 |
|
|
RENESAS TOOL NEWS on March 1, 2005: RSO-M3T-NC30WA_3-050301D
A Note on Using C-Compiler Package
M3T-NC30WA V.5.30 Release 02
|
Please take note of the following problem in using the M3T-NC30WA
C-compiler package, which is used for the M16C/60, M16C/30, M16C/Tiny,
M16C/20, M16C/10, and R8C/Tiny series of MCUs:
- On passing the address of an object qualified as const as an argument to a function
- Product and Version Concerned
M3T-NC30WA V.5.30 Release 02
- Description
Consider that a function takes the address of an object qualified as const as an argument.
When such a function is called, an error message appears even if a
correct type of argument is passed. However, code is properly generated in this case.
- 2.1 Conditions
- This problem occurs if the following conditions are all satisfied:
| (1) | A parameter to the function to be called is a pointer pointing to
an object qualified as const. |
| (2) | The argument corresponding to the parameter in (1) is either of the
following:
- The result of operation where an address operator is applied to an object qualified as const
- The name of an array qualified as const
|
| (3) | The object and the array in (2) above are of the same type as the
object pointed to by the pointer in (1). |
- 2.2 Examples
-
---------------------------------------------------------------------
const int ten = 10; /* Condition (3) */
const int arr[2] = { 1, 2 }; /* Condition (3) */
void subr(const int *); /* Conditions (1) and (3) */
void mainr(void)
{
subr(&ten); /* Condition (2) */
subr(arr); /* Condition (2) */
)
---------------------------------------------------------------------
Examples of messages
---------------------------------------------------------------------
[Warning(ccom):example.c,line 8] assignment from const pointer to
non-const pointer
===> subr(&ten);
[Warning(ccom):example.c,line 9] assignment from const pointer to
non-const pointer
===> subr(arr);
---------------------------------------------------------------------
- Workaround
Operate a cast operator on the argument to which a warning message is sent.
--------------------------------------------------------------------
void mainr(void)
{
subr((const int *)&ten); /* Cast operator operated */
subr((const int *)arr); /* Cast operator operated */
)
--------------------------------------------------------------------
- Schedule of Fixing the Problem
We plan to fix this problem in the next release of the product.
|
|
