compos: switch to clap's derive pattern

Since clap can handle the string->enum automatically, it's nicer to
avoid the string matching in code.

Bug: 246385183
Test: atest ComposHostTestCases
Change-Id: If127392e375a425821a34dcc644aa46765a5b133
diff --git a/compos/Android.bp b/compos/Android.bp
index 6aa9d3d..ea7c4d6 100644
--- a/compos/Android.bp
+++ b/compos/Android.bp
@@ -13,7 +13,6 @@
         "libandroid_logger",
         "libanyhow",
         "libbinder_rs",
-        "libclap",
         "libcompos_common",
         "liblibc",
         "liblog_rust",
diff --git a/compos/composd_cmd/composd_cmd.rs b/compos/composd_cmd/composd_cmd.rs
index d5feed8..b6d82aa 100644
--- a/compos/composd_cmd/composd_cmd.rs
+++ b/compos/composd_cmd/composd_cmd.rs
@@ -31,30 +31,32 @@
     },
 };
 use anyhow::{bail, Context, Result};
+use clap::Parser;
 use compos_common::timeouts::TIMEOUTS;
 use std::sync::{Arc, Condvar, Mutex};
 use std::time::Duration;
 
+#[derive(Parser)]
+enum Actions {
+    /// Compile classpath for real. Output can be used after a reboot.
+    StagedApexCompile {},
+
+    /// Compile classpath in a debugging VM. Output is ignored.
+    TestCompile {
+        /// If any APEX is staged, prefer the staged version.
+        #[clap(long)]
+        prefer_staged: bool,
+    },
+}
+
 fn main() -> Result<()> {
-    #[rustfmt::skip]
-    let app = clap::App::new("composd_cmd")
-        .subcommand(
-            clap::SubCommand::with_name("staged-apex-compile"))
-        .subcommand(
-            clap::SubCommand::with_name("test-compile")
-                .arg(clap::Arg::with_name("prefer-staged").long("prefer-staged")),
-        );
-    let args = app.get_matches();
+    let action = Actions::parse();
 
     ProcessState::start_thread_pool();
 
-    match args.subcommand() {
-        Some(("staged-apex-compile", _)) => run_staged_apex_compile()?,
-        Some(("test-compile", sub_matches)) => {
-            let prefer_staged = sub_matches.is_present("prefer-staged");
-            run_test_compile(prefer_staged)?;
-        }
-        _ => panic!("Unrecognized subcommand"),
+    match action {
+        Actions::StagedApexCompile {} => run_staged_apex_compile()?,
+        Actions::TestCompile { prefer_staged } => run_test_compile(prefer_staged)?,
     }
 
     println!("All Ok!");
diff --git a/compos/verify/verify.rs b/compos/verify/verify.rs
index 2ece8f5..3abdc74 100644
--- a/compos/verify/verify.rs
+++ b/compos/verify/verify.rs
@@ -20,6 +20,7 @@
 use android_logger::LogId;
 use anyhow::{bail, Context, Result};
 use binder::ProcessState;
+use clap::{Parser, ValueEnum};
 use compos_common::compos_client::{ComposClient, VmParameters};
 use compos_common::odrefresh::{
     CURRENT_ARTIFACTS_SUBDIR, ODREFRESH_OUTPUT_ROOT_DIR, PENDING_ARTIFACTS_SUBDIR,
@@ -37,6 +38,24 @@
 
 const MAX_FILE_SIZE_BYTES: u64 = 100 * 1024;
 
+#[derive(Parser)]
+struct Args {
+    /// Type of the VM instance
+    #[clap(long, value_enum)]
+    instance: Instance,
+
+    /// Starts the VM in debug mode
+    #[clap(long, action)]
+    debug: bool,
+}
+
+#[derive(ValueEnum, Clone)]
+enum Instance {
+    Current,
+    Pending,
+    Test,
+}
+
 fn main() {
     android_logger::init_once(
         android_logger::Config::default()
@@ -57,23 +76,11 @@
 }
 
 fn try_main() -> Result<()> {
-    let matches = clap::App::new("compos_verify")
-        .arg(
-            clap::Arg::with_name("instance")
-                .long("instance")
-                .takes_value(true)
-                .required(true)
-                .possible_values(&["current", "pending", "test"]),
-        )
-        .arg(clap::Arg::with_name("debug").long("debug"))
-        .get_matches();
-
-    let debug_mode = matches.is_present("debug");
-    let (instance_dir, artifacts_dir) = match matches.value_of("instance").unwrap() {
-        "current" => (CURRENT_INSTANCE_DIR, CURRENT_ARTIFACTS_SUBDIR),
-        "pending" => (CURRENT_INSTANCE_DIR, PENDING_ARTIFACTS_SUBDIR),
-        "test" => (TEST_INSTANCE_DIR, TEST_ARTIFACTS_SUBDIR),
-        _ => unreachable!("Unexpected instance name"),
+    let args = Args::parse();
+    let (instance_dir, artifacts_dir) = match args.instance {
+        Instance::Current => (CURRENT_INSTANCE_DIR, CURRENT_ARTIFACTS_SUBDIR),
+        Instance::Pending => (CURRENT_INSTANCE_DIR, PENDING_ARTIFACTS_SUBDIR),
+        Instance::Test => (TEST_INSTANCE_DIR, TEST_ARTIFACTS_SUBDIR),
     };
 
     let instance_dir = Path::new(COMPOS_DATA_ROOT).join(instance_dir);
@@ -104,7 +111,7 @@
         instance_image,
         &idsig,
         &idsig_manifest_apk,
-        &VmParameters { debug_mode, ..Default::default() },
+        &VmParameters { debug_mode: args.debug, ..Default::default() },
     )?;
 
     let service = vm_instance.connect_service()?;