CMake built with the Zig build system

Builds CMake (v4.3) from source using build.zig, relying only on Zig's bundled libc/libc++ toolchain. Everything CMake needs (kwsys, libuv, jsoncpp, librhash, zlib, bzip2, zstd, expat, curl, libarchive) is vendored in the CMake source tree, so there are no system dependencies and cross-compilation works out of the box.

Requirements

• Zig 0.16.0 or master
• Nothing else — no system CMake, OpenSSL, or other libraries are needed.

Build

There are two flavors, selected by -Dfull:

Flavor	Flag	Result
Bootstrap (default)	(none)	Minimal self-hosting cmake (runs cmake -E …); no --help/--version/docs.
Full	-Dfull	A real cmake: --version, --help, generators, configure/generate/build.

Targets

zig build -Dfull -Dtarget=x86_64-linux-musl     # Linux (static, host-runnable)
zig build -Dfull -Dtarget=aarch64-macos         # macOS (frameworkless)
zig build -Dfull -Dtarget=x86_64-windows-gnu    # Windows (mingw)
# and others, run 'zig targets' to check all available targets

Optional flags: -Doptimize=ReleaseFast|ReleaseSmall|ReleaseSafe|Debug (default Debug).

Use

The full build installs the runtime data (Modules/, Templates/) next to the binary at zig-out/share/cmake-4.3, so cmake resolves CMAKE_ROOT automatically — run it directly from zig-out.

# Version & help
./zig-out/bin/cmake --version
./zig-out/bin/cmake -h

# Command mode (works in both bootstrap and full builds)
./zig-out/bin/cmake -E echo "hello"
./zig-out/bin/cmake -E make_directory build
./zig-out/bin/cmake -E tar cf archive.tar file1 file2

Configure & build a project

# Given a project with a CMakeLists.txt in ./src:
./zig-out/bin/cmake -S src -B build      # configure + generate (Unix Makefiles)
cmake --build build                       # or: make -C build

Example src/CMakeLists.txt:

cmake_minimum_required(VERSION 3.10)
project(hello C)
add_executable(hello main.c)

./zig-out/bin/cmake -S src -B build
make -C build
./build/hello

How it works

build.zig replicates the upstream bootstrap script's logic in Zig:

• All preprocessor configuration flows through addCMacro / addConfigHeader (cmake-style @VAR@ / #cmakedefine templates rendered per target OS).
• Each vendored third-party library is compiled as its own static archive (cLib(...)) and linked into the final cmake executable.
• No build-time globbing — source lists are explicit arrays.

See the comments in build.zig for the per-OS specifics (config-header values, the macOS frameworkless CoreFoundation stubs, the Windows winsock/mingw fixes, etc.).

License

• This build glue (build.zig, build.zig.zon, this README) — MIT
• The CMake source it builds — BSD-3-Clause, © Kitware, Inc. and Contributors, retained as LICENSE.cmake.

BSD-3-Clause is permissive and compatible with MIT; the only requirement is preserving CMake's copyright notice, which LICENSE.cmake does.