Turbopack: compute code hash per `use cache` function (#94234)
This computes the implementation hash of a given `use cache`:
- it includes the module containing the `use cache` function, plus all transitive imports of that module (including externals via NFT)
- what does it hash
- for bundled code, it hashes the generated code (so including any AST transforms, inlined env vars, etc)
- for NFTd files, it hashes the file content on disk
- So this is basically equivalent to hashing the generated JS chunks, except that it's scoped to only what the given actions module uses
- (so notably, if you have multiple use cache functions in a given file, then they will all have the same hash)
<br/>
- [x] Gate behind experimental flag
- [x] Only compute hash for `use cache` functions, not all server actions
- [ ] `final_read_hint` is a problem. Some chunk items are now codgened twice, so it recomputes the AST
- [x] disable for dev for now
- [ ] Measure perf impact
```jsonc
// .next/server/server-reference-manifest.json
{
"node": {
"806f4954cfbb75404a19d6d405065ed9059cc0cab2": {
"workers": {
"app/rsc/page": {
"moduleId": "[project]/bench/app-router-server/.next-internal/server/app/rsc/page/actions.js { ACTIONS_MODULE0 => \"[project]/bench/app-router-server/app/rsc/logic.js [app-rsc] (ecmascript)\" } [app-rsc] (server actions loader, ecmascript)",
"async": false,
"exportedName": "$$RSC_SERVER_CACHE_0",
"filename": "bench/app-router-server/app/rsc/logic.js",
"codeHash": "413e394d9597b35df12828a6a7fd6363" // <------------
}
},
"filename": "bench/app-router-server/app/rsc/logic.js",
"exportedName": "$$RSC_SERVER_CACHE_0"
}
},
"edge": {},
"encryptionKey": "jOF2TbpNLjp2oOhl3VPBwGE7luodnei9clJPq/gaYQo="
}
```
