ability to depend on zig modules

[andrewrk]

Extracted from #14265.

Terminology clarification: #14307

Something like this:

build.zig.zon

.{
    .name = "clap",
    .url = "...",
    .hash = "...",
}

build.zig

// "clap" here references the dependency.name field of the build.zig.zon file.
const clap_pkg = b.dependency("clap", .{});

const exe = b.addExecutable("app", "src/main.zig");

// "clap" here is the string used when calling b.addModule (see code snippet below)
const clap_module = clap_pkg.module("clap");

// "clap" here is the name used for `@import` within src/main.zig
exe.addModule("clap", clap_module);

The build.zig file for clap:

const module = b.addModule("clap", ".", "clap.zig");

const example = b.addExecutable("simple", "example/simple.zig");
example.addModule("clap", module);
example.setBuildMode(mode);
example.setTarget(target);
example.install();

See #14282 for depending on pure zig modules without executing build.zig logic.

See #14286 for running build.zig logic in a sandbox.

[antlilja]

How are you supposed to handle pure zig packages which in turn depend on for example system libraries? Are you supposed to create a CompilationArtifact as well as a Module and the package consumer needs to link against both, or is the Module supposed to have knowledge about its non pure zig dependencies?

const lib = b.addStaticLibrary("a", "a.zig");
lib.linkSystemLibrary("some-system-library");
lib.linkLibC();

const module = b.addModule("a", "a.zig");

const module = b.addModule("a", "a.zig");
module.linkSystemLibrary("some-system-library");
module.linkLibC();

[tisonkun]

Nice to see the evolution in package management!

FWIW - I'm caching these changes in my toy project https://github.com/korandoru/zig-uuid to demonstrate the usage for new build APIs.