Use object URLs for inlined linked modules (#4067)

Author: daxpedda

CHANGELOG.md

@@ -141,6 +141,9 @@
 * Updated the WebGPU WebIDL to the current draft as of 2024-08-05.
   [#4062](https://github.com/rustwasm/wasm-bindgen/pull/4062)
 
+* Use object URLs for linked modules without `--split-linked-modules`.
+  [#4067](https://github.com/rustwasm/wasm-bindgen/pull/4067)
+
 ### Fixed
 
 * Copy port from headless test server when using `WASM_BINDGEN_TEST_ADDRESS`.

Cargo.toml

@@ -43,6 +43,7 @@ xxx_debug_only_print_generated_code = [
 ]
 
 [dependencies]
+once_cell = "1.12"
 wasm-bindgen-macro = { path = "crates/macro", version = "=0.2.92" }
 serde = { version = "1.0", optional = true }
 serde_json = { version = "1.0", optional = true }

crates/backend/src/codegen.rs

@@ -190,16 +190,18 @@ impl TryToTokens for ast::LinkToModule {
         let link_function_name = self.0.link_function_name(0);
         let name = Ident::new(&link_function_name, Span::call_site());
         let wasm_bindgen = &self.0.wasm_bindgen;
-        let abi_ret = quote! { #wasm_bindgen::convert::WasmRet<<std::string::String as #wasm_bindgen::convert::FromWasmAbi>::Abi> };
+        let abi_ret = quote! { #wasm_bindgen::convert::WasmRet<<#wasm_bindgen::__rt::alloc::string::String as #wasm_bindgen::convert::FromWasmAbi>::Abi> };
         let extern_fn = extern_fn(&name, &[], &[], &[], abi_ret);
         (quote! {
             {
                 #program
                 #extern_fn
 
-                unsafe {
-                    <std::string::String as #wasm_bindgen::convert::FromWasmAbi>::from_abi(#name().join())
-                }
+                static __VAL: #wasm_bindgen::__rt::Lazy<String> = #wasm_bindgen::__rt::Lazy::new(|| unsafe {
+                    <#wasm_bindgen::__rt::alloc::string::String as #wasm_bindgen::convert::FromWasmAbi>::from_abi(#name().join())
+                });
+
+                #wasm_bindgen::__rt::alloc::string::String::clone(&__VAL)
             }
         })
         .to_tokens(tokens);

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

@@ -3262,9 +3262,11 @@ impl<'a> Context<'a> {
                         '`' | '\\' | '$' => escaped.extend(['\\', c]),
                         _ => escaped.extend([c]),
                     });
-                    Ok(format!(
-                        "\"data:application/javascript,\" + encodeURIComponent(`{escaped}`)"
-                    ))
+                    prelude.push_str(&format!("const val = `{escaped}`;\n"));
+                    Ok("typeof URL.createObjectURL === 'undefined' ? \
+                        \"data:application/javascript,\" + encodeURIComponent(val) : \
+                        URL.createObjectURL(new Blob([val], { type: \"text/javascript\" }))"
+                        .to_owned())
                 } else {
                     Err(anyhow!("wasm-bindgen needs to be invoked with `--split-linked-modules`, because \"{}\" cannot be embedded.\n\
                         See https://rustwasm.github.io/wasm-bindgen/reference/cli.html#--split-linked-modules for details.", path))

crates/cli/tests/reference/raw.js

@@ -6,26 +6,6 @@ export function __wbg_set_wasm(val) {
 }
 
 
-const lTextDecoder = typeof TextDecoder === 'undefined' ? (0, module.require)('util').TextDecoder : TextDecoder;
-
-let cachedTextDecoder = new lTextDecoder('utf-8', { ignoreBOM: true, fatal: true });
-
-cachedTextDecoder.decode();
-
-let cachedUint8ArrayMemory0 = null;
-
-function getUint8ArrayMemory0() {
-    if (cachedUint8ArrayMemory0 === null || cachedUint8ArrayMemory0.byteLength === 0) {
-        cachedUint8ArrayMemory0 = new Uint8Array(wasm.memory.buffer);
-    }
-    return cachedUint8ArrayMemory0;
-}
-
-function getStringFromWasm0(ptr, len) {
-    ptr = ptr >>> 0;
-    return cachedTextDecoder.decode(getUint8ArrayMemory0().subarray(ptr, ptr + len));
-}
-
 const heap = new Array(128).fill(undefined);
 
 heap.push(undefined, null, true, false);
@@ -45,6 +25,26 @@ function takeObject(idx) {
     dropObject(idx);
     return ret;
 }
+
+const lTextDecoder = typeof TextDecoder === 'undefined' ? (0, module.require)('util').TextDecoder : TextDecoder;
+
+let cachedTextDecoder = new lTextDecoder('utf-8', { ignoreBOM: true, fatal: true });
+
+cachedTextDecoder.decode();
+
+let cachedUint8ArrayMemory0 = null;
+
+function getUint8ArrayMemory0() {
+    if (cachedUint8ArrayMemory0 === null || cachedUint8ArrayMemory0.byteLength === 0) {
+        cachedUint8ArrayMemory0 = new Uint8Array(wasm.memory.buffer);
+    }
+    return cachedUint8ArrayMemory0;
+}
+
+function getStringFromWasm0(ptr, len) {
+    ptr = ptr >>> 0;
+    return cachedTextDecoder.decode(getUint8ArrayMemory0().subarray(ptr, ptr + len));
+}
 /**
 * @param {number} test
 * @returns {number}
@@ -110,11 +110,11 @@ export function __wbg_test2_39fe629b9aa739cf() {
     return addHeapObject(ret);
 };
 
-export function __wbindgen_throw(arg0, arg1) {
-    throw new Error(getStringFromWasm0(arg0, arg1));
-};
-
 export function __wbindgen_object_drop_ref(arg0) {
     takeObject(arg0);
 };
 
+export function __wbindgen_throw(arg0, arg1) {
+    throw new Error(getStringFromWasm0(arg0, arg1));
+};
+

src/lib.rs

@@ -1518,6 +1518,7 @@ pub mod __rt {
     use alloc::alloc::{alloc, dealloc, realloc, Layout};
     use alloc::boxed::Box;
     use alloc::rc::Rc;
+    pub use once_cell::sync::Lazy;
 
     #[macro_export]
     #[doc(hidden)]