Adding in wrapper file to fix circular dependency with Webpack 5 (#2110)

* Adding in wrapper file to fix circular dependency with Webpack 5

* Running rustfmt

* Fixing unit tests

Author: Pauan

crates/cli-support/src/js/mod.rs

@@ -167,7 +167,10 @@ impl<'a> Context<'a> {
         Ok(())
     }
 
-    pub fn finalize(&mut self, module_name: &str) -> Result<(String, String), Error> {
+    pub fn finalize(
+        &mut self,
+        module_name: &str,
+    ) -> Result<(String, String, Option<String>), Error> {
         // Finalize all bindings for JS classes. This is where we'll generate JS
         // glue for all classes as well as finish up a few final imports like
         // `__wrap` and such.
@@ -273,9 +276,10 @@ impl<'a> Context<'a> {
         &mut self,
         module_name: &str,
         needs_manual_start: bool,
-    ) -> Result<(String, String), Error> {
+    ) -> Result<(String, String, Option<String>), Error> {
         let mut ts = self.typescript.clone();
         let mut js = String::new();
+        let mut start = None;
 
         if let OutputMode::NoModules { global } = &self.config.mode {
             js.push_str(&format!("let {};\n(function() {{\n", global));
@@ -340,15 +344,15 @@ impl<'a> Context<'a> {
                 ));
                 for (id, js) in crate::sorted_iter(&self.wasm_import_definitions) {
                     let import = self.module.imports.get_mut(*id);
-                    import.module = format!("./{}.js", module_name);
+                    import.module = format!("./{}_bg.js", module_name);
                     footer.push_str("\nexport const ");
                     footer.push_str(&import.name);
                     footer.push_str(" = ");
                     footer.push_str(js.trim());
                     footer.push_str(";\n");
                 }
                 if needs_manual_start {
-                    footer.push_str("\nwasm.__wbindgen_start();\n");
+                    start = Some("\nwasm.__wbindgen_start();\n".to_string());
                 }
             }
 
@@ -394,7 +398,7 @@ impl<'a> Context<'a> {
             js = js.replace("\n\n\n", "\n\n");
         }
 
-        Ok((js, ts))
+        Ok((js, ts, start))
     }
 
     fn js_import_header(&self) -> Result<String, Error> {

crates/cli-support/src/lib.rs

@@ -61,6 +61,7 @@ struct JsGenerated {
     mode: OutputMode,
     js: String,
     ts: String,
+    start: Option<String>,
     snippets: HashMap<String, Vec<String>>,
     local_modules: HashMap<String, String>,
     npm_dependencies: HashMap<String, (PathBuf, String)>,
@@ -421,7 +422,7 @@ impl Bindgen {
                 .unwrap();
             let mut cx = js::Context::new(&mut module, self, &adapters, &aux)?;
             cx.generate()?;
-            let (js, ts) = cx.finalize(stem)?;
+            let (js, ts, start) = cx.finalize(stem)?;
             Generated::Js(JsGenerated {
                 snippets: aux.snippets.clone(),
                 local_modules: aux.local_modules.clone(),
@@ -430,6 +431,7 @@ impl Bindgen {
                 npm_dependencies: cx.npm_dependencies.clone(),
                 js,
                 ts,
+                start,
             })
         };
 
@@ -568,6 +570,16 @@ impl OutputMode {
             _ => false,
         }
     }
+
+    fn esm_integration(&self) -> bool {
+        match self {
+            OutputMode::Bundler { .. }
+            | OutputMode::Node {
+                experimental_modules: true,
+            } => true,
+            _ => false,
+        }
+    }
 }
 
