Undefined floating point symbols on `x86_64-unknown-none`

[mkroening]

The following symbols are not available on x86_64-unknown-none:

• fmin
• fminf
• fmax
• fmaxf
• fmod
• fmodf

Reproduction:

// foo.rs
#![no_std]
#![no_main]

#[no_mangle]
pub extern "C" fn _start() -> ! {
    use core::hint::black_box;

    let f = black_box(1.0_f32);
    black_box(f.min(1.0));
    black_box(f.max(1.0));
    black_box(f % 1.0);

    let f = black_box(1.0_f64);
    black_box(f.min(1.0));
    black_box(f.max(1.0));
    black_box(f % 1.0);

    panic!()
}

#[panic_handler]
fn panic(_: &core::panic::PanicInfo) -> ! {
    loop {}
}

$ rustc +nightly-2022-12-07 --target x86_64-unknown-none foo.rs
error: linking with `rust-lld` failed: exit status: 1
  |
  = note: "rust-lld" "-flavor" "gnu" "/var/folders/25/fkdqct450w39l8ws39k941jh0000gn/T/rustceBzca5/symbols.o" "foo.foo.aba6b5b9-cgu.0.rcgu.o" "foo.foo.aba6b5b9-cgu.1.rcgu.o" "foo.foo.aba6b5b9-cgu.2.rcgu.o" "foo.foo.aba6b5b9-cgu.3.rcgu.o" "--as-needed" "-L" "/Users/mkroening/.rustup/toolchains/nightly-2022-12-07-aarch64-apple-darwin/lib/rustlib/x86_64-unknown-none/lib" "-Bstatic" "/Users/mkroening/.rustup/toolchains/nightly-2022-12-07-aarch64-apple-darwin/lib/rustlib/x86_64-unknown-none/lib/librustc_std_workspace_core-4bf14777d6346759.rlib" "/Users/mkroening/.rustup/toolchains/nightly-2022-12-07-aarch64-apple-darwin/lib/rustlib/x86_64-unknown-none/lib/libcore-205d88bf497b2586.rlib" "/Users/mkroening/.rustup/toolchains/nightly-2022-12-07-aarch64-apple-darwin/lib/rustlib/x86_64-unknown-none/lib/libcompiler_builtins-f0aaa0512d1a096b.rlib" "-Bdynamic" "--eh-frame-hdr" "-znoexecstack" "-L" "/Users/mkroening/.rustup/toolchains/nightly-2022-12-07-aarch64-apple-darwin/lib/rustlib/x86_64-unknown-none/lib" "-o" "foo" "--gc-sections" "-pie" "-zrelro" "-znow"
  = note: rust-lld: error: undefined symbol: fmax
          >>> referenced by foo.aba6b5b9-cgu.1
          >>>               foo.foo.aba6b5b9-cgu.1.rcgu.o:(core::f64::_$LT$impl$u20$f64$GT$::max::hb8f56ded435178fc)
          
          rust-lld: error: undefined symbol: fmin
          >>> referenced by foo.aba6b5b9-cgu.1
          >>>               foo.foo.aba6b5b9-cgu.1.rcgu.o:(core::f64::_$LT$impl$u20$f64$GT$::min::h96fdc18609326941)
          
          rust-lld: error: undefined symbol: fmodf
          >>> referenced by foo.aba6b5b9-cgu.2
          >>>               foo.foo.aba6b5b9-cgu.2.rcgu.o:(_start)
          
          rust-lld: error: undefined symbol: fmod
          >>> referenced by foo.aba6b5b9-cgu.2
          >>>               foo.foo.aba6b5b9-cgu.2.rcgu.o:(_start)
          
          rust-lld: error: undefined symbol: fmaxf
          >>> referenced by foo.aba6b5b9-cgu.3
          >>>               foo.foo.aba6b5b9-cgu.3.rcgu.o:(core::f32::_$LT$impl$u20$f32$GT$::max::h44f01d00f3d26d49)
          
          rust-lld: error: undefined symbol: fminf
          >>> referenced by foo.aba6b5b9-cgu.3
          >>>               foo.foo.aba6b5b9-cgu.3.rcgu.o:(core::f32::_$LT$impl$u20$f32$GT$::min::h4f3c8d0acfd3c696)
          

error: aborting due to previous error

CC: @haraldh, @mikeleany (x86_64-unknown-none target maintainers)