cannot link object files with different floating-point ABI on RV32 target

[XiangYyang]

Zig Version

0.13.0

Steps to Reproduce and Observed Behavior

Start a new project and use zig init. Then, set the target in build.zig.

    const target_query = .{
        .cpu_arch = .riscv32,
        .cpu_model = .{ .explicit = &std.Target.riscv.cpu.baseline_rv32 },
        .os_tag = .freestanding,
        .abi = .eabi,
    };

    // reslove target
    const target = b.resolveTargetQuery(target_query);

    // ...
    const exe = b.addExecutable(.{
        .name = "test",
        .root_source_file = b.path("src/main.zig"),
        .target = target,
        .optimize = optimize,
    });

Then, create an assembly source file like the following, and add it to the exe archive.

; A rv32 asm source file, like `src/asmfile.s`
.section    .text._start, "ax", @progbits
.globl       _start
.align      1
_start:
	    j   _start 

// add it into `exe`
exe.addAssemblyFile(b.path("src/asmfile.s"));

Now try to run zig build, and if everything works, you will get an elf file. However, when I enable lto, an error occurs. Modify the build.zig to add the LTO.

exe.want_lto = true;

And re-run zig build, the ld.lld said.

error: ld.lld: D:\a\test\.zig-cache\o\somehash\test.lto.o:
       cannot link object files with different floating-point ABI from D:\a\test\.zig-cache\o\somehash\asmfile.o

I tried reading the elf header file with readelf and found that the header of asmfile.o is different from the header of the zig build output file without LTO.

# asmfile.o
ELF Header:
  ...
  Flags:                             0x5, RVC, double-float ABI

# `zig build` output with exe.want_lto = true; excluding the assembly file
ELF Header:
  ...
  Flags:                             0x0

# `zig build` output with exe.want_lto = false; excluding the assembly file
ELF Header:
  ...
  Flags:                             0x5, RVC, double-float ABI

It looks like it's caused by something missing from the ELF header on the LTO output.

Is this a bug? how should I fix it

Expected Behavior

baseline_rv32 is rv32iamcd, so it includes the D extension, so LTO's ELF Header should include double-float ABI

1. The ELF Header for LTO's output should also have double-float ABI