Distributions are mostly patching software for (not specific for Rustc): * Paths - distro don't need to keep path detection and can simplify it (ex: headers de

Distributions are mostly patching software for (not specific for Rustc): * Paths - distro don't need to keep path detection and can simplify it (ex: headers detections) * Archs that upstream don't care about (ex: m86k). * Kernel that upstream don't care about (kfreebsd) * Some old CPU support. example: https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/debian/patches/d-rustc-i686-baseline.patch https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/de... * simplification of the build system (ex: skipping windows support) * Use libraries provided by the system (ex: compiler-rt for rustc: https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/debian/patches/u-allow-system-compiler-rt.patch https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/de...). This could be forwarded upstream. * Some minor doc changes - for example, https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/debian/patches/d-bootstrap-use-local-css.patch https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/de... will use the local css file and not a remote css file (for offline support) * Cherry-pick upstream fixes before the next upstream release: https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/debian/patches/u-stdarch-1278.patch https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/de... * etc As you can see, these patches do not impact the quality of Rustc itself. Some could be forwarded upstream (it is a pain for packagers to maintain patches - so, we do have strong incentives to contribute upstream).