Generate metadata for sub-contracts in multi contract workspace

[ascjones]

Following on from #58, we should support generating of metadata for the non-root contract in a multi contract workspace.

For example, the delegator example hosts multiple contracts which are dependencies of the main contract.

Proposal

• All metadata files will be written to the target directory of the workspace root, with the file name the same as the contract module name e.g. delegator.json, incrementer.json etc.
• cargo contract generate-metadata in the root workspace dir generates just the metadata for the root contract (in this case the delegator
• Sub contracts: e.g cd adder && cargo contract generate-metadata generates just the metadata for that sub contract.
• Alternatively cargo contract generate-metadata -p adder from the root does the same, mirroring cargo functionality.
• cargo contract generate-metadata --all will generate metadata files for all contracts in the workspace, e.g. delegator.json, adder.json, subber.json

Implementation notes

• Need to auto remove the ink-as-dependency feature in the root workspace manifest for the sub contracts

[ii-ii-ii]

@ascjones hi, I would like to know if this issue is solved. Because I'm working on multiple contracts and I'll have some trouble if I can't generate abi for sub-contracts.

[ascjones]

It's not solved yet. It should still work if you run cargo-contract from a sub contract's directory, or use the --manifest-path argument

[ii-ii-ii]

When I try to execute cargo +nightly contract build in a subdirectory I get an error:

error[E0463]: can't find crate for `contract`
 --> .ink/metadata_gen/main.rs:1:1
  |
1 | extern crate contract;
  | ^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: could not compile `metadata-gen`

To learn more, run the command again with --verbose.

It can get a wasm file, but cannot generate abi. Using --manifest-path also gives the same error

[ascjones]

My mistake, I thought it would have worked. I'll look at implementing this soon.