[WIP] Introduce wasm-opt

src/command/build.rs

@@ -1,4 +1,5 @@
 use bindgen;
+use opt;
 use build;
 use command::utils::{create_pkg_dir, set_crate_path};
 use emoji;
@@ -245,4 +246,18 @@ impl Build {
         );
         Ok(())
     }
+
+    fn step_run_wasm_opt(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+        info!(&log, "Optimizing the wasm bindings...");
+        opt::run_wasm_opt(
+            &self.crate_path,
+            &self.crate_name,
+            &self.build_config.opt_passes(),
+        )?;
+        info!(
+            &log,
+            "wasm bindings were optimized at {:#?}.",
+            &self.crate_path.join("pkg")
+        );
+    }
 }

src/opt.rs

@@ -0,0 +1,64 @@
+//! Functionality related to checking and running `wasm-opt`.
+
+use emoji;
+use error::Error;
+use progressbar::Step;
+use std::path::Path;
+use std::process::Command;
+use PBAR;
+use manifest::BuildConfig;
+
+/// Check the `wasm-opt` CLI.
+fn check_install_wasm_opt(step: &Step) -> Result<(), Error> {
+    let msg = format!("{}Checking WASM-opt...", emoji::DOWN_ARROW);
+    PBAR.step(step, &msg);
+    // check whether `wasm-opt` is installed.
+    let output = Command::new("command")
+        .args(&["-v", "wasm-opt"])
+        .output()?;
+    if !output.status.success() {
+        let s = String::from_utf8_lossy(&output.stderr);
+        if s.contains("No such file") {
+            Error::cli(
+                "wasm-opt isn't installed. \
+                please follow the build instruction in \
+                https://github.com/WebAssembly/binaryen#binaryen",
+                s
+            )
+        }
+    } else {
+        Ok(())
+    }
+}
+
+/// Run the `wasm-bindgen` CLI to optimize the current crate's `.wasm`.
+pub fn run_wasm_opt(
+    path: &Path,
+    name: &str,
+    build_config: &BuildConfig,
+    step: &Step,
+) -> Result<(), Error> {
+    check_install_wasm_opt(step)?;
+
+    let msg = format!("{}Running WASM-opt...", emoji::RUNNER);
+    PBAR.step(step, &msg);
+    let binary_name = name.replace("-", "_");
+    let release_or_debug = if debug { "debug" } else { "release" };
+    let wasm_path = format!(
+        "target/wasm32-unknown-unknown/{}/{}.wasm",
+        release_or_debug, binary_name
+    );
+
+    let output = Command::new("wasm-opt")
+        .current_dir(path)
+        .arg(&wasm_path)
+        // FIXME(csmoe): opt_passes() needs to be supported at upper buildconfig.
+        .args(build_config.opt_passes())
+        .output()?;
+    if !output.status.success() {
+        let s = String::from_utf8_lossy(&output.stderr);
+        Error::cli("wasm-opt failed to execute properly", s)
+    } else {
+        Ok(())
+    }
+}