Build Mode

Build Mode

Zig has four build modes:

Debug (default)
ReleaseFast
ReleaseSafe
ReleaseSmall

To add standard build options to a build.zig file:

build.zig

const std = @import("std");
pub fn build(b: *std.Build) void {
    const optimize = b.standardOptimizeOption(.{});
    const exe = b.addExecutable(.{
        .name = "example",
        .root_source_file = .{ .path = "example.zig" },
        .optimize = optimize,
    });
    b.default_step.dependOn(&exe.step);
}

This causes these options to be available:

-Doptimize=Debug

Optimizations off and safety on (default)

-Doptimize=ReleaseSafe

Optimizations on and safety on

-Doptimize=ReleaseFast

Optimizations on and safety off

-Doptimize=ReleaseSmall

Size optimizations on and safety off

Debug

Shell

$ zig build-exe example.zig

Fast compilation speed
Safety checks enabled
Slow runtime performance
Large binary size
No reproducible build requirement

ReleaseFast

Shell

$ zig build-exe example.zig -O ReleaseFast

Fast runtime performance
Safety checks disabled
Slow compilation speed
Large binary size
Reproducible build

ReleaseSafe

Shell

$ zig build-exe example.zig -O ReleaseSafe

Medium runtime performance
Safety checks enabled
Slow compilation speed
Large binary size
Reproducible build

ReleaseSmall

Shell

$ zig build-exe example.zig -O ReleaseSmall

Medium runtime performance
Safety checks disabled
Slow compilation speed
Small binary size
Reproducible build