`stringop-overflow` on GCC 13.3.0

[Neverlord]

/usr/include/c++/13/bits/stl_construct.h:97:14: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
   97 |     { return ::new((void*)__location) _Tp(std::forward<_Args>(__args)...); }
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

best guess the source location for that one is

    inlined from 'void caf::json_writer::push(type)' at /scratch/vern/zeek-vssl/auxil/broker/caf/libcaf_core/src/json_writer.cpp:463:19:

(reported via Slack)

[Neverlord]

I don't see this warning on GCC 16. I tried a default configure and configure --build-type=release in Zeek. The only stringop-overflow warning I get is in binpac:

/Users/neverlord/github/zeek/topic/neverlord/broker-json/tools/binpac/src/pac_cstr.cc:112:22: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
  112 |         new_s[i - 1] = '\0';
      |         ~~~~~~~~~~~~~^~~~~~
/Users/neverlord/github/zeek/topic/neverlord/broker-json/tools/binpac/src/pac_cstr.cc:95:35: note: at offset -1 into destination object of size [0, 2147483647] allocated by 'operator new []'
   95 |         char* new_s = new char[len];
      |                                   ^

json_writer.cpp:463 would be the push_back here:

void json_writer::push(type t) {
  stack_.push_back({t, false});
}

The stack_ member variable is a std::vector. Looks like a false positive on GCC 13 to me. There's not much we could do if it's complaining about code in the STL. 😕