checking whether the C compiler works... no

Question

I recently uninstalled Xcode 4.2 and re-installed Xcode 4.3.1. Installed Command Line Tools also. The error says 'C compiler doesn't work`. On searching for this error, it said that it happens when Xcode is not installed. What am I missing?

rvm install 1.9.3 --with-gcc=clang
Installing Ruby from source to: /Users/ava/.rvm/rubies/ruby-1.9.3-preview1, this may take a while depending on your cpu(s)...

ruby-1.9.3-preview1 - #fetching 
ruby-1.9.3-preview1 - #extracting ruby-1.9.3-preview1 to /Users/ava/.rvm/src/ruby-1.9.3-preview1
ruby-1.9.3-preview1 - #extracted to /Users/ava/.rvm/src/ruby-1.9.3-preview1
Fetching yaml-0.1.4.tar.gz to /Users/ava/.rvm/archives
Extracting yaml-0.1.4.tar.gz to /Users/ava/.rvm/src
Configuring yaml in /Users/ava/.rvm/src/yaml-0.1.4.
ERROR: Error running ' ./configure --prefix="/Users/ava/.rvm/usr"  --with-gcc=clang           --build=x86_64-apple-darwin11.3.0           --host=x86_64-apple-darwin11.3.0           --build=x86_64-apple-darwin11.3.0           --host=x86_64-apple-darwin11.3.0 ', please read /Users/ava/.rvm/log/ruby-1.9.3-preview1/yaml/configure.log
Compiling yaml in /Users/ava/.rvm/src/yaml-0.1.4.
ERROR: Error running '/usr/bin/make ', please read /Users/ava/.rvm/log/ruby-1.9.3-preview1/yaml/make.log
Installing yaml to /Users/ava/.rvm/usr
ERROR: Error running '/usr/bin/make install', please read /Users/ava/.rvm/log/ruby-1.9.3-preview1/yaml/make.install.log
ruby-1.9.3-preview1 - #configuring 
ERROR: Error running ' ./configure --prefix=/Users/ava/.rvm/rubies/ruby-1.9.3-preview1 --enable-shared --disable-install-doc  --with-gcc=clang           --build=x86_64-apple-darwin11.3.0           --host=x86_64-apple-darwin11.3.0           --build=x86_64-apple-darwin11.3.0           --host=x86_64-apple-darwin11.3.0 --with-libyaml-dir=/Users/ava/.rvm/usr ', please read /Users/ava/.rvm/log/ruby-1.9.3-preview1/configure.log
ERROR: There has been an error while running configure. Halting the installation.


➜  yaml git:(master) ✗ vi configure.log 

[2012-03-18 21:03:00]  ./configure --prefix="/Users/ava/.rvm/usr"  --with-gcc=clang           --build=x86_64-apple-darwin11.3.0           --host=x86_64-apple-darwin11.3.0           --build=x86_64-apple-darwin11.3.0           --host=x86_64-apple-darwin11.3.0
configure: WARNING: unrecognized options: --with-gcc
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... config/install-sh -c -d
checking for gawk... no
checking for mawk... no
checking for nawk... no
checking for awk... awk
checking whether make sets $(MAKE)... yes
checking for x86_64-apple-darwin11.3.0-gcc... no
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/Users/ava/.rvm/src/yaml-0.1.4':
configure: error: C compiler cannot create executables
See `config.log' for more details


➜  ~ git:(master) ✗ gcc -v   
Using built-in specs.
Target: i686-apple-darwin11
Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2336.9~22/src/configure --disable-checking --enable-werror --prefix=/Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2 --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-prefix=llvm- --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin11 --enable-llvm=/private/var/tmp/llvmgcc42/llvmgcc42-2336.9~22/dst-llvmCore/Developer/usr/local --program-prefix=i686-apple-darwin11- --host=x86_64-apple-darwin11 --target=i686-apple-darwin11 --with-gxx-include-dir=/usr/include/c++/4.2.1
Thread model: posix
gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.9.00)


➜  ~ git:(master) ✗ which gcc
/usr/bin/gcc

Answer 1

In the Terminal:

sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer

Also, in Xcode, make sure the Command Line Tools are installed. Choose Xcode > Preferences, click on Downloads, and if necessary, click the Install button next to "Command Line Tools".

Answer 2

1. you use old RVM which does not know about latest ruby pathclevel, update with rvm get head

2. Ruby is not yet fully ready for LLVM, your get best chances for compilation using osx-gcc-installer and --with-gcc=gcc-4.2