Fix panic for WHERE filter over SHOW VARIABLES (#1892)

Author: jycor

enginetest/queries/queries.go

@@ -4996,6 +4996,20 @@ Select * from (
 			{"version_comment", "Dolt"}, {"version_compile_machine", ""}, {"version_compile_os", ""}, {"version_compile_zlib", ""}, {"wait_timeout", 28800}, {"windowing_use_high_precision", 1},
 		},
 	},
+	{
+		Query: `SHOW VARIABLES WHERE "1" and variable_name = 'autocommit'`,
+		Expected: []sql.Row{
+			{"autocommit", 1},
+		},
+	},
+	{
+		Query:    `SHOW VARIABLES WHERE "0" and variable_name = 'autocommit'`,
+		Expected: []sql.Row{},
+	},
+	{
+		Query:    `SHOW VARIABLES WHERE "abc" and variable_name = 'autocommit'`,
+		Expected: []sql.Row{},
+	},
 	{
 		Query: `SHOW GLOBAL VARIABLES LIKE '%mode'`,
 		Expected: []sql.Row{

sql/rowexec/show.go

@@ -529,7 +529,12 @@ func (b *BaseBuilder) buildShowVariables(ctx *sql.Context, n *plan.ShowVariables
 			if err != nil {
 				return nil, err
 			}
-			if !res.(bool) {
+			res, _, err = types.Boolean.Convert(res)
+			if err != nil {
+				ctx.Warn(1292, err.Error())
+				continue
+			}
+			if res.(int8) == 0 {
 				continue
 			}
 		}