Pass same mangling option as terser to SWC minifier (#56281)

### What? Pass `keep_classnames: true` to the SWC minifier, as we are passing it to `terser`. ### Why? https://github.com/vercel/next.js/blob/5f7faac1e676be0819dd5d828bffed8a7105a78e/packages/next/src/build/webpack-config.ts#L953-L958 ### How? Closes WEB-1676 Fixes #55682
vercel · Oct 2, 2023 · 83c18de · 83c18de
1 parent 5f7faac
commit 83c18de
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/packages/next/src/build/webpack/plugins/terser-webpack-plugin/src/index.ts b/packages/next/src/build/webpack/plugins/terser-webpack-plugin/src/index.ts
@@ -166,7 +166,12 @@ export class TerserPlugin {
                       }
                     : {}),
                   compress: true,
-                  mangle: true,
+                  // This is the same option as terser
+                  mangle: {
+                    toplevel: true,
+                    keep_classnames: true,
+                    keep_fnames: true,
+                  },
                 }
               )