Since packaging 1.15 has been delayed, I thought you might be stuck on the build errors.

Rust 1.15 enabled the new "rustbuild" system [0] by default. Some kinks need to be ironed out to make that work.

Attached is a PKGBUILD (and a diff for convenience) that successfully builds with extra-{i686,x86_64}-build from 'devtools'.

Explanations:

* NEEDED: The 2 patches (destdir [1] and jemalloc [2]) are backports from 1.16 to prevent build errors. They can be removed in the next version.

* NEEDED: --enable-llvm-link-shared : old build system in 1.14 sorta implied this, rustbuild 1.15+ has this explicit flag instead, see [3]

* CLEANUP: cmake [4], libffi, ninja [5] and perl are really only needed to build the vendored llvm or statically link it, but we use shared system-llvm. I've removed all things relating to that from the PKGBUILD.

* CLEANUP+: '!strip' does cause some (harmless) warnings for the *.rlib files, but I think *.so should still be stripped so I removed that. It makes the package smaller (~10M stripped vs unstripped 1.15)

* CLEANUP: 'staticlibs' is useless as there are no *.a files in the package to keep.

* CLEANUP: Removed a few more rust-installer files that were left in the pkg (e.g. uninstall.sh)

* OPTIONAL: --enable-local-rust --local-rust-root=/usr --enable-vendor :
This is for bootstrapping from previous version that I suggested last time [6]. With rustbuild from 1.15+ using cargo as well, another binary that we already have is downloaded during build. The previous issues with point releases have been fixed (as a data point: I've followed the transitions 1.12.1->1.13.0->1.14.0->1.15.0->1.15.1 successfully on my dev setup).


Future stuff: looks like building rust and cargo at once is being worked on, see [7]: "port cargo build to the rust extended build system". We'll see what comes from that.

Just ask if you need more info.



[0] https://github.com/rust-lang/rust/pull/37817
[1] https://github.com/rust-lang/rust/issues/38441
[2] https://github.com/rust-lang/rust/issues/39215
[3] https://github.com/rust-lang/rust/commit/b1da18f
[4] https://github.com/rust-lang/rust/blob/1.15.1/configure#L856
[5] https://github.com/rust-lang/rust/blob/1.15.1/configure#L638
[6] https://bugs.archlinux.org/task/51335
[7] https://github.com/rust-lang/rust/issues/38531