Updating RMagick and Imagemagick is a painful expierence. I have updated the Imagemagick version on my mac (MacOS El Capitan Version 10.11.5) with homebrew for one project in Ruby 2.3 to 6.9.5-9
$ convert --version
Version: ImageMagick 6.9.5-9 Q16 x86_64 2016-09-09
Now an older project in Ruby 1.8.7 refuses to work with the error message "this installation of RMagick was configured with ImageMagick 6.8.9 but ImageMagick 6.9.5-9 is in use". Thus I uninstalled "rmagick", but it can not be installed again
$ gem install rmagick -v 2.16.0
Building native extensions. This could take a while...
ERROR: Error installing rmagick:
ERROR: Failed to build gem native extension.
checking for /usr/local/opt/gcc46/bin/gcc-4.6... yes
checking for Magick-config... yes
checking for outdated ImageMagick version (<= 6.4.9)... no
checking for presence of MagickWand API (ImageMagick version >= 6.9.0)... no
checking for Ruby version >= 1.8.5... yes
checking for stdint.h... no
checking for sys/types.h... no
checking for wand/MagickWand.h... no
Can't install RMagick 2.16.0. Can't find MagickWand.h.
And if it can not be installed, the whole application can not be started. I tried all the answers from here, and none of them works on MacOS :-( I reinstalled imagemagick and pkg-config with homebrew, and tried various version of RMagick without success. 2.16.0 is the latest version of RMagick currently.
MagicWand seems to be used in ImageMagick version > 6.9, and it can be found on the machine:
find /usr/local -name MagickWand.h
=> /usr/local/Cellar/imagemagick/6.9.5-9_1/include/ImageMagick-6/wand/MagickWand.h
find /usr/local -name MagickWand.pc
=> /usr/local/Cellar/imagemagick/6.9.5-9_1/lib/pkgconfig/MagickCore.pc
It does not work even if I specifiy the these paths during the gem install (same error as above) :-(
C_INCLUDE_PATH=/usr/local/Cellar/imagemagick/6.9.5-9_1/include/ImageMagick-6 PKG_CONFIG_PATH=/usr/local/lib/pkgconfig gem install rmagick
UPDATE:
The error only occurs for Ruby 1.8.7, it is possible to install RMagick for Ruby 2.0 and Ruby 2.3. Ruby 1.8.7 and ImageMagick 6.9.5 do not seem to be compatible.
Something was severely wrong on my system, so badly that it was completely f*d up, but I was finally to able to install RMagick for Ruby 1.8.7 again after I installed
The installation of a new Ruby version with RVM rvm install 1.8.7 also installed a new GCC compiler: it removed an older GCC version 4.6 and installed GCC version 4.9. Apparently GCC was not able to find the right headers despite pkg-config.