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Source code

const std = @import("std");
var rand: std.Random = undefined;

const Error = error{
    Account_Is_Empty,
    Investment_Lost,
};

const ErrorOrigin = enum {
    f2,
    f3,
};

fn f1() !void {
    const n: u8 = rand.uintLessThan(u8, 9) + 1;
    if (n % 2 == 0) {
        return Error.Account_Is_Empty;
    }
    return Error.Investment_Lost;
}

fn f2() !void {
    try f1();
}

fn f3() !void {
    try f1();
}

fn f4(error_origin: ?*ErrorOrigin) !void {
    const n: u8 = rand.uintLessThan(u8, 9) + 1;
    if (n % 2 == 0) {
        f2() catch |err| {
            if (error_origin) |diagn| diagn.* = .f2;
            return err;
        };
    }

f3() catch |err| {
        if (error_origin) |diagn| diagn.* = .f2;
        return err;
    };
}

const std_out = std.io.getStdOut().writer();

pub fn main() !void {
    var DefaultPrng = std.Random.DefaultPrng.init(@intCast(std.time.microTimestamp()));
    rand = DefaultPrng.random();

var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const alloc = gpa.allocator();

var error_origin: ErrorOrigin = undefined;
    f4(&error_origin) catch |err| {
        switch (error_origin) {
            .f2 => switch (err) {
                Error.Account_Is_Empty => try std_out.print("Aand it's gone\n", .{}),
                else => try std_out.print("This line is for bank members only\n", .{}),
            },
            .f3 => switch (err) {
                Error.Investment_Lost => try std_out.print("The money in your account didn't do well\n", .{}),
                else => try std_out.print("This line is for bank members only\n", .{}),
            },
        }
        try printTrace(err, alloc);
    };

try std_out.print("\n\n", .{});
}

inline fn printTrace(err: Error, alloc: std.mem.Allocator) !void {
    const stack_trace: *std.builtin.StackTrace = @errorReturnTrace().?;
    const debug_info = try std.debug.getSelfDebugInfo();