zig linkage failure 0.9.0-dev.1936+77836e08a

build.zig

const std = @import("std");

pub fn build(b: *std.build.Builder) void {
    // Standard target options allows the person running `zig build` to choose
    // what target to build for. Here we do not override the defaults, which
    // means any target is allowed, and the default is native. Other options
    // for restricting supported target set are available.
    const target = b.standardTargetOptions(.{});

    // Standard release options allow the person running `zig build` to select
    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
    const mode = b.standardReleaseOptions();

    const exe = b.addExecutable("call-c", "main.zig");
    exe.linkLibC();
    exe.linkSystemLibrary("libsystemd");
    exe.setTarget(target);
    exe.setBuildMode(mode);
    exe.install();

    const run_cmd = exe.run();
    run_cmd.step.dependOn(b.getInstallStep());
    if (b.args) |args| {
        run_cmd.addArgs(args);
    }

    const run_step = b.step("run", "Run the app");
    run_step.dependOn(&run_cmd.step);

    const exe_tests = b.addTest("main.zig");
    exe_tests.setBuildMode(mode);

    const test_step = b.step("test", "Run unit tests");
    test_step.dependOn(&exe_tests.step);
}

main.zig

const std = @import("std");

const c = @cImport(@cInclude("systemd/sd-bus.h"));

pub fn main() anyerror!void {
    var bus: ?*c.sd_bus = null;
    var r = c.sd_bus_default_system(&bus);
    if (r <= 0) {
        std.log.info("dbus failed: {}", .{r});
        return;
    }

    defer c.sd_bus_unrefp(&bus);

    var msg: ?*c.sd_bus_message = null;
    var err = c.sd_bus_error{ .name = null, .message = null, ._need_free = 0 };

    r = c.sd_bus_get_property(bus, "org.freedesktop.timedate1", "/org/freedesktop/timedate1", "org.freedesktop.timedate1", "TimeUSec", &err, &msg, "t");

    if (r < 0) {
        std.log.info("SD bus error: {s} - {s}", .{ err.name, err.message });
        return;
    }

    defer c.sd_bus_message_unrefp(&msg);

    if (msg) |m| {
        var ts: c_ulonglong = 0;
        _ = c.sd_bus_message_read_basic(m, 't', &ts);

        std.log.info("The time is: {}", .{ts});
    }
}

test "basic test" {
    try std.testing.expectEqual(10, 3 + 7);
}