Link warning does not fail the build and is not shown on subsequent builds

[pfgithub]

Zig Version

0.14.0-dev.1570+8ddce90e6

Steps to Reproduce and Observed Behavior

// a.zig
export fn add(a: i32, b: i32) i32 {
    return a + b;
}

// b.zig
extern fn add(a: i32) i32;

test "add" {
    try @import("std").testing.expectEqual(@as(i32, 5), add(5));
}

// build.zig
const std = @import("std");

pub fn build(b: *std.Build) !void {
    const optimize = b.standardOptimizeOption(.{});
    const obj = b.addObject(.{
        .name = "a",
        .root_source_file = b.path("a.zig"),
        .target = b.resolveTargetQuery(try std.Build.parseTargetQuery(.{.arch_os_abi = "wasm32-freestanding"})),
        .optimize = optimize,
    });
    const test_exe = b.addTest(.{
        .root_source_file = b.path("b.zig"),
        .target = b.resolveTargetQuery(try std.Build.parseTargetQuery(.{.arch_os_abi = "wasm32-wasi-musl"})),
        .optimize = optimize,
    });
    test_exe.addObject(obj);
    b.installArtifact(test_exe);
}

Run zig build once. Note the warning:

$> zig build
install
└─ install test
   └─ zig test Debug wasm32-wasi-musl failure
error: warning(link): unexpected LLD stderr:
wasm-ld: warning: function signature mismatch: add
>>> defined as (i32) -> i32 in test.wasm.o
>>> defined as (i32, i32) -> i32 in a.o
$> echo $?
0

Run zig build again. No output.

$> zig build
$> echo $?
0

Expected Behavior

The first build should have failed, or at minimum the error message should be cached and subsequent builds should display the same error.

[pfgithub]

Maybe it should not fail the build because some other link warnings don't seem to cause any problems, but it should show on every build.

This seemingly causes no problems:

error: warning(link): unexpected LLD stderr:
ld.lld: warning: libzdawn.a: archive member 'libdawn.a' is neither ET_REL nor LLVM bitcode