli_name = cmd.get_name().to_owned();
+
+ clap_complete::generate(self.shell, &mut cmd, cli_name, &mut std::io::stdout());
+ Ok(())
+ }
+}
+
 fn main() -> Result<()> {
  return Wasmtime::parse().execute();
 }

supply-chain/audits.toml

@@ -3814,6 +3814,12 @@ user-id = 6743 # Ed Page (epage)
 start = "2023-03-28"
 end = "2025-09-20"
 
+[[trusted.clap_complete]]
+criteria = "safe-to-deploy"
+user-id = 6743 # Ed Page (epage)
+start = "2021-12-31"
+end = "2025-09-25"
+
 [[trusted.clap_derive]]
 criteria = "safe-to-deploy"
 user-id = 6743 # Ed Page (epage)

supply-chain/imports.lock

@@ -815,6 +815,13 @@ user-id = 6743
 user-login = "epage"
 user-name = "Ed Page"
 
+[[publisher.clap_complete]]
+version = "4.5.28"
+when = "2024-09-17"
+user-id = 6743
+user-login = "epage"
+user-name = "Ed Page"
+
 [[publisher.clap_derive]]
 version = "4.3.12"
 when = "2023-07-14"