feat: experimental isolated declaration support

build.config.ts

@@ -0,0 +1,11 @@
+import { transform } from "esbuild/lib/main";
+import { defineBuildConfig } from "./src";
+
+export default defineBuildConfig({
+  rollup: {
+    // https://github.com/unplugin/unplugin-isolated-decl
+    isolatedDecl: {
+      transformer: "oxc",
+    },
+  },
+});

package.json

@@ -54,6 +54,7 @@
     "rollup-plugin-dts": "^6.1.1",
     "scule": "^1.3.0",
     "ufo": "^1.5.3",
+    "unplugin-isolated-decl": "^0.4.0",
     "untyped": "^1.4.2"
   },
   "devDependencies": {

src/build.ts

@@ -148,6 +148,7 @@ async function _build(
           compilerOptions: { preserveSymlinks: false },
           respectExternal: true,
         },
+        isolatedDecl: false, // Experimental
       },
     },
   ) as BuildOptions;

src/builders/rollup/build.ts

@@ -76,7 +76,7 @@ export async function rollupBuild(ctx: BuildContext): Promise<void> {
   }
 
   // Types
-  if (ctx.options.declaration) {
+  if (ctx.options.declaration && !ctx.options.rollup.isolatedDecl) {
     rollupOptions.plugins = [
       ...rollupOptions.plugins,
       dts(ctx.options.rollup.dts),

src/builders/rollup/config.ts

@@ -1,5 +1,6 @@
 import type { OutputOptions, PreRenderedChunk } from "rollup";
 import commonjs from "@rollup/plugin-commonjs";
+import isolatedDeclPlugin from "unplugin-isolated-decl/rolldown";
 import { nodeResolve } from "@rollup/plugin-node-resolve";
 import alias from "@rollup/plugin-alias";
 import replace from "@rollup/plugin-replace";
@@ -113,6 +114,11 @@ export function getRollupOptions(ctx: BuildContext): RollupOptions {
           ...ctx.options.rollup.resolve,
         }),
 
+      // Should be before esbuild to preserve source
+      ctx.options.declaration &&
+        ctx.options.rollup.isolatedDecl &&
+        isolatedDeclPlugin(ctx.options.rollup.isolatedDecl),
+
       ctx.options.rollup.json &&
         JSONPlugin({
           ...ctx.options.rollup.json,

src/types.ts

@@ -14,6 +14,7 @@ import type { RollupAliasOptions } from "@rollup/plugin-alias";
 import type { RollupNodeResolveOptions } from "@rollup/plugin-node-resolve";
 import type { RollupJsonOptions } from "@rollup/plugin-json";
 import type { Options as RollupDtsOptions } from "rollup-plugin-dts";
+import type { Options as RollupDeclOptions } from "unplugin-isolated-decl";
 import type commonjs from "@rollup/plugin-commonjs";
 import type { Jiti, JitiOptions } from "jiti";
 import type { EsbuildOptions } from "./builders/rollup/plugins/esbuild";
@@ -136,6 +137,15 @@ export interface RollupBuildOptions {
    * Read more: [rollup-plugin-dts](https://www.npmjs.com/package/rollup-plugin-dts)
    */
   dts: RollupDtsOptions;
+
+  /**
+   * Isolated declarations plugin options
+   *
+   * @experimental Set to an empty object to enable the plugin and disable `dts`.
+   *
+   * Read more: [unplugin-isolated-decl](https://github.com/unplugin/unplugin-isolated-decl)
+   */
+  isolatedDecl: RollupDeclOptions | false;
 }
 
 export interface BuildOptions {