Build fails when using gcc installed by homebrew

$  uname -sr 

Darwin 20.5.0

$ gcc --version

gcc (Homebrew GCC 11.1.0_1) 11.1.0

Copyright (C) 2021 Free Software Foundation, Inc.

This is free software; see the source for copying conditions.  There is NO

warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++ --version

g++ (Homebrew GCC 11.1.0_1) 11.1.0

Copyright (C) 2021 Free Software Foundation, Inc.

This is free software; see the source for copying conditions.  There is NO

warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ cmake --version

cmake version 3.19.7

CMake suite maintained and supported by Kitware (kitware.com/cmake).

$ cd build

$ cmake -DCMAKE_C_COMPILER=/usr/local/bin/gcc -DCMAKE_CXX_COMPILER=/usr/local/bin/g++ ..

$ cmake --build . --config Debug -j 8

.....

In file included from server/sql/structs.h:26,

                 from server/sql/handler.h:34,

                 from server/storage/innobase/include/trx0xa.h:27,

                 from server/storage/innobase/include/trx0trx.h:34,

                 from server/storage/innobase/btr/btr0pcur.cc:30:

server/include/my_time.h: In function 'void my_timeval_trunc(timeval*, uint)':

server/include/my_time.h:249:65: error: conversion from 'long int' to '__darwin_suseconds_t' {aka 'int'} may change value [-Werror=conversion]

  249 |   tv->tv_usec-= my_time_fraction_remainder(tv->tv_usec, decimals);

.....