<![CDATA[MISRA Discussion Forums - 8.6 Types]]> https://forum.misra.org.uk/ Thu, 05 Nov 2026 15:13:24 +0000 MyBB <![CDATA[Rule 6.1 Declaration of bitfields with the C90 compiler that accepts the ANSI C diale]]> https://forum.misra.org.uk/showthread.php?tid=1672 Fri, 23 Feb 2024 02:01:47 +0000 tomoko.mabuchi]]> https://forum.misra.org.uk/showthread.php?tid=1672 Is it possible in C90, without violating MISRA Rule 6.1, to declare bitfields defined as an explicitly signed or explicitly unsigned integer type other than the unsigned int and signed int types allowed by the compiler?
According to section 8.6, this is allowed in C99. However, the compiler I use has a setting to accept the ANSI C dialect conforming to X3.159-1989. With this setting enabled, bitfields can have base types that are enumerated or integral types besides int and unsigned int. This matches A.6.5.8 in the ANSI Common Extensions appendix.
With this setting, I think the declaration of bitfields below is a permitted deviation. Is my understanding correct?
Code:
typedef struct
{
    unsigned char bit0 :1;
    unsigned char bit1 :1;
    unsigned char bit2 :1;
    unsigned char dummy :5;
} st_sample;
]]> Is it possible in C90, without violating MISRA Rule 6.1, to declare bitfields defined as an explicitly signed or explicitly unsigned integer type other than the unsigned int and signed int types allowed by the compiler?
According to section 8.6, this is allowed in C99. However, the compiler I use has a setting to accept the ANSI C dialect conforming to X3.159-1989. With this setting enabled, bitfields can have base types that are enumerated or integral types besides int and unsigned int. This matches A.6.5.8 in the ANSI Common Extensions appendix.
With this setting, I think the declaration of bitfields below is a permitted deviation. Is my understanding correct?
Code:
typedef struct
{
    unsigned char bit0 :1;
    unsigned char bit1 :1;
    unsigned char bit2 :1;
    unsigned char dummy :5;
} st_sample;
]]> <![CDATA[Rule 6.1]]> https://forum.misra.org.uk/showthread.php?tid=1016 Wed, 15 Jan 2014 06:48:45 +0000 Akhil]]> https://forum.misra.org.uk/showthread.php?tid=1016
For C99 : The appropriate types are :

1. either unsigned or signed int.
This refers to unsigned int and signed int only OR any other datatype..?

2. Another explicitly signed or explicitly unsigned integer type that is premitted by the implementation.
What all types does this refer to ? Does this refer to unsigned short OR unsigned short int etc.

Please clarify.]]>
For C99 : The appropriate types are :

1. either unsigned or signed int.
This refers to unsigned int and signed int only OR any other datatype..?

2. Another explicitly signed or explicitly unsigned integer type that is premitted by the implementation.
What all types does this refer to ? Does this refer to unsigned short OR unsigned short int etc.

Please clarify.]]>