How to Check the Version of my gcc?

Question

In file included from /usr/include/c++/4.8.2/locale:41:0,
                 from /usr/include/c++/4.8.2/iomanip:43,
                 from [...omitted by myself as it is irrelevant]
/usr/include/c++/4.8.2/bits/locale_facets_nonio.h:59:39: error: ‘locale’ has not been declared
     struct __timepunct_cache : public locale::facet

Above is the first error in my build log.

I didn't try to compile glibc/gcc myself, and I installed them via yum.

One fishy thing I found is:

$ ll /usr/include/c++/
total 4
drwxr-xr-x. 12 root root 4096 Dec 17 14:16 4.8.2
lrwxrwxrwx   1 root root    5 Dec 17 14:16 4.8.5 -> 4.8.2
$

And yum showed only 1 version of gcc:

$ yum info gcc-c++
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: centos.uhost.hk
 * epel: mirrors.hustunique.com
 * extras: centos.uhost.hk
 * updates: centos.uhost.hk
Installed Packages
Name        : gcc-c++
Arch        : x86_64
Version     : 4.8.5
Release     : 4.el7
Size        : 16 M
Repo        : installed
From repo   : base
Summary     : C++ support for GCC
URL         : http://gcc.gnu.org
License     : GPLv3+ and GPLv3+ with exceptions and GPLv2+ with exceptions and LGPLv2+ and BSD
Description : This package adds C++ support to the GNU Compiler Collection.
            : It includes support for most of the current C++ specification,
            : including templates and exception handling.

Any idea how to verify the headers in /usr/include/c++/4.8.2 is indeed from 4.8.5 package?

Thanks in advance.

P.S. I think probably glibc is irrelevant but here is the info:

$ ldd --version
ldd (GNU libc) 2.17
Copyright (C) 2012 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.
Written by Roland McGrath and Ulrich Drepper.

Answer 1

The symlink to the 4.8.2 directory is nothing to worry about, it's normal for the libstdc++ headers on Red Hat Enterprise Linux (and therefore CentOS) to be arranged like that.

gcc --version will tell you the version of the gcc executable in your path.

rpm -q libstdc++-devel will tell you the version of the package that owns the C++ standard library headers.

rpm -ql libstdc++-devel will list the files installed by that package, which will include the files under /usr/include/c++/4.8.2

rpm --verify libstdc++-devel will check that you haven't messed up the C++ headers by replacing them with something else.

The error is more concerning, that implies you have messed something up. My guess would be it's in the from [...omitted by myself as it is irrelevant] part, which may actually be very relevant. std::locale should be declared in <bits/locale_classes.h> which is included before <bits/locale_facets_nonio.h>, so if it wasn't declared my guess is that you have some header that defines _LOCALE_CLASSES_H and prevents the standard library header from being read. Do not define include guards that start with underscores, they are reserved names.