Fixed BUG#2776: Stored procedure crash if variable assigned to default.

Keep track on the default value and use it. (Or NULL, if not declared.)

mysql-test/r/sp.result

@@ -1021,6 +1021,29 @@ select bug2772()|
 bug2772()
 a
 drop function bug2772|
+create procedure bug2776_1(out x int)
+begin
+declare v int;
+set v = default;
+set x = v;
+end|
+create procedure bug2776_2(out x int)
+begin
+declare v int default 42;
+set v = default;
+set x = v;
+end|
+set @x = 1|
+call bug2776_1(@x)|
+select @x|
+@x
+NULL
+call bug2776_2(@x)|
+select @x|
+@x
+42
+drop procedure bug2776_1|
+drop procedure bug2776_2|
 drop table if exists fac|
 create table fac (n int unsigned not null primary key, f bigint unsigned)|
 create procedure ifac(n int unsigned)

mysql-test/t/sp.test

@@ -1188,6 +1188,33 @@ create function bug2772() returns char(10) character set latin2
 select bug2772()|
 drop function bug2772|
 
+#
+# BUG#2776
+#
+create procedure bug2776_1(out x int)
+begin
+  declare v int;
+
+  set v = default;
+  set x = v;
+end|
+
+create procedure bug2776_2(out x int)
+begin
+  declare v int default 42;
+
+  set v = default;
+  set x = v;
+end|
+
+set @x = 1|
+call bug2776_1(@x)|
+select @x|
+call bug2776_2(@x)|
+select @x|
+drop procedure bug2776_1|
+drop procedure bug2776_2|
+
 
 #
 # Some "real" examples

sql/sp_pcontext.cc

@@ -118,6 +118,7 @@ sp_pcontext::push_pvar(LEX_STRING *name, enum enum_field_types type,
     p->mode= mode;
     p->offset= m_pvar.elements;
     p->isset= (mode == sp_param_out ? FALSE : TRUE);
+    p->dflt= NULL;
     insert_dynamic(&m_pvar, (gptr)&p);
   }
 }

sql/sp_pcontext.h

@@ -36,6 +36,7 @@ typedef struct sp_pvar
   sp_param_mode_t mode;
   uint offset;			// Offset in current frame
   my_bool isset;
+  Item *dflt;
 } sp_pvar_t;
 
 typedef struct sp_label
@@ -130,6 +131,15 @@ class sp_pcontext : public Sql_alloc
       p->isset= val;
   }
 
+  inline void
+  set_default(uint i, Item *it)
+  {
+    sp_pvar_t *p= find_pvar(i);
+
+    if (p)
+      p->dflt= it;
+  }
+
   void
   push_pvar(LEX_STRING *name, enum enum_field_types type, sp_param_mode_t mode);
 

sql/sql_yacc.yy

@@ -1365,6 +1365,7 @@ sp_decl:
 
 	        lex->sphead->add_instr(in);
 	        lex->spcont->set_isset(i, TRUE);
+		lex->spcont->set_default(i, it);
 	      }
 	    }
 	    $$.vars= $2;
@@ -6246,15 +6247,25 @@ option_value:
 	    }
             else
 	    { /* An SP local variable */
+	      sp_pvar_t *spv;
+              sp_instr_set *i;
+	      Item *it;
+
 	      if ($3 && $3->type() == Item::SUBSELECT_ITEM)
 	      {  /* QQ For now, just disallow subselects as values */
 	        send_error(lex->thd, ER_SP_SUBSELECT_NYI);
 	        YYABORT;
 	      }
-	      sp_pvar_t *spv= lex->spcont->find_pvar(&$1.base_name);
-              sp_instr_set *i= new sp_instr_set(lex->sphead->instructions(),
-	                                        spv->offset, $3, spv->type);
+	      spv= lex->spcont->find_pvar(&$1.base_name);
 
+	      if ($3)
+	        it= $3;
+	      else if (spv->dflt)
+	        it= spv->dflt;
+	      else
+	        it= new Item_null();
+              i= new sp_instr_set(lex->sphead->instructions(),
+	                          spv->offset, it, spv->type);
 	      lex->sphead->add_instr(i);
 	      spv->isset= TRUE;
 	    }