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compiler fails to detect error when comparing pointer to enum to enum value

clinthelton
Prodigy 20 points

Using CCS version 4.0.1.01001, which uses cl2000 version 5.2.1, a major error is not detected.

In the following code sequence, on the second line of the function, the compiler should detect that a pointer to enum is being compared with an enum value:

typedef enum {
    NVMTYPES_DRIVER_UNEXECUTED,
    NVMTYPES_DRIVER_IN_PROGRESS,
    NVMTYPES_DRIVER_COMPLETE
} NvmTypes_TypeDriverStatus;

void EepromDrvr_GetWriteStatus(NvmTypes_TypeDriverStatus* EepromDrvr_OpStatus, int *ptr) {
    int val = 1;
    if (EepromDrvr_OpStatus != NVMTYPES_DRIVER_UNEXECUTED) {
        return;
    }
    if (ptr == val) {
        return;
    }
}

The instruction should dereference the pointer to get its value.

Please correct the compiler to detect and report this error. Note that g++ does detect this.

 

  • 0
    TI__Guru**** 244930 points

    When I compile that code, this is what I see ...

    % cl2000 try1.c
"try1.c", line 12: error: operand types are incompatible ("int *" and "int")
1 error detected in the compilation of "try1.c".

>> Compilation failure

    What do you see?

    Thanks and regards,

    -George

  • 0
    Expert 2355 points

    clinthelton said:

    Using CCS version 4.0.1.01001, which uses cl2000 version 5.2.1, a major error is not detected.

    In the following code sequence, on the second line of the function, the compiler should detect that a pointer to enum is being compared with an enum value:

    typedef enum {
        NVMTYPES_DRIVER_UNEXECUTED,
        NVMTYPES_DRIVER_IN_PROGRESS,
        NVMTYPES_DRIVER_COMPLETE
    } NvmTypes_TypeDriverStatus;

    void EepromDrvr_GetWriteStatus(NvmTypes_TypeDriverStatus* EepromDrvr_OpStatus, int *ptr) {
        int val = 1;
        if (EepromDrvr_OpStatus != NVMTYPES_DRIVER_UNEXECUTED) {
            return;
        }
        if (ptr == val) {
            return;
        }
    }

     

    When I compile that code, this is what I see ...

    % cl2000 try1.c
"try1.c", line 12: error: operand types are incompatible ("int *" and "int")
1 error detected in the compilation of "try1.c".

>> Compilation failure

    What do you see?

    Thanks and regards,

    -George

    Just an observation but isn't that error referring to the line:

        if (ptr == val) {

    which is comparing a pointer to a value?

    Tim

  • 0 in reply to Tim King61612
    TI__Guru**** 244930 points

    Tim King said:

    Just an observation but isn't that error referring to the line:

        if (ptr == val) {

    which is comparing a pointer to a value?

    Oops.  Sorry about that.  I focused on the wrong thing.  You are wondering why this line

    Tim King said:
    if (EepromDrvr_OpStatus != NVMTYPES_DRIVER_UNEXECUTED) {

    does not get an error diagnostic.  It turns out that line is equivalent to something like this ...

    if (ptr_to_enum != ENUM_VALUE_OF_ZERO)

    In C, it is OK to compare a pointer to 0, even if the value 0 comes from an enumeration type.  C++ is more paranoid about such things, and complains.  The g++ compiler complains about this because it is a C++ compiler.  If you run cl2000 in C++ mode, it complains too.  To do that, either change the file extension to .cpp, or add the build option --cpp_default.  Another change that results in an error is to compare against some enum value other than NVMTYPES_DRIVER_UNEXECUTED.

    Thanks and regards,

    -George