Zig Build System Internals
2 days ago
- The Zig build system uses build.zig for configuration and the zig build CLI for execution, compiling a build binary first then executing it as a child process.
- The build binary is built from build_runner.zig in the standard library, which imports the user's build.zig as the @build package.
- The build binary is cached and only recompiled when build.zig or its imports change, avoiding recompilation on subsequent runs.
- The build binary does not embed the Zig compiler; it subprocesses to zig build-exe or other commands to compile artifacts.
- Build steps are defined declaratively in the build function using the Builder API, with dependencies and execution order handled by the build runner.
- Each step has a makeFn function pointer, dependencies, and flags to detect loops and ensure each step executes once.
- The build function supports both void and error union return types, detected via comptime introspection.
- Understanding the internals removes the 'magic' and helps users become more productive with the build system.