title: Can't install Ruby under Lion with RVM – GCC issues
body: <p>Most questions regarding this problem are due to missing Xcode; I have Xcode 4.2 installed.</p>
  
  <p>Install attempt:</p>
  
  <pre><code>rvm install 1.9.3
  Installing Ruby from source to: /Users/jamie/.rvm/rubies/ruby-1.9.3-p0, this may take a while depending on your cpu(s)...
  
  ruby-1.9.3-p0 - #fetching 
  ruby-1.9.3-p0 - #extracted to /Users/jamie/.rvm/src/ruby-1.9.3-p0 (already extracted)
  Fetching yaml-0.1.4.tar.gz to /Users/jamie/.rvm/archives
  Extracting yaml-0.1.4.tar.gz to /Users/jamie/.rvm/src
  Configuring yaml in /Users/jamie/.rvm/src/yaml-0.1.4.
  Compiling yaml in /Users/jamie/.rvm/src/yaml-0.1.4.
  Installing yaml to /Users/jamie/.rvm/usr
  ruby-1.9.3-p0 - #configuring 
  ERROR: Error running ' ./configure --prefix=/Users/jamie/.rvm/rubies/ruby-1.9.3-p0 --enable-shared --disable-install-doc --with-libyaml-dir=/Users/jamie/.rvm/usr ', please read /Users/jamie/.rvm/log/ruby-1.9.3-p0/configure.log
  ERROR: There has been an error while running configure. Halting the installation.
  </code></pre>
  
  <p>configure.log:</p>
  
  <pre><code>[2011-11-07 04:32:17]  ./configure --prefix=/Users/jamie/.rvm/rubies/ruby-1.9.3-p0 --enable-shared --disable-install-doc --with-libyaml-dir=/Users/jamie/.rvm/usr 
  configure: WARNING: unrecognized options: --with-libyaml-dir
  checking build system type... x86_64-apple-darwin11.2.0
  checking host system type... x86_64-apple-darwin11.2.0
  checking target system type... x86_64-apple-darwin11.2.0
  checking whether the C compiler works... no
  configure: error: in `/Users/jamie/.rvm/src/ruby-1.9.3-p0':
  configure: error: C compiler cannot create executables
  See `config.log' for more details
  </code></pre>
  
  <p>GCC is available:</p>
  
  <pre><code>gcc -v
  Using built-in specs.
  Target: i686-apple-darwin11
  Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2336.1~1/src/configure --disable-checking --enable-werror --prefix=/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/llvmgcc42-2336.1~1/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 2336.1.00)
  
  ls /usr/bin | grep gcc         
  gcc
  i686-apple-darwin11-llvm-gcc-4.2
  llvm-gcc
  llvm-gcc-4.2
  </code></pre>
  
  <p>Based on config.log (posted at bottom due to size) I tried symlinking gcc-4.2 to gcc and then installing:</p>
  
  <pre><code>rvm install 1.9.3                       
  ERROR: The autodetected CC(/usr/bin/gcc-4.2) is LLVM based, it is not yet fully supported by ruby and gems, please read `rvm requirements`, and set CC=/path/to/gcc .
  </code></pre>
  
  <p>So I could probably just grab gcc elsewhere, but I'm mostly concerned as to why this is happening. Shouldn't installing Xcode be enough?</p>
  
  <p>config.log:</p>
  
  <pre><code>This file contains any messages produced by compilers while
  running configure, to aid debugging if configure makes a mistake.
  
