A fix and a test case for Bug#24179 "select b into $var" fails with

--cursor_protocol": fix a misleading error message in case of
SELECT .. INTO.


sql/sql_class.cc:
  Implement select_result::check_simple_select hierarchy to 
  support correct error messages in case of SELECT .. INTO and C API 
  cursors.
sql/sql_class.h:
  Set the error message inside the function that checks for the error
  condition (simple_select, renamed to check_simple_select).
sql/sql_prepare.cc:
  Use a new method that now sets the error.
tests/mysql_client_test.c:
  Add a test case for Bug#24179 "select b into $var" fails with 
  --cursor_protocol" (check for the right error message and error code).

1 files changed, 10 insertions, 2 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index 41845dc5c76..ec03b9cb4a6 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1724,7 +1724,14 @@ public:
   virtual bool initialize_tables (JOIN *join=0) { return 0; }
   virtual void send_error(uint errcode,const char *err);
   virtual bool send_eof()=0;
-  virtual bool simple_select() { return 0; }
+  /**
+    Check if this query returns a result set and therefore is allowed in
+    cursors and set an error message if it is not the case.
+
+    @retval FALSE     success
+    @retval TRUE      error, an error message is set
+  */
+  virtual bool check_simple_select() const;
   virtual void abort() {}
   /*
     Cleanup instance of this class for next execution of a prepared
@@ -1762,7 +1769,7 @@ public:
   bool send_fields(List<Item> &list, uint flags);
   bool send_data(List<Item> &items);
   bool send_eof();
-  bool simple_select() { return 1; }
+  virtual bool check_simple_select() const { return FALSE; }
   void abort();
 };
 
@@ -2202,6 +2209,7 @@ public:
   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_data(List<Item> &items);
   bool send_eof();
+  virtual bool check_simple_select() const;
   void cleanup();
 };