"cannot link object files with different floating-point ABI" (nightly-2021-03-23)

[yvt]

riscv and riscv-rt crates cause a linker error when building with a recent nightly compiler for a hard-float target.

git clone https://github.com/riscv-rust/k210-crates.git --recursive
cd k210-crates
cd k210-example
sed -i .bak -e 's/riscv64imac/riscv64gc/g' .cargo/config
cargo +nightly-2021-03-23 build --release

Output:

error: linking with `rust-lld` failed: exit code: 1
  |
  = note: "rust-lld" "-flavor" "gnu" "-L" [...]
  = note: rust-lld: error: [redacted]/target/riscv64gc-unknown-none-elf/release/deps/libriscv-3f21992281a58781.rlib(riscv.o): cannot link object files with different floating-point ABI
          rust-lld: error: [redacted]/target/riscv64gc-unknown-none-elf/release/deps/libriscv_rt-db1e8f195a4770c0.rlib(riscv-rt.o): cannot link object files with different floating-point ABI


error: aborting due to previous error

error: could not compile `k210-example`

To learn more, run the command again with --verbose.

It appears that this started happening somewhere between nightly-2021-03-10 and nightly-2021-03-23 (inclusive).

• 1.50.0: ok
• nightly-2021-02-19: ok
• nightly-2021-02-23: ok
• nightly-2021-03-09: ok
• nightly-2021-03-23: fail

[yvt]

This might have been caused by rust-lang/rust#83231