Add RBS support module for sig/ loading and validation

`RDoc::RbsSupport` provides:
- `load_signatures` to load types from .rbs files via
  `RBS::EnvironmentLoader`
- `merge_into_store` to attach sig/ types to code objects
  (inline `#:` annotations take priority)
- `validate_method_type`/`validate_type` for syntax checking

Auto-detects `sig/` directory during generation and merges types
after `store.complete`.

Author: st0012

lib/rdoc/rbs_support.rb

@@ -0,0 +1,88 @@
+# frozen_string_literal: true
+
+require 'rbs'
+
+##
+# RBS type signature support.
+# Loads type information from .rbs files and validates inline annotations.
+
+module RDoc::RbsSupport
+
+  ##
+  # Validates an RBS method type signature string.
+  # Returns nil if valid, or an error message string if invalid.
+
+  def self.validate_method_type(sig)
+    RBS::Parser.parse_method_type(sig, require_eof: true)
+    nil
+  rescue RBS::ParsingError => e
+    e.message
+  end
+
+  ##
+  # Validates an RBS type signature string.
+  # Returns nil if valid, or an error message string if invalid.
+
+  def self.validate_type(sig)
+    RBS::Parser.parse_type(sig, require_eof: true)
+    nil
+  rescue RBS::ParsingError => e
+    e.message
+  end
+
+  ##
+  # Loads RBS signatures from the given directories.
+  # Returns a Hash mapping "ClassName#method_name" => "type sig string".
+
+  def self.load_signatures(*dirs)
+    loader = RBS::EnvironmentLoader.new(core_root: nil)
+    dirs.each { |dir| loader.add(path: Pathname(dir)) }
+
+    env = RBS::Environment.new
+    loader.load(env: env)
+
+    signatures = {}
+
+    env.class_decls.each do |type_name, entry|
+      class_name = type_name.to_s.delete_prefix('::')
+
+      entry.each_decl do |decl|
+        decl.members.each do |member|
+          case member
+          when RBS::AST::Members::MethodDefinition
+            key = member.singleton? ? "#{class_name}::#{member.name}" : "#{class_name}##{member.name}"
+            sigs = member.overloads.map { |o| o.method_type.to_s }
+            signatures[key] = sigs.join("\n")
+          when RBS::AST::Members::AttrReader, RBS::AST::Members::AttrWriter, RBS::AST::Members::AttrAccessor
+            key = "#{class_name}.#{member.name}"
+            signatures[key] = member.type.to_s
+          end
+        end
+      end
+    end
+
+    signatures
+  end
+
+  ##
+  # Merges loaded RBS signatures into the store's code objects.
+  # Inline #: annotations take priority and are not overwritten.
+
+  def self.merge_into_store(store, signatures)
+    store.all_classes_and_modules.each do |cm|
+      cm.method_list.each do |method|
+        next if method.type_signature
+
+        key = method.singleton ? "#{cm.full_name}::#{method.name}" : "#{cm.full_name}##{method.name}"
+        method.type_signature = signatures[key] if signatures[key]
+      end
+
+      cm.attributes.each do |attr|
+        next if attr.type_signature
+
+        key = "#{cm.full_name}.#{attr.name}"
+        attr.type_signature = signatures[key] if signatures[key]
+      end
+    end
+  end
+end

lib/rdoc/rdoc.rb

@@ -5,6 +5,7 @@
 require 'fileutils'
 require 'pathname'
 require 'time'
+require_relative 'rbs_support'
 
 ##
 # This is the driver for generating RDoc output.  It handles file parsing and
@@ -492,6 +493,13 @@ def document(options)
 
     @store.complete @options.visibility
 
+    # Load RBS signatures from sig/ directory
+    sig_dir = File.join(@options.root.to_s, 'sig')
+    if File.directory?(sig_dir)
+      signatures = RDoc::RbsSupport.load_signatures(sig_dir)
+      RDoc::RbsSupport.merge_into_store(@store, signatures) unless signatures.empty?
+    end
+
     @stats.coverage_level = @options.coverage_report
 
     if @options.coverage_report then

test/rdoc/rbs_support_test.rb

@@ -0,0 +1,83 @@
+# frozen_string_literal: true
+
+require_relative 'helper'
+require 'rdoc/rbs_support'
+
+class RDocRbsSupportTest < RDoc::TestCase
+  def test_validate_method_type_valid
+    assert_nil RDoc::RbsSupport.validate_method_type('(String) -> void')
+    assert_nil RDoc::RbsSupport.validate_method_type('(Integer, ?String) -> bool')
+    assert_nil RDoc::RbsSupport.validate_method_type('() -> Array[String]')
+  end
+
+  def test_validate_method_type_invalid
+    error = RDoc::RbsSupport.validate_method_type('(String ->')
+    assert_kind_of String, error
+  end
+
+  def test_validate_type_valid
+    assert_nil RDoc::RbsSupport.validate_type('String')
+    assert_nil RDoc::RbsSupport.validate_type('Array[Integer]')
+    assert_nil RDoc::RbsSupport.validate_type('String?')
+  end
+
+  def test_validate_type_invalid
+    error = RDoc::RbsSupport.validate_type('String[')
+    assert_kind_of String, error
+  end
+
+  def test_load_signatures_from_directory
+    Dir.mktmpdir do |dir|
+      File.write(File.join(dir, 'test.rbs'), <<~RBS)
+        class Greeter
+          def greet: (String name) -> void
+          attr_reader language: String
+        end
+      RBS
+
+      sigs = RDoc::RbsSupport.load_signatures(dir)
+      assert_equal '(String name) -> void', sigs['Greeter#greet']
+      assert_equal 'String', sigs['Greeter.language']
+    end
+  end
+
+  def test_merge_into_store
+    top_level = @store.add_file 'test.rb'
+    cm = top_level.add_class RDoc::NormalClass, 'Greeter'
+
+    m = RDoc::AnyMethod.new(nil, 'greet')
+    m.params = '(name)'
+    cm.add_method m
+
+    a = RDoc::Attr.new(nil, 'language', 'R', '')
+    cm.add_attribute a
+
+    signatures = {
+      'Greeter#greet' => '(String name) -> void',
+      'Greeter.language' => 'String'
+    }
+
+    RDoc::RbsSupport.merge_into_store(@store, signatures)
+
+    assert_equal '(String name) -> void', m.type_signature
+    assert_equal 'String', a.type_signature
+  end
+
+  def test_merge_does_not_overwrite_inline_annotations
+    top_level = @store.add_file 'test.rb'
+    cm = top_level.add_class RDoc::NormalClass, 'Greeter'
+
+    m = RDoc::AnyMethod.new(nil, 'greet')
+    m.params = '(name)'
+    m.type_signature = '(String) -> void'
+    cm.add_method m
+
+    signatures = {
+      'Greeter#greet' => '(String name, ?Integer count) -> void'
+    }
+
+    RDoc::RbsSupport.merge_into_store(@store, signatures)
+
+    assert_equal '(String) -> void', m.type_signature
+  end
+end