Bug#18761: constant expression as UDF parameters not passed in as constant

The code that set up data to be passed to user-defined functions was very
old and analyzed the "Type" of the data that was passed into the UDF, when
it really should analyze the "return_type", which is hard-coded for simple
Items and works correctly for complex ones like functions.
---
Added test at Sergei's behest.


mysql-test/r/udf.result:
  Verify that various arguments work.
  ---
  Added test at Sergei's behest.
mysql-test/t/udf.test:
  Verify that various arguments work.
  ---
  Added test at Sergei's behest.
sql/item_func.cc:
  For function-Items, test whether it is constant and set the struct members 
  for the UDF parameter appropriately.
  
  Replace tabs with spaces in affected code.
sql/udf_example.c:
  Include a simple function that is useful in testing.

1 files changed, 38 insertions, 1 deletions

diff --git a/mysql-test/t/udf.test b/mysql-test/t/udf.test
index 96e559f5c05..c62d7829b05 100644
--- a/mysql-test/t/udf.test
+++ b/mysql-test/t/udf.test
@@ -143,4 +143,41 @@ DROP FUNCTION lookup;
 DROP FUNCTION reverse_lookup;
 DROP FUNCTION avgcost;
 
-
+#
+# Bug#18761: constant expression as UDF parameters not passed in as constant
+#
+--replace_result $UDF_EXAMPLE_LIB UDF_EXAMPLE_LIB
+eval CREATE FUNCTION is_const RETURNS STRING SONAME "$UDF_EXAMPLE_LIB";
+
+select
+  is_const(3) as const,
+  is_const(3.14) as const,
+  is_const('fnord') as const,
+  is_const(2+3) as const,
+  is_const(rand()) as 'nc rand()',
+  is_const(sin(3.14)) as const,
+  is_const(upper('test')) as const;
+
+create table bug18761 (n int);
+insert into bug18761 values (null),(2);
+select
+  is_const(3) as const,
+  is_const(3.14) as const,
+  is_const('fnord') as const,
+  is_const(2+3) as const,
+  is_const(2+n) as 'nc  2+n  ',
+  is_const(sin(n)) as 'nc sin(n)',
+  is_const(sin(3.14)) as const,
+  is_const(upper('test')) as const,
+  is_const(rand()) as 'nc rand()',
+  is_const(n) as 'nc   n   ',
+  is_const(is_const(n)) as 'nc ic?(n)',
+  is_const(is_const('c')) as const
+from
+  bug18761;
+drop table bug18761;
+
+--error 1241
+select is_const((1,2,3));
+
+drop function if exists is_const;