SSR support circular dependency

[axe-me]

• Read the docs.
• Use Vite >=2.0. (1.x is no longer supported)
• If the issue is related to 1.x -> 2.0 upgrade, read the Migration Guide first.

Describe the bug

When loading an SSR module with circular dependency (Many to many relationships TypeORM entities for example), the cli is stuck.
And sometime I get the Circular dependency: warning, sometimes I don't.

To be honest, I'm not sure this is a bug, lots of backend code written in this pattern. In my opinion, circular dependency should be allowed for SSR. But I'm not sure how can you patch the modGraph with circular dependency in it.

Reproduction

https://github.com/axe-me/repro-vite-circular-dependency

System Info

• vite version: 2.0.3
• Operating System: macos
• Node version: 14
• Package manager (npm/yarn/pnpm) and version: npm 7

Logs (Optional if provided reproduction)

[airhorns]

FWIW I have seen circular module references work fine with vite SSR so there might be something deeper going on here. Also, it seems a bit weird that you'd be requiring code for SSR that does TypeORM stuff -- are you using TypeORM on the client? If not, you may be able to get around your issue by requiring only the code that needs to go out to the client through vite SSR.

[axe-me]

@airhorns I wrote a plugin https://github.com/axe-me/vite-plugin-node for using vite as node dev server. Even for SSR, some vue projects using VuexORM etc will also have similar issue.

[pmatisko]

Dev SSR circular dependencies don't work in a very simple example. SPA works, final SSR build works too.

//a.js
export function a() { ... }

//b.js
import { a } from '@IoC'

export function b() {  
   a()   
} 

//IoC.js
export { a } from 'a'
export { b } from 'b'