feat: add module declaration support

crates/js-component-bindgen-component/src/lib.rs

@@ -75,6 +75,7 @@ impl Guest for JsComponentBindgenComponent {
             no_namespaced_exports: options.no_namespaced_exports.unwrap_or(false),
             multi_memory: options.multi_memory.unwrap_or(false),
             import_bindings: options.import_bindings.map(Into::into),
+            declare_imports: options.declare_imports.unwrap_or(false),
         };
 
         let js_component_bindgen::Transpiled {
@@ -160,6 +161,7 @@ impl Guest for JsComponentBindgenComponent {
             no_namespaced_exports: false,
             multi_memory: false,
             import_bindings: None,
+            declare_imports: false,
         };
 
         let files = generate_types(name, resolve, world, opts).map_err(|e| e.to_string())?;

crates/js-component-bindgen-component/wit/js-component-bindgen.wit

@@ -58,6 +58,9 @@ world js-component-bindgen {
     /// Whether to generate namespaced exports like `foo as "local:package/foo"`.
     /// These exports can break typescript builds.
     no-namespaced-exports: option<bool>,
+
+    /// Whether to generate module declarations like `declare module "local:package/foo" {...`.
+    declare-imports: option<bool>,
 
     /// Whether to output core Wasm utilizing multi-memory or to polyfill
     /// this handling.
@@ -91,6 +94,8 @@ world js-component-bindgen {
     map: option<maps>,
     /// Features that should be enabled as part of feature gating
     features: option<enabled-feature-set>,
+    /// Whether to generate module declarations like `declare module "local:package/foo" {...`.
+    declare-imports: option<bool>,
   }
 
   enum export-type {

crates/js-component-bindgen/src/transpile_bindgen.rs

@@ -68,6 +68,8 @@ pub struct TranspileOpts {
     /// Whether to output core Wasm utilizing multi-memory or to polyfill
     /// this handling.
     pub multi_memory: bool,
+    /// Whether to generate module declarations like `declare module "local:package/foo" {...`.
+    pub declare_imports: bool,
 }
 
 #[derive(Default, Clone, Debug)]

crates/js-component-bindgen/src/ts_bindgen.rs

@@ -219,6 +219,7 @@ pub fn ts_bindgen(
                     *id,
                     files,
                     opts.instantiation.is_some(),
+                    opts.declare_imports,
                 );
                 export_aliases.push((iface_name.to_lower_camel_case(), local_name));
             }
@@ -368,7 +369,7 @@ impl TsBindgen {
         files: &mut Files,
     ) -> String {
         // in case an imported type is used as an exported type
-        let local_name = self.generate_interface(name, resolve, id, files);
+        let local_name = self.generate_interface(name, resolve, id, files, false);
         uwriteln!(
             self.import_object,
             "{}: typeof {local_name},",
@@ -388,15 +389,15 @@ impl TsBindgen {
             if iface_name == "*" {
                 uwrite!(self.import_object, "{}: ", maybe_quote_id(import_name));
                 let name = resolve.interfaces[id].name.as_ref().unwrap();
-                let local_name = self.generate_interface(name, resolve, id, files);
+                let local_name = self.generate_interface(name, resolve, id, files, false);
                 uwriteln!(self.import_object, "typeof {local_name},",);
                 return;
             }
         }
         uwriteln!(self.import_object, "{}: {{", maybe_quote_id(import_name));
         for (iface_name, &id) in ifaces {
             let name = resolve.interfaces[id].name.as_ref().unwrap();
-            let local_name = self.generate_interface(name, resolve, id, files);
+            let local_name = self.generate_interface(name, resolve, id, files, false);
             uwriteln!(
                 self.import_object,
                 "{}: typeof {local_name},",
@@ -428,8 +429,9 @@ impl TsBindgen {
         id: InterfaceId,
         files: &mut Files,
         instantiation: bool,
+        declare_imports: bool,
     ) -> String {
-        let local_name = self.generate_interface(export_name, resolve, id, files);
+        let local_name = self.generate_interface(export_name, resolve, id, files, declare_imports);
         if instantiation {
             uwriteln!(
                 self.export_object,
@@ -472,6 +474,7 @@ impl TsBindgen {
         resolve: &Resolve,
         id: InterfaceId,
         files: &mut Files,
+        declare_imports: bool,
     ) -> String {
         let iface = resolve
             .interfaces
@@ -522,7 +525,15 @@ impl TsBindgen {
 
         let mut gen = self.ts_interface(resolve, false);
 
-        uwriteln!(gen.src, "export namespace {camel} {{");
+        uwriteln!(
+            gen.src,
+            "{}",
+            if declare_imports {
+                format!("declare module '{id_name}' {{")
+            } else {
+                format!("export namespace {camel} {{")
+            }
+        );
         for (_, func) in resolve.interfaces[id].functions.iter() {
             // Ensure that the function  the world item for stability guarantees and exclude if they do not match
             if !feature_gate_allowed(resolve, package, &func.stability, &func.name)

src/jco.js

@@ -79,6 +79,7 @@ program.command('types')
   .option('-q, --quiet', 'disable output summary')
   .option('--feature <feature>', 'enable one specific WIT feature (repeatable)', collectOptions, [])
   .option('--all-features', 'enable all features')
+  .option('--declare-imports', 'declare imports as modules in the generated types')
   .action(asyncAction(types));
 
 program.command('run')

xtask/src/build/jco.rs

@@ -84,6 +84,7 @@ fn transpile(component_path: &str, name: String, optimize: bool) -> Result<()> {
         no_namespaced_exports: true,
         multi_memory: true,
         import_bindings: Some(BindingsMode::Js),
+        declare_imports: false,
     };
 
     let transpiled = js_component_bindgen::transpile(&adapted_component, opts)?;

xtask/src/generate/wasi_types.rs

@@ -38,6 +38,7 @@ pub(crate) fn run() -> Result<()> {
             no_namespaced_exports: true,
             multi_memory: false,
             import_bindings: Some(BindingsMode::Js),
+            declare_imports: false,
         };
 
         let files = generate_types(name, resolve, world, opts)?;