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Hello,

I have a request for clarification for rule 4-5-1:

Quote:Rule 4–5–1
(Required)
Expressions with type bool shall not be used as operands to built-in operators other than the assignment operator = , the logical operators && , || , ! , the equality operators == and !=, the unary & operator, and the conditional operator.

I'm having a disagreement with my tool vendor over the essential types of constant variables.

Note this post was made by jonesthechip, but was lost when the bulletin board was migrated to MISRA's new website. It's been resubmitted by  misra cpp


Unread post by jonesthechip » Wed May 26, 2021 10:27 am

A code base derived from an earlier C product has a large number of #define XYZ = {{1,2,3}} statements in a header.
The string defined by XYZ is used to initialise part of a ROM constant array, as follows:-

SpecialType ABC = {XYZ, 0, 1, pointer};

'SpecialType' is a structure with a three byte array that gets loaded with the replacement data from XYZ, and other sundry components.

This gets expanded to SpecialType ABC = {{{1,2,3}}, 0, 1, pointer};

The header file groups a number of replacements strings defined as XYZ, PQR, UTC, etc to keep the data (access parameters for comms) in one 'logical' place. Some replacement strings are used once, some in several other files to initialise other structures.

To achieve MISRA compliance means getting rid of all of these *&!^%$ macros. (Or more deviations than you can shake a stick at... Not ideal!)

However, it appears to be a classic case of "you don't really want to start from here"...

The optimum fix would be to re-write the code to use a pointer to a fixed string and bin the macros, putting all of the three byte arrays into a set of constant structures and sharing pointers to individual elements. This would lead to an unholy amount of retesting (and possibly my head on a stake, to deter others).

The least worst practical approach appears to be to bin the macros and edit the text replacement directly into all of the files, which although time-consuming does generate identical output binary files and therefore requires no re-testing. However, this does break the link between copies of the same data sets, so that a change to a particular set would require a search and edit through the code base.

So, today's question is: any better suggestions, please?

Regard

Sid Jones

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Hi,

With regards to Rule 6-4-2

Quote:All if … else if constructs shall be terminated with an
else clause.

Hi,

I have a few questions about rule M11-0-1:

Rule 11–0–1
(Required)
Member data in non-POD class types shall be private.

* As posted in a previous question, "class types" here means "class, struct or union". Is my understanding correct?
* Why should the fact that a type is POD or not influence access control?

Let's have the following controversial example. Having the following POD type:

Hello Sir,

I was going through MISRA C 2012 rules, Does MISRA says any guidelines to choose compiler for C as there are many compilers available in the market.

Regards
Subhra

The MISRA C:2012 Permits are now available as a free download from the "Resources" section of this Bulletin Board.

The MISRA C:2012 Permits presents a number of deviation permits covering commonly-encountered use cases for use with the MISRA C:2012 guidelines. It should be used in conjunction with MISRA Compliance:2020, a companion document which describes the purpose of deviation permits and which sets out the principles by which the concept of MISRA Compliance is governed.

No sooner had the MISRA C:2004 Permits been published, the question was asked “When will MISRA C:2012 Permits be published?” The wait is now over ...

MISRA C:2012 Permits provides a set of permits to aid compliance, particularly in the lower-levels (e.g. hardware access), but also to make compliance easier where automatically generated code is being created.

A related Guideline Reclassification Plan for Automatically Generated Code is being worked on, and will be released in due course.

This document presents a number of deviation permits covering commonly-encountered use cases for use with the MISRA C:2012 guidelines. It should be used in conjunction with MISRA Compliance:2020, a companion document which describes the purpose of deviation permits and which sets out the principles by which the concept of MISRA Compliance is governed.

The number of deviation permits within this document is expected to grow and it is possible that existing deviation permits may be revised. The document contains a table with a record of these changes.

The current release is Edition 1, published March 2021.

Attached Files

  MISRA C 2012 Permits (First Edition).pdf (Size: 269.03 KB / Downloads: 85)

Hello,

6-5-4 says "The loop-counter shall be modified by one of: --, ++, - = n, or + = n; where n remains constant for the duration of the loop"

Should this code below raise 6-5-4?

int main() {
int k = 8;

for (int j = 0; j < 10; j += k + 3) {
}
}

If 'n' concerns variable only, I would say 'Yes'.
If 'n' concerns expressions, I would say 'No'.

What do you think?
Thanks in advance for your help.

Nadège