Excluding header files from MISRA checking

Introduction

The advice in this technical note is for the built-in MISRA checkers (which are part of the Embedded Workbench toolchain).

Note for C-STAT: If you are using the C-STAT MISRA checkers, read the C-STAT documentation for advice.

Discussion

When you enable one of the built-in MISRA checkers, numerous messages can be produced. Because many of the messages concern content in the header files, messages concerning the C-source might go unnoticed.

It can be helpful to disable MISRA checks for some types of header files. Such header files are:

• IAR Systems header files (automatically excluded).
• Third-party header files, where you cannot change the file contents.
• Your own header files, where the contents are not to be changed.

For such header files, use the ‘Main solution’ or the ‘Alternative solution’.

Main Solution

The #pragma diag_suppress=tag[,tag,...] directive can be used to suppress messages from the built-in MISRA C checker.

To avoid writing a long list of MISRA C tags for every #include directive, you can use the following two macros:

#define MISRAC_DISABLE _Pragma ("diag_suppress= \
    Pm001,Pm002,Pm003,Pm004,Pm005,Pm006,Pm007,Pm008,Pm009,Pm010,Pm011,\
    Pm012,Pm013,Pm014,Pm015,Pm016,Pm017,Pm018,Pm019,Pm020,Pm021,Pm022,\
    Pm023,Pm024,Pm025,Pm026,Pm027,Pm028,Pm029,Pm030,Pm031,Pm032,Pm033,\
    Pm034,Pm035,Pm036,Pm037,Pm038,Pm039,Pm040,Pm041,Pm042,Pm043,Pm044,\
    Pm045,Pm046,Pm047,Pm048,Pm049,Pm050,Pm051,Pm052,Pm053,Pm054,Pm055,\
    Pm056,Pm057,Pm058,Pm059,Pm060,Pm061,Pm062,Pm063,Pm064,Pm065,Pm066,\
    Pm067,Pm068,Pm069,Pm070,Pm071,Pm072,Pm073,Pm074,Pm075,Pm076,Pm077,\
    Pm078,Pm079,Pm080,Pm081,Pm082,Pm083,Pm084,Pm085,Pm086,Pm087,Pm088,\
    Pm089,Pm090,Pm091,Pm092,Pm093,Pm094,Pm095,Pm096,Pm097,Pm098,Pm099,\
    Pm100,Pm101,Pm102,Pm103,Pm104,Pm105,Pm106,Pm107,Pm108,Pm109,Pm110,\
    Pm111,Pm112,Pm113,Pm114,Pm115,Pm116,Pm117,Pm118,Pm119,Pm120,Pm121,\
    Pm122,Pm123,Pm124,Pm125,Pm126,Pm127,Pm128,Pm129,Pm130,Pm131,Pm132,\
    Pm133,Pm134,Pm135,Pm136,Pm137,Pm138,Pm139,Pm140,Pm141,Pm142,Pm143,\
    Pm144,Pm145,Pm146,Pm147,Pm148,Pm149,Pm150,Pm151,Pm152,Pm153,Pm154,\
    Pm155")

#define MISRAC_ENABLE _Pragma ("diag_default= \
    Pm001,Pm002,Pm003,Pm004,Pm005,Pm006,Pm007,Pm008,Pm009,Pm010,Pm011,\
    Pm012,Pm013,Pm014,Pm015,Pm016,Pm017,Pm018,Pm019,Pm020,Pm021,Pm022,\
    Pm023,Pm024,Pm025,Pm026,Pm027,Pm028,Pm029,Pm030,Pm031,Pm032,Pm033,\
    Pm034,Pm035,Pm036,Pm037,Pm038,Pm039,Pm040,Pm041,Pm042,Pm043,Pm044,\
    Pm045,Pm046,Pm047,Pm048,Pm049,Pm050,Pm051,Pm052,Pm053,Pm054,Pm055,\
    Pm056,Pm057,Pm058,Pm059,Pm060,Pm061,Pm062,Pm063,Pm064,Pm065,Pm066,\
    Pm067,Pm068,Pm069,Pm070,Pm071,Pm072,Pm073,Pm074,Pm075,Pm076,Pm077,\
    Pm078,Pm079,Pm080,Pm081,Pm082,Pm083,Pm084,Pm085,Pm086,Pm087,Pm088,\
    Pm089,Pm090,Pm091,Pm092,Pm093,Pm094,Pm095,Pm096,Pm097,Pm098,Pm099,\
    Pm100,Pm101,Pm102,Pm103,Pm104,Pm105,Pm106,Pm107,Pm108,Pm109,Pm110,\
    Pm111,Pm112,Pm113,Pm114,Pm115,Pm116,Pm117,Pm118,Pm119,Pm120,Pm121,\
    Pm122,Pm123,Pm124,Pm125,Pm126,Pm127,Pm128,Pm129,Pm130,Pm131,Pm132,\
    Pm133,Pm134,Pm135,Pm136,Pm137,Pm138,Pm139,Pm140,Pm141,Pm142,Pm143,\
    Pm144,Pm145,Pm146,Pm147,Pm148,Pm149,Pm150,Pm151,Pm152,Pm153,Pm154,\
    Pm155")

To disable the MISRA C check for a header file, you can write:

MISRAC_DISABLE
#include "myincludes.h"
MISRAC_ENABLE

Alternative Solution

You can get inspiration and suggestions from the IAR header files. These header files are not written to comply with MISRA C, they are written to work efficiently.

There is an intentionally undocumented #pragma directive used in IAR Systems header files.

#pragma system_include

You can add it early in all your header files that produce MISRA C errors.

Conclusion

Use these suggestions to avoid being overwhelmed with messages when you use the built-in (MISRAC-1998 and MISRAC-2004) checkers.

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