[Chaoqi31]

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

With moduleIdGeneratorAlgorithm: 'deep-hash', DeepHashedModuleOpaqueKeyFactory.createForDynamic() hashes the serialized dynamic metadata. The serializer, fast-safe-stringify, follows JSON.stringify semantics, so a Map, Set or RegExp anywhere in the metadata becomes {}. Two imports of the same dynamic module whose options differ only there get the same token, for example options holding new Map([['a', 1]]) and new Map([['b', 2]]), new Set(['x']) and new Set(['y']), or /^\/api/ and /^\/admin/.

NestContainer.addModule() then finds the token, returns the first module with inserted: false, and the second import's providers are dropped, so its consumers get the first import's options. The option's JSDoc says the id "is generated based on the serialized module definition", and nothing in the specs pins the collisions.

The new spec against the current factory:

 × should serialize maps, sets and regular expressions in a dynamic metadata object
Expected: "{"providers":[{"provide":"Options","useValue":{"map":{"Map":[["a",1]]},"set":{"Set":["b"]},"pattern":{"RegExp":"/c/i"}}}]}"
Received: "{"providers":[{"provide":"Options","useValue":{"map":{},"set":{},"pattern":{}}}]}"

Issue Number: N/A

What is the new behavior?

replacer serializes a Map as { Map: [...entries] }, a Set as { Set: [...values] } and a RegExp as { RegExp: value.toString() }. The tag keeps them apart from a plain array or string with the same content; a plain object literally shaped { Map: [...] }, { Set: [...] } or { RegExp: '...' } still gets the same token as the real value. Every other value serializes as before, so tokens of modules without these values do not change, and identical options still share one module. The default reference algorithm is not affected.

One limit: fast-safe-stringify does not look inside a Map or Set when it removes circular references, so metadata with a cycle through one of them now serializes to its fallback string ([unable to serialize, circular reference is too complex to analyze]) instead of {}. That string carries no module id or name, so every dynamic module with such metadata gets the same token. BigInt values already reach the same fallback.

Does this PR introduce a breaking change?

• Yes
• No

Other information

npx vitest run packages/core: 1395 passed.