Support RBS::AST::Members::ClassVariable

This supports class variables (`@@var`) in RBS files.

Author: sinsoku

lib/typeprof/core/ast.rb

@@ -417,6 +417,8 @@ def self.create_rbs_member(raw_decl, lenv)
         SigInstanceVariableNode.new(raw_decl, lenv, false)
       when RBS::AST::Members::ClassInstanceVariable
         SigInstanceVariableNode.new(raw_decl, lenv, true)
+      when RBS::AST::Members::ClassVariable
+        SigClassVariableNode.new(raw_decl, lenv)
       else
         raise "unsupported: #{ raw_decl.class }"
       end

lib/typeprof/core/ast/sig_decl.rb

@@ -473,6 +473,44 @@ def install0(genv)
       end
     end
 
+    class SigClassVariableNode < Node
+      def initialize(raw_decl, lenv)
+        super(raw_decl, lenv)
+        @var = raw_decl.name
+        @cpath = lenv.cref.cpath
+        @type = AST.create_rbs_type(raw_decl.type, lenv)
+      end
+
+      attr_reader :cpath, :type
+      def subnodes = { type: }
+      def attrs = { cpath: }
+
+      def define0(genv)
+        @type.define(genv)
+        cvar = genv.resolve_cvar(cpath, @var)
+        cvar.add_decl(self)
+        cvar
+      end
+
+      def define_copy(genv)
+        cvar = genv.resolve_cvar(cpath, @var)
+        cvar.add_decl(self)
+        cvar.remove_decl(@prev_node)
+        super(genv)
+      end
+
+      def undefine0(genv)
+        genv.resolve_cvar(cpath, @var).remove_decl(self)
+        @type.undefine(genv)
+      end
+
+      def install0(genv)
+        box = @changes.add_type_read_box(genv, @type)
+        @changes.add_edge(genv, box.ret, @static_ret.vtx)
+        box.ret
+      end
+    end
+
     class SigGlobalVariableNode < Node
       def initialize(raw_decl, lenv)
         super(raw_decl, lenv)

scenario/rbs/cvar.rb

@@ -0,0 +1,16 @@
+## update: test.rbs
+class Foo
+  @@foo: String
+end
+
+## update: test.rb
+class Foo
+  def check
+    @@foo
+  end
+end
+
+## assert: test.rb
+class Foo
+  def check: -> String
+end