Add macro methods for Alias (#14261)

spec/compiler/macro/macro_methods_spec.cr

@@ -2618,6 +2618,18 @@ module Crystal
       end
     end
 
+    describe Alias do
+      node = Alias.new("Foo".path, Generic.new(Path.new(["Bar", "Baz"], global: true), ["T".path] of ASTNode))
+
+      it "executes name" do
+        assert_macro %({{x.name}}), %(Foo), {x: node}
+      end
+
+      it "executes type" do
+        assert_macro %({{x.type}}), %(::Bar::Baz(T)), {x: node}
+      end
+    end
+
     describe "visibility modifier methods" do
       node = VisibilityModifier.new(Visibility::Protected, Def.new("some_def"))
 

src/compiler/crystal/macros.cr

@@ -2234,8 +2234,22 @@ module Crystal::Macros
     end
   end
 
-  # class Alias < ASTNode
-  # end
+  # An `alias` statement.
+  #
+  # Every statement `node` is equivalent to:
+  #
+  # ```
+  # alias {{ node.name }} = {{ node.type }}
+  # ```
+  class Alias < ASTNode
+    # Returns the name of the alias.
+    def name : Path
+    end
+
+    # Returns the name of the type this alias is equivalent to.
+    def type : ASTNode
+    end
+  end
 
   # A metaclass in a type expression: `T.class`
   class Metaclass < ASTNode

src/compiler/crystal/macros/methods.cr

@@ -1560,6 +1560,19 @@ module Crystal
     end
   end
 
+  class Alias
+    def interpret(method : String, args : Array(ASTNode), named_args : Hash(String, ASTNode)?, block : Crystal::Block?, interpreter : Crystal::MacroInterpreter, name_loc : Location?)
+      case method
+      when "name"
+        interpret_check_args { @name }
+      when "type"
+        interpret_check_args { @value }
+      else
+        super
+      end
+    end
+  end
+
   class OffsetOf
     def interpret(method : String, args : Array(ASTNode), named_args : Hash(String, ASTNode)?, block : Crystal::Block?, interpreter : Crystal::MacroInterpreter, name_loc : Location?)
       case method