zig/lib/std/Build/LogStep.zig

const std = @import("../std.zig");
const log = std.log;
const Step = std.Build.Step;
const LogStep = @This();

pub const base_id = .log;

step: Step,
builder: *std.Build,
data: []const u8,

pub fn init(builder: *std.Build, data: []const u8) LogStep {
    return LogStep{
        .builder = builder,
        .step = Step.init(builder.allocator, .{
            .id = .log,
            .name = builder.fmt("log {s}", .{data}),
            .makeFn = make,
        }),
        .data = builder.dupe(data),
    };
}

fn make(step: *Step, prog_node: *std.Progress.Node) anyerror!void {
    _ = prog_node;
    const self = @fieldParentPtr(LogStep, "step", step);
    log.info("{s}", .{self.data});
}