[Bug c/106823] New: #pragma GCC diagnostic ignored "-Wattribute-warning" doesn't work for -flto

[jiangning.liu at amperecomputing dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106823

            Bug ID: 106823
           Summary: #pragma GCC diagnostic ignored "-Wattribute-warning"
                    doesn't work for -flto
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jiangning.liu at amperecomputing dot com
  Target Milestone: ---

$ cat foo.cpp
extern "C" __attribute__((__warning__("xxxx"))) void _foo(int) {};

void foo(int num) {
#pragma GCC diagnostic ignored "-Wattribute-warning"
  ::_foo(num);
}

int main()
{
    foo(1);
}
$ g++ foo.cpp
$ g++ -flto foo.cpp
foo.cpp: In function ‘foo’:
foo.cpp:5:9: warning: call to ‘_foo’ declared with attribute warning: xxxx
[-Wattribute-warning]
    5 |   ::_foo(num);
      |         ^