Fix constant resolution

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## master
 
+* Fix constant resolution [#288](https://github.com/ruby/rbs/pull/288)
+
 ## 0.2.0
 
 * The first release of RBS gem.

lib/rbs/cli.rb

@@ -362,7 +362,7 @@ def run_constant(args, options)
       name = Namespace.parse(args[0]).to_type_name
       stdout.puts "Constant name: #{name}"
 
-      constant = table.resolve_constant_reference(name, context: namespace)
+      constant = table.resolve_constant_reference(name, context: namespace.ascend.to_a)
 
       if constant
         stdout.puts " => #{constant.name}: #{constant.type}"

lib/rbs/constant_table.rb

@@ -30,17 +30,18 @@ def split_name(name)
     end
 
     def resolve_constant_reference(name, context:)
+      raise "Context cannot be empty: Specify `[Namespace.root]`" if context.empty?
+
       head, *tail = split_name(name)
 
       head_constant = case
                       when name.absolute?
                         name_to_constant(TypeName.new(name: head, namespace: Namespace.root))
-                      when !context || context.empty?
+                      when context == [Namespace.root]
                         name_to_constant(TypeName.new(name: head, namespace: Namespace.root))
                       else
                         resolve_constant_reference_context(head, context: context) ||
-                          resolve_constant_reference_inherit(head,
-                                                             scopes: constant_scopes(context.to_type_name))
+                          resolve_constant_reference_inherit(head, scopes: constant_scopes(context.first.to_type_name))
                       end
 
       if head_constant
@@ -53,11 +54,11 @@ def resolve_constant_reference(name, context:)
     end
 
     def resolve_constant_reference_context(name, context:)
-      if context.empty?
-        nil
-      else
-        name_to_constant(TypeName.new(name: name, namespace: context)) ||
-          resolve_constant_reference_context(name, context: context.parent)
+      head, *tail = context
+
+      if head
+        name_to_constant(TypeName.new(name: name, namespace: head)) ||
+          resolve_constant_reference_context(name, context: tail)
       end
     end
 
@@ -125,7 +126,7 @@ def constant_scopes0(name, scopes: [])
 
         scopes.unshift namespace
       else
-        raise "Unexpected declaration: #{name}"
+        raise "Unexpected declaration: #{name} (#{decl.class})"
       end
 
       env.each_extension(name).sort_by {|e| e.extension_name.to_s }.each do |extension|

lib/rbs/namespace.rb

@@ -87,5 +87,23 @@ def self.parse(string)
         new(path: string.split("::").map(&:to_sym), absolute: false)
       end
     end
+
+
+    def ascend
+      if block_given?
+        current = self
+
+        until current.empty?
+          yield current
+          current = current.parent
+        end
+
+        yield current
+
+        self
+      else
+        enum_for(:ascend)
+      end
+    end
   end
 end

test/rbs/constant_table_test.rb

@@ -43,13 +43,19 @@ def test_reference_top_level
         builder = DefinitionBuilder.new(env: env)
         table = ConstantTable.new(builder: builder)
 
-        table.resolve_constant_reference(TypeName.new(name: :Name, namespace: Namespace.empty), context: nil).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :Name, namespace: Namespace.empty),
+          context: [Namespace.root]
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Name", constant.name.to_s
           assert_equal "::String", constant.type.to_s
         end
 
-        table.resolve_constant_reference(TypeName.new(name: :ABC, namespace: Namespace.empty), context: nil).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :ABC, namespace: Namespace.empty),
+          context: [Namespace.root]
+        ).tap do |constant|
           assert_nil constant
         end
       end
@@ -68,15 +74,21 @@ class Foo
       manager.build do |env|
         builder = DefinitionBuilder.new(env: env)
         table = ConstantTable.new(builder: builder)
-        context = Namespace.parse("::Foo")
+        namespace = Namespace.parse("::Foo")
 
-        table.resolve_constant_reference(TypeName.new(name: :Name, namespace: Namespace.empty), context: context).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :Name, namespace: Namespace.empty),
+          context: namespace.ascend.to_a
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Foo::Name", constant.name.to_s
           assert_equal '"Foo::Name"', constant.type.to_s
         end
 
-        table.resolve_constant_reference(TypeName.new(name: :Name, namespace: Namespace.root), context: context).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :Name, namespace: Namespace.root),
+          context: namespace.ascend.to_a
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Name", constant.name.to_s
           assert_equal '"::Name"', constant.type.to_s
@@ -85,6 +97,37 @@ class Foo
     end
   end
 
