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| -rw-r--r-- | tvix/docs/src/TODO.md | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/tvix/docs/src/TODO.md b/tvix/docs/src/TODO.md index c686f8ab64eb..20ad07eb2505 100644 --- a/tvix/docs/src/TODO.md +++ b/tvix/docs/src/TODO.md @@ -25,6 +25,32 @@ sure noone is working on this, or has some specific design in mind already. with a different level of `--strict`, but the toplevel doc-comment suggests its generic? +### crate2nix for WASM +Most of Tvix is living inside a `//tvix` cargo workspace, and we use `crate2nix` +as a build system, to get crate-level build granularity (and caching), keeping +compile times somewhat manageable. + +In the future, for Store/Build, we want to build some more web frontends, +exposing some data by calling to the API. Being able to write this in Rust, +and reusing most of our existing code dealing with the data structures would +be preferred. + +However, using the crate2nix tooling in combination with compiling for WASM is +a bumpy ride (and `//web.tvixbolt` works around this by using +`rustPlatform.buildRustPackage` instead, which invokes cargo inside a FOD): + +`buildRustCrate` in nixpkgs (which is used by `crate2nix` under the hood) +doesn't allow specifying another `--target` explicitly, but relies on the cross +machinery in nixpkgs exclusively. + +`doc/languages-frameworks/rust.section.md` suggests it should be a matter of +re-instantiating nixpkgs for `wasm32-unknown-unknown`, but that's no recognized +as a valid architecture. +The suggested alternative, setting only `rustc.config` to it seems to get us +further, but the `Crate.nix` logic for detecting arch-conditional crates doesn't +seem to cover that case, and tries to build crates (`cpufeatures` for `sha{1,2}`) +which are supposed to be skipped. + ## Perf - String Contexts currently do a lot of indirections (edef) (NixString -> NixStringInner -> HashSet[element] -> NixContextElement -> String -> data) |