[Fix #11033] Change warning message for Lint/Syntax when using LSP

lib/rubocop/cop/base.rb

@@ -481,6 +481,12 @@ def range_for_original(range)
           range.end_pos + @current_offset
         )
       end
+
+      # This experimental feature has been under consideration for a while.
+      # @api private
+      def lsp_mode?
+        ARGV.include?('--lsp')
+      end
     end
   end
 end

lib/rubocop/cop/lint/syntax.rb

@@ -17,9 +17,12 @@ def on_other_file
         private
 
         def add_offense_from_diagnostic(diagnostic, ruby_version)
-          message =
-            "#{diagnostic.message}\n(Using Ruby #{ruby_version} parser; " \
-            'configure using `TargetRubyVersion` parameter, under `AllCops`)'
+          message = if lsp_mode?
+                      diagnostic.message
+                    else
+                      "#{diagnostic.message}\n(Using Ruby #{ruby_version} parser; " \
+                        'configure using `TargetRubyVersion` parameter, under `AllCops`)'
+                    end
           add_offense(diagnostic.location, message: message, severity: diagnostic.level)
         end
 

lib/rubocop/rspec/shared_contexts.rb

@@ -128,6 +128,12 @@ def source_range(range, buffer: source_buffer)
   end
 end
 
+RSpec.shared_context 'lsp mode' do
+  before do
+    allow(cop).to receive(:lsp_mode?).and_return(true)
+  end
+end
+
 RSpec.shared_context 'ruby 2.0' do
   let(:ruby_version) { 2.0 }
 end

lib/rubocop/rspec/support.rb

@@ -13,6 +13,7 @@
   config.include HostEnvironmentSimulatorHelper
   config.include_context 'config', :config
   config.include_context 'isolated environment', :isolated_environment
+  config.include_context 'lsp mode', :lsp_mode
   config.include_context 'maintain registry', :restore_registry
   config.include_context 'ruby 2.0', :ruby20
   config.include_context 'ruby 2.1', :ruby21

spec/rubocop/cop/lint/syntax_spec.rb

@@ -50,6 +50,12 @@
           expect(offense.severity).to eq(:fatal)
         end
       end
+
+      context 'with `--lsp` option', :lsp_mode do
+        it 'does not include a configuration information in the offense message' do
+          expect(offenses.first.message).to eq('unexpected token $end')
+        end
+      end
     end
 
     context 'with a parser error' do