Ensure symbols passed to `select` are always quoted

Our general contract in Active Record is that strings are assumed to be
SQL literals, and symbols are assumed to reference a column. If a from
clause is given, we shouldn't include the table name, but we should
still quote the value as if it were a column.

Upon fixing this, the tests were still failing on SQLite. This was
because the column name being returned by the query was `"\"join\""`
instead of `"join"`. This is actually a bug in SQLite that was fixed a
long time ago, but I was using the version of SQLite included by OS X
which has this bug. Since I'm guessing this will be a common case for
contributors, I also added an explicit check with a more helpful error
message.

Fixes #20360

1 files changed, 7 insertions, 9 deletions

diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index fd78db2e95..f85dc35e89 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -1001,15 +1001,13 @@ module ActiveRecord
     end
 
     def arel_columns(columns)
-      if from_clause.value
-        columns
-      else
-        columns.map do |field|
-          if (Symbol === field || String === field) && columns_hash.key?(field.to_s)
-            arel_table[field]
-          else
-            field
-          end
+      columns.map do |field|
+        if (Symbol === field || String === field) && columns_hash.key?(field.to_s) && !from_clause.value
+          arel_table[field]
+        elsif Symbol === field
+          connection.quote_table_name(field.to_s)
+        else
+          field
         end
       end
     end