meta-rust does not build for qemuriscv64

[rwmacleod]

Version(s) of meta-rust

Version(s) of poky and/or oe-core

I used the master branches of oe-core, meta-oe, meta-rust:

Build Configuration: [55/1893]
BB_VERSION = "1.43.1"
BUILD_SYS = "x86_64-linux"
NATIVELSBSTRING = "ubuntu-18.04"
TARGET_SYS = "riscv64-oe-linux"
MACHINE = "qemuriscv64"
DISTRO = "nodistro"
DISTRO_VERSION = "nodistro.0"
TUNE_FEATURES = "riscv64"
meta = "master:36670f3989ef129d285b2a17c289f8fc7a44b320"
meta-oe = "master:ef1b17f4ef537325f212d847ec7e5f7bd3447066"
meta-rust.git = "master:11aed43748d7dd194dc6c06a35a16104400d1090"

Expected result

Rust supports qemuriscv64 and rust-hello-world builds and runs

Actual result

...
ERROR: libstd-rs-1.37.0-r0 do_compile: Execution of '/.../tmp-glibc/work/riscv64-oe-linux/libstd-rs/1
.37.0-r0/temp/run.do_compile.28375' failed with exit code 101:
warning: /.../tmp-glibc/work/riscv64-oe-linux/libstd-rs/1.37.0-r0/rustc-1.37.0-src/src/tools/miri/Car
go.toml: the cargo feature default-run is now stable and is no longer necessary to be listed in the manifest
error: failed to run rustc to learn about target-specific information

Caused by:
process didn't exit successfully: rustc - --crate-name ___ --print=file-names -L /.../tmp-glibc/wo rk/riscv64-oe-linux/libstd-rs/1.37.0-r0/recipe-sysroot/usr/lib/rust --remap-path-prefix=/.../tmp-glib c/work/riscv64-oe-linux/libstd-rs/1.37.0-r0=/usr/src/debug/libstd-rs/1.37.0-r0 -L /.../tmp-glibc/work /riscv64-oe-linux/libstd-rs/1.37.0-r0/recipe-sysroot/usr/lib -C link-arg=-Wl,-soname,libstd.so --target riscv64-oe-linux --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro (exit code: 1)
--- stderr
error: Could not create LLVM TargetMachine for triple: riscv64-unknown-linux-gnu: No available targets are compatible with triple "riscv64-unknown-lin
ux-gnu"

Steps to reproduce

MACHINE=qemuriscv64 bitbake rust-hello-world

[rwmacleod]

Works with rust-1.47 or earlier:

qemuriscv64 login: root
root@qemuriscv64:# uname -r
5.10.12-yocto-standard
root@qemuriscv64:# rust-hello-world
Hello, world!