Document preArch mutators

var preArch = []RegisterMutatorFunc{

	RegisterNamespaceMutator,

	// Rename package module types.

	//

	// The package module type does not have a name property, instead its name is determined

	// by the location of the containing .bp file relative to the root of the file structure

	// being built by Soong. Unfortunately, due to limitations in LoadHook the module has to

	// be given a synthetic temporary name which is then fixed up by these mutators.

	RegisterPackageRenamer,

	// Create an association between prebuilt modules and their corresponding source

	// modules (if any).

	RegisterPrebuiltsPreArchMutators,

	// Check the visibility rules are valid.

	//

	// This must run after the package renamer mutators so that any issues found during

	// validation of the package's default_visibility property are reported using the

	// correct package name and not the synthetic name.

	//

	// This must also be run before defaults mutators as the rules for validation are

	// different before checking the rules than they are afterwards. e.g.

	//    visibility: ["//visibility:private", "//visibility:public"]

	// would be invalid if specified in a module definition but is valid if it results

	// from something like this:

	//

	//    defaults {

	//        name: "defaults",

	//        // Be inaccessible outside a package by default.

	//        visibility: ["//visibility:private"]

	//    }

	//

	//    defaultable_module {

	//        name: "defaultable_module",

	//        defaults: ["defaults"],

	//        // Override the default.

	//        visibility: ["//visibility:public"]

	//    }

	//

	RegisterVisibilityRuleChecker,

	// Apply properties from defaults modules to the referencing modules.

	RegisterDefaultsPreArchMutators,

	// Gather the visibility rules for all modules for us during visibility enforcement.

	//

	// This must come after the defaults mutators to ensure that any visibility supplied

	// in a defaults module has been successfully applied before the rules are gathered.

	RegisterVisibilityRuleGatherer,

}