Unable to install Jekyll gem since upgrading to Xcode 4.1

I have previously successfully installed the Jekyll gem on a Mac with the gcc compiler that shipped with Xcode 3. Unfortunately I can't install it on a different Mac that now has Xcode 4.1. This Mac used to have Xcode 3, but I uninstalled it using the command sudo /Developer-3.2.5/Library/uninstall-devtools --mode=all.

When trying to sudo gem install jekyll I get the compilation error shown below:

Building native extensions.  This could take a while...
ERROR:  Error installing jekyll:
    ERROR:开发者_如何学JAVA Failed to build gem native extension.

/usr/local/bin/ruby extconf.rb
creating Makefile

make
gcc -I. -I/usr/local/lib/ruby/1.8/i686-darwin10.3.2 -I/usr/local/lib/ruby/1.8/i686-darwin10.3.2 -I. -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE   -fno-common -D_XOPEN_SOURCE=1  -fno-common -pipe -fno-common   -c porter.c
porter.c:31:44: error: stdlib.h: No such file or directory
porter.c:32:47: error: string.h: No such file or directory
porter.c: In function ‘create_stemmer’:
porter.c:85: warning: incompatible implicit declaration of built-in function ‘malloc’
porter.c: In function ‘setto’:
porter.c:199: warning: incompatible implicit declaration of built-in function ‘memmove’
make: *** [porter.o] Error 1


Gem files will remain installed in /usr/local/lib/ruby/gems/1.8/gems/fast-stemmer-1.0.0 for inspection.
Results logged to /usr/local/lib/ruby/gems/1.8/gems/fast-stemmer-1.0.0/ext/gem_make.out

There seems to be a fairly fundamental problem here! How can I fix this? I'm using Ruby 1.8.7 and RubyGems 1.3.7 1.8.10.

Thanks in advance.

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Now this is weird. I reinstalled Xcode 4.1 last night and it's fixed the problem: I can compile the native extensions and install the Jekyll gem.

I was able to reinstall Xcode because according to the Mac App Store it wasn't installed at all, even though I've been happily using it! I think the store must look for the existence of the Install XCode application in the /Applications folder, which I'd deleted because it's just an installer and takes up over 3GB.

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Before running gem install jekyll try entering export CC=gcc-4.2 as per: RVM with Lion If this fixes your issue, it's because gems is depending on GCC instead of LLVM, which is now default in 4.1. Add the export CC=gcc-4.2 to your ~/.bashrc file to not have to enter it every time you need to compile gem.

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RubyGems 1.3.7 is quite out of date. We're talking about 1.8.9... I suggest you to upgrade it.

I'm using Lion without any issue, but I have to admit I'm not using system Ruby. I installed a different 1.8.7 (and 1.9.2) version using RVM.