Backport my_strntod() from 5.0

Change string->float conversion to delay division as long as possible.
This gives us more exact integer->float conversion for numbers of type '123.45E+02' (Bug #7740)




client/mysql.cc:
  Fix wront usage of charset (found during review of pushed code)
include/m_string.h:
  Backported my_strtod() from 5.0
mysql-test/mysql-test-run.sh:
  Run also mysql_client_test with --debug
mysql-test/r/ps_1general.result:
  Safety fix (if mysql_client_test.test fails)
mysql-test/r/type_float.result:
  More test
mysql-test/t/mysql_client_test.test:
  Comments for what to do if this test fails
mysql-test/t/ps_1general.test:
  Safety fix (if mysql_client_test.test fails)
mysql-test/t/type_float.test:
  More test to better test new strtod() function
  Test also bug #7740 (wrong comparsion between integer and float-in-integer-range)
sql/field.cc:
  Backport my_strntod() from 5.0
sql/item.cc:
  Backport my_strntod() from 5.0
sql/item.h:
  Backport my_strntod() from 5.0
sql/item_func.h:
  Backport my_strntod() from 5.0
sql/item_strfunc.cc:
  Backport my_strntod() from 5.0
sql/item_sum.cc:
  Backport my_strntod() from 5.0
sql/item_sum.h:
  Backport my_strntod() from 5.0
sql/procedure.h:
  Backport my_strntod() from 5.0
strings/ctype-simple.c:
  Backport my_strntod() from 5.0
strings/ctype-ucs2.c:
  Backport my_strntod() from 5.0
strings/strtod.c:
  Backport my_strntod() from 5.0
  Change conversion to delay division as long as possible.
  This gives us more exact integer-> float conversion for numbers of type '123.45E+02'

1 files changed, 7 insertions, 4 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 4b3acbe5a3c..76cbaa99029 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -1140,8 +1140,9 @@ double Item_param::val()
   case LONG_DATA_VALUE:
     {
       int dummy_err;
+      char *end_not_used;
       return my_strntod(str_value.charset(), (char*) str_value.ptr(),
-                        str_value.length(), (char**) 0, &dummy_err);
+                        str_value.length(), &end_not_used, &dummy_err);
     }
   case TIME_VALUE:
     /*
@@ -2585,10 +2586,12 @@ double Item_cache_str::val()
   DBUG_ASSERT(fixed == 1);
   int err;
   if (value)
+  {
+    char *end_not_used;
     return my_strntod(value->charset(), (char*) value->ptr(),
-		      value->length(), (char**) 0, &err);
-  else
-    return (double)0;
+		      value->length(), &end_not_used, &err);
+  }
+  return (double)0;
 }