Backport from trunk of:

Bug#12532830 - SIGFPE OR ASSERTION (PRECISION <= ((9 * 9) - 8*2)) && (DEC <= 30)

mysql-test/r/func_if.result

@@ -196,3 +196,17 @@ c
 NULL
 0
 DROP TABLE t1;
+#
+# Bug#12532830 
+# SIGFPE OR ASSERTION (PRECISION <= ((9 * 9) - 8*2)) && (DEC <= 30)
+#
+select
+sum(distinct(if('a',
+(select adddate(elt(convert(9999999999999999999999999999999999999,decimal(64,0)),count(*)),
+interval 1 day))
+, .1))) as foo;
+foo
+0.1
+Warnings:
+Warning	1292	Truncated incorrect DOUBLE value: 'a'
+Warning	1292	Truncated incorrect DOUBLE value: 'a'

mysql-test/suite/innodb/r/innodb_bug54044.result

 CREATE TEMPORARY TABLE table_54044 ENGINE = INNODB
 AS SELECT IF(NULL  IS NOT NULL, NULL, NULL);
-ERROR HY000: Can't create table 'test.table_54044' (errno: -1)
+SHOW CREATE TABLE table_54044;
+Table	Create Table
+table_54044	CREATE TEMPORARY TABLE `table_54044` (
+  `IF(NULL  IS NOT NULL, NULL, NULL)` binary(0) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE table_54044;
+CREATE TABLE tmp ENGINE = INNODB AS SELECT COALESCE(NULL, NULL, NULL);
+ERROR HY000: Can't create table 'test.tmp' (errno: -1)
+CREATE TABLE tmp ENGINE = INNODB AS SELECT GREATEST(NULL, NULL);
+ERROR HY000: Can't create table 'test.tmp' (errno: -1)

mysql-test/suite/innodb/t/innodb_bug54044.test

@@ -3,9 +3,17 @@
 
 --source include/have_innodb.inc
 
-# This 'create table' operation should fail because of
-# using NULL datatype
---error ER_CANT_CREATE_TABLE
+# This 'create table' operation no longer uses the NULL datatype.
+
 CREATE TEMPORARY TABLE table_54044 ENGINE = INNODB
  AS SELECT IF(NULL  IS NOT NULL, NULL, NULL); 
+SHOW CREATE TABLE table_54044;
+DROP TABLE table_54044;
 
+# These 'create table' operations should fail because of
+# using NULL datatype
+
+--error ER_CANT_CREATE_TABLE
+CREATE TABLE tmp ENGINE = INNODB AS SELECT COALESCE(NULL, NULL, NULL);
+--error ER_CANT_CREATE_TABLE
+CREATE TABLE tmp ENGINE = INNODB AS SELECT GREATEST(NULL, NULL);

mysql-test/t/func_if.test

@@ -177,3 +177,15 @@ INSERT INTO t1 VALUES (NULL, 0), (NULL, 1);
 SELECT IF(b, (SELECT a FROM t1 LIMIT 1), b) c FROM t1 GROUP BY c;
 
 DROP TABLE t1;
+
+--echo #
+--echo # Bug#12532830 
+--echo # SIGFPE OR ASSERTION (PRECISION <= ((9 * 9) - 8*2)) && (DEC <= 30)
+--echo #
+
+let $nines= 9999999999999999999999999999999999999;
+eval select
+sum(distinct(if('a',
+                (select adddate(elt(convert($nines,decimal(64,0)),count(*)),
+                                interval 1 day))
+                , .1))) as foo;

sql/field.cc

@@ -9159,8 +9159,9 @@ void Create_field::init_for_tmp_table(enum_field_types sql_type_arg,
     pack_flag= FIELDFLAG_INTERVAL;
     break;
 
-  case MYSQL_TYPE_DECIMAL:
   case MYSQL_TYPE_NEWDECIMAL:
+    DBUG_ASSERT(decimals_arg <= DECIMAL_MAX_SCALE);
+  case MYSQL_TYPE_DECIMAL:
   case MYSQL_TYPE_FLOAT:
   case MYSQL_TYPE_DOUBLE:
     pack_flag= FIELDFLAG_NUMBER |

sql/item_cmpfunc.cc

@@ -2625,37 +2625,43 @@ Item_func_if::fix_fields(THD *thd, Item **ref)
 }
 
 
-void
-Item_func_if::fix_length_and_dec()
+void Item_func_if::cache_type_info(Item *source)
 {
-  maybe_null=args[1]->maybe_null || args[2]->maybe_null;
-  decimals= max(args[1]->decimals, args[2]->decimals);
-  unsigned_flag=args[1]->unsigned_flag && args[2]->unsigned_flag;
+  collation.set(source->collation);
+  cached_field_type=  source->field_type();
+  cached_result_type= source->result_type();
+  decimals=           source->decimals;
+  max_length=         source->max_length;
+  maybe_null=         source->maybe_null;
+  unsigned_flag=      source->unsigned_flag;
+}
 
-  enum Item_result arg1_type=args[1]->result_type();
-  enum Item_result arg2_type=args[2]->result_type();
-  bool null1=args[1]->const_item() && args[1]->null_value;
-  bool null2=args[2]->const_item() && args[2]->null_value;
 
-  if (null1)
+void
+Item_func_if::fix_length_and_dec()
+{
+  // Let IF(cond, expr, NULL) and IF(cond, NULL, expr) inherit type from expr.
+  if (args[1]->type() == NULL_ITEM)
   {
-    cached_result_type= arg2_type;
-    collation.set(args[2]->collation);
-    cached_field_type= args[2]->field_type();
-    max_length= args[2]->max_length;
+    cache_type_info(args[2]);
+    maybe_null= true;
+    // If both arguments are NULL, make resulting type BINARY(0).
+    if (args[2]->type() == NULL_ITEM)
+      cached_field_type= MYSQL_TYPE_STRING;
     return;
   }
-
-  if (null2)
+  if (args[2]->type() == NULL_ITEM)
   {
-    cached_result_type= arg1_type;
-    collation.set(args[1]->collation);
-    cached_field_type= args[1]->field_type();
-    max_length= args[1]->max_length;
+    cache_type_info(args[1]);
+    maybe_null= true;
     return;
   }
 
   agg_result_type(&cached_result_type, args + 1, 2);
+  maybe_null= args[1]->maybe_null || args[2]->maybe_null;
+  decimals= max(args[1]->decimals, args[2]->decimals);
+  unsigned_flag=args[1]->unsigned_flag && args[2]->unsigned_flag;
+
   if (cached_result_type == STRING_RESULT)
   {
     if (agg_arg_charsets_for_string_result(collation, args + 1, 2))

sql/item_cmpfunc.h

@@ -750,6 +750,8 @@ public:
   void fix_length_and_dec();
   uint decimal_precision() const;
   const char *func_name() const { return "if"; }
+private:
+  void cache_type_info(Item *source);
 };