Add a custom eslint rule to forbid imports from <package>/src

[fvictorio]

When a plugin imports something from hardhat, it can import both from hardhat/foo and from hardhat/src/foo, but only the first one is correct. The second one works, but it can cause some issues (see #2260, for example).

More generally, we should forbid any import that starts with package/src or @org/package/src.

[kanej]

Maybe something like https://eslint.org/docs/rules/no-restricted-imports or maybe there is something in the eslint import plugin.

[fvictorio]

Great find @kanej. I think that won't work for avoiding all package/src imports, because allowing things like ../src seems hard with gitignore-like patterns. But it works pretty well for preventing hardhat/src, which is the more likely error for us. I added it to #2272, but let's keep this issue open for now in case we want to do a custom rule for this at some point.

[github-actions]

This issue was marked as stale because it didn't have any activity in the last 30 days. If you think it's still relevant, please leave a comment indicating so. Otherwise, it will be closed in 7 days.

[fvictorio]

Not stale.

[jrocca82]

I'll work on this one if no one else is

[fvictorio]

@jrocca82 this is about implementing a custom eslint rule, similar to this one. A contribution for this would be super welcome, but keep in mind that it's not a very straightforward thing to do.