A separate function to link the libraries

[paveloom]

Hello there.

Long story short, here's what I've done to override one of the packages with project-specific options inside build.zig:

// <...>

// Create an option to enable Tracy integration
const tracy_enabled_option = b.option(
    bool,
    "tracy",
    "Enable Tracy integration",
) orelse false;
// Create an option to override Tracy's default call stack capture depth
const tracy_depth_option = b.option(
    c_int,
    "tracy-depth",
    "Override Tracy's default call stack capture depth",
) orelse 0;
// Add these options to a separate group of options
const tracy_options = b.addOptions();
exe.addOptions("tracy_options", tracy_options);
tracy_options.addOption(bool, "tracy", tracy_enabled_option);
tracy_options.addOption(c_int, "tracy_depth", tracy_depth_option);
// Link the Tracy package to the executable
if (deps.pkgs.tracy.pkg) |tracy_pkg| {
    // Add the options as a dependency to the Tracy package
    exe.addPackage(std.build.Pkg{
        .name = "tracy",
        .source = .{ .path = tracy_pkg.source.path },
        .dependencies = &[_]std.build.Pkg{
            .{ .name = "tracy_options", .source = tracy_options.getSource() },
        },
    });
    // If Tracy integration is enabled, link the libraries
    if (tracy_enabled_option) {
        // Gotta call this snippet until there is a nicer way
        inline for (comptime std.meta.declarations(deps.package_data)) |decl| {
            const pkg = @as(deps.Package, @field(deps.package_data, decl.name));
            for (pkg.system_libs) |item| {
                exe.linkSystemLibrary(item);
            }
            inline for (pkg.c_include_dirs) |item| {
                exe.addIncludePath(@field(deps.dirs, decl.name) ++ "/" ++ item);
            }
            inline for (pkg.c_source_files) |item| {
                exe.addCSourceFile(@field(deps.dirs, decl.name) ++ "/" ++ item, pkg.c_source_flags);
            }
        }
    }
}

As you can see, I called the following part of the addAllTo function manually:

zigmod/src/cmd/fetch.zig

Lines 56 to 80 in b47ad60

	\\ var llc = false;
	\\ var vcpkg = false;
	\\ inline for (comptime std.meta.declarations(package_data)) |decl| {
	\\ const pkg = @as(Package, @field(package_data, decl.name));
	\\ for (pkg.system_libs) |item| {
	\\ exe.linkSystemLibrary(item);
	\\ llc = true;
	\\ }
	\\ for (pkg.frameworks) |item| {
	\\ if (!std.Target.current.isDarwin()) @panic(exe.builder.fmt("a dependency is attempting to link to the framework {s}, which is only possible under Darwin", .{item}));
	\\ exe.linkFramework(item);
	\\ llc = true;
	\\ }
	\\ inline for (pkg.c_include_dirs) |item| {
	\\ exe.addIncludePath(@field(dirs, decl.name) ++ "/" ++ item);
	\\ llc = true;
	\\ }
	\\ inline for (pkg.c_source_files) |item| {
	\\ exe.addCSourceFile(@field(dirs, decl.name) ++ "/" ++ item, pkg.c_source_flags);
	\\ llc = true;
	\\ }
	\\ vcpkg = vcpkg or pkg.vcpkg;
	\\ }
	\\ if (llc) exe.linkLibC();
	\\ if (builtin.os.tag == .windows and vcpkg) exe.addVcpkgPaths(.static) catch |err| @panic(@errorName(err));

I would like to suggest to create a separate function here for linking libraries, so users can call it separately in the case they need to mess around with packages.