[false positive] style: struct member is never used. [unusedStructMember] when member is only used in offsetof()

[Yann Droneaud]

Hi,

cppcheck is reporting struct member as unused despite it being used in
offsetof():

#include <stddef.h>

struct foobar {
   char unused;
};

size_t offset_unused = offsetof(struct foobar, unused);

cppcheck reports

struct-offsetof.c:4:8: style: struct member 'foobar::unused' is never used. [unusedStructMember]
  char unused;
       ^

offsetof() macro is part of the language since C89 I believe.

Is it possible to extend cppcheck so that it has some knowledge of the
macro without parsing <stddef.h> ?</stddef.h>

Regards.

[Yann Droneaud]

Hi,

I thought this was worth a bug report and it was the proper channel for it to be recorded in https://trac.cppcheck.net/ as I don't have an account there.

Is it possible to open a bug for this issue ?

Regards.

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/13345

[Yann Droneaud]

And it's already fixed ( https://github.com/danmar/cppcheck/pull/7041 ). Thanks a lot !