Bootstrapping `psm` is non-trivial

[kayabaNerve]

I'm working on bootstrapping a Rust toolchain and psm was a compiled dependency. Due to the amount of binary artifacts included in the vendored Rust tarball, I added a pass to remove all .o, .a, .so, .lib, .dll, and .exe files while also stripping all executable bits. In doing so, I noted psm failed to build due to expecting wasm.o.

Building wasm.o myself was easy enough, the command to do included in the wasm.s file. Unfortunately, my wasm.o differs from the vendored wasm.o, so not only can I not reproduce the wasm.o included in the repository (presumably due to the age of the toolchain it was created with), the Rust build won't continue as the package's digest has changed.

While I can continue the work on patching the build system on my end, just patching the .cargo-checksum.json file (which I have to do for all other crates which also committed binary artifacts, and the Cargo.locks) I'd like to open the issue upstream that psm cannot be bootstrapped/reproduced and request the build.rs build the wasm.o, as done for all other targets. I would guess the decision was made years ago to ship the artifact due to the lack of WASM toolchains laying around, but I'd hope this can be revisited now?

[nagisa]

I'm not sure if there will be llvm-mc or a similar wasm "assembler" laying around for us to use usually. The best I can think of is compiling wat as a dependency of build.rs but that sounds pretty expensive to impose on everybody… maybe we could make it a cargo feature 🤷

[nagisa]

I guess I can also require that they have wabt or wasm-tools available at build time, but idk how that is going to work with regards to linking…

[kayabaNerve]

Anecdotally, I do have llvm-mc available as part of my distribution's clang and/or llvm-tools. This also could be a candidate for Rust's toolchain, which already includes a wasm-component-ld, but that'd a much longer discussion.

Distinctly, many existing crates in the ecosystem which ship artifacts allow opting into/out of source builds with features and/or environment variables. It can always be made so configurable such that building only fails if both options are unavailable.