Issue with installing ImageMagick and rmagick on Mountain Lion

Question

I am facing issues with installing rmagick in mountain lion. I have installed Xcode 4.4 and developer tools. Still facing this issue.

    Installing rmagick (2.13.1) with native extensions Unfortunately, a fatal error has occurred. Please report this error to the Bundler issue tracker at https://github.com/carlhuda/bundler/issues so that we can fix it. Thanks!
    /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:552:in `rescue in block in build_extensions': ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)

            /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/bin/ruby extconf.rb 
    checking for Ruby version >= 1.8.5... yes
    extconf.rb:128: Use RbConfig instead of obsolete and deprecated Config.
    checking for clang... yes
    checking for Magick-config... yes
    checking for ImageMagick version >= 6.4.9... yes
    checking for HDRI disabled version of ImageMagick... yes
    checking for stdint.h... *** extconf.rb failed ***
    Could not create Makefile due to some reason, probably lack of
    necessary libraries and/or headers.  Check the mkmf.log file for more
    details.  You may need configuration options.

    Provided configuration options:
        --with-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/Users/mohit/.rvm/rubies/ruby-1.9.3-p125/bin/ruby
    /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
    You have to install development tools first.
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:506:in `try_cpp'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:931:in `block in have_header'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:254:in `open'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:254:in `open'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:930:in `have_header'
        from extconf.rb:193:in `<main>'


    Gem files will remain installed in /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/rmagick-2.13.1 for inspection.
    Results logged to /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/rmagick-2.13.1/ext/RMagick/gem_make.out
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:530:in `block in build_extensions'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:505:in `each'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:505:in `build_extensions'
        from /Users/mohit/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:180:in `install'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/source.rb:90:in `block in install'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/rubygems_integration.rb:82:in `preserve_paths'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/source.rb:89:in `install'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/installer.rb:73:in `block in install_gem_from_spec'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/rubygems_integration.rb:97:in `with_build_args'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/installer.rb:72:in `install_gem_from_spec'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/installer.rb:56:in `block in run'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/installer.rb:55:in `run'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/installer.rb:12:in `install'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/cli.rb:220:in `install'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/vendor/thor/task.rb:22:in `run'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/vendor/thor/invocation.rb:118:in `invoke_task'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/vendor/thor.rb:263:in `dispatch'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/lib/bundler/vendor/thor/base.rb:386:in `start'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/gems/bundler-1.1.0/bin/bundle:13:in `<top (required)>'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/bin/bundle:19:in `load'
        from /Users/mohit/.rvm/gems/ruby-1.9.3-p125/bin/bundle:19:in `<main>'

Answer 1

I just updated to Mountain Lion this morning and had rmagick troubles. I had installed ImageMagick through homebrew at some point in the past, so this worked for me after installing the new commandline tools through xcode's preferences window.

brew update
brew uninstall ImageMagick
brew install ImageMagick
gem uninstall rmagick
gem install rmagick

I didn't have to get funky with gcc like some above posts mentioned.