  It was created by configure, which was
  generated by GNU Autoconf 2.68.  Invocation command line was
  
    $ ./configure --prefix=/Users/jamie/.rvm/rubies/ruby-1.9.3-p0 --enable-shared --disable-install-doc --with-libyaml-dir=/Users/jamie/.rvm/usr
  
  ## --------- ##
  ## Platform. ##
  ## --------- ##
  
  hostname = Wilson.local
  uname -m = x86_64
  uname -r = 11.2.0
  uname -s = Darwin
  uname -v = Darwin Kernel Version 11.2.0: Tue Aug  9 20:54:00 PDT 2011; root:xnu-1699.24.8~1/RELEASE_X86_64
  
  /usr/bin/uname -p = i386
  /bin/uname -X     = unknown
  
  /bin/arch              = unknown
  /usr/bin/arch -k       = unknown
  /usr/convex/getsysinfo = unknown
  /usr/bin/hostinfo      = Mach kernel version:
       Darwin Kernel Version 11.2.0: Tue Aug  9 20:54:00 PDT 2011; root:xnu-1699.24.8~1/RELEASE_X86_64
  Kernel configured for up to 4 processors.
  4 processors are physically available.
  4 processors are logically available.
  Processor type: i486 (Intel 80486)
  Processors active: 0 1 2 3
  Primary memory available: 8.00 gigabytes
  Default processor set: 110 tasks, 546 threads, 4 processors
  Load average: 1.28, Mach factor: 2.71
  /bin/machine           = unknown
  /usr/bin/oslevel       = unknown
  /bin/universe          = unknown
  
  PATH: /Users/jamie/.rvm/usr/bin
  PATH: /usr/bin
  PATH: /bin
  PATH: /usr/sbin
  PATH: /sbin
  PATH: /usr/local/bin
  PATH: /usr/X11/bin
  PATH: /Users/jamie/bin
  PATH: /Users/jamie/.rvm/bin
  PATH: /Users/jamie/.rvm/bin
  
  
  ## ----------- ##
  ## Core tests. ##
  ## ----------- ##
  
  configure:2764: checking build system type
  configure:2778: result: x86_64-apple-darwin11.2.0
  configure:2849: checking host system type
  configure:2862: result: x86_64-apple-darwin11.2.0
  configure:2882: checking target system type
  configure:2895: result: x86_64-apple-darwin11.2.0
  configure:3376: checking for C compiler version
  configure:3385: gcc-4.2 --version &gt;&amp;5
  ./configure: line 3387: gcc-4.2: command not found
  configure:3396: $? = 127
  configure:3385: gcc-4.2 -v &gt;&amp;5
  ./configure: line 3387: gcc-4.2: command not found
  configure:3396: $? = 127
  configure:3385: gcc-4.2 -V &gt;&amp;5
  ./configure: line 3387: gcc-4.2: command not found
  configure:3396: $? = 127
  configure:3385: gcc-4.2 -qversion &gt;&amp;5
  ./configure: line 3387: gcc-4.2: command not found
  configure:3396: $? = 127
  configure:3416: checking whether the C compiler works
  configure:3438: gcc-4.2    conftest.c  &gt;&amp;5
  ./configure: line 3440: gcc-4.2: command not found
  configure:3442: $? = 127
  configure:3480: result: no
  configure: failed program was:
  | /* confdefs.h */
  | #define PACKAGE_NAME ""
  | #define PACKAGE_TARNAME ""
  | #define PACKAGE_VERSION ""
  | #define PACKAGE_STRING ""
  | #define PACKAGE_BUGREPORT ""
  | #define PACKAGE_URL ""
  | #define CANONICALIZATION_FOR_MATHN 1
  | /* end confdefs.h.  */
  | 
  | int
  | main ()
  | {
  | 
  |   ;
  |   return 0;
  | }
  configure:3485: error: in `/Users/jamie/.rvm/src/ruby-1.9.3-p0':
  configure:3487: error: C compiler cannot create executables
  See `config.log' for more details
  
