HMR should handle cyclic dependencies

[zen0wu]

Description

Previously in #2314, we've decided that HMR will not handle cyclic dependencies and instead reload the entire app, and we think that's the only way that it's correct.

However, I think we should reconsider that decision. Webpack apparently supports reloading app with circular dependencies, I haven't dig into the code, but webpack HMR works with our app with many many circular imports in it. so it's theoretically possible.

Suggested solution

Let's say I have 3 modules, A <-> B -> C,

• If B is changed, we can clearly see that we only need to reload A + B, but leaving C
• Theoretically, when a module is changed, it should only go up until all its transitive importers change, and whenever we hit a cycle, we should return instead of bail out the HMR.
• This logic made me believe this is a simple change, but maybe I missed something obvious.

Alternative

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[bradleysimard]

We just migrated from CRA to ViteJS and after all the work required found that Vite's HMR is apparently not very good at handling cyclical dependencies when CRA handled it like a champ.

[alex-radulescu-b1]

We just migrated from CRA to ViteJS and after all the work required found that Vite's HMR is apparently not very good at handling cyclical dependencies when CRA handled it like a champ.

Same here. Vite is awesome, but some pieces for more complex apps still need a bit of work. Any chance of better circular dependency handling please?

[mahnunchik]

I'm looking forward for this feature.

[MahoushoujoMadoka]

I'm looking forward for this feature.

[rkurbatov]

[sztadii]

@yyx990803 @patak-dev @sapphi-red do you have any updates or thoughts about this issue? In the current project, I am using Vite, and I have never seen this cyclic problem in CRA / Webpack. It seems that only Vite has some issues with it. Could you please tell us if there is any work being done related to this issue?

[sztadii]

@bluwy any thoughts about this issue? I would love to see the fix for it 🙏

[bluwy]

I looked into this issue a couple weeks ago actually, and got side-tracked into #14654, but I'll take a look at this again. I'm still not sure if it's completely safe and possible to do so, the previous fix to always reload didn't have tests to prevent a regression.

Anyways feel free to contribute a PR too if you like to see this fixed.

[zam157]

I think this issue should not to be closed: #14975 #15053

If Vite 5's handling of dependency cycles is just page reload, it will frustrate many people's confidence in migrating from webpack

[newives]

Completely agree, it is equivalent to saying that vite5 does not support hmr in circular dependencies, but it is normal operation to introduce modules into each other.