Make blake3 C library usable as meson subproject

[nirs]

The meson build system[1] support subprojects - a way to use another project in your build. The blake3 C library can be used like this, but meson requires that the subproject root directory has either meson.build (for meson projects) or CMakeLists.txt (meson can build cmake projects).

Add CMakeLists.txt in the root directory with the project info, including the c subdirectory. With this you can add blake3 as subproject to a meson project.

Example wrap file (using test release from my fork):

% cat subprojects/blake3.wrap
[wrap-file]
directory = BLAKE3-1.4.1-cmake
source_url = https://github.com/nirs/BLAKE3/archive/refs/tags/1.4.1-cmake.tar.gz
source_filename = BLAKE3-1.4.1-cmake.tar.gz
source_hash = 6c6f053ede700d76d12a7ced7bbd640e7a47f97122fe4cbe718aa9406251d043

With this wrap file, you can use blake3 in your meson project[2] like this:

% cat meson.build
project('blake3-meson', 'c', default_options: ['buildtype=release'])
cmake = import('cmake')
blake3_subproj = cmake.subproject('blake3')
blake3_dep = blake3_subproj.dependency('blake3')
executable(example, ['example.c'], dependencies: blake3_dep)

[1] https://mesonbuild.com/
[2] https://github.com/nirs/blake3-meson

[nirs]

I also started to work on adding meson build system, but it requires more work:
https://github.com/nirs/BLAKE3/tree/meson

Reusing the existing cmake build is more practical.

[oconnor663]

Is there no way to tell Meson to look in the c/ subdirectory? I've been thinking about cleaning up the root so that everything's under c/, rust/, etc. This feels like moving in other direction.

[nirs]

Is there no way to tell Meson to look in the c/ subdirectory?

Unfortunately no, it requires build files at the root.

I've been thinking about cleaning up the root so that everything's under c/, rust/, etc. This feels like moving in other direction.

Moving everything but the build files sounds like a good idea. It is nice that the you can do everything from the root, and it make the project more friendly to various tools.

[BurningEnlightenment]

If we were to go with this, I would prefer moving the whole CMakeLists.txt to the root directory. Our CMakeLists.txt is less than 200 lines long, therefore I think splitting would decrease readability for no benefit.