I can't install cocoapods. I'm doing this:
gem install cocoapods
And I get all these errors:
Building native extensions.  This could take a while...
ERROR:  Error installing cocoapods:
    ERROR: Failed to build gem native extension.
    current directory: /usr/local/lib/ruby/gems/2.4.0/gems/json-1.8.3/ext/json/ext/generator
/usr/local/opt/ruby/bin/ruby -r ./siteconf20161228-19158-1ru87yt.rb extconf.rb
creating Makefile
current directory: /usr/local/lib/ruby/gems/2.4.0/gems/json-1.8.3/ext/json/ext/generator
make "DESTDIR=" clean
current directory: /usr/local/lib/ruby/gems/2.4.0/gems/json-1.8.3/ext/json/ext/generator
make "DESTDIR="
compiling generator.c
generator.c:861:25: error: use of undeclared identifier 'rb_cFixnum'
    } else if (klass == rb_cFixnum) {
                        ^
generator.c:863:25: error: use of undeclared identifier 'rb_cBignum'
    } else if (klass == rb_cBignum) {
                        ^
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2163:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs+1, varc, vari+1))
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2168:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs+1, varc, vari+1))
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 5 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/ruby/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6 warnings and 2 errors generated.
make: *** [generator.o] Error 1
make failed, exit code 2
Gem files will remain installed in /usr/local/lib/ruby/gems/2.4.0/gems/json-1.8.3 for inspection.
Results logged to /usr/local/lib/ruby/gems/2.4.0/extensions/x86_64-darwin-16/2.4.0/json-1.8.3/gem_make.out
I have been searching a lot and I can't find anything about those errors.
How can I solve that?
 
     
     
    