automatically download appropriate Go version when necessary

There are three scenarios where we might need to do this:

- Go is not installed at all
- Go is installed, but the version is too old
- Go is installed and the version is new enough, but the target world uses async features and the installed Go lacks [the required patch](golang/go#76775)

In any of those cases, we'll download a suitable version, install it in the
current user's cache directory, and run it from there.

This also adds a new `--export-pkg-name` parameter corresponding to
bytecodealliance/wit-bindgen#1572.

Author: dicej

Cargo.lock

@@ -13,6 +13,10 @@ members = ["./tests"]
 
 [workspace.dependencies]
 anyhow = "1.0.102"
+bzip2 = "0.6.1"
+once_cell = "1.21.3"
+reqwest = { version = "0.13.1", features = ["blocking"] }
+tar = "0.4"
 
 [workspace.package]
 version = "0.2.0"
@@ -34,11 +38,19 @@ unnecessary_cast = 'warn'
 allow_attributes_without_reason = 'warn'
 
 [dependencies]
-anyhow = { workspace = true}
+anyhow = { workspace = true }
+bzip2 = { workspace = true }
+reqwest = { workspace = true }
+tar = { workspace = true }
 clap = { version = "4.5.60", features = ["derive"] }
 regex = "1.12.3"
 serde = { version = "1.0.228", features = ["derive"] }
 toml = "1.1.0"
-wit-bindgen-go = { git = "https://github.com/bytecodealliance/wit-bindgen", rev = "3ee9fe20a5bce398360d5d291e81a4224a6d7c76" }
+# TODO: Switch back to upstream once
+# https://github.com/bytecodealliance/wit-bindgen/pull/1572 is merged:
+wit-bindgen-go = { git = "https://github.com/dicej/wit-bindgen", rev = "b163b3b5" }
 wit-component = "0.245.1"
 wit-parser = "0.245.1"
+which = "8.0.2"
+dirs = "6.0.0"
+

Cargo.toml

@@ -1,20 +1,18 @@
-use crate::utils::{make_path_absolute, parse_wit};
+use crate::utils::make_path_absolute;
 use anyhow::Result;
 use std::path::{Path, PathBuf};
+use wit_parser::{Resolve, WorldId};
 
 #[allow(clippy::too_many_arguments)]
 pub fn generate_bindings(
-    paths: &[impl AsRef<Path>],
-    worlds: &[String],
-    ignore_toml_files: bool,
-    features: &[String],
-    all_features: bool,
+    resolve: &mut Resolve,
+    world: WorldId,
     generate_stubs: bool,
     should_format: bool,
     output: Option<&Path>,
     pkg_name: Option<String>,
+    export_pkg_name: Option<String>,
 ) -> Result<()> {
-    let (mut resolve, world) = parse_wit(paths, worlds, ignore_toml_files, features, all_features)?;
     let mut files = Default::default();
 
     let format = if should_format {
@@ -37,13 +35,14 @@ pub fn generate_bindings(
         generate_stubs,
         format,
         pkg_name,
+        export_pkg_name,
         ..Default::default()
     }
     .build()
-    .generate(&mut resolve, world, &mut files)?;
+    .generate(resolve, world, &mut files)?;
 
     let output_path = match output {
-        Some(p) => make_path_absolute(&p.to_path_buf())?,
+        Some(p) => make_path_absolute(p)?,
         None => PathBuf::from("."),
     };
 

src/cmd_bindings.rs

@@ -1,22 +1,16 @@
 use crate::utils::{check_go_version, make_path_absolute};
 use anyhow::{Result, anyhow};
-use std::{path::PathBuf, process::Command};
+use std::{
+    path::{Path, PathBuf},
+    process::Command,
+};
 
 /// Compiles a Go application to a wasm module with `go build`.
 ///
 /// If the module is not going to be adapted to the component model,
 /// set the `only_wasip1` arg to true.
-pub fn build_module(
-    out: Option<&PathBuf>,
-    go_path: Option<&PathBuf>,
-    only_wasip1: bool,
-) -> Result<PathBuf> {
-    let go = match &go_path {
-        Some(p) => make_path_absolute(p)?,
-        None => PathBuf::from("go"),
-    };
-
-    check_go_version(&go)?;
+pub fn build_module(out: Option<&PathBuf>, go: &Path, only_wasip1: bool) -> Result<PathBuf> {
+    check_go_version(go)?;
 
     let out_path_buf = match &out {
         Some(p) => make_path_absolute(p)?,
@@ -53,13 +47,13 @@ pub fn build_module(
     ];
 
     let output = if only_wasip1 {
-        Command::new(&go)
+        Command::new(go)
             .args(module_args)
             .env("GOOS", "wasip1")
             .env("GOARCH", "wasm")
             .output()?
     } else {
-        Command::new(&go)
+        Command::new(go)
             .args(component_args)
             .env("GOOS", "wasip1")
             .env("GOARCH", "wasm")

src/cmd_build.rs

@@ -12,15 +12,10 @@ use std::{
 pub fn build_test_module(
     path: &Path,
     output_dir: Option<&PathBuf>,
-    go_path: Option<&PathBuf>,
+    go: &Path,
     only_wasip1: bool,
 ) -> Result<PathBuf> {
-    let go = match &go_path {
-        Some(p) => make_path_absolute(p)?,
-        None => PathBuf::from("go"),
-    };
-
-    check_go_version(&go)?;
+    check_go_version(go)?;
 
     let test_wasm_path = {
         // The directory in which the test component will be placed
@@ -68,7 +63,7 @@ pub fn build_test_module(
     ];
 
     let output = if only_wasip1 {
-        Command::new(&go)
+        Command::new(go)
             .args(module_args)
             .env("GOOS", "wasip1")
             .env("GOARCH", "wasm")
@@ -80,7 +75,7 @@ pub fn build_test_module(
 
         // TODO: for when we figure out how wasip2 tests are to be run
         #[allow(unreachable_code)]
-        Command::new(&go)
+        Command::new(go)
             .args(component_args)
             .env("GOOS", "wasip1")
             .env("GOARCH", "wasm")