Evaluate custom ink! lints using Dylint

[cmichi]

This blog post describes how to add project-specific lints to clippy using the Dylint crate. We should evaluate if it's possible to use this crate for implementing custom ink! lints.

A scenario that comes to my mind is the usage of accidental nested lazy data structures. For example, our collections in ink_storage are lazy anyway. So e.g. Lazy<Vec<u32>> doesn't provide additional benefits, but instead only adds computation overhead. It should be possible to access this type information using LateLintPass("[…] the LateLintPass has access to type information while the EarlyLintPass doesn't", source).

ToDo

• Make cargo contract run a custom lint before each build/check.
• The lint should output a warning (error?) if X in Lazy<X> is from ink_storage::collections.

[Robbepop]

A scenario that comes to my mind is the usage of accidental nested lazy data structures. For example, our collections in ink_storage are lazy anyway. So e.g. Lazy<Vec> doesn't provide additional benefits, but instead only adds computation overhead. It should be possible to access this type information using LateLintPass("[…] the LateLintPass has access to type information while the EarlyLintPass doesn't", source).

Sounds like a really good prototype in order to see if the approach works for our use case.

[HCastano]

There are two existing Clippy lints which could come in handy as references for the implementation of this lint:

• box_vec
• boxed_local