pdPASS macro doesn’t work with GNU C++ 14

Hi, while working on a C++ project I noticed something wrong when using the pdPASS macro: /home/fjrg76/git/prueba1114lap/freertos10.0.1/inc/projdefs.h:47:27: error: ISO C++ forbids comparison between pointer and integer [-fpermissive] #define pdPASS ( pdTRUE ) ^ /home/fjrg76/git/prueba1114lap/prueba11/inc/FreeRTOSConfig.h:103:33: note: in definition of macro ‘configASSERT’ #define configASSERT( x ) if( ( x ) == 0 ) { taskDISABLE_INTERRUPTS(); for( ;; ); } ^ ../src/prueba11.cpp:112:39: note: in expansion of macro ‘*pdPASS*’ * configASSERT( myTimer.GetHandle() == pdPASS );* But if I change pdPASS to pdFAIL, then it compiles: configASSERT( myTimer.GetHandle() != pdFAIL ); From FreeRTOS/projdefs.h

define pdFALSE ( ( BaseType_t ) 0 )

define pdTRUE ( ( BaseType_t ) 1 )

define pdPASS ( pdTRUE ) // <– Eclipse IDE has placed an

error mark (X) in this line

define pdFAIL ( pdFALSE )

From my file prueba11.cpp: class Timer { public: // …
  • TimerHandle_t GetHandle() const*
  • {*
  • return this->handle;*
  • }*
protected: TimerHandle_t handle = pdFAIL; }; class MyTimer:public Timer {//}; int main(void) { // …
MyTimer myTimer{ pdMS_TO_TICKS( 100 ), pdTRUE, 0, 7 };
  • configASSERT( myTimer.GetHandle() == pdPASS );*
    • if ( myTimer.GetHandle() != pdPASS ) while(1);*
    if( myTimer.Start() == false ) while(1); vTaskStartScheduler(); return 0 ; }
Any hints? Of course I can use pdFAIL instead of pdPASS throughout all my code/project, but this situation (bug?) might be more serious than it appears. As said, I’m using the GNU C++ 14 compiler under a Linux Box (maybe it’s not important) — M.I. Fco. Javier Rodríguez G.

pdPASS macro doesn’t work with GNU C++ 14

Why are you asserting that GetHandle will return pdPASS? That is almost certainly not true. Handles are pointers, and pointers having the value of 1 are very rare. Do you mean that the handle isn’t 0 (NULL)?

pdPASS macro doesn’t work with GNU C++ 14

Hi, You are getting this warning because your code is wrong – it is helping you find a bug. The only integer constant you can safely compare with a pointer is 0, because that is a “null pointer constant”. (Note you can’t compare a pointer to an int that happens to be 0 – you can only compare to the constant 0.) What you are trying to do is check that the handle is valid – i.e., it is non-zero. You do /can/ that by:
configASSERT(myTimer.GetHandle() != pdFAIL);
You /cannot/ do it by asserting that the handle value is pdPASS. It is almost certainly better, IMHO, to simply assert that the handle is valid by a conversion to bool:
This is idiomatic C and C++. Adding ” != pdFAIL” gives no benefits, while ” == pdPASS” is directly wrong. I have not looked in the context of projedefs.h or how these macros are intended to be used. But as a general point, I am always highly sceptical about using “home-made booleans”. FreeRTOS is designed to work with pre-C99 C, and thus needs to use them – your code is C++14, and does not need them. When you need a boolean type, use “bool” – when you need boolean values, use “true” and “false”. And when you need a null pointer constant, use nullptr (for C++11 onwards) or NULL (for C). You can also use 0 directly, but prefer nullptr when you can, NULL when you can’t. Avoid using cast expressions like you get from the pdFAIL macro.