Control: tag -1 +pending On Sat, 18 Apr 2026 10:08:37 +0200 =?UTF-8?Q?Fabian_Gr=C3=BCnbichler?= <[email protected]> wrote: > On Fri, Apr 17, 2026, at 11:05 PM, Jonas Smedegaard wrote:
> [..] > > It sounds like there is no bug here at all. Feel free to close this if > > that's how you see it. > > I think I'll leave it open to track maybe finding a way to support > -Zbuild-std in packaging context as well (e.g., to unlock some firmware > building usecase in the future, that might require a custom libstd). > > It's a bit of a tough nut to crack though, because there can only be one > replacement for crates.io (which we already use for packaged crates), so > we'd probably need to ship a copy of the vendored crates as part of > rust-src, and adapt all the dependencies to be path dependencies, and so > on. It turned out that this is actually easier than I thought. Starting with the next rustc upload, rust-src will ship a copy of the few vendored crates needed to rebuild std/core/alloc. If you make them available to cargo (i.e. by linking them into the fake registry), a lot of build-std variants already work (some targets will of course require extra setup or dependencies, like special linkers or LLVM bits). Upstream will start doing that as well: https://github.com/rust-lang/rust/pull/156196 and plans to later switch build-std over to automatically pick those up, at which point even linking them into the registry would no longer be required.
