I happened to try to compile my pet project through emscripten for the first time yesterday. The experience was pretty bad overall. Installing the emscripten toolchain was slow and painful, and in the end the installation took 25 gigabytes. That’s more than all the other software on my laptop combined, including the operating system.
When I finally got it running, the compiler crashed with some assertion error deep in the emscripten internals. My other, smaller projects compiled just fine, so I think my toolchain is sound, I guess it couldn’t handle some of my project’s dependencies. I haven’t gotten around to posting a proper issue anywhere, mostly because I don’t really know where to start, I’m not familiar enough with the toolchain to know which part failed.
It’s possible none of these problems were really Rust’s fault, but wasm and asmjs are definitely far from being Tier 1 targets.