Building wheels for collected packages: grpcio
  Building wheel for grpcio (setup.py) ... error
...
    clang -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include -I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include -D_WIN32_WINNT=1536 -DOPENSSL_NO_ASM=1 -DGPR_BACKWARDS_COMPATIBILITY_MODE=1 -DHAVE_CONFIG_H=1 -DGRPC_ENABLE_FORK_SUPPORT=1 -DPyMODINIT_FUNC=extern "C" __attribute__((visibility ("default"))) PyObject* -DGRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK=1 -Isrc/python/grpcio -Iinclude -I. -Ithird_party/abseil-cpp -Ithird_party/address_sorting/include -Ithird_party/cares -Ithird_party/cares/cares -Ithird_party/cares/config_darwin -Ithird_party/re2 -Ithird_party/boringssl-with-bazel/src/include -Ithird_party/upb -Isrc/core/ext/upb-generated -Isrc/core/ext/upbdefs-generated -Ithird_party/zlib -I/Users/huon/.pyenv/versions/sg/include -I/Users/huon/.pyenv/versions/3.8.7/include/python3.8 -c third_party/zlib/gzlib.c -o python_build/temp.macosx-11.1-arm64-3.8/third_party/zlib/gzlib.o -stdlib=libc++ -fvisibility=hidden -fno-wrapv -fno-exceptions -pthread
    third_party/zlib/gzlib.c:252:9: error: implicit declaration of function 'lseek' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
            LSEEK(state->fd, 0, SEEK_END);  /* so gzoffset() is correct */
            ^
    third_party/zlib/gzlib.c:14:17: note: expanded from macro 'LSEEK'
    #  define LSEEK lseek
                    ^
    third_party/zlib/gzlib.c:252:9: note: did you mean 'fseek'?
    third_party/zlib/gzlib.c:14:17: note: expanded from macro 'LSEEK'
    #  define LSEEK lseek
                    ^
    /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h:162:6: note: 'fseek' declared here
    int      fseek(FILE *, long, int);
             ^
    third_party/zlib/gzlib.c:258:24: error: implicit declaration of function 'lseek' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
            state->start = LSEEK(state->fd, 0, SEEK_CUR);
                           ^
    third_party/zlib/gzlib.c:14:17: note: expanded from macro 'LSEEK'
    #  define LSEEK lseek
                    ^
    third_party/zlib/gzlib.c:359:9: error: implicit declaration of function 'lseek' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
            ^
    third_party/zlib/gzlib.c:14:17: note: expanded from macro 'LSEEK'
    #  define LSEEK lseek
                    ^
    third_party/zlib/gzlib.c:400:15: error: implicit declaration of function 'lseek' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
            ret = LSEEK(state->fd, offset - state->x.have, SEEK_CUR);
                  ^
    third_party/zlib/gzlib.c:14:17: note: expanded from macro 'LSEEK'
    #  define LSEEK lseek
                    ^
    third_party/zlib/gzlib.c:496:14: error: implicit declaration of function 'lseek' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        offset = LSEEK(state->fd, 0, SEEK_CUR);
                 ^
    third_party/zlib/gzlib.c:14:17: note: expanded from macro 'LSEEK'
    #  define LSEEK lseek
                    ^
  5 errors generated.
...
  ----------------------------------------
  ERROR: Failed building wheel for grpcio