Add support for generic<T> syntax for type variables

This is the syntax used by Solargraph for generic type variables.

Author: apiology

lib/sord/type_converter.rb

@@ -199,6 +199,17 @@ def self.yard_to_parlour(yard, item, config)
           .map { |x| yard_to_parlour(x, item, config) }
         if SINGLE_ARG_GENERIC_TYPES.include?(relative_generic_type) && parameters.length > 1
           Parlour::Types.const_get(relative_generic_type).new(Parlour::Types::Union.new(parameters))
+        elsif relative_generic_type == 'generic'
+          if parameters.length == 1
+            # used by solargraph to indicate a type variable.  Until
+            # Parlour needs to support separate namespaces, convert to
+            # the same namespaces as raw types:
+            yard_to_parlour(parameters.first, nil, config)
+          else
+            handle_sord_error(parameters.map(&:describe).join,
+                              "Invalid generic<>, must have exactly one type variable: #{yard.inspect}.", item,
+                              config.replace_errors_with_untyped)
+          end
         elsif relative_generic_type == 'Class'
           if parameters.length == 1
             Parlour::Types::Class.new(parameters.first)

spec/type_converter_spec.rb

@@ -250,6 +250,16 @@ def self.path
       end
     end
 
+    context 'with a solargraph-style type variable' do
+      it 'handles type variables by converting back to RBS-style unified namespace' do
+        expect(yard_to_parlour_default('generic<Foo>')).to eq Types::Raw.new('Foo')
+      end
+
+      it 'handles generic<> with more than one argument' do
+        expect(yard_to_parlour_default('generic<F, T>')).to eq Types::Raw.new('SORD_ERROR_FT')
+      end
+    end
+
     context 'when given an untyped generic' do
       it 'handles Hash correctly' do
         expect(yard_to_parlour_default('Hash')).to eq Types::Hash.new(Types::Untyped.new, Types::Untyped.new)
@@ -339,7 +349,7 @@ def self.path
         Sord::TypeConverter::Configuration.new(
           output_language: :rbs,
           replace_errors_with_untyped: false,
-          replace_unresolved_with_untyped: false,  
+          replace_unresolved_with_untyped: false,
         )
       end