  ## ---------------- ##
  ## Cache variables. ##
  ## ---------------- ##
  
  ac_cv_build=x86_64-apple-darwin11.2.0
  ac_cv_env_CCC_set=
  ac_cv_env_CCC_value=
  ac_cv_env_CC_set=
  ac_cv_env_CC_value=
  ac_cv_env_CFLAGS_set=
  ac_cv_env_CFLAGS_value=
  ac_cv_env_CPPFLAGS_set=
  ac_cv_env_CPPFLAGS_value=
  ac_cv_env_CPP_set=
  ac_cv_env_CPP_value=
  ac_cv_env_CXXFLAGS_set=
  ac_cv_env_CXXFLAGS_value=
  ac_cv_env_CXX_set=
  ac_cv_env_CXX_value=
  ac_cv_env_LDFLAGS_set=
  ac_cv_env_LDFLAGS_value=
  ac_cv_env_LIBS_set=
  ac_cv_env_LIBS_value=
  ac_cv_env_build_alias_set=
  ac_cv_env_build_alias_value=
  ac_cv_env_host_alias_set=
  ac_cv_env_host_alias_value=
  ac_cv_env_target_alias_set=
  ac_cv_env_target_alias_value=
  ac_cv_host=x86_64-apple-darwin11.2.0
  ac_cv_prog_CC=gcc-4.2
  ac_cv_target=x86_64-apple-darwin11.2.0
  
