How to set gcc 4.8 as default gcc compiler

Question

I recently installed gcc 4.8 using brew on OSX 10.7.5 (Lion). I can now compile using gcc 4.8 by using

g++-4.8 some_file.c

or using the default gcc 4.2 by using

g++ some_file.c

I want to use gcc 4.8 as the default compiler for Xcode and if I type gcc at the terminal. I suppose I must alter gcc-related links within dirname $(which gcc).

When I do

ls -al $(dirname $(which gcc)) | grep 'gcc\|g++\|c++'

I get the following:

lrwxr-xr-x     1 root   wheel         7 Jul 31 12:17 c++ -> clang++
-rwxr-xr-x     1 root   wheel    909360 Nov 18  2011 c++filt
lrwxr-xr-x     1 root   wheel         5 Jul 31 12:17 clang++ -> clang
lrwxr-xr-x     1 root   wheel        12 Jul 31 12:17 g++ -> llvm-g++-4.2
lrwxr-xr-x     1 root   wheel        12 Jul 31 12:17 gcc -> llvm-gcc-4.2
lrwxr-xr-x     1 root   wheel        28 Jul 31 12:17 gcov-4.2 -> ../llvm-gcc-4.2/bin/gcov-4.2
lrwxr-xr-x     1 root   wheel        52 Jul 31 12:17 i686-apple-darwin11-llvm-g++-4.2 -> ../llvm-gcc-4.2/bin/i686-apple-darwin11-llvm-g++-4.2
lrwxr-xr-x     1 root   wheel        52 Jul 31 12:17 i686-apple-darwin11-llvm-gcc-4.2 -> ../llvm-gcc-4.2/bin/i686-apple-darwin11-llvm-gcc-4.2
lrwxr-xr-x     1 root   wheel        32 Jul 31 12:17 llvm-cpp-4.2 -> ../llvm-gcc-4.2/bin/llvm-cpp-4.2
lrwxr-xr-x     1 root   wheel        32 Jul 31 12:17 llvm-g++ -> ../llvm-gcc-4.2/bin/llvm-g++-4.2
lrwxr-xr-x     1 root   wheel        32 Jul 31 12:17 llvm-g++-4.2 -> ../llvm-gcc-4.2/bin/llvm-g++-4.2
lrwxr-xr-x     1 root   wheel        32 Jul 31 12:17 llvm-gcc -> ../llvm-gcc-4.2/bin/llvm-gcc-4.2
lrwxr-xr-x     1 root   wheel        32 Jul 31 12:17 llvm-gcc-4.2 -> ../llvm-gcc-4.2/bin/llvm-gcc-4.2

When I run: which gcc-4.8 I get /usr/local/bin/gcc-4.8.

Steps to get this done would be very helpful.

Please and thank you.

Answer 1

Thanks to you all for your help. I ended up just creating aliases within ~/.bash_profile as follows:

alias gcc='gcc-4.8'
alias cc='gcc-4.8'
alias g++='g++-4.8'
alias c++='c++-4.8'

The answer from Lynken is very helpful, but I adapted it with aliases since that's easier for me to undo if necessary.

Specifically, if PATH is set such that /usr/local/bin (where brew puts the link to gcc 4.8) appears before appears /usr/bin (where gcc is linked by default), then creating links as Lyken suggested within /usr/local/bin should theoretically work for me. In practice, it doesn't for some reason -- failing with a linker error and aliases work around that error without me needing to solve that issue, too.

The other benefit of aliases is that I'm not having to link which I want homebrew to handle and not have to compete with that tool for which version of gcc is linked in /usr/local

Answer 2

Assuming you're using bash (it's the default), then you can add /usr/local/bin as your top priority in PATH like this:

echo "PATH=\"/usr/local/bin:$PATH\"" >> ~/.bash_profile

This will ensure that /usr/local/bin is checked before all other areas of your path. Then just start a new terminal session to load the new variable.

Another way to do this:

  cd /usr/bin
  rm cc gcc c++ g++
  ln -s /usr/local/bin/gcc-4.8 cc
  ln -s /usr/local/bin/gcc-4.8 gcc
  ln -s /usr/local/bin/c++-4.8 c++
  ln -s /usr/local/bin/g++-4.8 g++

Answer 3

I use to gcc-4.8:

export CC=/usr/local/bin/gcc

export CXX=/usr/local/bin/g++

export CPP=/usr/local/bin/cpp

export LD=/usr/local/bin/gcc

alias c++=/usr/local/bin/c++

alias g++=/usr/local/bin/g++

alias gcc=/usr/local/bin/gcc

alias cpp=/usr/local/bin/cpp

alias ld=/usr/local/bin/gcc

alias cc=/usr/local/bin/gcc

and back to apple gcc:

export CC=/usr/bin/gcc

export CXX=/usr/bin/g++

export CPP=/usr/bin/cpp

export LD=/usr/bin/ld

alias c++=/usr/bin/c++

alias g++=/usr/bin/g++

alias gcc=/usr/bin/gcc

alias cpp=/usr/bin/cpp

alias cc=/usr/bin/gcc

alias ld=/usr/bin/ld

or put it in file and then: source <file>

Answer 4

On Mac M1, if you use brew install gcc, gcc will be installed on "/opt/homebrew/bin/".

I am facing the same issue. Specifically, when I issue gcc --version, the terminal shows:

Apple clang version 14.0.0 (clang-1400.0.29.202)
Target: arm64-apple-darwin22.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Further looking into this, I found that in $PATH the path /opt/homebrew/bin/ was actually before /usr/bin/. But in the former location there is only gcc-12 in the folder, which causes gcc points to the later location (/usr/bin/).

In order for the GNU gcc to be found, I used this: ln -s gcc-12 gcc.

Restart the terminal and it's been solved:

gcc --version
gcc (Homebrew GCC 12.2.0) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Answer 5

Let's assume your actual shell initialization is done through ~/.profile, then you will have to modify it so as to put /usr/local/bin ahead of any other PATH component where gcc and all its associated binary are.

Here is the way to perform this clean modification:

cd

_shell_init=`egrep '(^| )PATH' .profile 2>/dev/null`

if [ "${_shell_init}" = "" ] ; then
    # PATH isn't defined in .profile
    # install there the first relative definition of PATH
    echo 'PATH=/usr/local/bin:${PATH}
export PATH' >>.profile
    . .profile
    exec ${SHELL}
else
    # remove all occurences of /usr/local/bin wherever they might be
    # set into PATH, and insert it ahead of all other components
    sed -E -e '/(^| )PATH=/s,:/usr/local/bin,,' \
        -e '/(^| )PATH=/s,/usr/local/bin:,,' \
        -e '/(^| )PATH=/s,,&/usr/local/bin:,' .profile >.profile.new
    mv .profile.new .profile
    . .profile
    exec ${SHELL}
fi

Beware: if your ~/.profile is already structured, this shell script will have to be manually tuned to fit correct PATH definition in the right place.