Misra2012 rules 11.3 compatibility

Kernel
1

This rule is “A cast shall not be performed between a pointer to object type and a pointer to a different object type”.

We found some violations:

// list.c: violation position
// List_t * const pxList
pxList->pxIndex = ( ListItem_t * ) &( pxList->xListEnd ); // violation

because the definition of MiniListItem_t in list.h:

// list.h: xList definition
typedef struct xLIST
{
    listFIRST_LIST_INTEGRITY_CHECK_VALUE      /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
    volatile UBaseType_t uxNumberOfItems;
    ListItem_t * configLIST_VOLATILE pxIndex; /*< Used to walk through the list.  Points to the last item returned by a call to listGET_OWNER_OF_NEXT_ENTRY (). */
    MiniListItem_t xListEnd;                  /*< List item that contains the maximum possible item value meaning it is always at the end of the list and is therefore used as a marker. */
    listSECOND_LIST_INTEGRITY_CHECK_VALUE     /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
} List_t;

// list.h: ListItem_t definition
struct xLIST_ITEM
{
    listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE           /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
    configLIST_VOLATILE TickType_t xItemValue;          /*< The value being listed.  In most cases this is used to sort the list in ascending order. */
    struct xLIST_ITEM * configLIST_VOLATILE pxNext;     /*< Pointer to the next ListItem_t in the list. */
    struct xLIST_ITEM * configLIST_VOLATILE pxPrevious; /*< Pointer to the previous ListItem_t in the list. */
    void * pvOwner;                                     /*< Pointer to the object (normally a TCB) that contains the list item.  There is therefore a two way link between the object containing the list item and the list item itself. */
    struct xLIST * configLIST_VOLATILE pxContainer;     /*< Pointer to the list in which this list item is placed (if any). */
    listSECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE          /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
};
typedef struct xLIST_ITEM ListItem_t;                   /* For some reason lint wants this as two separate definitions. */

// list.h: MiniListItem_t definition
#if ( configUSE_MINI_LIST_ITEM == 1 )
    struct xMINI_LIST_ITEM
    {
        listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
        configLIST_VOLATILE TickType_t xItemValue;
        struct xLIST_ITEM * configLIST_VOLATILE pxNext;
        struct xLIST_ITEM * configLIST_VOLATILE pxPrevious;
    };
    typedef struct xMINI_LIST_ITEM MiniListItem_t;
#else
    typedef struct xLIST_ITEM      MiniListItem_t;
#endif

If the definition of MiniListItem_t comes from typedef struct xMINI_LIST_ITEM MiniListItem_t, this rule is violated.

I think this is for speed, but there is also another violation:

// FreeRTOS.h
typedef struct xSTATIC_EVENT_GROUP
{
    TickType_t xDummy1;
    StaticList_t xDummy2;

    #if ( configUSE_TRACE_FACILITY == 1 )
        UBaseType_t uxDummy3;
    #endif

    #if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) )
        uint8_t ucDummy4;
    #endif
} StaticEventGroup_t;


// event_groups.c
typedef struct EventGroupDef_t
{
    EventBits_t uxEventBits;
    List_t xTasksWaitingForBits; /*< List of tasks waiting for a bit to be set. */

    #if ( configUSE_TRACE_FACILITY == 1 )
        UBaseType_t uxEventGroupNumber;
    #endif

    #if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) )
        uint8_t ucStaticallyAllocated; /*< Set to pdTRUE if the event group is statically allocated to ensure no attempt is made to free the memory. */
    #endif
} EventGroup_t;

// event_groups.c
// StaticEventGroup_t * pxEventGroupBuffer
pxEventBits = ( EventGroup_t * ) pxEventGroupBuffer; // violation
2

Users have the option to use the mini-list if they wish to save RAM memory, or use the full list if using the mini list results in compliance issues.

The code comment on that line deviates the rule with the following explanation: “/*lint !e740 !e9087 EventGroup_t and StaticEventGroup_t are deliberately aliased for data hiding purposes and guaranteed to have the same size and alignment requirement - checked by configASSERT(). */”

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