 /// Remove a number of internal exports that are synthesized by Rust's linker,
@@ -613,7 +625,7 @@ impl Output {
             Generated::InterfaceTypes => self.stem.clone(),
             Generated::Js(_) => format!("{}_bg", self.stem),
         };
-        let wasm_path = out_dir.join(wasm_name).with_extension("wasm");
+        let wasm_path = out_dir.join(&wasm_name).with_extension("wasm");
         fs::create_dir_all(out_dir)?;
         let wasm_bytes = self.module.emit_wasm();
         fs::write(&wasm_path, wasm_bytes)
@@ -660,9 +672,35 @@ impl Output {
         } else {
             "js"
         };
+
+        fn write<P, C>(path: P, contents: C) -> Result<(), anyhow::Error>
+        where
+            P: AsRef<Path>,
+            C: AsRef<[u8]>,
+        {
+            fs::write(&path, contents)
+                .with_context(|| format!("failed to write `{}`", path.as_ref().display()))
+        }
+
         let js_path = out_dir.join(&self.stem).with_extension(extension);
-        fs::write(&js_path, reset_indentation(&gen.js))
-            .with_context(|| format!("failed to write `{}`", js_path.display()))?;
+
+        if gen.mode.esm_integration() {
+            let js_name = format!("{}_bg.{}", self.stem, extension);
+
+            let start = gen.start.as_deref().unwrap_or("");
+
+            write(
+                &js_path,
+                format!(
+                    "import * as wasm from \"./{}.wasm\";\nexport * from \"./{}\";{}",
+                    wasm_name, js_name, start
+                ),
+            )?;
+
+            write(&out_dir.join(&js_name), reset_indentation(&gen.js))?;
+        } else {
+            write(&js_path, reset_indentation(&gen.js))?;
+        }
 
         if gen.typescript {
             let ts_path = js_path.with_extension("d.ts");

crates/cli/tests/reference.rs

@@ -112,7 +112,7 @@ fn runtest(test: &Path) -> Result<()> {
         let wat = sanitize_wasm(&wasm)?;
         assert_same(&wat, &test.with_extension("wat"))?;
     } else {
-        let js = fs::read_to_string(td.path().join("reference_test.js"))?;
+        let js = fs::read_to_string(td.path().join("reference_test_bg.js"))?;
         assert_same(&js, &test.with_extension("js"))?;
         let wat = sanitize_wasm(&td.path().join("reference_test_bg.wasm"))?;
         assert_same(&wat, &test.with_extension("wat"))?;

crates/cli/tests/reference/anyref-empty.js

@@ -11,5 +11,3 @@ export const __wbindgen_init_anyref_table = function() {
     ;
 };
 
-wasm.__wbindgen_start();
-

crates/cli/tests/reference/anyref-empty.wat

@@ -1,6 +1,6 @@
 (module
   (type (;0;) (func))
-  (import "./reference_test.js" "__wbindgen_init_anyref_table" (func (;0;) (type 0)))
+  (import "./reference_test_bg.js" "__wbindgen_init_anyref_table" (func (;0;) (type 0)))
   (table (;0;) 32 anyref)
   (memory (;0;) 16)
   (export "memory" (memory 0))

crates/cli/tests/reference/anyref-import-catch.js

@@ -64,5 +64,3 @@ export const __wbindgen_init_anyref_table = function() {
     ;
 };
 
-wasm.__wbindgen_start();
-

crates/cli/tests/reference/anyref-import-catch.wat

@@ -2,7 +2,7 @@
   (type (;0;) (func))
   (type (;1;) (func (result i32)))
   (type (;2;) (func (param i32)))
-  (import "./reference_test.js" "__wbindgen_init_anyref_table" (func (;0;) (type 0)))
+  (import "./reference_test_bg.js" "__wbindgen_init_anyref_table" (func (;0;) (type 0)))
   (func $__wbindgen_exn_store (type 2) (param i32))
   (func $__anyref_table_alloc (type 1) (result i32))
   (func $exported (type 0))

crates/cli/tests/reference/anyref-nop.js

@@ -17,5 +17,3 @@ export const __wbindgen_init_anyref_table = function() {
     ;
 };
 
-wasm.__wbindgen_start();
-

crates/cli/tests/reference/anyref-nop.wat

@@ -1,6 +1,6 @@
 (module
   (type (;0;) (func))
-  (import "./reference_test.js" "__wbindgen_init_anyref_table" (func (;0;) (type 0)))
+  (import "./reference_test_bg.js" "__wbindgen_init_anyref_table" (func (;0;) (type 0)))
   (func $foo (type 0))
   (table (;0;) 32 anyref)
   (memory (;0;) 17)