Fixed https://pkg.go.dev/ didn't generate documentation for auto-generated code

_tools/ruby_h_to_go/config.yml

@@ -0,0 +1,6 @@
+# This tag appears in https://pkg.go.dev/github.com/ruby-go-gem/go-gem-wrapper/ruby
+default_tag: ruby_3_3
+
+available_tags:
+  - ruby_3_3
+  - ruby_3_4

_tools/ruby_h_to_go/lib/ruby_h_to_go.rb

@@ -3,11 +3,13 @@
 require "forwardable"
 require "ruby_header_parser"
 require "go_gem/util"
+require "yaml"
 
 require_relative "ruby_h_to_go/type_helper"
 
 require_relative "ruby_h_to_go/argument_definition"
 require_relative "ruby_h_to_go/cli"
+require_relative "ruby_h_to_go/config"
 require_relative "ruby_h_to_go/go_util"
 require_relative "ruby_h_to_go/enum_definition"
 require_relative "ruby_h_to_go/function_definition"
@@ -17,4 +19,8 @@
 
 # Generate Go binding from ruby.h
 module RubyHToGo
+  # @return [RubyHToGo::Config]
+  def self.config
+    @config ||= RubyHToGo::Config.new
+  end
 end

_tools/ruby_h_to_go/lib/ruby_h_to_go/config.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module RubyHToGo
+  # Manage config.yml
+  class Config
+    def initialize
+      @config = YAML.load_file(File.expand_path("../../config.yml", __dir__))
+    end
+
+    # @return [String]
+    def default_tag
+      @config["default_tag"]
+    end
+
+    # @return [Array<String>]
+    def available_tags
+      @config["available_tags"]
+    end
+  end
+end

_tools/ruby_h_to_go/lib/ruby_h_to_go/go_util.rb

@@ -2,7 +2,7 @@
 
 module RubyHToGo
   # helper methods for generating go code
-  module GoUtil
+  module GoUtil # rubocop:disable Metrics/ModuleLength
     # @param str [String]
     # @return [String]
     def self.snake_to_camel(str)
@@ -13,19 +13,38 @@ def self.snake_to_camel(str)
 
     # Generate initial go file whether not exists
     # @param go_file_path [String]
-    def self.generate_initial_go_file(go_file_path)
+    def self.generate_initial_go_file(go_file_path) # rubocop:disable Metrics/MethodLength
       return if File.exist?(go_file_path)
 
-      ruby_build_tag = GoGem::Util.ruby_minor_version_build_tag
-
-      File.binwrite(go_file_path, <<~GO)
+      header = +<<~GO
         // THE AUTOGENERATED LICENSE. ALL THE RIGHTS ARE RESERVED BY ROBOTS.
 
         // WARNING: This file has automatically been generated
         // Code generated by ruby_h_to_go. DO NOT EDIT.
 
-        //go:build #{ruby_build_tag}
+      GO
+
+      ruby_build_tag = GoGem::Util.ruby_minor_version_build_tag
+
+      header <<
+        if ruby_build_tag == RubyHToGo.config.default_tag
+          other_tags = RubyHToGo.config.available_tags - [RubyHToGo.config.default_tag]
+          condition = other_tags.map { |tag| "!#{tag}" }.join(" && ")
 
+          <<~GO
+            // FIXME: https://pkg.go.dev/ doesn't support custom build tag.
+            //        Therefore, if no build tag is passed, treat it as the default tag
+            //go:build #{ruby_build_tag} || (#{condition})
+
+          GO
+        else
+          <<~GO
+            //go:build #{ruby_build_tag}
+
+          GO
+        end
+
+      header << <<~GO
         package ruby
 
         /*
@@ -38,6 +57,8 @@ def self.generate_initial_go_file(go_file_path)
         )
 
       GO
+
+      File.binwrite(go_file_path, header)
     end
 
     C_TYPE_TO_GO_TYPE = {