Extract sanitize_as_sql_comment from SQL visitor into connection

Probably that is useful for any other feature as well.

activerecord/lib/active_record/connection_adapters/abstract/quoting.rb

@@ -138,6 +138,10 @@ module ActiveRecord
         "'#{quote_string(value.to_s)}'"
       end
 
+      def sanitize_as_sql_comment(value) # :nodoc:
+        value.to_s.gsub(%r{ (/ (?: | \g<1>) \*) \+? \s* | \s* (\* (?: | \g<2>) /) }x, "")
+      end
+
       private
         def type_casted_binds(binds)
           if binds.first.is_a?(Array)

activerecord/lib/arel/visitors/ibm_db.rb

@@ -10,7 +10,8 @@ module Arel # :nodoc: all
         end
 
         def visit_Arel_Nodes_OptimizerHints(o, collector)
-          collector << "/* <OPTGUIDELINES>#{sanitize_as_sql_comment(o).join}</OPTGUIDELINES> */"
+          hints = o.expr.map { |v| sanitize_as_sql_comment(v) }.join
+          collector << "/* <OPTGUIDELINES>#{hints}</OPTGUIDELINES> */"
         end
 
         def visit_Arel_Nodes_Limit(o, collector)

activerecord/lib/arel/visitors/informix.rb

@@ -43,7 +43,8 @@ module Arel # :nodoc: all
         end
 
         def visit_Arel_Nodes_OptimizerHints(o, collector)
-          collector << "/*+ #{sanitize_as_sql_comment(o).join(", ")} */"
+          hints = o.expr.map { |v| sanitize_as_sql_comment(v) }.join(", ")
+          collector << "/*+ #{hints} */"
         end
 
         def visit_Arel_Nodes_Offset(o, collector)

activerecord/lib/arel/visitors/mssql.rb

@@ -82,7 +82,8 @@ module Arel # :nodoc: all
         end
 
         def visit_Arel_Nodes_OptimizerHints(o, collector)
-          collector << "OPTION (#{sanitize_as_sql_comment(o).join(", ")})"
+          hints = o.expr.map { |v| sanitize_as_sql_comment(v) }.join(", ")
+          collector << "OPTION (#{hints})"
         end
 
         def get_offset_limit_clause(o)

activerecord/lib/arel/visitors/to_sql.rb

@@ -219,7 +219,8 @@ module Arel # :nodoc: all
         end
 
         def visit_Arel_Nodes_OptimizerHints(o, collector)
-          collector << "/*+ #{sanitize_as_sql_comment(o).join(" ")} */"
+          hints = o.expr.map { |v| sanitize_as_sql_comment(v) }.join(" ")
+          collector << "/*+ #{hints} */"
         end
 
         def collect_nodes_for(nodes, collector, spacer, connector = COMMA)
@@ -785,10 +786,9 @@ module Arel # :nodoc: all
           @connection.quote_column_name(name)
         end
 
-        def sanitize_as_sql_comment(o)
-          o.expr.map { |v|
-            v.gsub(%r{ (/ (?: | \g<1>) \*) \+? \s* | \s* (\* (?: | \g<2>) /) }x, "")
-          }
+        def sanitize_as_sql_comment(value)
+          return value if Arel::Nodes::SqlLiteral === value
+          @connection.sanitize_as_sql_comment(value)
         end
 
         def collect_optimizer_hints(o, collector)