CODEWITHSUNDEEP
cmisra
Epik
Epik

Reputation: 47

MISRA C 2012 21.1

#define and#undefshall not be used on a reserved identifier or reserved macro name.

I have a violation for this rule for this code

"#define _POSIX_C_SOURCE 200809L".

_POSIX_C_SOURCE is a reserved identifier for macro.

Which is a formal deviation for this code?

Upvotes: 0

Views: 879

Answers (2)

Lundin
Lundin

Reputation: 213842

This isn't just a MISRA violation but a standard C violation as well. See for example C11 7.1.3:

  • All identifiers that begin with an underscore and either an uppercase letter or another underscore are always reserved for any use.

Where "reserved for any use" means reserved for the compiler/library implementation.

The problem lies in the Glibc naming of the identifier. If the implementation vouches for this identifier, then you should be able to use it.

But here's the catch: getting Glibc MISRA compliant is mission impossible. And professional MISRA-C implementations don't allow non-compliant libraries to be used.

If you still insist on using these libraries, you have to create some massive, project-wide deviation for the whole of the standard libraries. The problem here is that a vast amount of the Glibc code relies on gcc non-standard extensions, such as writing code that would otherwise have poorly-defined behavior outside the library implementation - for the sake of writing a standard lib where normal C rules don't apply. You cannot possibly make an argument that such code is to be trusted from a MISRA-C perspective.

I'd ask the person who made the call to combine POSIX, Glibc and MISRA-C in the same project how to carry on from here...

Upvotes: 2

jubnzv
jubnzv

Reputation: 1574

Yes, that's right, there is a violation of rule 21.1 here.

One of the points in the text of rule 21.1 states that identifiers or macro names beginning with and underscore should not be used.

Rationale of this rule is that macro definitions started from underscore are used in standard library headers.

Upvotes: 1

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