https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91187
Bug ID: 91187
Summary: Is it possible to make -Wzero-as-null-pointer-constant
learn about extern "C"?
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: aacid at kde dot org
Target Milestone: ---
This is more a wish than a bug report, sorry if this is not the proper place to
talk about this.
It also contains two scenarios that for my "i know nothing about compilers"
seem to be the same thing, but if you prefer me to close this and file two
different issues i'm happy to also do that :)
I like to have -Wzero-as-null-pointer-constant enabled, but when interfacing
with C libraries it's painful because it says "you're using a 0 when you should
use nullptr", but in some cases "you can't".
Scenario 1:
#### main.cpp ####
extern "C" {
#include "myzlib.h"
}
int main(int argc, char **argv)
{
void *bla = Z_NULL;
}
#### myzlib.h ####
#define Z_NULL 0
I guess you could argue here that one could stop using Z_NULL and use nullptr
directly but given that Z_NULL is what the documentation says to use, it would
be cool if one could see that Z_NULL is defined as 0 inside an include wrapped
by extern "C" and not give a warning
Scenario 2:
#### main.cpp ####
extern "C" {
#include "clib.h"
}
int main(int argc, char **argv)
{
simple(3);
}
#### clib.h ####
typedef struct {
int value;
int *something;
} MyStruct;
#define simple(x) MyStruct s; s.value = x; s.something = 0;
In this case the use of 0 as nullptr is totally inside the extern "C" header,
so there's nothing one can do to not have a warning.
