Summary

This PR fixes dyn-compatibility of DatabaseCommit for downstream users like Foundry that use dyn DatabaseExt (which extends DatabaseCommit).

Problem

While integrating recent revm codebase with Foundry, I discovered that DatabaseCommit is not dyn-compatible due to how #[auto_impl] generates implementations.

Foundry defines DatabaseExt which extends DatabaseCommit:

pub trait DatabaseExt: Database<Error = DatabaseError> + DatabaseCommit + Debug { ... }

And uses it as a trait object throughout the codebase:

  pub struct FoundryEvm<'db, I: InspectorExt> {
      db: &'db mut dyn DatabaseExt,
      // ...
  }

The issue is that #[auto_impl(&mut, Box)] generates implementations like:

  impl<T: DatabaseCommit + ?Sized> DatabaseCommit for &mut T {
      fn commit_iter(&mut self, changes: impl IntoIterator<Item = (Address, Account)>) {
          T::commit_iter(*self, changes) 
      }
  }

This fails because commit_iter uses impl Trait in argument position (which requires Self: Sized). When T is ?Sized (like dyn DatabaseCommit), the generated code tries to call a method that requires Sized on a ?Sized type.

Solution

1. commit_iter now uses &mut dyn Iterator: this keeps the method in the vtable and callable on trait objects
2. impl dyn DatabaseCommit provides ergonomic commit_from_iter(impl IntoIterator) wrapper
3. Add tests for dyn-compatibility including a compile-time check mirroring Foundry's approach