Question

Most questions regarding this problem are due to missing Xcode; I have Xcode 4.2 installed.

Install attempt:

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.

configure.log:

[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

GCC is available:

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

Based on config.log (posted at bottom due to size) I tried symlinking gcc-4.2 to gcc and then installing:

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 .

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?

config.log:

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 >&5
./configure: line 3387: gcc-4.2: command not found
configure:3396: $? = 127
configure:3385: gcc-4.2 -v >&5
./configure: line 3387: gcc-4.2: command not found
configure:3396: $? = 127
configure:3385: gcc-4.2 -V >&5
./configure: line 3387: gcc-4.2: command not found
configure:3396: $? = 127
configure:3385: gcc-4.2 -qversion >&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  >&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='${docdir}'
prefix='/Users/jamie/.rvm/rubies/ruby-1.9.3-p0'
program_transform_name='s&^&&'
psdir='${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

Answer 1

This answer was edited multiple times and now contains several alternative solutions. Try the simple “Edit 3” solution first.

Ruby 1.9.3-p125 and later have official support for clang, so if you are installing such a version you should not need GCC. If you’re installing an older version of Ruby, read on.

To compile Ruby with GCC, you need a non-LLVM version of GCC, which is no longer included with Xcode 4.2. Install it yourself (or downgrade to Xcode 4.1 temporarily), then do CC=/usr/local/bin/gcc-4.2 rvm install 1.9.3 --enable-shared (substituting the path to your non-LLVM gcc).

Edit: https://github.com/kennethreitz/osx-gcc-installer/downloads may help for installing GCC. There is also some info available by running rvm requirements.

Edit 2: For an easier solution, you can try adding --with-gcc=clang to the arguments to configure for Ruby to use clang instead of GCC.

Edit 3: rvm install 1.9.3 --with-gcc=clang does that for you.

Note: With current versions of Xcode you need to install the command-line tools separately from the Xcode menu -> Preferences -> Downloads -> Components. This is a pre-requisite for doing any compiling with Xcode on the command-line, not just Ruby.

Note 2: If something doesn’t work after following the steps, try doing a reboot or re-login to ensure that the environment gets set correctly.

Note 3: Ruby versions prior to 1.9.3-p125 may not always be fully compatible with clang, so test your software thoroughly if using the “edit 3” solution in a production environment.