RISC-V has different triples for clang and rustc.

[trissylegs]

Same as #1211 Clang and rust use a different target triples on riscv.

I'm already trying to fix it. Using a similar solution to #1211. (I found the issue due to a comment on rust_to_clang_target)

Rust uses riscv64gc-unknown-linux-gnu, but clang uses riscv64-unknown-linux-gnu.
The difference is that riscv64gc has the extra features needed to run Linux. (ie Mutiplication, Floats, Atomics, Fences and CSRs), as well as Compressed instructions (16-bit encodings).

Clang instead uses -march to specify which extensions to use: eg (-march=rv6gc). Maybe should consider setting that too.

The example below is taken from authenticator-rs: https://github.com/mozilla/authenticator-rs/blob/660a701b45977cb5d184380061dfc8cec4f696be/build.rs#L12

Input C/C++ Header

// Literally anything

Bindgen Invocation

    let bindings = bindgen::Builder::default()
        .header("src/linux/hidwrapper.h")
        .whitelist_var("_HIDIOCGRDESCSIZE")
        .whitelist_var("_HIDIOCGRDESC")
        .generate()
        .expect("Unable to get hidraw bindings");

Actual Results

  error: unknown target triple 'riscv64gc-unknown-linux-gnu', please use -triple or -arch
  thread 'main' panicked at 'libclang error; possible causes include:
  - Invalid flag syntax
  - Unrecognized flags
  - Invalid flag arguments
  - File I/O errors
  If you encounter an error missing from this list, please file an issue or a PR!', /home/user/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/bindgen-0.51.1/src/ir/context.rs:571:15
  stack backtrace:
     0: rust_begin_unwind
               at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:517:5
     1: core::panicking::panic_fmt
               at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:100:14
     2: core::panicking::panic_display
               at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:64:5
     3: core::option::expect_failed
               at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/option.rs:1638:5
     4: core::option::Option<T>::expect
               at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/option.rs:709:21
     5: bindgen::ir::context::BindgenContext::new
               at /home/user/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/bindgen-0.51.1/src/ir/context.rs:565:13
     6: bindgen::Bindings::generate
               at /home/user/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/bindgen-0.51.1/src/lib.rs:1875:27
     7: bindgen::Builder::generate
               at /home/user/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/bindgen-0.51.1/src/lib.rs:1244:9
     8: build_script_build::main
               at ./build.rs:12:20
     9: core::ops::function::FnOnce::call_once
               at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Expected Results

Expected results are that bindgen uses clang with the matching target triple.

Workarond

Specify .clang_arg("--target=riscv64-unknown-linux-gnu") on riscv
Eg: https://github.com/trissylegs/authenticator-rs/blob/abcf07a231667e16a50da855d3e86765c158f0a2/build.rs#L19

[emilio]

Fixed by #2137

[XieJiSS]

Hi @emilio , would it be possible for you to release a new minor version which contains PR #2137's code? Currently we have to manually import the patch from that PR. Thanks in advance!

[kupiakos]

This is also a problem for riscv32imc-unknown-none-elf. Our workaround is to do .clang_arg("--target=riscv32-unknown-none-elf").