Two misc ideas for Nix itself

ideas/2024.md

@@ -4,6 +4,22 @@ Welcome to our Google Summer of Code ideas list!
 
 ## small (90 hours)
 
+### Nix cleanup: merge `ParsedDerivation` into `BasicDerivation`, improve JSON format
+
+Nix currently special-cases some environment variables in derivations to convey extra meaning ("system features", "prefer local build", etc.).
+We're stuck with this in the [`.drv` A-Term format](https://nixos.org/manual/nix/stable/protocols/derivation-aterm) and `builtins.derivation` because of backwards compatibility requirements, but that doesn't mean our internal data structures and (currently experimental, i.e. not yet stabilized and immobile) JSON format cannot be improved.
+
+This project would be about doing just that: Fix the internal data structures, and then use that refactor to make the JSON format better.
+
+As a stretch goal, we can then start proposing/prototyping a worthy successor to `builtins.derivation` that would better support this stuff.
+(C.f. the "structured attrs" work in Nixpkgs.)
+
+See https://github.com/NixOS/nix/issues/9846
+and https://github.com/NixOS/nix/issues/9866.
+
+Possible mentors:
+- [@Ericson2314](https://github.com/Ericson2314)
+
 ### nixpkgs library networking functions
 
 Many things in NixOS use the Internet Protocol and other network related technologies, thus a lot of modules and service have to deal with them.
@@ -77,6 +93,20 @@ We have [boot counting](https://github.com/NixOS/nixpkgs/pull/273062) that is on
 
 ## medium (175 hours)
 
+### Nix Internals: Use `std::filesystem::path` for `Path`
+
+Nix currently has a bunch of home-grown file system and file path utilities.
+However in recent years ([C++17](https://en.wikipedia.org/wiki/C%2B%2B17#Language)) the standard library has gained a new [`std::fileystem`](https://en.cppreference.com/w/cpp/filesystem) library which has much of the same functionality.
+
+The purpose of this project is to use `std::filesystem` where possible, with a particular emphasis on using the `std::filesystem::path` type rather than our own `Path` (which is just an alias for `std::string`).
+
+This shrinks Nix (no need to maintain redundant code!), and will also aid in porting Nix to Windows, since an explicit design goal of `std::filesystem` is to be portable between Unix and Windows.
+
+See https://github.com/NixOS/nix/issues/9205 for details.
+
+Possible mentors:
+ - [@Ericson2314](https://github.com/Ericson2314)
+
 ### nixpkgs pnpm tooling
 
 pnpm is a package manager that claims to be up to 2x faster than npm and more efficient than npm when it comes to disk space usage, because of this benefits more and more projects are using pnpm.