fix: support #[wasm_bindgen(start)]

deno.json

@@ -19,14 +19,14 @@
   },
   "tasks": {
     "fmt": "deno fmt && cargo fmt",
-    "build": "deno run -A ./main.ts -p wasmbuild",
-    "build:bindgen-upgrade": "WASMBUILD_BINDGEN_UPGRADE=1 deno task build",
+    "build": "WASMBUILD_BINDGEN_UPGRADE=1 deno run -A ./main.ts -p wasmbuild",
     "build:lkg": "deno run -A jsr:@deno/wasmbuild@^0.15.4 -p wasmbuild",
-    "test": "cd tests && rm -rf lib lib_out_js_file lib_inline lib_no_cache && deno task test:main && deno task test:js-ext && deno task test:inline && deno test -A && deno task test:check",
+    "test": "cd tests && rm -rf lib lib_out_js_file lib_inline lib_no_cache && deno task test:main && deno task test:js-ext && deno task test:inline && deno test -A && deno task test:check && deno task test:start",
     "test:main": "cd tests && deno run -A ../main.ts -p deno_test",
     "test:js-ext": "deno task test:main --js-ext mjs --out lib_out_js_file && cat tests/lib_out_js_file/deno_test.mjs > /dev/null",
     "test:check": "deno task test:main --check",
-    "test:inline": "deno task test:main --inline --out lib_inline"
+    "test:inline": "deno task test:main --inline --out lib_inline",
+    "test:start": "cd tests && deno run -A ../main.ts -p deno_test --features start && deno test -A test.ts"
   },
   "imports": {
     "@david/path": "jsr:@david/path@^0.2.0",

lib/bindgen.ts

@@ -14,6 +14,7 @@ export interface BindgenOutput {
   ts: BindgenTextFileOutput;
   snippets: Map<string, string[]>;
   localModules: Map<string, string>;
+  start: string | undefined;
   wasm: {
     name: string;
     bytes: number[];
@@ -72,6 +73,7 @@ async function generateForSelfBuild(filePath: Path): Promise<BindgenOutput> {
     },
     localModules: new Map(),
     snippets: new Map(),
+    start: undefined,
     wasm: {
       name: "wasmbuild_bg.wasm",
       bytes: Array.from(wasmBytes),

lib/commands/build_command.ts

@@ -91,6 +91,7 @@ import * as wasm from "./${output.wasmFileName}";
 export * from "./${output.bindingJsBg.path.basename()}";
 import { __wbg_set_wasm } from "./${output.bindingJsBg.path.basename()}";
 __wbg_set_wasm(wasm);
+${output.hasStart ? "wasm.__wbindgen_start();" : ""}
 `),
   }, {
     path: output.bindingJsBg.path,

lib/pre_build.ts

@@ -25,6 +25,8 @@ export interface PreBuildOutput {
     path: Path;
     text: string;
   };
+  /// If the wasm module has a #[wasm_bindgen(start)] attribute
+  hasStart: boolean;
   sourceHash: string;
   wasmFileName: string;
 }
@@ -146,6 +148,8 @@ export async function runPreBuild(
 
 ${await getFormattedText(getLibraryDts(bindgenOutput))}`,
     },
+    hasStart: bindgenOutput.start != null &&
+      bindgenOutput.start.includes("__wbindgen_start"),
     sourceHash,
     wasmFileName: bindgenOutput.wasm.name,
   };

lib/wasmbuild.js

@@ -3,9 +3,10 @@
 // deno-lint-ignore-file
 // deno-fmt-ignore-file
 // @ts-self-types="./wasmbuild.d.ts"
-// source-hash: 42abdfbeb5cf210c856f23fe256f0194e6faf8d0
 
+// source-hash: 83d37b1995d7d2a25021c644fccb57e2aa5331d6
 import * as wasm from "./wasmbuild_bg.wasm";
 export * from "./wasmbuild_bg.js";
 import { __wbg_set_wasm } from "./wasmbuild_bg.js";
 __wbg_set_wasm(wasm);
+

rs_lib/src/lib.rs

@@ -32,6 +32,7 @@ pub struct Output {
   pub ts: Option<BindgenTextFileOutput>,
   pub snippets: HashMap<String, Vec<String>>,
   pub local_modules: HashMap<String, String>,
+  pub start: Option<String>,
   pub wasm: BindgenBytesFileOutput,
 }
 
@@ -85,6 +86,7 @@ fn inner(name: &str, ext: &str, wasm_bytes: Vec<u8>) -> Result<Output> {
     },
     snippets: x.snippets().clone(),
     local_modules: x.local_modules().clone(),
+    start: x.start().cloned(),
     wasm: BindgenBytesFileOutput {
       name: format!("{}.wasm", name),
       bytes: x.wasm_mut().emit_wasm(),

tests/Cargo.toml

@@ -5,6 +5,9 @@ edition = "2021"
 authors = ["the Deno authors"]
 license = "MIT"
 
+[features]
+start = []
+
 [dependencies]
 wasm-bindgen = "0.2.90"
 

tests/lib.rs

@@ -1,12 +1,22 @@
+use std::sync::Mutex;
+
 use wasm_bindgen::prelude::*;
 
+static VALUE: Mutex<u32> = Mutex::new(0);
+
 #[wasm_bindgen(module = "/add.js")]
 extern "C" {
   fn add(a: u32, b: u32) -> u32;
 }
 
 #[wasm_bindgen]
 pub fn greet(name: &str) -> String {
-  let result = add(1, 2);
+  let result = add(1, 2) + *VALUE.lock().unwrap();
   format!("Hello, {}! Result: {}", name, result)
 }
+
+#[cfg(feature = "start")]
+#[wasm_bindgen(start)]
+pub fn main_js() {
+  *VALUE.lock().unwrap() = 1;
+}

tests/test.ts

@@ -3,7 +3,14 @@ import * as wasm from "./lib/deno_test.js";
 import * as wasm2 from "./lib_inline/deno_test.js";
 
 Deno.test("test works export", () => {
-  assertEquals(wasm.greet("Deno"), "Hello, Deno! Result: 3");
+  function hasStart() {
+    return Deno.readTextFileSync(import.meta.dirname + "/lib/deno_test.js")
+      .includes("__wbindgen_start");
+  }
+  assertEquals(
+    wasm.greet("Deno"),
+    hasStart() ? "Hello, Deno! Result: 4" : "Hello, Deno! Result: 3",
+  );
 });
 
 Deno.test("test inline works", () => {