Call for further testing: wasi-sdk-20 and corresponding LLVM toolchain(s)

From: Charlie Li <>
Date: Wed, 21 Jun 2023 04:10:21 UTC

The main mozilla-central/comm-central codebases (Firefox, Thunderbird, 
etc) have been buildable and functional with LLVM toolchains newer than 
the hardcoded LLVM 13 we have in This diff not only 
enables that, but more importantly updates the WASI SDK components to 
enable using newer LLVM toolchains. USES=llvm controls which version to 
use through your ${DEFAULT_VERSIONS} setting.

As a reminder, LTO only works when the LLVM version between Rust and 
everything else matches exactly. Since the current Rust 1.70.0 uses LLVM 
16, LTO will only work with LLVM 16 (currently only Firefox non-ESR).

Since this has a sizeable blast radius, I'm not committing any of this 
until we reach consensus on the maintenance plan going forward.

Charlie Li
…nope, still don't have an exit line.