Use structopt instead of docopt.

This commit refactors the Wasmtime CLI tools to use `structopt` instead of
`docopt`.

The `wasmtime` tool now has the following subcommands:

* `config new` - creates a new Wasmtime configuration file.
* `run` - runs a WebAssembly module.
* `wasm2obj` - translates a Wasm module to native object file.
* `wast` - runs a test script file.

If no subcommand is specified, the `run` subcommand is used. Thus,
`wasmtime foo.wasm` should continue to function as expected.

The `wasm2obj` and `wast` tools still exist, but delegate to the same
implementation as the `wasmtime` subcommands.  The standalone `wasm2obj` and
`wast` tools may be removed in the future in favor of simply using `wasmtime`.

Included in this commit is a breaking change to the default Wasmtime
configuration file: it has been renamed from `wasmtime-cache-config.toml` to
simply `config.toml`.  The new name is less specific which will allow for
additional (non-cache-related) settings in the future.

There are some breaking changes to improve command line UX:

* The `--cache-config` option has been renamed to `--config`.
* The `--create-config-file` option has moved to the `config new` subcommand.
As a result, the `wasm2obj` and `wast` tools cannot be used to create a new
config file.
* The short form of the `--optimize` option has changed from
`-o` to `-O` for consistency.
* The `wasm2obj` command takes the output object file as a
required positional argument rather than the former required output *option*
(e.g. `wasmtime wasm2obj foo.wasm foo.obj`).

src/bin/wast.rs

@@ -1,148 +1,12 @@
-//! CLI tool to run wast tests using the wasmtime libraries.
+//! The `wast` command line tool.
+//!
+//! Runs WebAssembly test script files.
+//! See `wast --help` for usage.
 
-#![deny(
-    missing_docs,
-    trivial_numeric_casts,
-    unused_extern_crates,
-    unstable_features
-)]
-#![warn(unused_import_braces)]
-#![cfg_attr(feature = "clippy", plugin(clippy(conf_file = "../../clippy.toml")))]
-#![cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default))]
-#![cfg_attr(
-    feature = "cargo-clippy",
-    warn(
-        clippy::float_arithmetic,
-        clippy::mut_mut,
-        clippy::nonminimal_bool,
-        clippy::option_map_unwrap_or,
-        clippy::option_map_unwrap_or_else,
-        clippy::unicode_not_nfc,
-        clippy::use_self
-    )
-)]
-
-use anyhow::{Context, Result};
-use docopt::Docopt;
-use serde::Deserialize;
-use std::path::Path;
-use std::process;
-use wasmtime::{Config, Engine, HostRef, Store};
-use wasmtime_cli::pick_compilation_strategy;
-use wasmtime_environ::{cache_create_new_config, cache_init};
-use wasmtime_wast::WastContext;
-
-const USAGE: &str = "
-Wast test runner.
-
-Usage:
-    wast [-do] [--enable-simd] [--disable-cache | --cache-config=<cache_config_file>] [--lightbeam \
-                     | --cranelift] <file>...
-    wast --create-cache-config [--cache-config=<cache_config_file>]
-    wast --help | --version
-
-Options:
-    -h, --help          print this help message
-    --version           print the Cranelift version
-    -o, --optimize      runs optimization passes on the translated functions
-    --disable-cache     disables cache system
-    --cache-config=<cache_config_file>
-                        use specified cache configuration;
-                        can be used with --create-cache-config to specify custom file
-    --create-cache-config
-                        creates default configuration and writes it to the disk,
-                        use with --cache-config to specify custom config file
-                        instead of default one
-    --lightbeam         use Lightbeam for all compilation
-    --cranelift         use Cranelift for all compilation
-    -d, --debug         enable debug output on stderr/stdout
-    --enable-simd       enable proposed SIMD instructions
-";
-
-#[derive(Deserialize, Debug, Clone)]
-struct Args {
-    arg_file: Vec<String>,
-    flag_debug: bool,
-    flag_function: Option<String>,
-    flag_optimize: bool,
-    flag_disable_cache: bool,
-    flag_cache_config: Option<String>,
-    flag_create_cache_config: bool,
-    flag_enable_simd: bool,
-    flag_lightbeam: bool,
-    flag_cranelift: bool,
-}
+use anyhow::Result;
+use structopt::StructOpt;
+use wasmtime_cli::commands::WastCommand;
 
 fn main() -> Result<()> {
-    let version = env!("CARGO_PKG_VERSION");
-    let args: Args = Docopt::new(USAGE)
-        .and_then(|d| {
-            d.help(true)
-                .version(Some(String::from(version)))
-                .deserialize()
-        })
-        .unwrap_or_else(|e| e.exit());
-
-    let log_config = if args.flag_debug {
-        pretty_env_logger::init();
-        None
-    } else {
-        let prefix = "cranelift.dbg.";
-        wasmtime_cli::init_file_per_thread_logger(prefix);
-        Some(prefix)
-    };
-
-    if args.flag_create_cache_config {
-        let path = cache_create_new_config(args.flag_cache_config)?;
-        println!(
-            "Successfully created new configuation file at {}",
-            path.display()
-        );
-        return Ok(());
-    }
-
-    let errors = cache_init(
-        !args.flag_disable_cache,
-        args.flag_cache_config.as_ref(),
-        log_config,
-    );
-
-    if !errors.is_empty() {
-        eprintln!("Cache initialization failed. Errors:");
-        for e in errors {
-            eprintln!("-> {}", e);
-        }
-        process::exit(1);
-    }
-
-    let mut cfg = Config::new();
-    // Enable verifier passes in debug mode.
-    cfg.cranelift_debug_verifier(cfg!(debug_assertions));
-
-    // Enable optimization if requested.
-    if args.flag_optimize {
-        cfg.cranelift_opt_level(wasmtime::OptLevel::Speed);
-    }
-
-    // Enable SIMD if requested
-    if args.flag_enable_simd {
-        cfg.wasm_simd(true);
-    }
-
-    // Decide how to compile.
-    cfg.strategy(pick_compilation_strategy(
-        args.flag_cranelift,
-        args.flag_lightbeam,
-    )?)?;
-    let store = HostRef::new(Store::new(&Engine::new(&cfg)));
-    let mut wast_context = WastContext::new(store);
-
-    wast_context
-        .register_spectest()
-        .context("error instantiating \"spectest\"")?;
-
-    for filename in &args.arg_file {
-        wast_context.run_file(Path::new(&filename))?;
-    }
-    Ok(())
+    WastCommand::from_args().execute()
 }