MISRA C:2012  Rule-6.1:  (Required)			Bit-fields shall only be declared with an appropriate type

Amplification:

The appropriate bit-field types are:

• C90: either unsigned int or signed int;
• C99: one of:
  • either unsigned int or signed int;
  • another explicitly signed or explicitly unsigned integer type that is permitted by the implementation;
  • _Bool.

Note: It is permitted to use typedefs to designate an appropriate type.

Example Code:

#pragma PRQA_MESSAGES_OFF 1056

#include "misra.h"
#include "m3cmex.h"

typedef enum { A, B, C } e_t;


struct T01 { char                bpc: 3; };             /* 0634 0635 */
struct T02 { signed char         bsc: 3; };             /*      0635 */
struct T03 { unsigned char       buc: 3; };             /*      0635 */

struct T11 { short               bps: 3; };             /* 0634 0635 */
struct T12 { signed short        bss: 3; };             /*      0635 */
struct T13 { unsigned short      bus: 3; };             /*      0635 */

struct T21 { int                 bpi: 3; };             /* 0634      */
struct T22 { signed int          bsi: 3; };             /*           */
struct T23 { unsigned int        bui: 3; };             /*           */

struct T31 { long                bpl: 3; };             /* 0634 0635 */
struct T32 { signed long         bsl: 3; };             /*      0635 */
struct T33 { unsigned long       bul: 3; };             /*      0635 */

struct T41 { e_t                 bet: 3; };             /*      0635 */

struct T51 { _Bool               bbl: 3; };             /*           */


extern int16_t rule_0601( void )
{
    return 0;
}

QAC messages that encompass this guideline:

0634	[I] Bit-fields in this struct/union have not been declared explicitly as unsigned or signed.
0635	[E] Bit-fields in this struct/union have been declared with types other than int, signed int or unsigned int.

Related rules:

Dir-1.1	Any implementation-defined behaviour on which the output of the program depends shall be documented and understood
Rule-1.2	Language extensions should not be used

(c) The Motor Industry Research Association, 2012

QA C Source Code Analyser 8.1.2 MISRA C:2012 Compliance Module 1.0 © 2013 Programming Research www.programmingresearch.com

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