Validate the type params of an entry once

lib/rbs/definition_builder.rb

@@ -504,6 +504,11 @@ def source_location(source, decl)
     def validate_type_params(definition, ancestors:, methods:)
       type_params = definition.type_params_decl
 
+      # Without type params nothing can violate the variance: the ancestor validation
+      # iterates the (empty) params, and the type params of the methods themselves are
+      # invariant, which `Result#compatible?` always accepts
+      return if type_params.empty?
+
       calculator = VarianceCalculator.new(builder: self)
       param_names = type_params.each.map(&:name)
 
@@ -1048,9 +1053,10 @@ def validate_type_presence(type)
     end
 
     def validate_type_name(name, location)
-      name = name.absolute! unless name.absolute?
-      return if env.type_name?(env.normalize_type_name(name))
+      absolute = name.absolute? ? name : name.absolute!
+      return if env.type_name?(env.normalize_type_name(absolute))
 
+      # Report the name as it is written in the signature
       raise NoTypeFoundError.new(type_name: name, location: location)
     end
   end

lib/rbs/environment/class_entry.rb

@@ -15,6 +15,7 @@ def initialize(name)
       def <<(context_decl)
         context_decls << context_decl
         @primary_decl = nil
+        @type_params_validated = nil
         self
       end
 
@@ -50,6 +51,10 @@ def type_params
       end
 
       def validate_type_params
+        # The entry only changes with `<<`, which resets the memo -- a failed
+        # validation is not recorded and raises again
+        return if @type_params_validated
+
         unless context_decls.empty?
           first_decl, *rest_decls = each_decl.to_a
           first_decl or raise
@@ -63,6 +68,8 @@ def validate_type_params
             end
           end
         end
+
+        @type_params_validated = true
       end
 
       def align_params(decl)

lib/rbs/environment/module_entry.rb

@@ -14,6 +14,7 @@ def initialize(name)
 
       def <<(context_decl)
         context_decls << context_decl
+        @type_params_validated = nil
         self
       end
 
@@ -72,6 +73,10 @@ def align_params(decl)
       end
 
       def validate_type_params
+        # The entry only changes with `<<`, which resets the memo -- a failed
+        # validation is not recorded and raises again
+        return if @type_params_validated
+
         unless context_decls.empty?
           first_decl, *rest_decls = each_decl.to_a
           first_decl or raise
@@ -85,6 +90,8 @@ def validate_type_params
             end
           end
         end
+
+        @type_params_validated = true
       end
     end
   end

sig/environment/class_entry.rbs

@@ -18,6 +18,8 @@ module RBS
 
       @primary_decl: declaration?
 
+      @type_params_validated: bool?
+
       def initialize: (TypeName) -> void
 
       def <<: (context_decl) -> self

sig/environment/module_entry.rbs

@@ -17,6 +17,8 @@ module RBS
 
       attr_reader context_decls: Array[context_decl]
 
+      @type_params_validated: bool?
+
       def initialize: (TypeName) -> void
 
       def <<: (context_decl) -> self

test/rbs/cli_test.rb

@@ -402,7 +402,7 @@ module Bar[B]
           cli.run(["-I", dir, "validate"])
         end
 
-        assert_include stdout.string, "a.rbs:2:13...2:14: Could not find ::A (RBS::NoTypeFoundError)"
+        assert_include stdout.string, "a.rbs:2:13...2:14: Could not find A (RBS::NoTypeFoundError)"
       end
     end
   end