console

$ zig build-exe evented_test_case.zig
broken LLVM module found: Basic Block in function 'std.child_process.ChildProcess.spawnPosix' does not have terminator!
label %OkResume
Instruction does not dominate all uses!
  %28 = load { %std.child_process.Term, i16 }*, { %std.child_process.Term, i16 }** %6, align 8, !dbg !6264
  %41 = bitcast { %std.child_process.Term, i16 }* %28 to i8*, !dbg !6264

This is a bug in the Zig compiler.
Unable to dump stack trace: debug info stripped
zsh: abort      zig build-exe evented_test_case.zig

evented_test_case.zig

const std = @import("std");
const stdout = std.io.getStdOut().writer();
const print = stdout.print;
const Allocator = std.mem.Allocator;

const Str = []const u8;
pub var A: *Allocator = undefined;

pub const io_mode = .evented;

const GitStatus = struct {
    // state: Str,
    branch: Str,
    status: Str,
    // stash: Table[Str, int]
};

fn run(argv: []const Str) !std.ChildProcess.ExecResult {
    return try std.ChildProcess.exec(.{
        .allocator = A,
        .argv = argv,
    });
}

fn concatStringArray(lists: []const []Str) ![]Str {
    return try std.mem.concat(A, Str, lists);
}

fn gitCmd(args: []Str, workingdir: Str) !std.ChildProcess.ExecResult {
    var gitcmd = [_]Str{"git", "-C", workingdir};
    var cmd_parts = [_][]Str{ &gitcmd, args };
    var cmd = try concatStringArray(&cmd_parts);
    return try run(cmd);
}

fn getBranch(dir: Str) !Str {
    var cmd1 = [_]Str{"symbolic-ref", "HEAD", "--short"};
    var result = try gitCmd(&cmd1, dir);
    if (result.term.Exited == 0)
        return result.stdout;

    var cmd2 = [_]Str{"describe", "--all", "--contains", "--always", "HEAD"};
    result = try gitCmd(&cmd2, dir);
    return result.stdout;
}

fn getStatus(dir: Str) !Str {
    // get and parse status codes
    var cmd = [_]Str{"status", "-zb"};
    var result = try gitCmd(&cmd, dir);
    if (result.term.Exited != 0)
        return error.GitStatusFailed;

    return result.stdout;
}

fn getFullRepoStatus(dir: Str) !GitStatus {
    var branch = async getBranch(dir);
    var status = async getStatus(dir);
    return GitStatus{
        // .state = getState(dir),
        .branch = try await branch,
        .status = try await status,
        // .stash = getRepoStashCounts(dir),
    };
}

pub fn main() !u8 {
    // allocator setup
    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    defer arena.deinit();
    A = &arena.allocator;

    var dir: Str = ".";
    var status = try getFullRepoStatus(dir);
    return 0;
}

Compiles and runs if you comment out:

pub const io_mode = .evented;