Make setup-wasm script work for local dev (#36355)

* Make setup-wasm script work for local dev

* Use copy instead of move

contributing.md

@@ -63,6 +63,8 @@ yarn prepublish
 
 By default the latest canary of the next-swc binaries will be installed and used. If you are actively working on Rust code or you need to test out the most recent Rust code that hasn't been published as a canary yet you can [install Rust](https://www.rust-lang.org/tools/install) and run `yarn --cwd packages/next-swc build-native`.
 
+If you want to test out the wasm build locally, you will need to [install wasm-pack](https://rustwasm.github.io/wasm-pack/installer/). Run `yarn --cwd packages/next-swc build-wasm --target <wasm_target>` to build and `node ./scripts/setup-wasm.mjs` to copy it into your `node_modules`. Run next with `NODE_OPTIONS='--no-addons'` to force it to use the wasm binary.
+
 If you need to clean the project for any reason, use `yarn clean`.
 
 ## Testing

scripts/setup-wasm.mjs

@@ -1,21 +1,33 @@
 import path from 'path'
 import { readFile, writeFile } from 'fs/promises'
-import { copy } from 'fs-extra'
+import { copy, pathExists } from 'fs-extra'
 ;(async function () {
+  try {
     let wasmDir = path.join(process.cwd(), 'packages/next-swc/crates/wasm')
     let wasmTarget = 'nodejs'
+
+    // CI restores artifact at pkg-${wasmTarget}
+    // This only runs locally
+    let folderName = (await pathExists(path.join(wasmDir, 'pkg')))
+      ? 'pkg'
+      : `pkg-${wasmTarget}`
+
     let wasmPkg = JSON.parse(
-    await readFile(path.join(wasmDir, `pkg-${wasmTarget}/package.json`))
+      await readFile(path.join(wasmDir, `${folderName}/package.json`))
     )
     wasmPkg.name = `@next/swc-wasm-${wasmTarget}`
 
     await writeFile(
-    path.join(wasmDir, `pkg-${wasmTarget}/package.json`),
+      path.join(wasmDir, `${folderName}/package.json`),
       JSON.stringify(wasmPkg, null, 2)
     )
 
     await copy(
-    path.join(wasmDir, `pkg-${wasmTarget}`),
-    path.join(process.cwd(), `node_modules/@next/swc-wasm-${wasmTarget}`)
+      path.join(wasmDir, `${folderName}`),
+      path.join(process.cwd(), `node_modules/@next/swc-wasm-${wasmTarget}`),
+      { overwrite: true }
     )
+  } catch (e) {
+    console.error(e)
+  }
 })()