Add the %a{warning: ...} annotation in

lib/steep/annotations_helper.rb

@@ -15,39 +15,59 @@ def deprecated_annotation?(annotations)
       nil
     end
 
-    def deprecated_type_name?(type_name, env)
-      annotations =
+    def warning_annotation?(annotations)
+      annotations.reverse_each do |annotation|
+        if match = annotation.string.match(/\Awarning(:\s*(?<message>.+))?\z/)
+          return [annotation, match[:message]]
+        end
+        if match = annotation.string.match(/\Asteep:warning(:\s*(?<message>.+))?\z/)
+          return [annotation, match[:message]]
+        end
+      end
+
+      nil
+    end
+
+    def type_name_annotations(type_name, env)
+      case
+      when type_name.class?
         case
-        when type_name.class?
-          case
-          when decl = env.class_decls.fetch(type_name, nil)
-            decl.each_decl.flat_map do |decl|
-              if decl.is_a?(RBS::AST::Declarations::Base)
-                decl.annotations
-              else
-                []
-              end
-            end
-          when decl = env.class_alias_decls.fetch(type_name, nil)
-            if decl.decl.is_a?(RBS::AST::Declarations::Base)
-              decl.decl.annotations
+        when decl = env.class_decls.fetch(type_name, nil)
+          decl.each_decl.flat_map do |decl|
+            if decl.is_a?(RBS::AST::Declarations::Base)
+              decl.annotations
             else
-              [] #: Array[RBS::AST::Annotation]
+              []
             end
           end
-        when type_name.interface?
-          if decl = env.interface_decls.fetch(type_name, nil)
-            decl.decl.annotations
-          end
-        when type_name.alias?
-          if decl = env.type_alias_decls.fetch(type_name, nil)
+        when decl = env.class_alias_decls.fetch(type_name, nil)
+          if decl.decl.is_a?(RBS::AST::Declarations::Base)
             decl.decl.annotations
+          else
+            [] #: Array[RBS::AST::Annotation]
           end
         end
+      when type_name.interface?
+        if decl = env.interface_decls.fetch(type_name, nil)
+          decl.decl.annotations
+        end
+      when type_name.alias?
+        if decl = env.type_alias_decls.fetch(type_name, nil)
+          decl.decl.annotations
+        end
+      end
+    end
 
-      if annotations
+    def deprecated_type_name?(type_name, env)
+      if annotations = type_name_annotations(type_name, env)
         deprecated_annotation?(annotations)
       end
     end
+
+    def warning_type_name?(type_name, env)
+      if annotations = type_name_annotations(type_name, env)
+        warning_annotation?(annotations)
+      end
+    end
   end
 end

lib/steep/diagnostic/lsp_formatter.rb

@@ -57,6 +57,8 @@ def format(diagnostic)
           when Signature::DeprecatedTypeName
             tags << LSP::Constant::DiagnosticTag::DEPRECATED
             severity = LSP::Constant::DiagnosticSeverity::WARNING
+          when Signature::WarningTypeName
+            severity = LSP::Constant::DiagnosticSeverity::WARNING
           end
 
           json = {

lib/steep/diagnostic/ruby.rb

@@ -1080,6 +1080,36 @@ def header_line
         end
       end
 
+      class WarningReference < Base
+        attr_reader :message
+
+        def initialize(node:, location:, message:)
+          super(node: node, location: location)
+          @message = message
+        end
+
+        def header_line
+          header =
+            case node&.type
+            when :send, :csend, :block, :numblock
+              "The method has a warning"
+            when :const, :casgn
+              "The constant has a warning"
+            when :gvar, :gvasgn
+              "The global variable has a warning"
+            else
+              raise "Unexpected node: #{node}"
+            end
+
+          if message
+            header = +header
+            header.concat(": ", message)
+          end
+
+          header
+        end
+      end
+
       ALL = ObjectSpace.each_object(Class).with_object([]) do |klass, array|
         if klass < Base
           array << klass
@@ -1101,6 +1131,7 @@ def self.default
             BlockTypeMismatch => :warning,
             BreakTypeMismatch => :hint,
             DeprecatedReference => :warning,
+            WarningReference => :warning,
             DifferentMethodParameterKind => :hint,
             FallbackAny => :hint,
             FalseAssertion => :hint,
@@ -1166,6 +1197,7 @@ def self.strict
             BlockTypeMismatch => :error,
             BreakTypeMismatch => :error,
             DeprecatedReference => :warning,
+            WarningReference => :warning,
             DifferentMethodParameterKind => :error,
             FallbackAny => :warning,
             FalseAssertion => :error,
@@ -1230,6 +1262,7 @@ def self.lenient
             BlockTypeMismatch => :information,
             BreakTypeMismatch => :hint,
             DeprecatedReference => :warning,
+            WarningReference => :warning,
             DifferentMethodParameterKind => nil,
             FallbackAny => nil,
             FalseAssertion => nil,

lib/steep/diagnostic/signature.rb

@@ -515,6 +515,26 @@ def header_line
         end
       end
 
+      class WarningTypeName < Base
+        attr_reader :type_name
+        attr_reader :message
+
+        def initialize(type_name, message, location:)
+          super(location: location)
+          @type_name = type_name
+          @message = message
+        end
+
+        def header_line
+          buffer = "Type `#{type_name}` has a warning"
+          if message
+            buffer = +buffer
+            buffer << ": " << message
+          end
+          buffer
+        end
+      end
+
       class InlineDiagnostic < Base
         attr_reader :diagnostic
 

lib/steep/signature/validator.rb

@@ -166,6 +166,7 @@ def validate_type_0(type)
 
         if type_name && location
           validate_type_name_deprecation(type_name, location)
+          validate_type_name_warning(type_name, location)
         end
 
         type.each_type do |child|
@@ -179,6 +180,12 @@ def validate_type_name_deprecation(type_name, location)
         end
       end
 
+      def validate_type_name_warning(type_name, location)
+        if (_, message = AnnotationsHelper.warning_type_name?(type_name, env))
+          @errors << Diagnostic::Signature::WarningTypeName.new(type_name, message, location: location)
+        end
+      end
+
       def ancestor_to_type(ancestor)
         case ancestor
         when RBS::Definition::Ancestor::Instance
@@ -328,6 +335,11 @@ def validate_one_class_decl(name, entry)
                   validate_type_name_deprecation(name, location[:name])
                 end
               end
+              unless AnnotationsHelper.warning_annotation?(decl.annotations)
+                if location = decl.location
+                  validate_type_name_warning(name, location[:name])
+                end
+              end
             end
           end
 
@@ -401,6 +413,7 @@ def validate_one_class_decl(name, entry)
                         end
                       if location
                         validate_type_name_deprecation(ancestor.name, location)
+                        validate_type_name_warning(ancestor.name, location)
                       end
                     end
                   end
@@ -695,6 +708,7 @@ def validate_one_class_alias(name, entry)
           validator.validate_class_alias(entry: entry)
           if location = entry.decl.location
             validate_type_name_deprecation(entry.decl.old_name, location[:old_name])
+            validate_type_name_warning(entry.decl.old_name, location[:old_name])
           end
         end
       end