Preface

If you've installed gcc-libs-multilib and gcc-multilib in your Arch Linux,
you might cannot $ sudo pacman -Syu because sometimes they will conflict with gcc-libs and gcc in [core] repository.

You have two choices:

1. Don't install gcc and gcc-libs to avoid the conflict, and wait until gcc-multilib and gcc-libs-multilib have new version.
   • Remove them from the list of packaged to install of this packages upgrade.
2. Force remove gcc-multilib and gcc-libs-multilib with $ sudo pacman -Rdd gcc-multilib gcc-libs-multilib.

If you do the latter, and break your pacman, then this blog post may be your salvation.
I just encountered this situation and that's why I wrote down this blog post.

Error Message

pacman: error while loading shared libraries: libstdc++.so.6: cannot open shared object file: No such file or directory

$ ldd $(which pacman)  

...  

libstdc++.so.6 => not found  
libgcc_s.so.1 => not found  

These two share objects are gone which make pacman broken.

Solution

Copy libstdc++.so.6 and libgcc_s.so.1 from other Arch Linux computer with same architecture.

If you have nothing to copy from, I've backed up these two shared objects with x86_64 architecutre below.

(If somehow you cannot download these two files or these doesn't work for you,
you can try the following link in the reference part.
Someone also backed up these two files and uploaded them in the reply of the forum thread.)

1. Download these 2 share objects:
   • libstdc++.so.6
     • sha256sum: 30c1b6ae5936f5f4afdba39f44465efc84422e957db13580e1891f081b615d0e
   • libgcc_s.so.1
     • sha256sum: 95298eef28aca7cef5b28d8388ef0ea3721add9e7c19df74054d7b1c41bcca2e
2. $ sudo mv libstdc++.so.6 libgcc_s.so.1 /usr/lib
3. $ sudo pacman -S --force gcc gcc-libs
   • Make sure you use --force option, or pacman will complain about these two files are conflict.

Reference

• pacman error: libstdc++.so.6 : archlinux