What to do if a peer dependency is a regular dependency of a subdependency?

[zkochan]

Let's assume we want our package/project to have react as a peer dependency.

{
  "name": "card",
  "dependencies": {
    "button": "1.0.0"
  },
  "devDependencies": {
    "react": "16"
  },
  "peerDependencies": {
    "react": "16"
  }
}

However, one of the dependencies of our project has react as a prod dependency (and it doesn't match the version that we want). This is the package.json of button:

{
  "name": "button",
  "version": "1.0.0",
  "dependencies": {
     "react": "15"
  }
}

Should pnpm print a warning in this case?
Should we forcefully convert any prod dependency to a peer dependency if the parent package has the given dependency in peers?
Should we support some new field in peerDependenciesMeta? Like force for instance?

[larixer]

First, it would be great to clarify from the npm team the semantics of peer dependencies in their docs:
https://docs.npmjs.com/cli/v7/configuring-npm/package-json#peerdependencies

Second, if the way I understand their docs is right, I think pnpm should not emit a warning in this case, because the resulting dependency graph will look like this:

.
├── card
│   └── [email protected]
│       └── react@15
└── react@16

and the card is installed along with react@16 peer dependency it has declared. From the npm docs the concept of peer dependencies revolves around along, plugin and host words: the card plugin should be installed along the react@16 host and this requirement is fulfilled by the dependency graph above.