feat: adding bindings command

Signed-off-by: Andrew Steurer <94206073+asteurer@users.noreply.github.com>

Author: asteurer

Cargo.lock

@@ -13,5 +13,6 @@ clap = { version = "4.5.53", features = ["derive"] }
 regex = "1.12.2"
 url = "2.5.7"
 wat = { version = "1.243.0"}
+wit-bindgen-go = "0.50.0"
 wit-component = "0.243.0"
 wit-parser = "0.243.0"

Cargo.toml

@@ -1,8 +1,8 @@
 generate-bindings:
-	wit-bindgen go --world bindings --out-dir . wit
+	componentize-go --world wasip2-example bindings
 
 build-component: generate-bindings
-	componentize-go --world bindings componentize
+	componentize-go --world wasip2-example componentize
 
 .PHONY: run
 run: build-component

examples/wasip2/Makefile

@@ -4,7 +4,6 @@
 - [**componentize-go**](https://github.com/asteurer/componentize-go) - Latest version
 - [**go**](https://go.dev/dl/) - v1.25+
 - [**wasmtime**](https://github.com/bytecodealliance/wasmtime)  - Latest version
-- [**wit-bindgen**](https://github.com/bytecodealliance/wit-bindgen) - Latest version
 
 ### Run
 ```sh

examples/wasip2/README.md

@@ -1,6 +1,6 @@
 // We actually don't use this; it's just to let bindgen! find the corresponding world in wit/deps.
 package wasmtime:wasi-http;
 
-world bindings {
+world wasip2-example {
   include wasi:http/proxy@0.2.0;
 }

examples/wasip2/wit/world.wit

@@ -5,10 +5,10 @@ $(GO)/bin/go:
 	tar xf $(GO).tbz
 
 generate-bindings:
-	wit-bindgen go --world bindings --out-dir . wit
+	componentize-go --world wasip3-example bindings
 
 build-component: generate-bindings $(GO)/bin/go
-	componentize-go --world bindings componentize --go $(GO)/bin/go
+	componentize-go --world wasip3-example componentize --go $(GO)/bin/go
 
 .PHONY: run
 run: build-component

examples/wasip3/Makefile

@@ -13,9 +13,8 @@ everything is merged, we'll be able to switch to the upstream releases.
 ## Building and Running
 ### Prerequisites
 - [**componentize-go**](https://github.com/asteurer/componentize-go) - Latest version
-- [**go**](https://github.com/dicej/go/releases/tag/go1.25.5-wasi-on-idle) - The Makefile installs this for you
+- [**go**](https://github.com/dicej/go/releases/tag/go1.25.5-wasi-on-idle) - The [Makefile](./Makefile) installs the patched version of Go.
 - [**wasmtime**](https://github.com/bytecodealliance/wasmtime)  - Latest version
-- [**wit-bindgen**](https://github.com/bytecodealliance/wit-bindgen) - Latest version
 
 This will build the dependencies, generate Go bindings from the
 `wasi:http@0.3.0-rc-2025-09-16` WIT files, build the component, and run it using

examples/wasip3/README.md

@@ -1,6 +1,6 @@
 // We actually don't use this; it's just to let bindgen! find the corresponding world in wit/deps.
 package wasmtime:wasi-http;
 
-world bindings {
+world wasip3-example {
   include wasi:http/proxy@0.3.0-rc-2025-09-16;
 }

examples/wasip3/wit/world.wit

@@ -0,0 +1,40 @@
+use crate::common::parse_wit;
+use anyhow::Result;
+use std::path::{Path, PathBuf};
+
+pub fn generate_bindings(
+    wit_path: &[impl AsRef<Path>],
+    world: Option<&str>,
+    features: &[String],
+    all_features: bool,
+    output: Option<&Path>,
+) -> Result<()> {
+    let (resolve, world) = parse_wit(wit_path, world, features, all_features)?;
+    let mut files = Default::default();
+
+    wit_bindgen_go::Opts::default()
+        .build()
+        .generate(&resolve, world, &mut files)?;
+
+    let output_path = match output {
+        Some(p) => {
+            if p.is_relative() {
+                std::env::current_dir()?.join(p)
+            } else {
+                p.to_path_buf()
+            }
+        }
+        None => PathBuf::from("."),
+    };
+
+    for (name, contents) in files.iter() {
+        let file_path = output_path.join(name);
+        if let Some(parent) = file_path.parent() {
+            std::fs::create_dir_all(parent)?;
+        }
+
+        std::fs::write(&file_path, contents)?;
+    }
+
+    Ok(())
+}

src/bindings.rs

@@ -1,4 +1,4 @@
-use crate::componentize;
+use crate::{bindings::generate_bindings, componentize};
 use anyhow::Result;
 use clap::{Parser, Subcommand};
 use std::{ffi::OsString, path::PathBuf};
@@ -48,6 +48,9 @@ pub struct Common {
 pub enum Command {
     /// Build a Go WebAssembly component.
     Componentize(Componentize),
+
+    /// Generate Go bindings for the world.
+    Bindings(Bindings),
 }
 
 #[derive(Parser)]
@@ -69,9 +72,19 @@ pub fn run<T: Into<OsString> + Clone, I: IntoIterator<Item = T>>(args: I) -> Res
     let options = Options::parse_from(args);
     match options.command {
         Command::Componentize(opts) => componentize(options.common, opts),
+        Command::Bindings(opts) => bindings(options.common, opts),
     }
 }
 
+#[derive(Parser)]
+pub struct Bindings {
+    /// Output directory for bindings (or current directory if `None`).
+    ///
+    /// This will be created if it does not already exist.
+    #[arg(long, short = 'o')]
+    pub output: Option<PathBuf>,
+}
+
 fn componentize(common: Common, componentize: Componentize) -> Result<()> {
     // Step 1: Build a WebAssembly core module using Go.
     let core_module = componentize::build_wasm_core_module(
@@ -93,3 +106,13 @@ fn componentize(common: Common, componentize: Componentize) -> Result<()> {
     componentize::core_module_to_component(&core_module)?;
     Ok(())
 }
+
+fn bindings(common: Common, bindings: Bindings) -> Result<()> {
+    generate_bindings(
+        common.wit_path.as_ref(),
+        common.world.as_deref(),
+        &common.features,
+        common.all_features,
+        bindings.output.as_deref(),
+    )
+}