Is Vite not able to externalize zod dependencies?

[ngdangtu-vn]

I think Vite couldn't externalize zod because the version with rollupOptions.external and the version without it has the same size.

So I have a package.json like this:

{
	"peerDependencies": {
		"zod": "3.25.28"
	},
	"devDependencies": {
		"zod": "3.25.28"
	}
}

And a vite.config.ts file like this:

import pkg from './package.json'

import { defineConfig } from 'vite'

/* ... */

export default defineConfig({
	/* ... */
	build: {
		lib: {/* ... */},
		rollupOptions: {
			external: Object.keys(pkg.peerDependencies),
		}
	},
})

When I run build tsc && vite build, it basically transpile and bundle into file properly but it has 1 warning message like this:

node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js (34:4): A comment

"// ) => core.output<T> = /* @__PURE__ */ core._parse(ZodError, parse) as any;"

in "node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js" contains an annotation that Rollup cannot interpret due to the position of the comment. The comment will be removed to avoid issues.
node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js (39:4): A comment

"// ) => ZodSafeParseResult<core.output<T>> = /* @__PURE__ */ core._safeParse(ZodError) as any;"

in "node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js" contains an annotation that Rollup cannot interpret due to the position of the comment. The comment will be removed to avoid issues.
node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js (44:4): A comment

"// ) => Promise<core.output<T>> = /* @__PURE__ */ core._parseAsync(ZodError) as any;"

in "node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js" contains an annotation that Rollup cannot interpret due to the position of the comment. The comment will be removed to avoid issues.
node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js (49:4): A comment

"// ) => Promise<ZodSafeParseResult<core.output<T>>> = /* @__PURE__ */ core._safeParseAsync(ZodError) as any;"

in "node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/classic/schemas.js" contains an annotation that Rollup cannot interpret due to the position of the comment. The comment will be removed to avoid issues.
node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/core/schemas.js (323:0): A comment

"// export const $ZodIP: core.$constructor<$ZodIP> = /*@__PURE__*/ core.$constructor("$ZodIP", (inst, def): void => {"

in "node_modules/.pnpm/[email protected]/node_modules/zod/dist/esm/v4/core/schemas.js" contains an annotation that Rollup cannot interpret due to the position of the comment. The comment will be removed to avoid issues.

Could you guy help me verify it? I want to know if this truly a bug before fire an issue. Thanks.

[hi-ogawa]

It appears external: Object.keys(pkg.peerDependencies) is not working, but it's expected to work. Can you provide a reproduction?

[ngdangtu-vn]

That's funny, the vscode can recognize it ok. Also, before this, I test with a plain string array ['zod'] and it didn't work. That's why I move this way.

As for reproduction, hold on.

[ngdangtu-vn]

@hi-ogawa Here is the reproduction version, I've tested again it and it still holds the same behaviour:

https://gist.github.com/ngdangtu-vn/e0b042420bfce84694f91f3db6562deb

[hi-ogawa]

You have import { z } from "zod/v4", so you need external: ["zod/v4"] or regex https://rollupjs.org/configuration-options/#external

[ngdangtu-vn]

Thanks god, it's fixed! Thank you for your enlightment!