GCC flips on realloc range about fltk HOT 3 CLOSED

$ gcc --version
gcc (Ubuntu 7.3.0-27ubuntu1~18.04) 7.3.0
$ cmake -DCMAKE_BUILD_TYPE=Release -GNinja ../..
[...]
Building CXX object src/CMakeFiles/fltk.dir/Fl_Table_Row.cxx.o
In function ‘void Fl_Table_Row::CharVector::size(int)’,
    inlined from ‘virtual void Fl_Table_Row::rows(int)’,
    inlined from ‘virtual void Fl_Table_Row::clear()’ at ../../FL/Fl_Table_Row.H:181:9:
../../src/Fl_Table_Row.cxx:56:25: warning: argument 2 range [18446744071562067969, 18446744073709551615] exceeds maximum object size 9223372036854775807 [-Walloc-size-larger-than=]
     arr = (char*)realloc(arr, count * sizeof(char));
                  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/7/cstdlib:75:0,
                 from /usr/include/c++/7/stdlib.h:36,
                 from ../../FL/fl_utf8.h:36,
                 from ../../FL/Fl.H:33,
                 from ../../FL/Fl_Widget.H:26,
                 from ../../FL/Fl_Group.H:25,
                 from ../../FL/Fl_Table.H:23,
                 from ../../FL/Fl_Table_Row.H:25,
                 from ../../src/Fl_Table_Row.cxx:27:
/usr/include/stdlib.h: In member function ‘virtual void Fl_Table_Row::clear()’:
/usr/include/stdlib.h:549:14: note: in a call to allocation function ‘void* realloc(void*, size_t)’ declared here
 extern void *realloc (void *__ptr, size_t __size)
              ^~~~~~~