+  def test_reference_constant_nested_context
+    SignatureManager.new do |manager|
+      manager.files[Pathname("foo.rbs")] = <<EOF
+class Foo
+end
+
+class Foo::Bar
+end
+
+class Foo::Bar::Baz
+end
+
+Foo::Bar::X: "Foo::Bar::X"
+X: "::X"
+EOF
+      manager.build do |env|
+        builder = DefinitionBuilder.new(env: env)
+        table = ConstantTable.new(builder: builder)
+
+        table.resolve_constant_reference(
+          TypeName.new(name: :X, namespace: Namespace.empty),
+          context: [Namespace.parse("::Foo"), Namespace.parse("::Foo::Bar::Baz")]
+        ).tap do |constant|
+          assert_instance_of Constant, constant
+          assert_equal "::X", constant.name.to_s
+          assert_equal '"::X"', constant.type.to_s
+        end
+      end
+    end
+  end
+
   def test_reference_constant_inherit
     SignatureManager.new do |manager|
       manager.files[Pathname("foo.rbs")] = <<EOF
@@ -106,13 +149,19 @@ module Mix
         builder = DefinitionBuilder.new(env: env)
         table = ConstantTable.new(builder: builder)
 
-        table.resolve_constant_reference(TypeName.new(name: :MAX, namespace: Namespace.empty), context: Namespace.parse("::Child")).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :MAX, namespace: Namespace.empty),
+          context: Namespace.parse("::Child").ascend.to_a
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Parent::MAX", constant.name.to_s
           assert_equal "10000", constant.type.to_s
         end
 
-        table.resolve_constant_reference(TypeName.new(name: :MIN, namespace: Namespace.empty), context: Namespace.parse("::Child")).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :MIN, namespace: Namespace.empty),
+          context: Namespace.parse("::Child").ascend.to_a
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Mix::MIN", constant.name.to_s
           assert_equal '0', constant.type.to_s
@@ -139,13 +188,19 @@ module Foo::Bar
         builder = DefinitionBuilder.new(env: env)
         table = ConstantTable.new(builder: builder)
 
-        table.resolve_constant_reference(TypeName.new(name: :Set, namespace: Namespace.empty), context: Namespace.parse("::Foo::Bar")).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :Set, namespace: Namespace.empty),
+          context: Namespace.parse("::Foo::Bar").ascend.to_a
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Set", constant.name.to_s
           assert_equal 'singleton(::Set)', constant.type.to_s
         end
 
-        table.resolve_constant_reference(TypeName.new(name: :X, namespace: Namespace.empty), context: Namespace.parse("::Foo::Bar")).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :X, namespace: Namespace.empty),
+          context: Namespace.parse("::Foo::Bar").ascend.to_a
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Baz::X", constant.name.to_s
           assert_equal '::Integer', constant.type.to_s
@@ -166,7 +221,10 @@ class Foo
         builder = DefinitionBuilder.new(env: env)
         table = ConstantTable.new(builder: builder)
 
-        table.resolve_constant_reference(TypeName.new(name: :Name, namespace: Namespace.parse("Foo")), context: Namespace.parse("::Foo")).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :Name, namespace: Namespace.parse("Foo")),
+          context: Namespace.parse("::Foo").ascend.to_a
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Foo::Name", constant.name.to_s
           assert_equal '"Foo::Name"', constant.type.to_s
@@ -190,21 +248,33 @@ class Stuff
         builder = DefinitionBuilder.new(env: env)
         table = ConstantTable.new(builder: builder)
 
-        table.resolve_constant_reference(TypeName.new(name: :ONE, namespace: Namespace.parse("Stuff")), context: nil).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :ONE, namespace: Namespace.parse("Stuff")),
+          context: [Namespace.root]
+        ).tap do |constant|
           assert_nil constant
         end
 
-        table.resolve_constant_reference(TypeName.new(name: :TWO, namespace: Namespace.parse("Stuff")), context: nil).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :TWO, namespace: Namespace.parse("Stuff")),
+          context: [Namespace.root]
+        ).tap do |constant|
           assert_nil constant
         end
 
-        table.resolve_constant_reference(TypeName.new(name: :THREE, namespace: Namespace.parse("Stuff")), context: nil).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :THREE, namespace: Namespace.parse("Stuff")),
+          context: [Namespace.root]
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::Kernel::THREE", constant.name.to_s
           assert_equal "3", constant.type.to_s
         end
 
-        table.resolve_constant_reference(TypeName.new(name: :FOUR, namespace: Namespace.parse("Stuff")), context: nil).tap do |constant|
+        table.resolve_constant_reference(
+          TypeName.new(name: :FOUR, namespace: Namespace.parse("Stuff")),
+          context: [Namespace.root]
+        ).tap do |constant|
           assert_instance_of Constant, constant
           assert_equal "::BasicObject::FOUR", constant.name.to_s
           assert_equal "4", constant.type.to_s