gem install pg doesn't work on OSX Lion

Question

There are variations of this question bouncing around SO, but none of them seem to have an answer that solves my problem.

I am running OSX Lion (10.7.3). The latest

Answer 1

Rather than updating RVM itself (https://stackoverflow.com/a/10430742/2807795), as above, it was the reinstallation of Ruby 2.0.0-p247 that did the trick, after trying all the other steps above without success.

rvm get head
rvm install 2.0.0

Answer 2

Similar problem on Mavericks 10.9 -- but it was caused by not having agreed to the Xcode license agreement. Blech.

Run sudo xcodebuild and agree to the junk. The everything works as expected.

Answer 3

If the output includes:

/Users/disaacs/.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.

then there really is something amiss with your compilation environment. Especially when the failure is the very first test that extconf.rb runs.

If you have XCode installed, then perhaps you don't have the command-line tools component of XCode installed? They were recently split out from XCode proper, so you need to install them separately.

Answer 4

Installing xcode from the app store is not enough. You will also need xcode's command line tools. https://developer.apple.com/library/ios/#documentation/DeveloperTools/Conceptual/WhatsNewXcode/Articles/xcode_4_3.html

After installing xcode from the app store, open xcode. Goto Xcode->Open Developer Tool->More Developer Tools Download and install the latest command line tools.

Open a terminal window and run: sudo gem install pg

Answer 5

I had a similar issue. Following an answer by bobfet1 for a similar issue I was able to get the gem installed by:

sudo env ARCHFLAGS="-arch x86_64" gem install pg -- --with-pg-config=/Applications/Postgres.app/Contents/MacOS/bin/pg_config

Answer 6

I finally found the cause of the problem! Though I am still uncertain how this problem came about.

Look at the contents of the mkmf.log file that is created when my install command fails (see my original post). It logs an attempt to run the following command

/usr/bin/gcc-4.2 ...and so on...

There is no /usr/bin/gcc-4.2 on my system. There is a gcc, which is symbolically linked to llvm-gcc-4.2. My solution was to create another symbolic link

sudo ln -s llvm-gcc-4.2 gcc-4.2 

After making this link, my gem install pg command worked without any problems.

I found the solution to this problem on the Frozen Canuck blog in the post Error Installing Ruby Gem with C Extension. He speculates that the problem can be caused by conflicting versions of XCode. whatever the cause, my eternal thanks!