gno.mod file support

[moul]

Description

By default, gnodev only supports importing contracts that are located in $gnoRepo/examples/....
The goal of gno.mod is to support additional import locations.

The first need is to support the equivalent of the replace ../ directive from go.mod.
Then, people should be able to bootstrap repos depending on their own contracts and official ones.

The second need would be to support the equivalent of go mod download and dependency caching.

Status

• gnodev mod download: Fetch required modules from chain.
• support require
• Create go.mod from gno.mod
• Create go.mod for fetched modules
• Lookup for fetched modules
• precompile fetched modules
• Add tests (and example)
• Remove duplicate require and replace
• Don't fetch replace modules (if replaced by Directory)
• Support replacing module with another module
• Fetch indirect dependencies (fetched modules)
• Fill dependencies in go.mod (fetched modules)
• Support gno mod init
• utilize ~/.gno. GNOPATH?
• make remote dynamic
• caching and checksum

Related PRs

#344, #479, #524, #533, #553, #602, #652

[harry-hov]

Reopened this issue to track the progress.

[moul]

Related with #522 and #526