feat: add experimental dts rollup using @microsoft/api-extractor (#983)

docs/README.md

@@ -193,6 +193,16 @@ If you have multiple entry files, each entry will get a corresponding `.d.ts` fi
 
 Note that `--dts` does not resolve external (aka in `node_modules`) types used in the `.d.ts` file, if that's somehow a requirement, try the experimental `--dts-resolve` flag instead.
 
+Since tsup version 7.4.0, you can also use `--experimental-dts` flag to generate declaration files. This flag use [@microsoft/api-extractor](https://www.npmjs.com/package/@microsoft/api-extractor) to generate declaration files, which is more reliable than the previous `--dts` flag. It's still experimental and we are looking for feedbacks. 
+
+To use `--experimental-dts`, you would need to install `@microsoft/api-extractor`, as it's a peer dependency of tsup:
+
+```bash
+npm i @microsoft/api-extractor -D
+# Or Yarn
+yarn add @microsoft/api-extractor --dev
+```
+
 #### Emit declaration file only
 
 The `--dts-only` flag is the equivalent of the `emitDeclarationOnly` option in `tsc`. Using this flag will only emit the declaration file, without the JavaScript files.
@@ -500,6 +510,8 @@ esbuild has [experimental CSS support](https://esbuild.github.io/content-types/#
 To use PostCSS, you need to install PostCSS:
 
 ```bash
+npm i postcss -D
+# Or Yarn
 yarn add postcss --dev
 ```
 

package.json

@@ -44,6 +44,7 @@
     "tree-kill": "^1.2.2"
   },
   "devDependencies": {
+    "@microsoft/api-extractor": "^7.38.3",
     "@rollup/plugin-json": "6.0.1",
     "@swc/core": "1.2.218",
     "@types/debug": "4.1.7",
@@ -74,6 +75,7 @@
   },
   "peerDependencies": {
     "@swc/core": "^1",
+    "@microsoft/api-extractor": "^7.36.0",
     "postcss": "^8.4.12",
     "typescript": ">=4.5.0"
   },
@@ -86,6 +88,9 @@
     },
     "@swc/core": {
       "optional": true
+    },
+    "@microsoft/api-extractor": {
+      "optional": true
     }
   },
   "engines": {