  ## ----------------- ##
  ## Output variables. ##
  ## ----------------- ##
  
  ALLOCA=''
  AR=''
  ARCHFILE=''
  ARCH_FLAG=''
  AS=''
  ASFLAGS=''
  BASERUBY='ruby'
  BUILTIN_ENCOBJS=''
  BUILTIN_TRANSOBJS=''
  BUILTIN_TRANSSRCS=''
  CAPITARGET=''
  CC='gcc-4.2'
  CCDLFLAGS=''
  CFLAGS=''
  CHDIR=''
  COMMON_HEADERS=''
  COMMON_LIBS=''
  COMMON_MACROS=''
  COUTFLAG=''
  CP=''
  CPP=''
  CPPFLAGS=''
  CPPOUTFILE=''
  CXX='g++-4.2'
  CXXFLAGS=''
  DEFS=''
  DLDFLAGS=''
  DLDLIBS=''
  DLEXT2=''
  DLEXT=''
  DLLWRAP=''
  DOT=''
  DOXYGEN=''
  ECHO_C='\c'
  ECHO_N=''
  ECHO_T=''
  EGREP=''
  ENABLE_SHARED=''
  EXECUTABLE_EXTS=''
  EXEEXT=''
  EXPORT_PREFIX=''
  EXTOUT=''
  EXTSTATIC=''
  GCC=''
  GNU_LD=''
  GREP=''
  INSTALLDOC=''
  INSTALL_DATA=''
  INSTALL_PROGRAM=''
  INSTALL_SCRIPT=''
  LDFLAGS=''
  LDSHARED=''
  LDSHAREDXX=''
  LIBEXT=''
  LIBOBJS=''
  LIBPATHENV=''
  LIBPATHFLAG=''
  LIBRUBY=''
  LIBRUBYARG=''
  LIBRUBYARG_SHARED=''
  LIBRUBYARG_STATIC=''
  LIBRUBY_A=''
  LIBRUBY_ALIASES=''
  LIBRUBY_DLDFLAGS=''
  LIBRUBY_LDSHARED=''
  LIBRUBY_RELATIVE=''
  LIBRUBY_SO=''
  LIBS=''
  LINK_SO=''
  LN_S=''
  LTLIBOBJS=''
  MAINLIBS=''
  MAJOR='1'
  MAKEDIRS=''
  MAKEFILES=''
  MANTYPE=''
  MINIOBJS=''
  MINIRUBY=''
  MINOR='9'
  MKDIR_P=''
  NM=''
  NROFF=''
  NULLCMD=''
  OBJCOPY=''
  OBJDUMP=''
  OBJEXT=''
  OUTFLAG=''
  PACKAGE=''
  PACKAGE_BUGREPORT=''
  PACKAGE_NAME=''
  PACKAGE_STRING=''
  PACKAGE_TARNAME=''
  PACKAGE_URL=''
  PACKAGE_VERSION=''
  PATH_SEPARATOR=':'
  PKG_CONFIG=''
  PREP=''
  RANLIB=''
  RDOCTARGET=''
  RI_BASE_NAME=''
  RM=''
  RMALL=''
  RMDIR=''
  RMDIRS=''
  RPATHFLAG=''
  RUBYW_BASE_NAME='rubyw'
  RUBYW_INSTALL_NAME=''
  RUBY_BASE_NAME='ruby'
  RUBY_INSTALL_NAME=''
  RUBY_PROGRAM_VERSION='1.9.3'
  RUBY_RELEASE_DATE='2011-10-30'
  RUBY_SO_NAME=''
  RUNRUBY=''
  SET_MAKE=''
  SHELL='/bin/sh'
  SOLIBS=''
  STATIC=''
  STRIP=''
  SYMBOL_PREFIX=''
  TEENY='1'
  TEST_RUNNABLE=''
  THREAD_MODEL=''
  TRY_LINK=''
  UNIVERSAL_ARCHNAMES=''
  UNIVERSAL_INTS=''
  USE_RUBYGEMS=''
  WERRORFLAG=''
  WINDRES=''
  XCFLAGS=''
  XLDFLAGS=''
  XRUBY=''
  XRUBY_LIBDIR=''
  XRUBY_RUBYHDRDIR=''
  XRUBY_RUBYLIBDIR=''
  ac_ct_CC=''
  ac_ct_CXX=''
  ac_ct_OBJCOPY=''
  ac_ct_OBJDUMP=''
  arch=''
  bindir='${exec_prefix}/bin'
  build='x86_64-apple-darwin11.2.0'
  build_alias=''
  build_cpu='x86_64'
  build_os='darwin11.2.0'
  build_vendor='apple'
  cflags=' ${optflags} ${debugflags} ${warnflags}'
  configure_args=''
  cppflags=''
  cxxflags=' ${optflags} ${debugflags} ${warnflags}'
  datadir='${datarootdir}'
  datarootdir='${prefix}/share'
  debugflags=''
  docdir='${datarootdir}/doc/${PACKAGE}'
  dvidir='${docdir}'
  exec=''
  exec_prefix='NONE'
  host='x86_64-apple-darwin11.2.0'
  host_alias=''
  host_cpu='x86_64'
  host_os='darwin11.2.0'
  host_vendor='apple'
  htmldir='${docdir}'
  includedir='${prefix}/include'
  infodir='${datarootdir}/info'
  libdir='${exec_prefix}/lib'
  libexecdir='${exec_prefix}/libexec'
  localedir='${datarootdir}/locale'
  localstatedir='${prefix}/var'
  mandir='${datarootdir}/man'
  oldincludedir='/usr/include'
  optflags=''
  pdfdir='${docdir}'
  prefix='/Users/jamie/.rvm/rubies/ruby-1.9.3-p0'
  program_transform_name='s&amp;^&amp;&amp;'
  psdir='${docdir}'
  ridir=''
  ruby_pc=''
  ruby_version=''
  rubyhdrdir=''
  rubylibprefix=''
  rubyw_install_name=''
  sbindir='${exec_prefix}/sbin'
  setup=''
  sharedstatedir='${prefix}/com'
  sitearch=''
  sitedir=''
  sitehdrdir=''
  sysconfdir='${prefix}/etc'
  target='x86_64-apple-darwin11.2.0'
  target_alias=''
  target_cpu='x86_64'
  target_os='darwin11.2.0'
  target_vendor='apple'
  try_header=''
  vendordir=''
  vendorhdrdir=''
  warnflags=''
  
  ## ----------- ##
  ## confdefs.h. ##
  ## ----------- ##
  
  /* confdefs.h */
  #define PACKAGE_NAME ""
  #define PACKAGE_TARNAME ""
  #define PACKAGE_VERSION ""
  #define PACKAGE_STRING ""
  #define PACKAGE_BUGREPORT ""
  #define PACKAGE_URL ""
  #define CANONICALIZATION_FOR_MATHN 1
  
  configure: exit 77
  </code></pre>