Update extconf.rb so Mac OS X always uses clang (if correct version is available) and stops looking for GCC

[xMinh129]

I'm having this issue while trying to install a gem. Anybody could help me? Appreciate it a lot!

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
/Users/minhvu/.rvm/gems/ruby-2.3.0/gems/bindex-0.5.0/ext/bindex
/Users/minhvu/.rvm/rubies/ruby-2.3.0/bin/ruby -r
./siteconf20170507-3967-bvkwf8.rb extconf.rb
creating Makefile

current directory:
/Users/minhvu/.rvm/gems/ruby-2.3.0/gems/bindex-0.5.0/ext/bindex
make "DESTDIR=" clean

current directory:
/Users/minhvu/.rvm/gems/ruby-2.3.0/gems/bindex-0.5.0/ext/bindex
make "DESTDIR="
compiling cruby.c
gcc: error: unrecognized command line option ‘-Wshorten-64-to-32’
gcc: error: unrecognized command line option ‘-Wdivision-by-zero’; did you mean
‘-Wdiv-by-zero’?
gcc: error: unrecognized command line option ‘-Wextra-tokens’; did you mean
‘--extra-warnings’?
make: *** [cruby.o] Error 1

make failed, exit code 2

Gem files will remain installed in
/Users/minhvu/.rvm/gems/ruby-2.3.0/gems/bindex-0.5.0 for inspection.
Results logged to
/Users/minhvu/.rvm/gems/ruby-2.3.0/extensions/x86_64-darwin-16/2.3.0/bindex-0.5.0/gem_make.out

An error occurred while installing bindex (0.5.0), and Bundler cannot
continue.
Make sure that `gem install bindex -v '0.5.0'` succeeds before bundling.

This is my ruby version : ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin16]

[v0dro]

If you're on Mac you should clang not gcc. #584

[translunar]

@v0dro We should probably fix this. The weird stuff in extconf is a workaround for when clang wasn't able to compile NMatrix and we had to use GCC. Now the reverse is true, and GCC won't work, but clang does.

[v0dro]

Yes you have a point. I don't have access to a Mac though so I can't work on this as of now.

I think it should be a small change in extconf which will first check the environment and set the variables in CONFIG appropriately.

See this: http://stackoverflow.com/questions/4554837/how-to-specify-compiler-for-gem-install

Or maybe use use rake-compiler.

[translunar]

We don't need to rewrite extconf totally. It's already overriding the system default to use GCC on Mac. We just need to remove the override.

[mikecmpbll]

If you're on Mac you should clang not gcc. #584

how exactly? don't assume i have any idea what i'm doing.

if someone's at least willing to help me understand the problem, i'd be happy to try and work out a solution.

[mikecmpbll]

worked around by temporarily symlinking to clang.

mv /usr/local/bin/gcc-4.9 /usr/local/bin/gcc-4.9-orig
mv /usr/local/bin/g++-4.9 /usr/local/bin/g++-4.9-orig
ln -s $(which clang) /usr/local/bin/gcc-4.9
ln -s $(which clang++) /usr/local/bin/g++-4.9
gem install nmatrix
rm /usr/local/bin/gcc-4.9 /usr/local/bin/g++-4.9
mv /usr/local/bin/gcc-4.9-orig /usr/local/bin/gcc-4.9
mv /usr/local/bin/g++-4.9-orig /usr/local/bin/g++-4.9

[lonny]

I am having this issue, too. Or one that is closely related. The error is:

mkmf.rb:50:in 'gplusplus_version': unable to determine g++ version (match to get version was nil) (RuntimeError)
extconf failed, exit code 1

This occurred both before and after I followed the instructions for OS X here: https://github.com/SciRuby/nmatrix/wiki/Installation

I also tried setting up a symbolic ink for g++-4.8, to match the one for gcc. When I did that, I got a different error, as shown in the mkmf.log file

gcc: error: unrecognized command line option '-Wshorten-64-to-32'
gcc: error: unrecognized command line option '-Wdivision-by-zero'
gcc: error: unrecognized command line option '-Wextra-tokens'
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main(int argc, char **argv)
4: {
5:   return 0;
6: }
/* end */

This is a big problem. mikecmpbll's fix didn't work for me, either, as I am now on OS X 10.10.5.

I should also note: this is a local problem. I did manage to get nmatrix installed on our Linux server. But once I did, every time we run a script we get the following message, repeated 8 times, whenever a script starts up (even scripts that do not use nmatrix):

DEPRECATION WARNING: alias_method_chain is deprecated. Please, use Module#prepend instead. From module, you can access the original method using super. (called from require at /home/deploy/.gem/ruby/2.3.0/gems/bundler-1.16.0/lib/bundler/runtime.rb:81)

That is on Ruby 2.3.3p222, Rails 5.0.0.1.

[translunar]

Okay. So, it now appears that in High Sierra, the default is clang. You can check this by doing

require 'mkmf'
puts CONFIG['CC']

If that's not the case for you, please let me know.

@lonny, I believe your issue is now resolved in #601.

[lonny]

@MohawkJohn Only if I can successfully upgrade to High Sierra. So far, it has been no go.

[translunar]

@lonny You should still be able to compile with clang/clang++. What happens if you open irb and do the thing I suggested above?

[lonny]

2.3.0 :002 > puts CONFIG['CC']
gcc
=> nil

[lonny]

I am going to continue my efforts to upgrade to High Sierra. But I have to do that on my "off time", as it were.

[translunar]

What about if you do CC=clang CXX=clang++ bundle exec rake compile?

[lonny]

<path>/mkmf.rb:50:in 'gplusplus_version': unable to determine g++ version (match to get version was nil) (RuntimeError)
from /Users/lonny/.rvm/gems/ruby-2.3.0@ey/gems/nmatrix-0.2.3/lib/nmatrix/mkmf.rb:71:in '<top (required)>'
from extconf.rb:28:in 'require'
from extconf.rb:28:in '<main>'

[lonny]

Just as a followup:

I checked the config for my ruby as in the description here:

https://stackoverflow.com/questions/4554837/how-to-specify-compiler-for-gem-install

and it is already set to use clang and clang++. When I type "which gcc" I get usr/bin/gcc/. When I type
gcc --version
it definitely says clang. Both in Yosemite (10.10.5) and El Capitan (10.11).