Memory leak example with different Zig build modes

leak.zig

//! Memory leak example with different Zig build modes.
//!
//! The program does not compile because zig detects a memory leak:
//! zig build-exe leak.zig -O Debug && ./leak
//! zig build-exe leak.zig -O ReleaseSafe && ./leak
//!
//! The program compiles, but there will be undefined behavior:
//! zig build-exe leak.zig -O ReleaseSmall && ./leak
//! zig build-exe leak.zig -O ReleaseFast && ./leak
//! See also:
//! https://ziglang.org/documentation/master/#Build-Mode
const std = @import("std");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer std.debug.assert(!gpa.deinit());

    const allocator = &gpa.allocator;

    const bytes = try allocator.alloc(u8, 100);
    // memory leak because we didn't call free on the `bytes` slice

    // Uncomment next line to free the slice, thus avoiding the memory leak
    // defer allocator.free(bytes);
}