resolveId hook importer inconsistent in pre stage

[DylanPiercey]

Describe the bug

If using the resolveId(importee, importer, opts) hook with enforce: "pre", the importer will be different in dev mode vs in build mode.

Specifically in dev mode the importer will always be the top level .html file.
For my specific use case this makes it impossible to determine what the top level scripts are without other work arounds.

I was thinking ideally I'd be able to do:

resolveId(importee, importer) {
  if (importer) {
    if (this.getModuleInfo(importer).isEntry) {
        // This tells me that the parent of importee` is the top level file, the `.html` file.
    }
  }
}

However using isEntry on getModuleInfo also only works in build mode.

Reproduction

See https://github.com/DylanPiercey/vite-issue-resolve-id-repro

System Info

System:
    OS: macOS 10.15.7
    CPU: (4) x64 Intel(R) Core(TM) i7-7567U CPU @ 3.50GHz
    Memory: 3.43 GB / 16.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 16.6.2 - ~/.nvm/versions/node/v16.6.2/bin/node
    Yarn: 1.22.5 - ~/.yarn/bin/yarn
    npm: 7.20.3 - ~/.nvm/versions/node/v16.6.2/bin/npm
  Browsers:
    Chrome: 95.0.4638.69
    Edge: 96.0.1054.43
    Firefox: 91.0
    Safari: 15.1

Used Package Manager

npm

Logs

No response

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/vue-next instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[patak-dev]

I don't see a way for Vite to be able to provide the importer to this hook. A request for a module from the browser will not carry this information. If we start to encode it in import analysis &importedFrom=..., then these will be considered different modules. I think we should close this issue by clarifying the documentation. @DylanPiercey would you create specific feature requests for what you were trying to solve here? Maybe we could devise another way?
@bholmesdev since you pointed me to this issue, would you also provide more information on your use case?

[patak-dev]

Currently, the importer is being set to a fake index root here

vite/packages/vite/src/node/server/pluginContainer.ts

Line 526 in 9a1c1ae

async resolveId(rawId, importer = join(root, 'index.html'), options) {

This seems arbitrary, and we could remove the default and pass undefined as the importer which may be better for plugins. I tried to do so, and there is only one failing test. I don't think we should change this at this point, looks like it hasn't been a big issue so far. But we may want to review this with more time in the next major.